Rachel M. Wald

Effects of Regional Dysfunction and Late Gadolinium Enhancement on Global Right Ventricular Function and Exercise Capacity in Patients With Repaired Tetralogy of Fallot

Background— The underlying mechanisms that contribute to global right ventricular (RV) dysfunction in patients with repaired tetralogy of Fallot are incompletely understood. We therefore sought to quantify regional RV abnormalities and to determine the relationship of these to global RV function and exercise capacity. Methods and Results— Clinical and cardiac magnetic resonance data from 62 consecutive patients with repaired tetralogy of Fallot were analyzed (median age at follow-up 23 years [limits 9 to 67 years]). Using cardiac magnetic resonance data, 3D RV endocardial surface models were reconstructed from segmented contours, and a correspondence between end diastole and end systole was computed with a novel algorithm. Regional RV abnormalities were quantified and expressed as segmental ejection fraction, spatial extent of dyskinetic area, displacement of dyskinetic area, and score of extent of late gadolinium enhancement. Regional abnormalities of function and hyperenhancement were greatest in the RV outflow tract (RVOT). These regional RVOT abnormalities correlated with global RV ejection fraction: RVOT ejection fraction r=0.64, P<0.0001; RVOT dyskinetic area r=−0.51, P<0.0001; RVOT displacement of dyskinetic area r=−0.49, P<0.0001; and RVOT late gadolinium enhancement score r=−0.33, P=0.01. Peak oxygen consumption during exercise correlated best with RVOT ejection fraction (r=0.56, P=0.0002) compared with the remainder of the RV (r=0.35, P=0.03). The only cardiac magnetic resonance variable independently predictive of aerobic capacity was RVOT ejection fraction (P=0.02). Conclusion— A greater extent of regional abnormalities in the RVOT adversely affects global RV function and exercise capacity after tetralogy of Fallot repair. These regional measures may have important implications for patient management, including RVOT reconstruction, at the time of pulmonary valve replacement.

B-Type Natriuretic Peptide in Pregnant Women With Heart Disease

OBJECTIVES The objectives of this study were to examine: 1) B-type natriuretic peptide (BNP) response to pregnancy in women with heart disease; and 2) the relationship between BNP levels and adverse maternal cardiac events during pregnancy. BACKGROUND Pregnancy imposes a hemodynamic stress on the heart. BNP might be a useful biomarker to assess the ability of the heart to adapt to the hemodynamic load of pregnancy. METHODS This was a prospective study of women with structural heart disease seen at our center. Serial clinical data and plasma BNP measurements were obtained during the first trimester, third trimester, and after delivery (>6 weeks). RESULTS Seventy-eight pregnant women were studied; 66 women with heart disease (age 31 ± 5 years), and 12 healthy women (age 33 ± 5 years). During pregnancy, the median peak BNP level was higher in women with heart disease compared with control subjects (median 79, interquartile range 51 to 152 pg/ml vs. median 35, interquartile range 21 to 43 pg/ml, p < 0.001). In women with heart disease, those with subaortic ventricular dysfunction had higher BNP levels (p = 0.03). A BNP >100 pg/ml was measured in all women with events during pregnancy (n = 8). Sixteen women had increased BNP levels during pregnancy but did not have clinical events. None of the women with BNP ≤100 pg/ml had events. BNP ≤100 pg/ml had a negative predictive value of 100% for identifying events during pregnancy. CONCLUSIONS Many pregnant women with heart disease have increased BNP levels during pregnancy. Incorporating serial BNP levels in into clinical practice can be helpful, specifically in adjudicating suspected adverse cardiac events during pregnancy.

Refining the assessment of pulmonary regurgitation in adults after tetralogy of Fallot repair: should we be measuring regurgitant fraction or regurgitant volume?

