Bio

Clinical Focus


  • Cardiology (Heart), Pediatric
  • Pediatric Cardiology

Academic Appointments


Administrative Appointments


  • Director of Ecocardiography, Lucile Packard Children's Hospital Heart Center (2008 - Present)

Professional Education


  • Fellowship:CS Mott Children's Hospital (1993) MI
  • Board Certification: Pediatric Cardiology, American Board of Pediatrics (1994)
  • Residency:University of Chicago Hospitals (1990) IL
  • Medical Education:University of Texas (1987) TX
  • BS, Loyola University of the South, Biology (1983)
  • Pediatric Cardiology, University of Michigan, Pediatric Cardiology (1993)
  • Pediatrics, University of Chicago Hospitals, Pediatrics (1990)
  • MD, UTMB, Medicine (1987)

Teaching

2016-17 Courses


Stanford Advisees


Publications

All Publications


  • Echocardiographic measures associated with early postsurgical myocardial dysfunction in pediatric patients with mitral valve regurgitation. Journal of the American Society of Echocardiography Arunamata, A., Selamet Tierney, E. S., Tacy, T. A., Punn, R. 2015; 28 (3): 284-293

    Abstract

    The assessment of left ventricular (LV) systolic function using conventional echocardiographic measures is problematic in the setting of mitral regurgitation (MR) given that altered loading conditions can mask underlying ventricular dysfunction. The purpose of this study was to characterize LV function and deformation before and after effective mitral valve repair or replacement to determine echocardiographic measures associated with early postoperative myocardial dysfunction.Baseline LV function was assessed retrospectively by conventional echocardiography and speckle-tracking strain analysis pre- and postoperatively in patients diagnosed with MR between January 2000 and March 2013, excluding patients with less than mild to moderate MR preoperatively, left-sided obstructive lesions, large septal defects, or more than mild MR postoperatively.Forty-six pediatric patients were evaluated (average age, 8.2 ± 6.4 years). Thirteen patients had normal preoperative ejection fractions but significant postoperative dysfunction (defined as an ejection fraction < 50%). Compared with the 33 patients with normal postoperative function, age (11.5 ± 7.1 vs 7.3 ± 5.7 years, P = .04), global circumferential strain (-13.2 ± 5.6% vs -17.1 ± 4.6%, P = .02), and global circumferential strain rate (-0.94 ± 0.40 vs -1.36 ± 0.42 sec(-1), P = .004) were found to be statistically different. Using receiver operating characteristic curves, an older preoperative age (area under the curve, 0.67; P = .03), lower global circumferential strain magnitude (area under the curve, 0.74; P = .007), and lower global circumferential strain rate magnitude (area under the curve, 0.80; P = .0004) were determined to be factors associated with early postoperative LV dysfunction after surgical repair of MR.Strain measurements may be useful as part of the echocardiographic assessment of patients with MR and can guide timing for surgical repair in the pediatric population.

    View details for DOI 10.1016/j.echo.2014.11.010

    View details for PubMedID 25555521

  • A novel approach to the management of critically ill neonatal Ebstein's anomaly: Veno-venous extracorporeal membrane oxygenation to promote right ventricular recovery. Annals of pediatric cardiology Bauser-Heaton, H., Nguyen, C., Tacy, T., Axelrod, D. 2015; 8 (1): 67-70

    Abstract

    This is the first report of the use of veno-venous extracorporeal membrane oxygenation in a neonate with severe Ebstein's anomaly. The report suggests the use of veno-venous extracorporeal membrane oxygenation in the immediate neonatal period may be a useful therapy in severe Ebstein's anomaly. By providing adequate oxygenation independent of the patient's native pulmonary blood flow, veno-venous extracorporeal membrane oxygenation allows the pulmonary vascular resistance to decrease and may promote right ventricular recovery.

    View details for DOI 10.4103/0974-2069.149527

    View details for PubMedID 25684893

  • Predictors of Mortality in Pediatric Patients on Venoarterial Extracorporeal Membrane Oxygenation PEDIATRIC CRITICAL CARE MEDICINE Punn, R., Axelrod, D. M., Sherman-Levine, S., Roth, S. J., Tacy, T. A. 2014; 15 (9): 870-877

    Abstract

    Currently, there are no established echocardiographic or hemodynamic predictors of mortality after weaning venoarterial extracorporeal membrane oxygenation in children. We wished to determine which measurements predict mortality.Over 3 years, we prospectively assessed six echo and six hemodynamic variables at 3-5 circuit rates while weaning extracorporeal membrane oxygenation flow. Hemodynamic measurements were heart rate, inotropic score, arteriovenous oxygen difference, pulse pressure, oxygenation index, and lactate. Echo variables included shortening/ejection fraction, outflow tract Doppler-derived stroke distance (velocity-time integral), degree of atrioventricular valve regurgitation, longitudinal strain (global longitudinal strain), and circumferential strain (global circumferential strain).Cardiovascular ICU at Lucille Packard Children's Hospital Stanford, CA.Patients were stratified into those who died or required heart transplant (Gr1) and those who did not (Gr2). For each patient, we compared the change for each variable between full versus minimum extracorporeal membrane oxygenation flow for each group.None.We enrolled 21 patients ranging in age from 0.02 to 15 years. Five had dilated cardiomyopathy, and 16 had structural heart disease with severe ventricular dysfunction. Thirteen of 21 patients (62%) comprised Gr1, including two patients with heart transplants. Eight patients constituted Gr2. Gr1 patients had a significantly greater increase in oxygenation index (35% mean increase; p < 0.01) off extracorporeal membrane oxygenation compared to full flow, but no change in velocity-time integral or arteriovenous oxygen difference. In Gr2, velocity-time integral increased (31% mean increase; p < 0.01), with no change in arteriovenous oxygen difference or oxygenation index. Pulse pressure increased modestly with flow reduction only in Gr1 (p < 0.01).Failure to augment velocity-time integral or an increase in oxygenation index during the extracorporeal membrane oxygenation weaning is associated with poor outcomes in children. We propose that these measurements should be performed during extracorporeal membrane oxygenation wean, as they may discriminate who will require alternative methods of circulatory support for survival.

