Comparison of the right and left ventricle as a systemic ventricle during exercise in patients with congenital heart disease

Comparative Noninvasive Measurement of Cardiac Output Based on the Inert Gas Rebreathing Method (Innocor®) and MRI in Patients with Univentricular Hearts

There are many complex cardiac malformations that are characterized by a functionally univentricular physiology. Staged surgical repair according to the Fontan principle separates the systemic and pulmonary circulations by connecting the systemic venous return to the pulmonary arteries. However, long-term follow-up studies demonstrate a gradual deterioration of cardiac function, particularly from the second or third decade. Noninvasive evaluation of the cardiac function is, therefore, important in the follow-up of these patients. The cardiac index (CI) is a reliable hemodynamic parameter and represents an important marker of cardiac function. We compared CI values determined by cardiac MRI (CMRI) with values obtained by noninvasive inert gas rebreathing (IGR; Innocor® system). Sixteen patients (age range: 7.2-32.7 years) with functionally univentricular hearts (UVH) following total cavopulmonary connection (TCPC) were compared with 12 healthy subjects (age range: 8.5-18.6 years). The standard treadmill protocol of the German Society of Pediatric Cardiology was used for exercise testing. CI was determined at rest and at two standardized submaximal exercise levels. In all subjects, CI increased under exercise conditions, but the values were significantly lower in patients with UVH. There was no significant difference between patients with UVH and predominantly right- or left-ventricular morphology. In comparison with CMRI measurements, the CI values obtained by the IGR method tended to be lower, with a mean difference of 1.02 l/min/m². Noninvasive measurement of CI with the IGR method is feasible at rest and during exercise, and appears to be suited for routine determination of CI in patients with UVH following TCPC.

Heart failure with preserved right ventricular ejection fraction in postoperative adults with congenital heart disease: A subtype of severe right ventricular pathophysiology

BACKGROUND

Right ventricle (RV) may determine heart failure (HF) severity in adults with congenital heart disease (ACHD). However, the association of RV properties with clinical profiles remains unclear.

PURPOSE

To clarify the associations of RV properties with biomarkers, exercise capacity, and unscheduled hospitalization (USH) in postoperative ACHD patients.

METHODS AND RESULTS

We evaluated determinants of RV end-diastolic volume (EDVI, ml/m(2)) and pressure (EDP, mmHg) in 260 patients who were divided into 4 groups, i.e., those with RVEDVI<100 and EDP≥10 (A, n=49, 19%), those with RVEDVI≥100 with EDP≥10 (B, n=22), those with RVEDVI<100 and EDP<10 (C, n=134), and those with RVEDVI≥100 and EDP<10 (D, n=55). EDVI, EDP, and ejection fraction (EF, %) of the RV were independently associated with the corresponding value of the left ventricle (LV) (p<0.0001 for all). Group A had a RV-EF of 53±8 and was defined HF with preserved RV-EF (RV-HFpEF). Younger age, lower platelet count, and elevated plasma γ-glutamyltransferase independently predicted the RV-HFpEF. When the presence of pulmonary hypertension and LV-HFpEF was included in the analysis, these two factors independently predicted the presence of RV-HFpEF (p<0.05-0.001). On multivariate analysis, older age, number of surgeries, cardiac index, and RV systolic pressure independently determined peak oxygen uptake (PVO2, p<0.05) and RV outflow reconstruction independently predicted USH. The RV-HFpEF group showed the lowest PVO2 and highest incidence of USH among the 4 groups (p<0.05).

CONCLUSIONS

Impaired RV characteristics, especially RV-HFpEF, with liver dysfunction and lower platelet count predicted lower exercise capacity with a poorer prognosis in postoperative ACHD patients.

Coronary Arteries in Childhood Heart Disease: Implications for Management of Young Adults

Survival of patients with congenital heart defects has improved dramatically. Many will undergo interventional catheter or surgical procedures later in life. Others will develop atherosclerotic or post-surgical coronary heart disease. The coronary artery anatomy in patients with congenital heart disease differs substantially from that seen in the structurally normal heart. This has implications for diagnostic procedures as well as interventions. The unique epicardial course seen in some defects could impair interpretation of coronary angiograms. Interventional procedures, especially at the base of the heart, risk injuring unusually placed coronary arteries so that coronary artery anatomy must be delineated thoroughly prior to the procedure. In this review, we will describe the variants of coronary artery anatomy and their implications for interventional and surgical treatment and for sudden death during late follow-up in several types of congenital heart defects including: tetralogy of Fallot, truncus arteriosus, transposition of the great arteries, double outlet right ventricle, congenitally corrected transposition of the great arteries and defects with functionally one ventricle. We will also discuss the coronary abnormalities seen in Kawasaki disease.

