Ventricular septal defect

Opinion statement Ventricular septal defects (VSDs) are the most common congenital heart malformations seen in children. Because spontaneous closure occurs frequently, patients with small VSDs should be followed clinically with no limitations except endocarditis prophylaxis. Surgical closure is recommended for only small defects with significant associated lesions such as aortic regurgitation, aortic valve prolapse, right or left ventricular outflow obstruction, tricuspid regurgitation, left ventricle to right atrial shunt, or recurrent endocarditis. Enlarging left ventricular size or deteriorating left ventricular function would also be an indication for surgical repair. Moderate and large VSDs in infancy often require treatment of congestive heart failure with diuretics, digitalis, and afterload reduction. Surgical closure before 9 months of age is indicated for large VSDs and by 2 years of age for moderate shunts to prevent pulmonary vascular obstructive disease and the consequences of long-standing volume overload. Device closure of VSD is still in the investigational stage but holds promise for treatment of apical or multiple muscular VSDs.     

Massive mitral and pulmonary valve incompetence in a patient with left ventricular, non-compacted myocardium

The case is reported of a patient who underwent cardiac surgery for pulmonary valve stenosis as a child, and presented as an adult with signs and symptoms of severe congestive heart failure. The left ventricle showed an increased trabecular pattern in the region of the apex, the mitral annulus was severely dilated with mitral incompetence, the right ventricular out-flow tract (RVOT) was largely dilated with aneurysm of both pulmonary arteries, and there was evidence of pulmonary valve incompetence. Previously, rare cases have been reported of persistent left ventricular non-compaction in patients with congenital left or RVOT obstruction. Non-compaction of the ventricular myocardium is an inherited autosomal dominant disorder; to date, four genes and one genetic locus have been found to be associated with non-compacted ventricular myocardium. The condition is characterized by arrhythmias, thromboembolic events and heart failure, but affected individuals may not be symptomatic. The present case represented a strange association between non-compacted left ventricle, mitral annular dilation with persistence of a normal leaflet and subvalvular mitral valve apparatus, and RVOT dilation with pulmonary artery aneurysms.     

Rechtsherzversagen bei chronischer pulmonaler Hypertonie und akuter Lungenembolie

Right-sided heart failure is a severe and often life-threatening complication of chronic pulmonary hypertension. The detection of trigger factors that induce right heart failure in previously stable patients is important to initiate a causal therapeutic strategy. Pulmonary embolism (PE) is a frequent cause of acute right heart failure and therapeutic strategies for PE are well documented in the current guidelines. Treatment of choice for chronic thromboembolic pulmonary hypertension (CTEPH) is surgical pulmonary endarterectomy (PEA) and patients with possible CTEPH should be referred to an experienced PEA surgeon without delay. Intensive care management for overt right heart failure is complex and includes the use of pulmonary vasodilators, individual adjustment of diuretic or volume therapy, augmentation of myocardial contractility and left ventricular afterload. Therapeutic regimens aim at optimized filling of the right ventricle, improvement of myocardial perfusion by avoiding tachycardia, elevating systemic pressure and reducing right ventricular afterload. Early communication with a specialized center for pulmonary hypertension is recommended.     

Right ventricular failure complicating heart failure: Pathophysiology,significance, and management strategies

Right heart failure most commonly results from the complication of left heart failure (systolic or nonsystolic dysfunction) or pulmonary hypertension. Over the past decade, greater attention has been paid to the role of right ventricular failure in the morbidity and mortality associated with cardiomyopathy and pulmonary hypertension. The right ventricle is distinct from the left ventricle not only in its spatial localization, but also in its response to increased afterload and signaling mechanisms. This article discusses the role of right ventricular failure in the setting of heart failure as well as the clinical diagnosis and management of right ventricular failure.     

Importance of right ventricular function in congestive heart failure

Failure of the right ventricle may be due to a congenital anomaly, intrinsic disease, pulmonary stenosis or pulmonary hypertension. Left ventricular failure may also lead to right ventricular failure if the heart fails totally or secondary to pulmonary hypertension, or if filling of the right ventricle is decreased due to left ventricular dilation or hypertrophy. Treatment of right ventricular failure has yielded disappointing results, except when caused by left ventricular failure that responds to therapy. Digitalis and diuretics may have more adverse than beneficial effects. In patients with both left and right ventricular failure, survival is usually less than 2 years.     