    View details for DOI 10.1097/PCC.0000000000000236

    View details for Web of Science ID 000346400100015

  • Fetal MRI correlates with postnatal CT angiogram assessment of pulmonary anatomy in tetralogy of Fallot with absent pulmonary valve. Congenital heart disease Sun, H. Y., Boe, J., Rubesova, E., Barth, R. A., Tacy, T. A. 2014; 9 (4): E105-9

    Abstract

    In tetralogy of Fallot with absent pulmonary valve, pulmonary stenosis and regurgitation results in significant pulmonary artery dilatation. Branch pulmonary artery dilatation often compresses the tracheobronchial tree, causing fluid trapping in fetal life and air trapping and/or atelectasis after birth. Prenatal diagnosis predicts poor prognosis, which depends on the degree of respiratory insufficiency from airway compromise and lung parenchymal disease after birth. Fetal magnetic resonance imaging (MRI) has been useful in evaluating the effects of congenital lung lesions on lung development and indicating severity of pulmonary hypoplasia. This report is the first demonstrating the utility of fetal MRI in tetralogy of Fallot/absent pulmonary valve patients, which predicted postnatal pulmonary artery size and visualized airway compression and lung parenchymal lesions. The distribution of lobar fluid trapping on fetal MRI correlated with air trapping on postnatal computed tomography angiogram.

    View details for DOI 10.1111/chd.12091

    View details for PubMedID 23701739

  • Fetal MRI Correlates with Postnatal CT Angiogram Assessment of Pulmonary Anatomy in Tetralogy of Fallot with Absent Pulmonary Valve CONGENITAL HEART DISEASE Sun, H. Y., Boe, J., Rubesova, E., Barth, R. A., Tacy, T. A. 2014; 9 (4): E105-E109

    View details for DOI 10.1111/chd.12091

    View details for Web of Science ID 000340525400001

  • Echocardiographic Predictors of Early Postsurgical Myocardial Dysfunction in Pediatric Patients With Aortic Valve Insufficiency PEDIATRIC CARDIOLOGY Lowenthal, A., Tacy, T. A., Behzadian, F., Punn, R. 2013; 34 (6): 1335-1343

    Abstract

    In chronic aortic insufficiency (AI), left-ventricular (LV) dysfunction must be detected early to allow timely surgery. Strain and strain rate have been used for this purpose in adults, but the value of this method in pediatric AI has not been established. Forty patients with moderate to severe AI were included in this retrospective study. LV function was assessed by strain analysis and conventional echocardiography both before and after surgery. Of the 32 patients with preserved preoperative ejection fraction (EF; >50 %), 8 had postoperative dysfunction (<50 %). Mean conventional indices of global LV systolic performance for the entire cohort of patients with AI were predominantly in the normal range before surgery. Preoperative values for LV global longitudinal strain (GLS) and strain rate (GLSr) were normal. After surgery, there was a significant decrease in shortening and EF. There was a significant decrease from preoperative to postoperative values for both GLS (-16.07 ± 3.82 vs. -11.06 ± 3.88; p < 0.0001) and GLSr (-0.89 ± 0.24 vs. -0.72 ± 0.27; p = 0.0021). A preoperative GLS of -15.3  (AUC = 0.83, CI = 0.69-0.98, p < 0.0001) and a GLSr of -0.79/s (AUC = 0.86, CI = 0.73-0.98, p < 0.0001) were determined to be predictors of early postoperative dysfunction after surgical repair of moderate to severe AI. A preoperative GLS value of ≤-15.3  and GLSr value of -0.79/s or less are predictors of postoperative ventricular dysfunction, which is defined by EF <50 %. GLS and GLSr value determination may be useful as part of the echocardiographic assessment AI and may help determine the optimal timing of surgery in pediatric patient with at least moderate AI.

    View details for DOI 10.1007/s00246-013-0646-z

    View details for Web of Science ID 000321919400006

  • Tricuspid Atresia With Progressive Ductal Restriction in a Fetus PEDIATRIC CARDIOLOGY Lowenthal, A., Lal, A., Tierney, E. S., Tacy, T. A. 2013; 34 (6): 1499-1501
  • Tricuspid atresia with progressive ductal restriction in a fetus. Pediatric cardiology Lowenthal, A., Lal, A., Selamet Tierney, E. S., Tacy, T. A. 2013; 34 (6): 1499-1501

    Abstract

    We report a unique case of tricuspid and pulmonary atresia with idiopathic progressive ductus arteriosus restriction in utero. Diligent predelivery planning and a controlled delivery environment led to a favorable outcome.

    View details for DOI 10.1007/s00246-012-0391-8

    View details for PubMedID 22729970

  • Decremental Left Ventricular Deformation after Pulmonary Artery Band Training and Subsequent Repair in Ventriculoarterial Discordance JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Sun, H. Y., Behzadian, F., Punn, R., Tacy, T. A. 2013; 26 (7): 765-774

    Abstract

    BACKGROUND: Patients with ventriculoarterial discordance, such as congenitally corrected and d-transposition of the great arteries, may undergo a morphologic left ventricular (LV) training strategy consisting of surgical pulmonary artery band (PAB) placement and subsequent anatomic repair to establish ventriculoarterial concordance. The purpose of this study was to characterize morphologic LV function and deformation longitudinally using speckle-tracking strain analysis in patients with ventriculoarterial discordance who underwent LV training. METHODS: Twenty-nine patients (12 with d-transposition of the great arteries and 17 with congenitally corrected transposition of the great arteries) who underwent LV training with PAB placement were evaluated retrospectively. LV ejection fraction and global and regional longitudinal strain and strain rate were measured before and 7 ± 5 days after PAB placement and subsequent anatomic repair. RESULTS: PAB placement caused reductions in the mean LV ejection fraction from 76.1 ± 10.2% to 66.7 ± 7.8% (P < .001), in mean global strain from -17.7 ± 9% to -13.3 ± 7.5% (P = .01), and in mean lateral wall strain from -23.3 ± 12.8% to -17.5 ± 10.3% (P = .01). After anatomic repair (a median of 21 months after PAB placement; range, 0.5-104 months), mean LV ejection fraction decreased further from 63.3 ± 8.6% to 52.4 ± 14.9% (P < .05). Mean global strain declined from -17.6% ± 4.4 to -12.6 ± 4% (P = .01), and mean lateral wall strain decreased from -18.2 ± 11.4% to -12.6 ± 5.3% (P = .04). CONCLUSIONS: In patients with ventriculoarterial discordance undergoing PAB placement for LV training and anatomic repair, the morphologic left ventricle demonstrated decremental systolic function and global longitudinal deformation acutely. Frequent functional assessment is warranted to understand long-term myocardial mechanics in these patients.

