Haemodynamic effects of exercise in isolated pulmonary stenosis before and after surgery

A prospective 5-year study of exercise performance following Melody valve implant

BACKGROUND

The long-term benefits of Melody valve implant for right ventricular outflow tract conduit obstruction or insufficiency on exercise capacity are undefined.

METHODS

As part of the Melody valve clinical trial, 136 patients with congenital heart disease underwent serial cardiopulmonary exercise testing prior to, 6 months after, and annually for up to 5 years postimplant.

RESULTS

Mean age at Melody valve implantation was 22.4 ± 0.9 years (range 7-53 years). The 95 patients who completed the study protocol provide the basis of this report. An initial improvement in % predicted workload was present at 6 months postimplant; however, at the final (5 year) follow-up, sustained or further improvements in workload were not demonstrated for the entire cohort compared to baseline. By subgroup analysis, age <17 years at implant and pulmonary regurgitation as the primary lesion were variables associated with sustained improvement in exercise performance. There were sustained improvements in the ventilatory equivalents for O₂ (minute ventilation/O₂ intake, P = .01) and CO₂ (minute ventilation/CO₂ output, P < .01) at the ventilatory anaerobic threshold at the study conclusion. Improvements in forced vital capacity were also observed during the study but not sustained at the final follow-up.

CONCLUSIONS

A cautious appraisal of the cardiovascular benefits of Melody valve implant on sustained improvements in exercise performance appears warranted. Although the observed changes in pulmonary function suggest improved restrictive lung physiology and more efficient gas exchange, after an initial increase in % predicted performance, neither sustained nor further improvements in exercise performance were observed, except in specific patient subgroups.

Pulmonic Valve Disease: Review of Pathology and Current Treatment Options

PURPOSE OF REVIEW

Our review is intended to provide readers with an overview of disease processes involving the pulmonic valve, highlighting recent outcome studies and guideline-based recommendations; with focus on the two most common interventions for treating pulmonic valve disease, balloon pulmonary valvuloplasty and pulmonic valve replacement.

RECENT FINDINGS

The main long-term sequelae of balloon pulmonary valvuloplasty, the gold standard treatment for pulmonic stenosis, remain pulmonic regurgitation and valvular restenosis. The balloon:annulus ratio is a major contributor to both, with high ratios resulting in greater degrees of regurgitation, and small ratios increasing risk for restenosis. Recent studies suggest that a ratio of approximately 1.2 may provide the most optimal results. Pulmonic valve replacement is currently the procedure of choice for patients with severe pulmonic regurgitation and hemodynamic sequelae or symptoms, yet it remains uncertain how it impacts long-term survival. Transcatheter pulmonic valve replacement is a rapidly evolving field and recent outcome studies suggest short and mid-term results at least equivalent to surgery. The Melody valve® was FDA approved for failing pulmonary surgical conduits in 2010 and for failing bioprosthetic surgical pulmonic valves in 2017 and has been extensively studied, whereas the Sapien XT valve®, offering larger diameters, was approved for failing pulmonary conduits in 2016 and has been less extensively studied. Patients with pulmonic valve disease deserve lifelong surveillance for complications. Transcatheter pulmonic valve replacement is a novel and attractive therapeutic option, but is currently only FDA approved for patients with failing pulmonary conduits or dysfunctional surgical bioprosthetic valves. New advances will undoubtedly increase the utilization of this rapidly expanding technology.

Cardiopulmonary exercise function among patients undergoing transcatheter pulmonary valve implantation in the US Melody valve investigational trial

OBJECTIVES

We assessed the hypothesis that there is an improvement in clinical and physiologic parameters of cardiopulmonary exercise testing (CPET) after implantation of a transcatheter pulmonary valve (TPV).

BACKGROUND

Transcatheter pulmonary valve provides a new tool for treating conduit stenosis and regurgitation in patients with right ventricle (RV) to pulmonary artery conduit dysfunction.