AIMS Pulmonary regurgitation (PR) is an important determinant of outcome after tetralogy of Fallot (TOF) repair. The physiologic impact of PR on the right ventricle remains incompletely understood. We hypothesized that a volumetric expression of PR would be a better measure of ventricular preload and a more accurate reflection of degree of insufficiency. METHODS AND RESULTS Patients (n = 64) with magnetic resonance imaging after TOF repair were identified. PR was quantified using: (i) phase contrast (PC) analysis of main pulmonary artery flow and (ii) differential right and left ventricular stroke volumes. PR was expressed as a volume (PR(volume)) and percentage of total forward flow (PR(fraction)). The median PC(PR volume) was 19 mL/m(2) (range 0-63 mL/m(2)) and PC(PR fraction) was 29% (range 0-58%). PR(fraction) was found to be highly variable in terms of absolute PR(volume). In those with significant PR, PR(volume) was better than PR(fraction) for the identification of severe RV dilation (receiver-operator curve area: 0.83 vs. 0.71, P = 0.003). PR(volume) using PC analysis was better at differentiating moderate from severe RV dilation (P = 0.005) as compared with PR(fraction) (P = 0.064). CONCLUSION PR(volume) and PR(fraction) are not interchangeable. PR(volume) may be a more accurate reflection of RV preload and may better represent physiologically significant PR as compared with PR(fraction).

Cardiac outcomes after pregnancy in women with congenital heart disease

Objective Women with congenital heart disease (CHD) are at risk for adverse cardiac events during pregnancy; however, the risk of events late after pregnancy (late cardiac events; LCE) has not been well studied. A study was undertaken to examine the frequency and determinants of LCE in a large cohort of women with CHD. Design Baseline characteristics and pregnancy were prospectively recorded. LCE (>6 months after delivery) were determined by chart review. Survival analysis was used to determine the risk factors for LCE. Setting A tertiary care referral hospital. Patients The outcomes of 405 pregnancies were studied (318 women; median follow-up 2.6 years). Main outcome measures LCE included cardiac death/arrest, pulmonary oedema, arrhythmia or stroke. Results LCE occurred after 12% (50/405) of pregnancies. The 5-year rate of LCE was higher in women with adverse cardiac events during pregnancy than in those without (27±9% vs 15±3%, HR 2.2, p=0.02). Women at highest risk for LCE were those with functional limitations/cyanosis (HR 3.9, 95% CI 1.2 to 13.0), subaortic ventricular dysfunction (HR 3.0, 95% CI 1.4 to 6.6), subpulmonary ventricular dysfunction and/or significant pulmonary regurgitation (HR 3.2, 95% CI 1.6 to 6.6), left heart obstruction (HR 2.6, 95% CI 1.2 to 5.2) and cardiac events before or during pregnancy (HR 2.6, 95% CI 1.3 to 4.9). In women with 0, 1 or >1 risk predictors the 5-year rate of LCE was 7±2%, 23±5% and 44±10%, respectively (p<0.001). Conclusions In women with CHD, pre-pregnancy maternal characteristics can help to identify women at increased risk for LCE. Adverse cardiac events during pregnancy are important and are associated with an increased risk of LCE.

Cardiac Magnetic Resonance Imaging and the Assessment of Ebstein Anomaly in Adults

No published studies have evaluated the role of cardiac magnetic resonance (CMR) imaging for the assessment of Ebstein anomaly. Our objective was to evaluate the right heart characteristics in adults with unrepaired Ebstein anomaly using contemporary CMR imaging techniques. Consecutive patients with unrepaired Ebstein anomaly and complete CMR studies from 2004 to 2009 were identified (n = 32). Volumetric measurements were obtained from the short-axis and axial views, including assessment of the functional right ventricular (RV) end-diastolic volume (EDV) and end-systolic volume. The volume of the atrialized portion of the right ventricle in end-diastole was calculated as the difference between the total RVEDV and the functional RVEDV. The reproducibility of the measurements in the axial and short-axis views was determined within and between observers. The median value derived from the short-axis and axial views was 136 ml/m(2) (range 59 to 347) and 136 ml/m(2) (range 63 to 342) for the functional RVEDV, 153 ml/m(2) (range 64 to 441) and 154 ml/m(2) (range 67 to 436) for the total RVEDV, 49% (range 32% to 46%) and 50% (range 40% to 64%) for the functional RV ejection fraction, respectively. The axial measurements demonstrated lower intraobserver and interobserver variability than the short-axis approach for all values, with the exception of the intraobserver functional RVEDV and interobserver total RVEDV for which the limits of agreement and variance were not significantly different between the 2 views. In conclusion, measurements of right heart size and systolic function in patients with Ebstein anomaly can be reliably achieved using CMR imaging. Axial imaging appeared to provide more reproducible data than that obtained from the short-axis views.