Intensive care unit management of patients with severe pulmonary hypertension and right heart failure

Despite advances in medical therapies, pulmonary arterial hypertension (PAH) continues to cause significant morbidity and mortality. Although the right ventricle (RV) can adapt to an increase in afterload, progression of the pulmonary vasculopathy that characterizes PAH causes many patients to develop progressive right ventricular failure. Furthermore, acute right ventricular decompensation may develop from disorders that lead to either an acute increase in cardiac demand, such as sepsis, or to an increase in ventricular afterload, including interruptions in medical therapy, arrhythmia, or pulmonary embolism. The poor reserve of the right ventricle, RV ischemia, and adverse right ventricular influence on left ventricular filling may lead to a global reduction in oxygen delivery and multiorgan failure. There is a paucity of data to guide clinicians caring for acute right heart failure in PAH. Treatment recommendations are frequently based on animal models of acute right heart failure or case series in humans with other causes of pulmonary hypertension. Successful treatment often requires that invasive hemodynamics be used to monitor the effect of strategies that are based primarily on biological plausibility. Herein we have developed an approach based on the current understanding of RV failure in PAH and have attempted to develop a treatment paradigm based on physiological principles and available evidence.     

Cardiovascular physiology-changes with aging

With aging there are changes in the cardiovascular system, which result in alterations in cardiovascular physiology. The changes in cardiovascular physiology must be differentiated from the effects of pathology, such as coronary artery disease, that occur with increasing frequency as age increases. The changes with age occur in everyone but not necessarily at the same rate, therefore accounting for the difference seen in some people between chronologic age and physiologic age. The changes in the cardiovascular system associated with aging are a decrease in elasticity and an increase in stiffness of the arterial system. This results in increased afterload on the left ventricle, an increase in systolic blood pressure, and left ventricular hypertrophy, as well as other changes in the left ventricular wall that prolong relaxation of the left ventricle in diastole. There is a dropout of atrial pacemaker cells resulting in a decrease in intrinsic heart rate. With fibrosis of the cardiac skeleton there is calcification at the base of the aortic valve and damage to the His bundle as it perforates the right fibrous trigone. Finally there is decreased responsiveness toβ adrenergic receptor stimulation, a decreased reactivity to baroreceptors and chemoreceptors, and an increase in circulating catecholamines. These changes set the stage for isolated systolic hypertension, diastolic dysfunction and heart failure, atrioventricular conduction defects, and aortic valve calcification, all diseases seen in the elderly.     

Balloon dilation of postoperative right ventricular outflow obstructions

Balloon dilation was attempted in 16 patients, aged 5 months to 19.5 years, with right ventricular outflow obstruction after repair of congenital heart defects. Stenosis of a valved conduit between the pulmonary ventricle and pulmonary artery was present in nine patients with a mean transvalvular peak systolic ejection gradient of 61.6 +/- 21.0 mm Hg and a mean right ventricle to aorta pressure ratio of 0.9 +/- 0.2. Supravalvular pulmonary stenosis was present in seven patients; in five, stenosis was at the anastomotic site after the arterial switch operation with a mean peak systolic ejection gradient of 72.2 +/- 10.6 mm Hg and mean right ventricle to aorta pressure ratio of 0.93 +/- 0.05. The other two patients had stenosis at a previous pulmonary artery band site with a peak systolic ejection gradient of 60 and 65 mm Hg and right ventricle to aorta pressure ratio of 0.75 and 0.72, respectively. Balloon dilation was successful in three of nine patients with a valved conduit; two of them had additional successful balloon dilation of the right pulmonary artery. In five of the nine patients (including one with successful dilation) the conduit was replaced 5.7 +/- 4.5 months after balloon dilation. Balloon dilation was successful in only one of the five patients with supravalvular pulmonary stenosis after the arterial switch operation and partially successful in the two patients with supravalvular pulmonary stenosis at a previous band site. The success rate of balloon dilation of postoperative right ventricular outflow obstruction is much lower than that for other right heart obstructions.     