METHODS

Patients who underwent a TPV placement between January 2007 and January 2010 (N = 150) were investigated with a standardized CPET protocol before and at 6 months after TPV placement. Cardiopulmonary exercise testing was performed on a mechanically braked cycle ergometer with respiratory gas exchange analysis.

RESULTS

Six months post TPV, small but statistically significant improvements were observed in the maximum workload (65.0% ± 18.8% to 68.3% ± 20.3% predicted, P < .001) and the ratio of minute ventilation to CO(2) production at the anaerobic threshold (30.8 ± 4.7 to 29.1 ± 4.1, P < .001). There was no significant change in peak oxygen consumption (VO(2)). Patients with pre-TPV hemodynamics consistent with RV dysfunction and patients with a lower pre-TPV peak VO(2) tended to have the greatest improvement in peak VO(2). The correlation between TPV-related improvements in peak VO(2) and baseline clinical variables were weak, however, and these variables could not be used to reliably identify patients likely to have improved peak VO(2) after TPV.

CONCLUSION

In patients with RV to pulmonary artery conduit dysfunction, TPV is associated with modest improvement in exercise capacity and gas exchange efficiency during exercise.

Impact of cardiac rehabilitation on the exercise function of children with serious congenital heart disease

OBJECTIVES

The exercise capacity of children with congenital heart disease (CHD) is often depressed. This depression is thought to be attributable to (1) residual hemodynamic defects and (2) deconditioning secondary to physical inactivity. We hypothesized that this latter component would be ameliorated by a formal cardiac rehabilitation program designed specifically for children. The objective of this study was to characterize the effect of a cardiac rehabilitation program on the exercise performance of children with CHD and to define the physiologic mechanisms that might account for any improvements that are observed.

METHODS

Nineteen patients with CHD who were referred for exercise testing and found to have a peak oxygen consumption (VO2) and/or peak work rate <80% of predicted were enrolled in the study. Sixteen patients (11 Fontan patients, 5 with other CHD) completed the program and had postrehabilitation exercise tests, results of which were compared with the prerehabilitation studies.

RESULTS

Improvements were found in 15 of 16 patients. Peak VO2 rose from 26.4 +/- 9.1 to 30.7 +/- 9.2 mL/kg per min; peak work rate from 93 +/- 32 to 106 +/- 34 W, and the ventilatory anaerobic threshold from 14.2 +/- 4.8 to 17.4 +/- 4.5 mL/kg per min. The peak heart rate and peak respiratory exchange ratio did not change, suggesting that the improvements were not attributable merely to an increased effort. In contrast, the peak oxygen pulse rose significantly, from 7.6 +/- 2.8 to 9.7 +/- 4.1 mL/beat, an improvement that can be attributed only to an increase in stroke volume and/or oxygen extraction at peak exercise. No patient experienced rehabilitation-related complications.

CONCLUSION

Cardiac rehabilitation can improve the exercise performance of children with CHD. This improvement is mediated by an increase in stroke volume and/or oxygen extraction during exercise. Routine use of formal cardiac rehabilitation may greatly reduce the morbidity of complex CHD.

Percutaneous balloon valvuloplasty

In the technique of percutaneous balloon valvuloplasty, one or more large balloons are inserted percutaneously and then inflated across a stenotic valve to decrease the degree of obstruction. Currently, the procedure is being performed for patients with pulmonic, mitral, or aortic stenosis. The results vary according to the type of valve and the age of the patient. In patients with pulmonic stenosis, balloon valvuloplasty can be performed safely and the results are excellent. Therefore, at many institutions it is the procedure of choice for the treatment of isolated pulmonic stenosis. In patients with mitral stenosis, the results depend on the morphologic features of the stenotic valve. In patients with highly calcified and fibrotic mitral valve leaflets, the risks of the procedure are increased and the results are suboptimal. In experienced hands, however, balloon valvuloplasty is excellent for patients with a pliable, noncalcified mitral valve or those for whom operation imposes an extremely high risk. The use of balloon valvuloplasty for aortic stenosis has been limited to the frail, elderly patient who either is not a surgical candidate or is at high risk for operation. Although mortality and restenosis rates are high on short-term follow-up, aortic balloon valvuloplasty provides palliation of symptoms in many patients who otherwise would have been unable to undergo any intervention. Long-term follow-up is necessary for determining the ultimate role of balloon valvuloplasty in cardiology.