Right ventricular function with standard and speckle-tracking echocardiography and clinical events in adults with D-transposition of the great arteries post atrial switch

BACKGROUND

The prognostic value of deformation parameters of the systemic right ventricle in adults with D-transposition of the great arteries and prior atrial switch has not been reported.

METHODS

Sixty-four adults with D-transposition of the great arteries and prior atrial switch (mean age, 29 ± 6 years; 22 women; mean right ventricular [RV] fractional area change, 22.9 ± 7.5%; 31 with pacemakers at baseline) and no histories of heart failure or ventricular tachycardia were prospectively evaluated. Global longitudinal strain (GS), global systolic strain rate (GSRs), and global early diastolic strain rate (GSRe) of the right ventricle were measured using speckle tracking from apical views and compared with standard parameters of RV function (fractional area change, tricuspid annular plane systolic excursion, tissue Doppler velocities, and isovolumic acceleration) for association with and potential prediction of clinical events, defined as incident stage C heart failure or ventricular tachycardia.

RESULTS

Baseline RV GS, GSRs, and GSRe were -12.5 ± 3.0%, -0.59 ± 0.14 sec(-1), and 0.68 ± 0.22 sec(-1), respectively. After a median of 2.4 years (interquartile range, 1.5-4.1 years), 12 patients (19%) presented with clinical events (heart failure in 11 patients, ventricular tachycardia in one patient). In Cox models, RV GS had the strongest association with clinical events (hazard ratio [HR] per 1%, 1.35; 95% confidence interval [CI], 1.14-1.58; P < .001), followed by GSRs (HR per 0.01 sec(-1), 1.06; 95% CI, 1.02-1.11; P = .006), GSRe (HR per -0.01 sec(-1), 1.04; 95% CI, 1.00-1.07; P = .031), and fractional area change (HR per -1%, 1.08; 95% CI, 1.00-1.17; P = .047). Other measures of RV function were not significantly associated with risk for events. In receiver operating characteristic analysis, RV GS ≥ -10% optimally predicted future events (C = 0.83; 95% CI, 0.71-0.91; P < .001).

CONCLUSIONS

Reduced longitudinal GS of the systemic right ventricle is associated with increased risk for clinical events among patients with D-transposition of the great arteries and prior atrial switch.

Long-term results of total cavopulmonary connection with low ejection fraction

PURPOSE

The aim of this study was to investigate the surgical outcomes and change in cardiac performance after total cavopulmonary connection (TCPC) in patients with reduced ventricular ejection preoperatively.

METHODS

Among the 195 patients undergoing TCPC between 1990 and 2001 were 52 who had a preoperative ejection fraction of ≤50% (30%-50%, mean 44%). A dominant ventricle was of the morphologically right type in 81% of patients.

RESULTS

A total of 9 of the 52 patients died early. Two patients died in the intermediate term. Postoperative exercise testing showed maximum oxygen uptake of 26.4 ± 5.8 ml/kg/min (anaerobic threshold 18.3 ± 3.2 ml/kg/ min). The cardiac index was 3.1 ± 0.9 l/min/m(2) at 1 year after TCPC, with no fundamental change at 5 years (3.1 ± 0.8 l/min/m(2)). The end-diastolic volume of the dominant ventricle was 130% ± 74% of the anticipated normal value at 1 year and 93% ± 27% at 5 years after TCPC, with ejection fractions of 48% ± 13% and 49% ± 9%, respectively. When these parameters were plotted for the individual patients, the ejection fraction increased during the first postoperative year, with the percent end-diastolic volume decreasing in 31 survivors; the trend appeared atypical in the remaining 12 survivors. Even in these patients, however, the parameters eventually changed toward favorable circumstances 5 years after TCPC.

CONCLUSION

Change in ventricular function was not necessarily pessimistic after TCPC in patients with reduced ventricular contraction preoperatively.