    View details for DOI 10.1016/j.echo.2013.03.017

    View details for Web of Science ID 000321051000011

  • Expanding the Phenotype of Cardiovascular Malformations in Adams-Oliver Syndrome AMERICAN JOURNAL OF MEDICAL GENETICS PART A Algaze, C., Esplin, E. D., Lowenthal, A., Hudgins, L., Tacy, T. A., Tierney, E. S. 2013; 161A (6): 1386-1389

    Abstract

    We describe a newborn with a phenotype consistent with Adams-Oliver syndrome and truncus arteriosus. Although cardiovascular malformations associated with this syndrome have been previously published in the literature, this is the first description of truncus arteriosus in a patient with Adams-Oliver syndrome. We review other reports of Adams-Oliver syndrome previously described with cardiovascular malformations, consider possible genetic and embryologic mechanisms, and emphasize the need for cardiology consultation when a diagnosis of Adams-Oliver syndrome is suspected in the differential diagnosis. © 2013 Wiley Periodicals, Inc.

    View details for DOI 10.1002/ajmg.a.35864

    View details for Web of Science ID 000320649700021

    View details for PubMedID 23613382

  • Congenital heart defects in a large, unselected cohort of monochorionic twins JOURNAL OF PERINATOLOGY Pettit, K. E., Merchant, M., Machin, G. A., Tacy, T. A., Norton, M. E. 2013; 33 (6): 457-461

    Abstract

    To determine the prevalence of congenital heart defects (CHDs) in a large, unselected cohort of monochorionic (MC) twins.We completed a chart review of all MC twin pregnancies in the Kaiser Permanente Northern California population from 1996 to 2003. CHDs were identified by diagnostic codes and confirmed by postnatal echocardiograms. Follow-up was obtained through one year of age.A total of 926 liveborn MC twins met inclusion criteria. The prevalence of CHDs was 7.5%, 11.6 times the general population rate (CI 9.2 to 14.5). Septal defects were most common. 20% of infants with heart defects had twin-to-twin transfusion syndrome (TTTS) versus 8% of infants without defects (P<0.01); this association remained significant when controlling for potential confounders.The prevalence of CHDs in this large cohort of MC twins was significantly higher than the general population rate, with TTTS an added risk factor.

    View details for DOI 10.1038/jp.2012.145

    View details for Web of Science ID 000319657300008

    View details for PubMedID 23223160

  • Myocardial Deformation in the Fetal Single Ventricle JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Truong, U. T., Sun, H. Y., Tacy, T. A. 2013; 26 (1): 57-63

    Abstract

    In postnatal life, patients with single ventricle (SV) with morphologic right ventricles have a worse prognosis than those with morphologic left ventricles. The aim of this study was to test the hypotheses that (1) the SV in fetuses with SV has decreased longitudinal strain compared with fetuses with normal cardiac anatomy, and (2) fetuses with SV right ventricular (RV) morphology have decreased strain compared with those with SV left ventricular (LV) morphology.Fetal echocardiograms with SV RV and SV LV morphology were retrospectively compiled. Postprocessing analysis of the dominant ventricle was done using syngo Velocity Vector Imaging version 2.0. Peak global longitudinal strain (GLS) and global longitudinal strain rate (GL SR) were generated. Both the right and left ventricles were analyzed in fetuses with normal cardiac anatomy for comparison.Fifty-four fetuses with SV (18 with LV morphology and 36 with RV morphology) were included in the study and compared with 54 controls matched for gestational age. Global longitudinal strain and GL SR were compared between fetuses with SV and normal fetuses and among SV subsets. When all four categories were compared (normal left ventricle, normal right ventricle, SV left ventricle, and SV right ventricle), there was no difference in GLS (P = .49) or in GL SR (P = .32) between any of the categories.Comparable GLS and GL SR values between fetal SV of LV or RV morphology, as well as normal fetal left and right ventricles, reflect in utero preservation of systolic function of the SV heart.

    View details for DOI 10.1016/j.echo.2012.10.007

    View details for Web of Science ID 000313012600010

    View details for PubMedID 23140844

  • Diagnosis of Tetralogy of Fallot and Its Variants in the Late First and Early Second Trimester: Details of Initial Assessment and Comparison with Later Fetal Diagnosis ECHOCARDIOGRAPHY-A JOURNAL OF CARDIOVASCULAR ULTRASOUND AND ALLIED TECHNIQUES Bhat, A. H., Kehl, D. W., Tacy, T. A., Moon-Grady, A. J., Hornberger, L. K. 2013; 30 (1): 81-87

    Abstract

    We sought to evaluate the completeness of echocardiographic diagnosis of fetal tetralogy of Fallot (fTOF) at 12-17 weeks gestation, and compare assessment and clinical outcomes to diagnoses made at >17 weeks gestation.We identified all fTOF diagnoses made in our experience from 2003 to 2008. Referral indication, anatomic detail by echocardiography and pregnancy outcomes were compared between fetuses diagnosed at ? 17 weeks (Group I) and >17 weeks gestation (Group II). A 10-point scoring tool was applied retrospectively to the echocardiograms at initial diagnosis (1 point each was ascribed to visualization of right ventricular outflow obstruction, pulmonary valve, pulmonary arteries including dimensions, pulmonary arterial flow, systemic and pulmonary venous anatomy, atrioventricular valves, ductus arteriosus, ductus flow, aortic arch morphology, sidedness and flow).There were 10 pregnancies in Group I (12-17 weeks) and 25 in Group II (mean gestation at diagnosis 23.5 ± 5.7). The most common reason for referral was extracardiac pathology in Group I (80%) and suspected fetal heart disease on obstetric ultrasound in Group II (64%). Transabdominal imaging was adequate in about half of Group I studies. Mean anatomic diagnosis score in Group I was 6.1(range 2.5-9) and Group II was 8.4 (range 6.5-10). Elective pregnancy termination occurred in 80% in Group I and 33% in Group II.fTOF can be diagnosed in first and early second trimesters with detailed anatomic assessment possible in most. Referral indication and pregnancy outcome differ considerably between early and later prenatal diagnosis of fTOF.