Long-term function of the morphologic right ventricle in adult patients with corrected transposition of the great arteries

Because of the concern about the ability of the morphologic right ventricle (MRV) to function over a long term as a systemic ventricle, adult patients with congenitally corrected transposition of the great arteries (CCTGA) were evaluated to determine the long-term function of the MRV. Morphologic right ventricular function was assessed by functional clinical classification and angiographic ejection fraction in 18 adult patients with congenitally corrected transposition of the great arteries. These patients had a mean age of 30.2 +/- 14.5 years (range 10 to 67 years). All but one had hemodynamically significant lesions, the most common being left atrioventricular valve regurgitation (11 patients), ventricular septal defect (seven patients), atrial septal defect (four patients), and pulmonic stenosis (three patients). The mean MRV ejection fraction at presentation was 55% +/- 11.5% (range 24% to 74%). Twelve of the 18 patients (67%) were followed clinically, with a mean follow-up time of 9.9 +/- 7.1 years (range 1 to 22 years). Eight were reassessed angiographically, with a mean MRV ejection fraction of 51.3% +/- 10.7% (range 30% to 67%). The other four were followed up clinically and evaluated by two-dimensional echocardiography, with normal MRV function in two patients. Eight of 12 patients (67%) were in functional class I at follow-up, one was in functional class II, one was in functional class III, and two had died. Our data suggest that the morphologic right ventricle can function appropriately over a long term in adult patients with congenitally corrected transposition of the great arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise after surgical repair of congenital cardiac lesions

Congenital heart defects arise in approximately 1% of all live births, independent of ethnic and geographical considerations. With the development of new surgical procedures and current technologies a large number of these heart lesions can be surgically corrected in infancy. In the majority of cases patients evaluated some 10 to 20 years after surgery are asymptomatic and can lead a normal life. Despite their satisfactory clinical outcome patients may, nevertheless, show an abnormal pattern of physiological responses when submitted to dynamic exercise. This paper reviews the scientific literature concerning the exercise capabilities and the cardiorespiratory adjustments to exercise in patients surgically corrected for 4 of the most common congenital heart lesions: isolated atrial septal defect, isolated ventricular septal defects, pulmonary stenosis and tetralogy of Fallot. The maximal exercise tolerance of postoperative congenital heart defect patients may usually be related to: (a) the age of the patients at the time of surgery; (b) the severity of the lesions remaining after surgery; and (c) the age of the patients at the time of investigation. Although normal maximal exercise capabilities may be found in a good number of patients operated for either of the 4 lesions considered, this does not imply normal exercise haemodynamics. A general observation made in these 4 groups of patients is that of a subnormal exercise cardiac output which may or may not be fully compensated by an increase in peripheral oxygen extraction. The limitation in exercising cardiac output may, in turn, be attributed to either a subnormal stroke volume or a limitation in the chronotropic response to exercise or a combination of both factors. Residual pulmonary stenosis, increased pulmonary vascular resistance, increased myocardial stiffness are all factors that may contribute to the cardiac output limitation. A thorough explanation of underlying causes for the abnormal haemodynamic response to exercise, however, still remains to be provided.