Early and intermediate outcome after anatomic repair of congenitally corrected transposition of the great arteries

BACKGROUND

Anatomic repair of congenitally corrected transposition of the great arteries has become a useful surgical strategy with potential advantages over conventional surgical repair. We describe early and intermediate outcomes after anatomic repair and analyze potential risk factors influencing these outcomes.

METHODS

A retrospective review was performed on all patients undergoing anatomic repair between January 1993 and January 2009. The primary outcome was in-hospital mortality. Variables potentially associated with outcome were identified a priori. Bivariate analyses were performed to determine the association between these variables and all outcome measures.

RESULTS

In 65 patients who underwent anatomic repair, 35 had Senning/arterial switch and 30 had Senning/Rastelli. Early and intermediate survival rates for Senning/arterial switch operations were 94% and 91%, respectively. Repairs were successful in patients with tricuspid regurgitation, left ventricular outflow obstruction, and left ventricular dysfunction. Predictors of outcome were not identified in this subset. Early and intermediate survival rates for Senning/Rastelli operations were 77% and 60%, respectively. Longer aortic cross-clamp (p = 0.03) and cardiopulmonary bypass times (p = 0.01) were associated with mortality. Ventricular septal defect enlargement was associated with surgical heart block (p < 0.01). Age, prior procedures, atrial-apical discordance, and tricuspid regurgitation were not associated with outcome.

CONCLUSIONS

Senning/arterial switch operations can be performed with excellent intermediate-term outcomes in patients with lesions previously thought to confer higher risk. Candidates for Senning/Rastelli procedures may be at increased risk for postoperative morbidity and mortality. More data are necessary to determine factors influencing outcome after anatomic repair.

Mechanisms for cardiac output augmentation in patients with a systemic right ventricle

BACKGROUND

Conflicting data have been published on the differences in cardiac response to exercise between patients with an atrially switched transposition of the great arteries (TGA), and patients with a congenitally corrected TGA (ccTGA). The purpose of our study was to evaluate the differences in cardiac response to exercise in these 2 patient groups with a systemic right ventricle (RV).

METHODS

Thirty four patients (62% male; mean 35, range 21-69 years) with a systemic RV (20 with an atrially switched TGA and 14 with a ccTGA) were included. Exercise tests with Portapres measurements were performed to assess maximal exercise capacity (V'O(2peak)), cardiac index, stroke volume index, and heart rate augmentation. Cardiac function was assessed by Cardiovascular Magnetic Resonance or Computed Tomography, and serum NT-proBNP levels.

RESULTS

We found that both groups were able to significantly augment cardiac index during exercise. Cardiac index augmentation during exercise was positively related to V'O(2peak) (r=0.37, p<0.05), and independent of resting cardiac function. Although the increase in cardiac index during exercise was similar in both patients with TGA and with ccTGA, mechanisms to achieve this increase differed between groups. ccTGA patients increased both stroke volume and heart rate during exercise. Atrially switched TGA patients augmented heart rate during exercise, but failed to increase stroke volume.

CONCLUSION

Mechanisms to achieve cardiac output augmentation differ between ccTGA patients and TGA patients. We suggest that therapeutic approaches should be tailored to the specific patient group to avoid counterproductive effects.

Physiologic versus anatomic repair of congenitally corrected transposition of the great arteries: meta-analysis of individual patient data

The objective of this meta-analysis of individual patients' data was to compare the immediate outcomes of anatomic and physiologic repair of congenitally corrected transposition of the great arteries. Eleven nonrandomized studies, involving 124 patients, met the inclusion criteria for this review. The Rastelli type anatomic repair and the era of surgery were significantly related to the outcome in different tested models. Entering all variables into the logistic regression model showed a significant protective effect of the Rastelli type anatomic repair (odds ratio = 0.05, 95% confidence interval: 0.01, 0.50, p = 0.02).

Physical Activity Patterns of Children After Neonatal Arterial Switch Operation

BACKGROUND

Physical inactivity is a major atherosclerosis risk factor. The exercise tolerance is usually excellent after neonatal arterial switch operation, but those patients in whom coronary anomalies remain the main late complication, risk developing atherosclerotic coronary disease owing to perceived physical activity restrictions.