    View details for DOI 10.1111/j.1540-8175.2012.01798.x

    View details for Web of Science ID 000314919400021

    View details for PubMedID 22963380

  • Tissue Doppler-Derived Measurement of Isovolumic Myocardial Contraction in the Pediatric Population PEDIATRIC CARDIOLOGY Punn, R., Behzadian, F., Tacy, T. A. 2012; 33 (5): 720-727

    Abstract

    Multiple echocardiographic techniques have been utilized to quantify systolic function. The shortening and ejection fraction remain the most commonly used and accepted methods. However, these measures are affected by altered loading conditions, and are not applicable when ventricular geometry differs from the prolate ellipsoid typical of a left ventricle. Mitral valve annular acceleration during isovolumic contraction (IVA) has been proposed as a load independent index of left ventricular contractility. However, published values for IVA demonstrating normal function vary. In addition, the value of IVA which may discern impaired systolic function has not been established. The purpose of this study is to determine a threshold IVA value for abnormal left ventricular function in the pediatric population. Structurally/functionally normal control (n = 90) and dilated cardiomyopathy (study = 64) patients were compared for differences in left ventricular: wall stress (WS), velocity of circumferential fiber shortening (VCFc), ejection fraction (EF), ejection force, and pulsed wave-derived medial and lateral wall IVA. No difference in body surface area (p = 0.61) or gender (p = 0.53) was noted. Left ventricular ejection fraction, ejection force, VCFc, and IVA were significantly lower and WS was significantly higher in the study group (p < 0.01). The medial IVA was 1.71 ± 0.89 m/s(2) for an EF <40%, 1.74 ± 0.70 m/s(2) for an EF = 40-50%, 2.46 ± 0.89 m/s(2) for an EF >50%. The lateral IVA was 1.81 ± 1.03 m/s(2) for an EF <40%, 2.07 ± 0.78 m/s(2) for an EF = 40-50%, 2.54 ± 0.99 m/s(2) for an EF >50%. ROC analysis demonstrated a medial IVA of 1.97 m/s(2) as the cut-off for predicting an EF <50% with a 77% sensitivity of and specificity of 66% (AUC = 0.75, CI = 0.67-0.83, p < 0.01). ROC analysis demonstrated a lateral IVA of 2.31 m/s(2) as the cut-off for predicting an EF <50% with a 73% sensitivity of and specificity of 63% (AUC = 0.72, CI = 0.63-0.82, p < 0.01). IVA lateral of 1.93 m/s(2) or less was associated with heart transplant and death. ICC analysis demonstrated some interobserver variability in IVA measurement (0.57-0.65). The normal IVA of the medial and lateral mitral valve annulus measure over 1.97 m/s(2) and 2.31 m/s(2), respectively; values less than this cut-off are associated with EF <50%. Despite some problems with reproducibility IVA remains a promising method of screening for diminished ventricular contractility in the setting of abnormal geometry.

    View details for DOI 10.1007/s00246-012-0200-4

    View details for Web of Science ID 000304458900006

    View details for PubMedID 22349669

  • Surgical Results in Patients With Pulmonary Atresia-Major Aortopulmonary Collaterals in Association With Total Anomalous Pulmonary Venous Connection ANNALS OF THORACIC SURGERY Mainwaring, R. D., Reddy, M., Reinhartz, O., Punn, R., Tacy, T., Hanley, F. L. 2011; 92 (5): 1756-1760

    Abstract

    Pulmonary atresia and major aortopulmonary collaterals (PA/MAPCAs) is a complex form of congenital heart disease. One to two percent of patients with PA/MAPCAs will also have total anomalous pulmonary venous connection (TAPVC). This study summarizes our surgical experience with this rare combination of life-threatening congenital heart defects.A retrospective review was performed to identify patients who had surgery for PA/MAPCAs in association with TAPVC. From November 2001 to March 2011, 9 patients presented with this combination of defects. Eight of the 9 patients had heterotaxy with an unbalanced atrioventricular canal and functional single ventricle. The ninth patient had double outlet right ventricle (two ventricles). Timing of surgical intervention was typically predicated on the degree of pulmonary venous obstruction. The median age at surgery was 14 days. All nine patients had surgical correction of TAPVC, unifocalization of MAPCA's into a central confluence, and placement of a shunt.There was one early mortality (< 30 days) and two late mortalities. For the 6 survivors, 5 have subsequently undergone a bidirectional Glenn procedure, and 3 had completion of their Fontan. Two patients are currently at the bidirectional Glenn stage; one is a good candidate for Fontan completion while the other is not suitable. The sixth patient is awaiting further assessment.The PA/MAPCAs, in association with TAPVC, is a challenging combination of defects. The data suggest that the combination of PA/MAPCAs and TAPVC can be undertaken with a reasonable midterm prognosis.

    View details for DOI 10.1016/j.athoracsur.2011.06.020

    View details for Web of Science ID 000296925400045

    View details for PubMedID 21944736

  • Annular Tilt as a Screening Test for Right Ventricular Enlargement in Patients with Tetralogy of Fallot JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Punn, R., Behzadian, F., Tacy, T. A. 2010; 23 (12): 1297-1302

    Abstract

    Right ventricular end-diastolic volume (RVEDV) greater than 150 mL/m² is a risk factor for sudden death in patients with tetralogy of Fallot (TOF) after repair. Because of its anterior placement and abnormal geometry, two-dimensional echocardiography is limited to a qualitative assessment of RVEDV. Cardiac magnetic resonance imaging (CMRI) and computed tomography angiography (CTA) are the accepted standards for quantifying RVEDV. This study evaluated the ability of a novel echocardiographic measure, the right ventricular annular tilt (RVAT), to identify patients with increased RVEDV.All patients with repaired TOF with an echocardiogram and CMRI or CTA were included in this retrospective study. The RVAT was determined by measuring the angle of the tricuspid valve plane relative to the mitral valve plane at end-diastole in the apical 4-chamber view in study (n = 38) and age-matched control (n = 74) patients. The RVEDV measurements were obtained by CMRI (n = 32) or CTA (n = 6). The study and control patients' ages were no different (11.3 and 11.8 years, P = .73).The study group RVAT was significantly higher than the control group RVAT (17.4 vs. 0.1 degrees; P < .0001). RVAT values greater than 20 degrees had a mean RVEDV of 166 ± 60 mL/m², whereas RVAT less than 20 degrees had a mean RVEDV of 122 ± 25 mL/m² (P = .0370). Receiver operating characteristic analysis demonstrated an RVAT of 17.9 degrees as the cutoff for predicting a RVEDV of greater than 150 mL/m² with a sensitivity of 75% and specificity of 73% (area under the curve = 0.76; confidence interval, 0.56-0.96; P = .0063). Intraclass correlation analysis demonstrated minimal interobserver and intraobserver variability when measuring RVAT (0.99 and 0.92).An RVAT less than 20 degrees is associated with an RVEDV less than 150 mL/m². RVAT is a useful echocardiographic technique for detecting increased RVEDV in patients with TOF and may help discern which patients should undergo RVEDV quantification by CMRI or CTA.