Radionuclide angiographic evaluation of ventricular function in isolated congenitally corrected transposition of the great arteries

Eight asymptomatic patients (mean age 19 years, range 7 to 32) with congenitally corrected transposition of the great arteries (CCTGA) underwent equilibrium gated radionuclide angiocardiography at rest and during supine bicycle exercise to assess systemic (morphologic right) and pulmonary (morphologic left) ventricular function. Five patients had normal intracardiac hemodynamic values, 2 had trivial atrioventricular valve regurgitation and 1 patient had trivial pulmonary ventricular outflow tract obstruction. Average exercise duration was 11 +/- 1 minute, with limitation due only to fatigue. At peak exercise, heart rate increased 225% and systolic blood pressure 152% over the rest value. Pulmonary ventricular ejection fraction at rest was 51 +/- 3% (mean +/- standard error of the mean); it did not change significantly at peak stress, 53 +/- 2%. Systemic ventricular ejection fraction was 48 +/- 4% at rest and increased to 64 +/- 4% at peak exercise (p less than 0.01). Count-based volume changes for the pulmonary chamber showed no significant change in end-diastolic or systolic counts at peak exercise (109 +/- 8% and 106 +/- 9% of rest value, respectively). However, end-diastolic counts decreased 13% (87 +/- 3% of rest value) and end-systolic counts 34% (62 +/- 7% of rest value) at peak exercise in the systemic ventricle. These data suggest normal systemic and impaired pulmonary ventricular function in patients with congenitally corrected transposition of the great arteries unaccompanied by significant associated lesions. These findings have important clinical implications in the setting of complex congenital heart disease in patients in whom a morphologic right ventricle functions as the systemic pumping chamber. Despite the pulmonary ventricular dysfunction, symptoms were not apparent at rest or during exercise.

Rest and exercise hemodynamics in pulmonary stenosis: comparison of children and adults

To better understand the hemodynamics of pulmonary stenosis (PS), 24 adults and 53 children with similar degrees of PS who had undergone cardiac catheterization at rest and during supine exercise were retrospectively studied. Three groups were defined. Group I consisted of 9 adults and 18 children with a pulmonary valve area of less than 0.5 cm2/m2; group II, 6 adults and 25 children with a pulmonary valve area of 0.5 to 1.0 cm2/m2; and group III, 9 adults and 10 children with pulmonary valve area of more than 1.0 cm2/m2. The mean ages of the adults were 29, 26 and 22 years for groups I, II, and III, respectively. The mean ages of the children were 11, 10 and 9 years for groups I, II and III, respectively. The pertinent data collected from catheterization included oxygen consumption, cardiac rate and index, arterial venous oxygen difference, stroke index, right ventricular (RV) systolic pressure and RV end-diastolic pressure. Adults and children in groups II and III had an appropriate response to exercise. Group I children responded abnormally by increasing their RV end-diastolic pressure and decreasing their stroke index. In group I adults both of these variables increased. Group I adults exhibited a significantly lower cardiac index at rest and exercise secondary to a significantly lower absolute cardiac rate. Long-standing severe PS results in hemodynamic compromise. Hence, early relief of PS is recommended.

Long-term follow-up of patients with malformations for which definitive surgical repair has been available for 25 years or more

The results of long-term follow-up studies of patients with five common congenital heart defects are reviewed. The lesions included are ventricular septal defect, atrial septal defect, patent ductus arteriosus, pulmonary stenosis and coarctation of the aorta. A definitive, rather than palliative, operation has been available for each of these lesions for more than 25 years. Therefore many patients who have undergone operation for one of these lesions are now reaching adulthood. Although most of these postoperative patients live a normal life, many have residuae or sequelae that require close observation or treatment. Other persistent abnormalities of the physical examination, electrocardiogram and chest radiogram are obvious but call for no precaution or treatment. We have drawn on our own experience and the published experience of others to identify those findings and historical factors that best reflect the long-term prognosis of these patients. In addition, recommendations concerning the need for continued prophylaxis against infective endocarditis, and the problems of insurability and employability of these postoperative patients are discussed.