METHODS

We investigated physical activity patterns of 52 unselected children 7 to 14 years after neonatal arterial switch operation for transposition of the great arteries by 24-hour continuous heart rate monitoring. The percentage of heart rate reserve was used to measure the amounts of activities. Comparisons were made with 35 children with repaired atrial or ventricular septal defect and with 127 age-matched healthy children.

RESULTS

Children after arterial switch operation accumulated 167.3 +/- 70.6, 25.3 +/- 12.9, and 15.7 +/- 11.3 minutes a day (mean +/- SD) of light, moderate, and vigorous physical activities, respectively. At the same activity levels, children with repaired septal defect accumulated 165.2 +/- 82.2, 26.2 +/- 11.7, and 16.2 +/- 9.1 minutes a day, and their healthy peers 164.8 +/- 74.5, 31.8 +/- 13.9, and 21.9 +/- 11.3 minutes a day. Both cardiac groups were significantly less active than the control group when considering moderate (p = 0.026) and vigorous activities (p = 0.006). Only 19% and 27% of the children after arterial switch operation engaged, respectively, in more than 30 minutes a day of moderate activity and 20 minutes a day of vigorous activity.

CONCLUSIONS

Children after arterial switch operation, just like other cardiac children, do not meet the guidelines for physical activity. We should encourage regular physical activity to offset adult sedentary behavior and to prevent atherosclerotic cardiovascular disease in those patients whose long-term function of the coronary arteries remains a matter of concern.

Management of the Failing Systemic Right Ventricle

Conditions in which the right ventricle serves as the systemic pumping chamber are frequently complicated by the development of right ventricular failure and tricuspid valve regurgitation. The right ventricle is the systemic ventricle in conditions of ventriculoarterial discordance with atrioventricular concordance (transposition of the great arteries) or with atrioventricular discordance (congenitally corrected transposition of the great arteries). Concerns regarding actual or potential systemic right ventricular failure in these cases may lead to surgical evaluation and treatment designed to reestablish the left ventricle as the systemic pump. In cases where the left ventricle has prolonged exposure to low pressures in the pulmonary circulation, the left ventricle must be "retrained" to assume a systemic pressure load. Anatomic repair, with or without a preparatory period of left ventricular retraining, is a consideration for three clinically relevant scenarios: (1) patients with transposition of the great arteries after an atrial level switch (Senning or Mustard procedure), (2) patients with congenitally corrected transposition who are unoperated or who have undergone physiologic ("classic") repair, and (3) unoperated patients with transposition who present after the neonatal period.

Is the Chronotropic Index Applicable to Children and Adolescents?

BACKGROUND

The aim of the present study was to investigate whether the chronotropic index (CRI) is independent of age, sex, stage of exercise testing, functional capacity and resting heart rate in children, as it is in adult populations.

METHODS AND RESULTS

A total of 129 normal children and adolescents underwent maximal treadmill exercise testing according to the Bruce protocol. Submaximal chronotropic response was assessed by the CRI at the end of stages 1, 2, 3, and 4 of Bruce treadmill exercise testing. The CRI assessed at each exercise stage was independent of sex, maximal oxygen uptake and resting heart rate. The CRI was independent of age when measured at stages 3 and 4 in boys and at stage 4 in girls, but was weakly correlated with age when measured at stages 1 and 2 in boys and at stages 1, 2 and 3 in girls. There was a significant effect of exercise intensity on the CRI: multiple comparisons revealed that, in girls, CRI assessed at stage 1 was greater than that assessed at stage 4. Also, lower exercise stages resulted in rather large variations in the measurement.

CONCLUSION

The results essentially confirm the potential applicability of the CRI for children and adolescents, although care should be taken in evaluating measurements of the CRI in the early stages of exercise testing to avoid misinterpretation of the results.

Impact of pregnancy on the systemic right ventricle after a Mustard operation for transposition of the great arteries

OBJECTIVES

We sought to determine the impact of pregnancy on the systemic right ventricle (RV) after a Mustard operation for transposition of the great arteries.

BACKGROUND

Dysfunction of the RV remains a continuing problem after a Mustard operation. Concerns exist about the potentially deleterious effects of pregnancy on this ventricle.

METHODS

The records of 16 women who completed 28 pregnancies were reviewed for clinical status, echocardiographic evaluation of RV dimensions, RV function, and tricuspid regurgitation (TR) before, during, and after pregnancy.