    View details for DOI 10.1016/j.echo.2010.09.002

    View details for Web of Science ID 000284624900012

    View details for PubMedID 20950999

  • Newborn with Persistent Truncus Arteriosus and Interrupted Aortic Arch Demonstrating Reverse Left Subclavian Artery Flow PEDIATRIC CARDIOLOGY Chan, E. L., Tacy, T. A., Punn, R. 2010; 31 (8): 1254-1256

    View details for DOI 10.1007/s00246-010-9817-3

    View details for Web of Science ID 000284157400025

    View details for PubMedID 20957476

  • Peripheral Arterial Function in Infants and Young Children With One-Ventricle Physiology and Hypoxemia AMERICAN JOURNAL OF CARDIOLOGY Natarajan, S., Heiss, C., Yeghiazarians, Y., Fineman, J. R., Teitel, D. F., Tacy, T. A. 2009; 103 (6): 862-866

    Abstract

    Patients with 1-ventricle (1V) physiology may be at risk for peripheral arterial dysfunction at a young age. To determine whether infants and young children with 1V physiology and hypoxemia have peripheral arterial dysfunction before undergoing the Fontan operation, we measured (1) flow-mediated vasodilation (FMD) in the brachial artery, (2) serum levels of vasoactive mediators endothelin-1 (ET-1) and metabolites of nitric oxide, and (3) arterial stiffness with pulse-wave velocity (PWV) in the aorta. Eighteen patients with 1V physiology before the Fontan procedure and hypoxemia and 19 patients with normoxemia and 2-ventricle (2V) physiology were studied. Measurements were collected during cardiac catheterization. FMD in the brachial artery was the diameter gain after 4.5 minutes of forearm occlusion measured with high-resolution ultrasound and edge-detection software. Nitric oxide and ET-1 levels were measured in venous blood. PWV between the left carotid and femoral arteries was measured using pulse Doppler ultrasound. FMD was lower (2.4 +/- 3.7% vs 11.3 +/- 6%, p <0.0005) and ET-1 levels were higher (35.5 +/- 11.3% vs 24.1 +/- 9.7%, p = 0.003) in subjects with 1V physiology versus those with 2V physiology, respectively. There were no differences in nitric oxide levels or PWV. In conclusion, infants and young children with 1V physiology and hypoxemia have blunted FMD and higher ET-1 levels before undergoing the Fontan operation compared with normoxemic subjects with 2V physiology. A further understanding of pathophysiologic mechanisms underlying peripheral arterial dysfunction, including the roles of hypoxemia, low cardiac index, and ET-1, may lead to targeted therapies and improve the long-term survival of patients with 1V physiology.

    View details for DOI 10.1016/j.amjcard.2008.11.059

    View details for Web of Science ID 000264514100020

    View details for PubMedID 19268746

  • Non-invasive estimation of pressure gradients in regurgitant jets: an overdue consideration EUROPEAN JOURNAL OF ECHOCARDIOGRAPHY Giardini, A., Tacy, T. A. 2008; 9 (5): 578-584

    Abstract

    This investigation sought to discern the relative accuracy of Doppler predictions of pressure drops in regurgitant jets across a broad spectrum of conditions, using an in vitro pulsatile flow model.We studied the accuracy of Doppler pressure gradients derived from regurgitant jet peak velocities using the simplified Bernoulli equation (SBE) using an in vitro flow model of atrio-ventricular valve regurgitation. We observed overall a good correlation (r = 0.89, P < 0.0001) with actual pressure gradient, when there is normal fluid viscosity and the jet is free of wall interaction. However, we observed various degrees of underestimation of pressure gradient by Doppler when regurgitant chamber size was reduced (P = 0.0003), when fluid viscosity was increased (P < 0.0001), or in the presence of wall interaction (P < 0.0001). Chamber compliance had no effect on the accuracy of pressure gradient prediction (P = 0.36). Significant underestimation error in pressure gradient prediction by Doppler of up to 43.2% was observed.When jet impingement or wall interaction are present, or when viscosity is increased, caution should be used in applying the SBE to a regurgitant jet, as significant underestimation in pressure gradient prediction may occur.

    View details for DOI 10.1093/ejechocard/jen156

    View details for Web of Science ID 000259408700002

    View details for PubMedID 18490278

  • Color M-mode propagation velocity, but not its ratio to early diastolic inflow velocity, changes throughout gestation in normal human fetuses ULTRASOUND IN OBSTETRICS & GYNECOLOGY Moon-Grady, A. J., Taylor, D., Bennett, S. H., Hornberger, L. K., Tacy, T. A. 2008; 31 (5): 535-541

    Abstract

    Color M-mode propagation velocity (Vp) is a measure of diastolic function in adults and, when combined with early diastolic inflow velocity (E), the ratio E/Vp reflects ventricular filling pressure. Early detection of diastolic compromise may benefit fetal patients at risk for developing heart failure. The objectives of this study were to measure values for Vp and inflow peak E in a group of normal fetuses, to analyze age-dependent alterations in these measurements, and to evaluate the interobserver and intraobserver variability of the measurements.Thirty-two normal fetuses at between 20 and 35 weeks' gestation underwent echocardiography. Color M-mode Vp was measured from the four-chamber view for the right (RV) and left (LV) ventricles, and mitral and tricuspid inflow velocities were determined by pulsed-wave Doppler ultrasound. The values obtained were compared with previously reported findings in adults.Adequate tracings were obtainable in 23 patients for the RV and 29 for the LV. Mean Vp values for the RV (15.3 +/- 3.2 cm/s) and LV (20.8 +/- 5.6 cm/s) were lower than normal adult values, and Vp values were significantly lower for the RV than the LV (P < 0.001). Applying Bazett's heart rate correction, values for RV (23.4 +/- 4.8 cm/s) and LV (31.9 +/- 8.7 cm/s) remained lower than normal adult values. There was a linear correlation of Vp with gestational age for the RV (R = 0.69, P < 0.001), and the ratio of E/Vp corrected for heart rate for the RV (1.51 +/- 0.26) remained constant throughout gestation. Interobserver bias was high but intraobserver bias low, at 19 and 1.1%, respectively.Vp is lower in fetal than in adult life. Vp for the RV changes in a manner indicative of improving diastolic function throughout normal gestation, providing insight into the alterations in diastolic function with gestation that contribute to increases in cardiac output. The use of Vp to assess diastolic function disturbance in fetuses is feasible, but high interobserver variability is problematic.