Pregnancy Outcomes in Women With Transposition of the Great Arteries and Arterial Switch Operation

There is a growing population of young women of child-bearing age with complete transposition of the great arteries (TGA) who have had an arterial switch operation (ASO). Pregnancy imposes a hemodynamic stress on the heart and, therefore, adverse cardiac events can occur during this period; however, pregnancy outcomes in this population have not been well studied. We sought to describe cardiac outcomes during pregnancy in women with TGA who had undergone an ASO in childhood. Women were identified from 2 large tertiary care hospitals. A retrospective chart review was performed to determine the prevalence of adverse maternal cardiac events during pregnancy. Overall, 74 women of child-bearing age were identified, 9 of whom had 17 pregnancies. There were 4 miscarriages. Six women (67%) had clinically important valve (n = 5) and ventricular (n = 1) lesions before the index pregnancy. Two women developed cardiac complications during pregnancy; 1 woman with impaired left ventricular systolic function had nonsustained ventricular tachycardia and 1 woman with a mechanical systemic atrioventricular valve developed postpartum valve thrombosis. There were no maternal deaths. In conclusion, young women with TGA from this early cohort repaired with ASO are reaching child-bearing age. A significant proportion have residua and/or sequelae that can confer risk for adverse cardiac events in pregnancy. Co-ordinated care between a congenital heart disease specialist and a high-risk obstetrician should be implemented.

The left heart after pulmonary valve replacement in adults late after tetralogy of Fallot repair.

BACKGROUND Adverse ventricular-ventricular interactions have been recognized in those with repaired tetralogy of Fallot (TOF) and severe pulmonary regurgitation. OBJECTIVE We aimed to examine the impact of pulmonary valve replacement (PVR) on the left heart late after TOF repair. METHODS AND RESULTS Left ventricular (LV) volumes and ejection fractions (EF) were analyzed in adults with severe pulmonary regurgitation after TOF repair with cardiac magnetic resonance imaging (CMR) before and after PVR. Thirty-nine patients (median age 33[20-65] years) were reviewed. Post-PVR, LVEF improved significantly in the entire cohort (50 ± 9%→54 ± 7%, p<0.001) and in those with moderately impaired (defined as LVEF ≤ 45%) preoperative LVEF (38 ± 5%→47 ± 6%, p<0.0001), but was not statistically different in those with relatively preserved (defined as LVEF >45%) preoperative LVEF. By multivariate linear regression analysis to evaluate independent CMR predictors of improved LVEF post-PVR for the entire cohort, the only CMR variable to emerge was preoperative LVEF (p=0.012, regression coefficient -0.54, SE 0.13). Whereas PVR resulted in increased LV filling in patients with relatively preserved preoperative LVEF reflected by an increase in LV end-diastolic volumes (77 ± 10→82 ± 16 mL/m(2), p=0.05), LV end-systolic volumes decreased after PVR in patients with impaired preoperative LVEF (65 ± 12→54 ± 10 mL/m(2), p=0.001) but LV end-diastolic volumes were not significantly changed. CONCLUSION When LVEF is decreased after TOF repair, PVR appears to have a salutary effect on postoperative LVEF, thereby supporting the concept of recovery of adverse right-left heart interactions. Mechanisms of left heart improvement post-PVR differ depending on degree of preoperative LV systolic dysfunction.