RESULTS

Women were in New York Heart Association functional class I (n = 21) and II (n = 7) before pregnancy. The functional class deteriorated in six women, with no return to the pre-pregnancy level after delivery in two. Data on RV dimensions were available in 18 pregnancies, on RV function in 21, and on TR in 20. Before pregnancy, RV dilation was absent (n = 4), mild/moderate (n = 12), or severe (n = 2) and progressed in five women (31%), with no recovery in all patients at the last follow-up. Right ventricular systolic dysfunction was absent (n = 16), mild/moderate (n = 4), or severe (n = 1) before pregnancy and progressed in four women (25%), with no recovery in three cases. Tricuspid regurgitation was absent (n = 8), mild (n = 9), or moderate (n = 3) before pregnancy and deteriorated in eight women (50%), with no recovery in three patients.

CONCLUSIONS

Pregnancy after a Mustard operation is clinically well tolerated but carries a risk of RV dysfunction, which is sometimes irreversible.

Congenitally Corrected Transposition of the Great Arteries: Current Treatment Options

Congenitally corrected transposition of the great arteries is a relatively rare cardiac malformation characterized by atrioventricular and ventriculoarterial discordance. This double discordance results in a physiologically corrected circulation with the morphologic right ventricle (RV) serving as the systemic pump. Associated anomalies are present in approximately 98% of cases and include most commonly ventricular septal defect, pulmonary stenosis, and anomalies of the systemic atrioventricular valve (SAVV). Conduction abnormalities are common as well, predisposing these patients to the development of complete heart block. The management of these patients is primarily determined by the presence and severity of the associated anomalies. Conventional repair, which leaves the morphologic RV as the systemic ventricle, has resulted in high incidence of tricuspid regurgitation (TR) and progressive dysfunction of the RV. In the majority of patients, congestive heart failure secondary to RV dysfunction occurs by the fifth or sixth decade. The cause and effect relationship between TR and RV dysfunction remains to be determined. The advent of the Double Switch operation, which restores the morphologic left ventricle (LV) as the systemic ventricle, has yielded favorable outcomes at early follow-up. This procedure should be applied in young patients to achieve optimal results. Retraining the LV by pulmonary artery banding is associated with high morbidity and mortality when attempted after infancy or early childhood. Long-term follow-up is needed to evaluate the potential superiority of this procedure and the incidence of rhythm, baffle, and conduit complications for this management option.

Combined arterial switch and Senning operation for congenitally corrected transposition of the great arteries: patient selection and intermediate results

OBJECTIVE

Late results after traditional methods of repair of congenitally corrected transposition of the great arteries are poor. The combined arterial switch and Senning (double switch) operation may improve outcomes by using the morphologically left ventricle and mitral valve in the systemic circulation. In this report we review patient selection and intermediate results after the double switch operation for congenitally corrected transposition of the great arteries.

METHODS

Since 1993, a total of 35 patients with congenitally corrected transposition of the great arteries with two ventricles of adequate size and no valvular pulmonary stenosis were potential candidates for a double switch operation. Eleven were not yet in need of further treatment, and 1 died during evaluation. The remaining 23 patients were entered into a protocol leading to anatomic repair. Their hospital records were reviewed, and follow-up data were obtained to evaluate early and intermediate outcomes.

RESULTS

The 23 patients were candidates for anatomic repair because of right ventricular dysfunction or tricuspid regurgitation (n = 15) or associated uncorrected defects (n = 8). Pulmonary artery banding was performed in a total of 15 patients, either for left ventricular retraining (n = 11) or for congestive heart failure (n = 4). In 2 patients, aged 12 and 14 years, retraining was unsuccessful because of left ventricular dysfunction. Four patients with banding are currently awaiting repair. Eight patients proceeded to undergo double switch operations without preliminary pulmonary artery banding. To date, 17 patients have undergone double switch operations, with no early or late mortality. One patient required cardiac transplantation for progressive left ventricular failure after a preliminary banding and double switch operation done at 7 years of age. Ventricular function and tricuspid regurgitation remained stable or improved in all other cases. No patient has surgically acquired arrhythmias or significant residual hemodynamic conditions. All patients are alive and clinically well at a mean follow-up of 36 months (range 1 month-8 years).