    View details for DOI 10.1002/uog.5303

    View details for Web of Science ID 000256107900010

    View details for PubMedID 18409181

  • Highlights of the 18th annual scientific sessions of the American Society of Echocardiography Seattle, Washington, June 16-20, 2007. Lang, R. M., Coon, P. D., Gardin, J. M., Spencer, K. T., Tacy, T. A., Vannan, M. A., Weissman, N. J., Zoghbi, W. A., Picard, M. H. 2007: 2415-2420

    View details for PubMedID 18154968

  • Usefulness of cardiopulmonary exercise to predict long-term prognosis in adults with repaired tetralogy of Fallot AMERICAN JOURNAL OF CARDIOLOGY Giardini, A., Specchia, S., Tacy, T. A., Coutsoumbas, G., Gargiulo, G., Donti, A., Formigari, R., Bonvicini, M., Picchio, F. M. 2007; 99 (10): 1462-1467

    Abstract

    Adults with tetralogy of Fallot (TOF) have increased long-term mortality. The identification of patients at greater risk for death or cardiac-related morbidity is challenging. This study was conducted to assess the prognostic value of cardiopulmonary exercise testing in adults with repaired TOF. One hundred eighteen consecutive adults with repaired TOF (mean age at repair 4.8 +/- 4.2 years) underwent cardiopulmonary exercise testing at a mean age of 24 +/- 8 years (range 16 to 59). The degree of pulmonary regurgitation, right ventricular function, and right ventricular systolic pressure were determined by transthoracic echocardiography. After the exercise tests, patients were regularly followed up for cardiac-related events. During a mean follow-up of 5.8 +/- 2.3 years (range 0.6 to 9.7), 9 patients died and 18 underwent hospitalization. Peak oxygen uptake (hazard ratio 0.974, 95% confidence interval 0.950 to 0.994), the slope of ventilation (VE) per unit of carbon dioxide production (VCO(2)) (hazard ratio 1.076, 95% confidence interval 1.038 to 1.115), and New York Heart Association functional class (hazard ratio 2.118, 95% confidence interval 1.344 to 3.542) were independent predictors of death or hospitalization. Patients with peak oxygen uptake < or =36% of predicted value and those with VE/VCO(2) slopes >39 were at greater risk for cardiac-related death (5-year mortality 48% vs 0%, p <0.0001, and 31% vs 0%, p <0.0001, respectively). In conclusion, the measurement of peak oxygen uptake and VE/VCO(2) slope in adults with repaired TOF can be prognostically important and could become a powerful tool to rationalize decisions regarding the prevention of premature sudden death and the need for reintervention.

    View details for DOI 10.1016/j.amjcard.2006.12.076

    View details for Web of Science ID 000246715900024

    View details for PubMedID 17493481

  • Reliability of two-dimensional echocardiography in the assessment of clinically significant abnormal hemidiaphragm motion in pediatric cardiothoracic patients: Comparison with fluoroscopy PEDIATRIC CRITICAL CARE MEDICINE Miller, S. G., Brook, M. M., Tacy, T. A. 2006; 7 (5): 441-444

    Abstract

    To assess the utility and reliability of echocardiographic assessment of hemidiaphragm motion abnormalities in pediatric cardiothoracic patients.Retrospective observational study, with post hoc blinded assessment of echocardiographic and fluoroscopic results.Tertiary care center.Thirty-six consecutive pediatric cardiothoracic patients with suspected hemidiaphragm paralysis were identified and included in the study.None.The results of both echocardiographic and fluoroscopic studies on all patients were included. In addition, blinded review of study results were performed. The sensitivity and specificity of fluoroscopy in identifying hemidiaphragms that needed plication were 100% and 74%, respectively. The positive predictive value was 55%; negative predictive value was 100%. Comparing reported diagnoses with blinded review of the studies showed poor agreement; reviewers agreed with 89% diagnosed as normal, 44% of paralyzed, and 76% of paradoxical hemidiaphragms. The sensitivity and specificity of echo in identifying hemidiaphragms that needed plication were 100% and 81%, respectively. The positive predictive value and negative predictive value were 66% and 100%. Comparing reported diagnoses with blinded review, reviewers agreed with 97% diagnosed as normal, 81% of paralyzed, and 100% of paradoxical hemidiaphragms. Echocardiography was less accurate in discriminating between paralyzed and paradoxical diaphragm motion. Echocardiography was specific for paradoxical motion, since both patients identified by echocardiography were confirmed by fluoroscopy, but it was not sensitive. In nine patients, echo showed paralyzed motion that was identified by fluoroscopy as paradoxical.This study supports the use of echocardiography in the assessment of diaphragm function. When the diaphragms are clearly visualized by echo, as they are in the majority of cases, the addition of an additional fluoroscopic study adds no clinical value. The differentiation between paralyzed and paradoxical motion is unreliable by both imaging modalities.

    View details for DOI 10.1097/01.PCC.0000227593.63141.36

    View details for Web of Science ID 000241390500005

    View details for PubMedID 16738495

  • Combined treatment with a nonselective nitric oxide synthase inhibitor (L-NMMA) and indomethacin increases ductus constriction in extremely premature newborns PEDIATRIC RESEARCH Keller, R. L., Tacy, T. A., Fields, S., Ofenstein, J. P., Aranda, J. V., Clyman, R. I. 2005; 58 (6): 1216-1221

    Abstract

    Studies in premature animals suggest that 1) prolonged tight constriction of the ductus arteriosus is necessary for permanent anatomic closure and 2) endogenous nitric oxide (NO) and prostaglandins both play a role in ductus patency. We hypothesized that combination therapy with an NO synthase (NOS) inhibitor [N(G)-monomethyl-L-arginine (L-NMMA)] and indomethacin would produce tighter ductus constriction than indomethacin alone. Therefore, we conducted a phase I and II study of combined treatment with indomethacin and L-NMMA in newborns born at <28 weeks' gestation who had persistent ductus flow by Doppler after an initial three-dose prophylactic indomethacin course (0.2, 0.1, 0.1 mg/kg/24 h). Twelve infants were treated with the combined treatment protocol [three additional indomethacin doses (0.1 mg/kg/24 h) plus a 72-hour L-NMMA infusion]. Thirty-eight newborns received three additional indomethacin doses (without L-NMMA) and served as a comparison group. Ninety-two percent (11/12) of the combined treatment group had tight ductus constriction with elimination of Doppler flow. In contrast, only 42% (16/38) of the comparison group had a similar degree of constriction. L-NMMA infusions were limited in dose and duration by acute side effects. Doses of 10-20 mg/kg/h increased serum creatinine and systemic blood pressure. At 5 mg/kg/h, serum creatinine was stable but systemic hypertension still limited L-NMMA dose. We conclude that combined inhibition of NO and prostaglandin synthesis increased the degree of ductus constriction in newborns born at <28 weeks' gestation. However, the combined administration of L-NMMA and indomethacin was limited by acute side effects in this treatment protocol.