Functional status of patients with large ventricular septal defect and pulmonary vascular disease 6 to 16 years after surgical closure of their defect in childhood

We have reviewed 27 patients now 6 to 16 years after closure of a ventricular septal defect at 3 to 12 years of age associated with pulmonary hypertension with a view to assessing their quality of life, respiratory function, and exercise performance. All the patients led normal unrestricted lives. Their subjective lack of symptoms was, in general, confirmed by the results obtained from assessment of lung function tests and two-stage exercise testing in 19 volunteers. Abnormal ventilation in relation to work load was noted in 5 patients and a slightly low exercise cardiac output in 6. Although the patients led normal lives and had a satisfactory response to exercise, measurement of pulmonary artery pressure showed striking pulmonary hypertension on effort. Despite the satisfactory progress of these patients their more long-term future must be one of conjecture and their residual pulmonary hypertension, indicative of residual pulmonary obstruction, must lend weight to arguments for earlier closure of ventricular septal defect before 1 to 2 years of age when changes in the pulmonary vascular bed may be reversed after closure of the defect.

Pre- and postoperative rest and exercise hemodynamics in children with pulmonary stenosis

Twenty children with pulmonary valvular stenosis were studied by cardiac catheterization both at rest and during submaximal supine exercise, prior to and following pulmonary valvotomy. The resting and exercise states were comparable preoperatively and postoperatively since cardiac output, heart rate, A - V O 2 difference and oxygen consumption were similar. Evidence of improved cardiac function was found postoperatively.

Both the rest and the exercise right ventricular end-diastolic pressure (RVEDP) decreased significantly following pulmonary valvotomy. Preoperatively, 12 of 20 patients showed an increase in RVEDP with exercise; in six of these there was a simultaneous fall in stroke index, indicating impaired myocardial function. No patient showed this response postoperatively.

This indicates that although altered cardiac function can be demonstrated in some children with pulmonary valvular stenosis, it is reversible by pulmonary valvotomy. This is in contrast to studies in adults, and suggests that a factor in the natural history of pulmonary valvular stenosis is the impact of chronically elevated afterload on the right ventricle. Hemodynamic measurements made during exercise provide a useful means of assessing patients with pulmonary stenosis before and after pulmonary valvotomy.

Postoperative assessment of patients with ventricular septal defect and pulmonary hypertension. Response to intense upright exercise

Circulatory function of patients with operatively closed ventricular septal defect and preoperative pulmonary arterial hypertension was evaluated in 11 asymptomatic subjects at rest and during intense treadmill exercise three to 15 years after operation. The pulmonary-to-systemic resistance ratio was normal or mildly to moderately elevated preoperatively. Postoperative mean pulmonary arterial pressure at the time of study was normal or mildly elevated at rest in 10 patients and moderately elevated in one (40 mm Hg). During intense upright exercise sufficient to lower pulmonary arterial oxygen saturation to 30%, cardiac output was below the normal range in five patients. Each of these patients had been operated upon after 10 years of age. The magnitude of the postoperative abnormality in cardiac output response to exercise was directly related to age at operation. Two of the five patients with impaired cardiac output response and two other patients manifested an abnormally elevated mean pulmonary arterial pressure during intense exercise. There was a positive correlation between pulmonary arterial pressure during intense exercise and age at operation. These results indicate that late postoperative cardiovascular function may be abnormal in patients with ventricular septal defect and preoperative pulmonary arterial hypertension, and that these abnormalities appear to be related to age at operation. Since all patients were asymptomatic, the long-term clinical significance of these hemodynamic abnormalities remains to be determined.

Exercise hemodynamics of pulmonary valvular stenosis. Study of 64 children

Sixty-four children with pulmonary stenosis were studied by cardiac catheterization both at rest and on exercise. Whereas milder degrees of stenosis were associated with normal right ventricular function, more severe stenosis was associated with fixed stroke index and elevated RVEDP, and suboptimal response of cardiac index. These changes result from altered right ventricular compliance. In several the compliance abnormality was related to myocardial hypertrophy, whereas in four patients it was most likely caused by myocardial fibrosis.