CONCLUSIONS

Congenitally corrected transposition of the great arteries with a normal pulmonary valve and two adequate ventricles can be managed with combined arterial switch and Senning operation with excellent intermediate results. Reconditioning the left ventricle may not be suitable for older patients. Late follow-up will be necessary to determine whether this management strategy provides a survival advantage for these patients.

Anatomic correction for corrected transposition after pulmonary unifocalization

A Senning plus Rastelli operation was performed in a patient who had a rare combination of congenitally corrected transposition of the great arteries (S,L,L) with dextrocardia, major aortopulmonary collaterals, and diminutive central pulmonary arteries with arborization defects. The patient required four preparatory operations including bilateral unifocalizations of the aortopulmonary artery collaterals. Pulmonary artery to systemic pressure ratio after the double switch operation was 0.6. The patient demonstrates good biventricular function on echocardiogram at 3 months after the operation.

Influence of ventricular morphology on aerobic exercise capacity in patients after the Fontan operation

OBJECTIVES

This study investigated the influences of ventricular morphology, hemodynamics and clinical findings on exercise capacity in patients after the Fontan operation.

BACKGROUND

Determinants of exercise capacity after the Fontan operation remain unclear.

METHODS

Peak oxygen uptake (PVo2) was determined in 105 patients by exercise test and compared to hemodynamics and clinical findings. Patients were divided into three groups based on ventricular morphology: those with a right ventricle (group RV), a biventricle (group BV) and a left ventricle (group LV).

RESULTS

Ten patients with atrioventricular valve regurgitation (AVVR) or hypoxia exhibited a low PVo2. After excluding these patients, although PVo2 did not correlate with hemodynamics, except ventricular ejection fraction (p < 0.02), it correlated with age at the Fontan operation and exercise test (p < 0.002). The PVo2 was higher in group LV (63+/-9%) than in groups RV (55+/-9%) and BV (55+/-12%) (p < 0.01), while an inverse correlation between PVo2 and age at operation was demonstrated only in group RV (p < 0.05). Groups RV or BV and age at exercise test were associated with a lower PVo2, whereas group LV was an independent predictor of a higher PVo2 (p < 0.01). During 4.2 years of follow-up, a decrease in peak heart rate was related to a decrease in PVo2 (p < 0.05). The PVo2 decreased in group RV (p < 0.01).

CONCLUSIONS

In addition to AVVR, hypoxia, and heart rate response, ventricular morphology is related to exercise capacity. Early Fontan operation may be beneficial in terms of exercise capacity, especially in the group RV patients.

Long-term assessment and serial evaluation of cardiorespiratory exercise performance and cardiac function in patients with atrial switch operation for complete transposition

BACKGROUND

At present, a considerable number of patients survive who underwent an atrial switch operation for correction of complete transposition. Our study aimed to assess their long-term exercise performance and the serial evolution of cardiac function.

METHODS

We studied 22 patients 5 to 17 years after an atrial switch operation, and followed them serially for 3.5 +/- 2 years after the first evaluation. Cardiorespiratory exercise function was assessed by analysis of gas exhange and by determination of the ventilatory anaerobic threshold. Echocardiography was performed on all evaluations.

RESULTS

All patients were in Class I of the classification of the New York Heart Association at all assessments. Ventilatory anaerobic threshold, however, was significantly lower than normal. It averaged 77.9% +/- 13.7 of the normal mean value at the initial evaluation, and remained stable when re-evaluated later (76.2 +/- 13.7%). At the initial study, the increase in oxygen uptake during graded exercise was below the 95% confidence limit in 6 of the patients, and was below this level in 10 patients at re-assessment. The subnormal values for oxygen uptake during submaximal exercise were associated with moderate to severe haemodynamic dysfunction. At echocardiography, 15 of 17 patients studied twice had mild to moderate right ventricular dilation and tricuspidregurgiation, which remained virtually the same at reasssesment. A stable sinus rhythm was initially present in 17 patients, and persisted in 15 patients during follow-up.

CONCLUSION

At medium term follow-up, cardiorespiratory exercise performance remains stable in patients after atrial switch repair. Serial exercise testing appears useful, because in individual patients in the present study, a decreasing exercise tolerance correlated with development of haemodynamic sequels.