    View details for DOI 10.1203/01.pdr.0000183659.20335.12

    View details for Web of Science ID 000233416500014

    View details for PubMedID 16306196

  • Effect of chamber capacitance on Doppler flow pattern across restrictive defects in obligatory atrial-level shunts JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Giardini, A., Schmitt, B., Azakie, A., Tacy, T. A. 2004; 17 (12): 1286-1291

    Abstract

    The right atrium has a significantly higher capacitance than the left atrium, and this may affect the Doppler flow pattern across an atrial septal defect (ASD) in unilateral atrioventricular (AV) valve atresia. This Doppler flow pattern is often used to assess ASD adequacy in this setting. We studied the effect of atrial capacitance and ASD size on the trans-ASD Doppler flow pattern in an in vivo flow model of alternate left or right AV valve atresia (LAVVA and RAVVA). We assessed trans-ASD Doppler flow patterns using the max/min velocity ratio and mean interatrial pressure gradients (PGs). In both models, ASD flow rate correlated with mean trans-ASD PG, but for similar flow rates the slope was higher in the LAVVA model. In LAVVA, a persistent PG was consistently observed, with low max/min ratio (median, 1.46; range, 1.03-3.13), whereas in RAVVA, phasic flow was common (median, 8.0; range, 2.8-20). Because atrial capacitance affects mean PG and Doppler flow pattern across the ASD, we propose that the assessment of ASD adequacy in RAVVA should not rely on Doppler findings.

    View details for DOI 10.1016/j.echo.2004.07.015

    View details for Web of Science ID 000225590900012

    View details for PubMedID 15562268

  • Gender differences in pediatric cardiac surgery: The cardiologist's perspective JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Miller-Hance, W. C., Tacy, T. A. 2004; 128 (1): 7-10

    View details for DOI 10.1016/j.jctvs.2004.04.008

    View details for Web of Science ID 000222406100003

    View details for PubMedID 15224013

  • Accuracy of coronary artery anatomy using two-dimensional echocardiography in d-transposition of great arteries using a two-reviewer method JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Gremmels, D. B., Tacy, T. A., Brook, M. M., Silverman, N. H. 2004; 17 (5): 454-460

    Abstract

    We evaluated echocardiographic accuracy for defining coronary artery course in d-transposition of great arteries and the impact of a 2-reviewer method on this accuracy. The echocardiogram reports of 108 patients with d-transposition of great arteries were reviewed for coronary anatomy and compared with the operative report. In method 1, from January 1995 to December 1997, a single reader performed the echocardiogram. In method 2, from January 1998 to December 2000, 2 readers scanned individually and a consensus diagnosis was made. Comparing methods 1 and 2, the sensitivity of the echocardiogram to detect variants in coronary anatomy was 68% versus 86%, and negative predictive value was 72% versus 91%. Using a 2-reviewer method improved the accuracy of echocardiographic diagnosis of coronary anatomy with d-transposition of great arteries, aiding in risk assessment and treatment of the patient preoperatively. This study also illustrates that echocardiographic accuracy may be lower in an institution with a surgical volume more representative of the usual pediatric cardiothoracic surgical center.

    View details for DOI 10.1016/j.echo.2004.02.001

    View details for Web of Science ID 000221253300011

    View details for PubMedID 15122186

  • Value of clinical and echocardiographic features in predicting outcome in the fetus, infant, and child with tetralogy of Fallot with absent pulmonary valve complex AMERICAN JOURNAL OF CARDIOLOGY Moon-Grady, A. J., Tacy, T. A., Brook, M. M., Hanley, F. L., Silverman, N. H. 2002; 89 (11): 1280-1285

    Abstract

    We describe clinical and echocardiographic features of tetralogy of Fallot with absent pulmonary valve complex (TOF/APVC) and hypothesized that outcome might be related to pulmonary artery enlargement or severity of illness. We examined the clinical records of all 23 patients evaluated at our institution before death or surgical correction of TOF/APVC between 1990 and 2000. Echocardiograms for 16 patients (including 5 fetuses) were also reviewed, and measurements of the semilunar valves and pulmonary arteries were obtained and compared with patient's aortic annulus size and with established normal subjects. Actuarial survival was 15 of 23 patients (68%) at 4 years. Four fetuses were hydropic and none survived; 7 patients were ventilator dependent at operation and only 3 survived. No difference was noted in pulmonary artery diameters in survivors versus nonsurvivors. Pulmonary valve annulus size was larger in nonsurvivors (103 +/- 25% vs 71 +/- 24% of normal, p = 0.03); however, when fetal examinations were excluded, this difference did not persist. Thus, only hydrops and ventilator dependence at diagnosis predicted mortality. There was no correlation between postnatal measurements of pulmonary arteries and outcome. Larger pulmonary annulus size in hydropic fetuses and poor survival among patients diagnosed in utero suggests that the pathophysiology in TOF/APVC is not due entirely to the aneurysmal dilation of the pulmonary arteries but may be related to right-sided cardiac dysfunction.

    View details for Web of Science ID 000175985300008

    View details for PubMedID 12031728

  • Systemic venous abnormalities: Embryologic and echocardiographic considerations ECHOCARDIOGRAPHY-A JOURNAL OF CARDIOVASCULAR ULTRASOUND AND ALLIED TECHNIQUES Tacy, T. A., Silverman, N. H. 2001; 18 (5): 401-413

    Abstract

    The echocardiographic diagnosis of systemic venous anomalies often is rendered difficult by the variety of lesions that exist. An understanding of the embryologic processes that result in these lesions is essential for accurate identification, since these lesions often are not obvious on routine echocardiographic examination. Standard echocardiographic views may demonstrate some lesions, whereas many require modified views to outline the abnormal systemic venous anatomy. This paper reviews the basic embryologic processes of the development of the normal and abnormal systemic venous system, as well as the echocardiographic identification of these major systemic venous malformations.

    View details for Web of Science ID 000170305600009

    View details for PubMedID 11466154

  • Late thrombosis of the native aortic root after Norwood reconstruction for hypoplastic left heart syndrome JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Brennan, T. V., Rodefeld, M. D., Tacy, T. A., Reddy, V. M., Hanley, F. L. 2001; 121 (3): 580-582

    View details for Web of Science ID 000167721100024

    View details for PubMedID 11241094

  • Radiofrequency ablation of human fetal sacrococcygeal teratoma AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY Paek, B. W., Jennings, R. W., Harrison, M. R., Filly, R. A., Tacy, T. A., Farmer, D. L., Albanese, C. T. 2001; 184 (3): 503-507

    Abstract

    Fetuses with solid, highly vascularized sacrococcygeal teratomas can die as a result of the vascular steal syndrome. This is the first report in which a percutaneous technique, radiofrequency ablation, was used to interrupt blood flow to a sacrococcygeal teratoma in 4 human fetuses.A radiofrequency ablation probe was percutaneously inserted into the fetal tumor under ultrasonographic guidance. In 2 fetuses a significant portion of the tumor mass was ablated, whereas in the other 2 fetuses only the major feeding vessels were targeted.Two infants were delivered at 28 and 31 weeks' gestation, respectively, and are doing well. In 2 other cases hemorrhage into the tumor led to an unfavorable fetal outcome.Ablation of a majority of the tumor tissue in sacrococcygeal teratoma is not necessary and proved fatal in two instances. Targeted ablation of the feeding tumor vessels diminishes blood flow sufficiently to reverse high-output fetal heart failure.