Cardiac magnetic resonance markers of progressive RV dilation and dysfunction after tetralogy of Fallot repair

Objective Patients with repaired tetralogy of Fallot (TOF) are followed serially by cardiac magnetic resonance (CMR) for surveillance of RV dilation and dysfunction. We sought to define the prevalence of progressive RV disease and the optimal time interval between CMR evaluations. Methods Candidates were selected from a multicentre TOF registry and were included if ≥2 CMR studies performed ≥6 months apart were available without interval cardiovascular interventions. Patients with ‘disease progression’ (defined as increase in RV end-diastolic volume index (RVEDVi) ≥30 mL/m2, decrease in RVEF ≥10% or decrease in LVEF ≥10%) were compared with those with ‘disease non-progression’ (defined as RVEDVi increase ≤5 mL/m2, RVEF decrease ≤3% and LVEF decrease ≤3%). Results A total of 849 CMR studies in 339 patients (median age at first CMR 23.6 years) were analysed. Over a median interval of 2.2 years between CMR pairs, RVEDVi increased 4±18 mL/m2 (p<0.001), RV end-systolic volume index increased 3±13 mL/m2 (p<0.001), RVEF decreased 1%±6% (p=0.02) and LVEF decreased 1%±6% (p=0.001). Disease progression was observed in 15% (n=76) and non-progression in 26% (n=133). There were no significant differences between those with and without progression in baseline demographic, anatomic, ECG, exercise or baseline CMR characteristics. The optimal time interval between CMR studies for detection of progression was a 3-year interval (63% sensitivity, 65% specificity, area under the receiver operating characteristic curve 0.65). Conclusions Although progressive RV dilation and decline in biventricular systolic function occur at a slow pace in the majority of adults with repaired TOF, 15% of patients experience rapid disease progression. The results of this study support the practice of serial CMR examinations to identify progressive disease at a time interval of up to 3 years.

Right heart characteristics and exercise parameters in adults with Ebstein anomaly: New perspectives from cardiac magnetic resonance imaging studies

BACKGROUND The utility of cardiac magnetic resonance imaging (CMR) for assessment of adults with Ebstein anomaly is not well-defined. We sought to evaluate CMR characteristics in this population and to relate these to exercise parameters. METHODS We analyzed CMR studies in adults with unrepaired Ebstein anomaly for measures of severity of Ebstein disease, including atrialized, functional and total right ventricular (RV) volumes, ejection fraction (EF) and severity index (area of atrialized RV+right atrium/functional RV+left ventricle+left atrium). We related these CMR values to cardiopulmonary exercise test measurements. RESULTS Twenty-seven adults (mean age 41 ± 14 years, 70% female) were included. Functional RV end-diastolic volume (EDV) was 150 ± 68 mL/m(2) and atrialized RVEDV was 25 ± 24 mL/m(2). In 17 patients (63%), the functional RVEDV was enlarged (>114 mL/m(2)). Percent predicted peak VO2 for the population was 65 ± 20%. On univariable analysis, peak VO2 was inversely related to atrialized RVEDV (p = 0.011), total RVEDV (p = 0.041), functional RVEDV/left ventricular EDV ratio (p = 0.015) and magnitude of tricuspid valve displacement (p = 0.031). In the multivariate model, the only CMR factor to relate to peak VO2 was atrialized RVEDV (p = 0.011, β = -0.48). No significant correlations were found between CMR measures and heart rate response or ventilatory response to exercise. CONCLUSION In adults with unrepaired Ebstein anomaly, atrialized RV volume was independently related to aerobic capacity. The volume of the atrialized RV is a novel CMR measure which may express severity of disease. Further research is needed to evaluate the prognostic relevance of this exploratory work.

Pulmonary Valve Replacement in Adults With Repaired Tetralogy of Fallot

There is a growing population of young adults with tetralogy of Fallot. Although surgical approaches have evolved, many adults with repaired tetralogy of Fallot have been left with residual pulmonary regurgitation. Pulmonary regurgitation is an important contributor to a number of late complications including exercise limitations, right heart failure, arrhythmia, and sudden death. Because bioprosthetic valves are used in this population, clinicians must weigh the beneficial effects of pulmonary valve replacement against the associated risks, including subsequent re-operation. In this review, we will appraise the evidence supporting pulmonary valve replacement in the adult with repaired tetralogy of Fallot, as well as the optimal timing and mode of intervention.