    View details for Web of Science ID 000167306100041

    View details for PubMedID 11228510

  • Rapid enlargement of neoaortic root after the Ross procedure in children AMERICAN JOURNAL OF CARDIOLOGY PUNTEL, R. A., Webber, S. A., Ettedgui, J. A., Tacy, T. A. 1999; 84 (6): 747-?

    Abstract

    Serial echocardiographic studies from 11 patients who underwent the Ross procedure were reviewed, and the rate of neoaortic annulus size increase was compared with that in a normal population. The rate of growth of the neoaortic annulus after the Ross procedure was significantly greater than that in the normal population.

    View details for Web of Science ID 000082536100025

    View details for PubMedID 10498152

  • Effect of aortic compliance on Doppler diastolic flow pattern in coarctation of the aorta JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Tacy, T. A., Baba, K., Cape, E. G. 1999; 12 (8): 636-642

    Abstract

    The spectral Doppler pattern at the site of an aortic coarctation (CoA) generally displays increased maximal velocity (Vmax) during systole with a slow velocity decay, resulting in the characteristic "sawtooth" pattern. If there is rapid velocity decay, the obstruction is often judged to be mild. The purpose of this study was to investigate if velocity decay is affected by proximal aortic compliance (C(p)). The relation between the velocity decay measured from the Doppler pattern and C(p) was studied with the use of an in vitro pulsatile flow model. The time (tau) between Vmax and 33% Vmax was the measure of velocity decay. The C(p) was varied from 0.7 to 2.6 mL/mm Hg for each of 4 levels of CoA severity. The various obstructions produced a Vmax range of 2.7 to 5.5 m/s. There was a positive linear relation between tau and C(p) (r(2) = 0.76). For a low C(p) (compliance = 0.7 mL/mm Hg), velocity decay was rapid (tau = 0.2 to 0.3 seconds) with no diastolic gradient. For equivalent obstructions, a high C(p) (2.6 mL/mm Hg) produced a persistent diastolic gradient and slow velocity decay (tau = 0.5 to 0.6 seconds). The Doppler pattern across a CoA is affected by C(p). Therefore, the absence of a sawtooth pattern should not exclude the diagnosis of significant CoA obstruction.

    View details for Web of Science ID 000082007600005

    View details for PubMedID 10441219

  • In vitro Doppler assessment of pressure gradients across modified Blalock-Taussig shunts AMERICAN JOURNAL OF CARDIOLOGY Tacy, T. A., Whitehead, K. K., Cape, E. G. 1998; 81 (10): 1219-?

    Abstract

    The relation between flow velocity and the pressure decrease is evaluated in Blalock-Taussig shunts used in congenital heart surgery and is related to the flow conditions and geometries of the shunts studied. The authors propose that the flow conditions within the shunt as well as shunt dimensions need to be taken into account when using Doppler velocimetry to predict pressure drops across these shunts.

    View details for Web of Science ID 000073622900013

    View details for PubMedID 9604952

  • In vitro analysis of regurgitant fraction using Doppler power-weighted sum of velocities JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Tacy, T. A., Snider, A. R., Vermilion, R. P. 1998; 11 (3): 266-273

    Abstract

    The power-weighted sum of velocities (PWS) is the sum of each velocity component of the Doppler signal multiplied by its power. The purpose of this study was to determine (1) whether PWS is linearly related to volume flow and (2) whether PWS can predict the regurgitant fraction in an in vitro pulsatile flow system simulating aortic regurgitation. Doppler analysis of aortic flow was performed with an intact valve and two regurgitant valves. For each valve a linear relation between the forward flow PWS and forward flow volume was demonstrated, with excellent correlation (r = 0.99). For the valves with regurgitant orifices, the values for the PWS-derived regurgitant fraction were compared with measured regurgitant fraction. A fair correlation was demonstrated (r = 0.59), with low accuracy in prediction (error 44% +/- 24%). The PWS was inaccurate in predicting flow ratios in our in vitro system despite the strong relation with forward flow volume. The error incurred may be due to effects of filters that remove low velocity and low amplitude information.

    View details for Web of Science ID 000072803200007

    View details for PubMedID 9560750

  • USE OF BACKSCATTERED DOPPLER SIGNAL INTENSITY IN ESTIMATION OF VOLUME FLOW RATIOS JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Tacy, T. A., Cape, E. G. 1995; 25 (6): 1474-1475

    View details for Web of Science ID A1995QV74200044

    View details for PubMedID 7722154

  • RANGE OF NORMAL VALVE ANNULUS SIZE IN NEONATES AMERICAN JOURNAL OF CARDIOLOGY Tacy, T. A., Vermilion, R. P., Ludomirsky, A. 1995; 75 (7): 541-543

    View details for Web of Science ID A1995QH85500031

    View details for PubMedID 7864012

  • PALLIATIVE ARTERIAL REPAIR FOR TRANSPOSITION, VENTRICULAR SEPTAL-DEFECT, AND PULMONARY VASCULAR-DISEASE ANNALS OF THORACIC SURGERY PRIDJIAN, A. K., Tacy, T. A., Teske, D., Bove, E. L. 1992; 54 (2): 355-356

    Abstract

    Failure to repair transposition of the great arteries and ventricular septal defect in the young infant results in the early development of pulmonary vascular occlusive disease. Complete repair, preferably by an arterial switch procedure and ventricular septal defect closure, may then not be possible. We report a palliative arterial switch procedure in a 5 1/2-year-old patient with transposition, ventricular septal defect, and severe pulmonary vascular obstructive disease in whom progressive hypoxemia and exercise intolerance developed. An arterial repair without ventricular septal defect closure was performed. After the operation, the child's systemic arterial oxygen saturation and exercise tolerance have substantially improved. Although the progression of pulmonary vascular disease may not be altered, arterial repair can provide effective palliation in this subset of patients.

    View details for Web of Science ID A1992JF48600032

    View details for PubMedID 1379034