Synchronization of the contraction of the right ventricle against an acute afterload increase. Left ventricle-like mechanical function of the right ventricle

AIM: The aim of this study was to demonstrate right ventricular contraction synchronization during acute and moderate afterload increase. MATERIAL AND METHOD: Right and left ventricular pressures, pulmonary and aortic pressures, pulmonary flow, and ventricular volumes by sonomicrometry were measured in seven anesthetized sheep. Pulmonary arterial hypertension was induced by Escherichia coli endotoxemia. RESULTS: Acute increase of the right ventricular afterload, measured as the mean arterial pulmonary pressure (11.9 1.3 to 24 3.6 mmHg) produced the following changes in the right ventricle without preload and contractility changes: a) maximal elastance shifted towards the end of the ejection (127.5 18.5 ms) and the ejection time shortened (57.5 20.3 ms), so that the negative peak of the first ventricular pressure derivative occurred at the end of the ejection; b) the pressure-volume loop became rectangular, i.e.; the systolic and diastolic phases were isovolumic, and c) the ejection showed a single phase. CONCLUSIONS: Asynchronous and sequential right ventricular contraction with normal afterload changed to a synchronic contraction pattern as in the left ventricle during an acute and moderate afterload increase. This left ventricle-like mechanical property establishes a novel mechanical reserve mechanism of the right heart, since it allows the right ventricle to maintain its systolic function during an afterload increase, independently of the preload and contractility.     

Caveats of balloon dilation of conduits and conduit valves

The results and complications of percutaneous balloon dilation involving 10 patients with a stenotic right ventricle to pulmonary artery prosthetic conduit and 1 patient with an obstructed right atrium to left pulmonary artery Dacron graft (modified Fontan) are reported. For the 10 patients (14.5 +/- 5 years) with a right ventricle to pulmonary artery conduit, the mean (+/- SD) predilation conduit valve gradient was 57 +/- 22 mm Hg, right ventricular pressure 104 +/- 21 mm Hg and right ventricle to pulmonary artery gradient 75 +/- 23 mm Hg; 2 of the patients had additional pulmonary artery stenosis requiring dilation. In one patient, the balloon could not be advanced across the conduit valve. In 9 of 10 patients in whom dilation was successfully performed, the conduit valve gradient decreased by 59 +/- 13%, right ventricle to pulmonary artery gradient by 43 +/- 22% and right ventricular pressure by 31 +/- 11%. After dilation, right ventricular pressure was less than 65% of systemic pressure in seven patients, although no pressure was less than 40%. In 8 of the 11 patients, surgery was avoided or postponed. Complications included loss of a balloon fragment after rupture during the unsuccessful dilation of the right atrium to left pulmonary artery graft and circumferential balloon rupture requiring catheter retrieval of the distal portion of the balloon from the femoral vein after successful dilation of the right ventricle to pulmonary artery conduit. Conduit valve dilation by balloon can reduce but rarely eliminate conduit obstruction, and balloon rupture may occur and can result in fragment loss or embolization.     

限制型心肌病的临床表现

本文报告限制型心肌病１０例，其中５例诊断为心内膜心肌纤维化（右室型４例，左室型１例）。其临床特点为慢性右心压塞征象；心室流入道收缩变形，心尖部闭塞，流出道增宽，巨大右房或左房扩大，房室瓣反流，左室收缩功能大致正常，舒张功能受限。其他５例诊断为特发性限制型心肌病，其特点为肺和体循环淤血，不同程度房室瓣反流，房性心律失常，心房明显扩大，左室不扩大，双室舒张末压升高，无明显心肌缺血或心包疾患。３例患者心脏病症状出现后半年至７年，死于顽固性心力衰竭。１例右室型，１例左室型心内膜心肌纤维化患者行心室内膜剥脱和房室瓣替换手术。     

Primitive ventricle with normally related great vessels and stenotic subpulmonary outlet chamber. Angiographic differentiation from tetralogy of Fallot

Four patients with primitive ventricle and normally related great vessels with stenotic subpulmonary outlet chamber (Holmes' heart with pulmonary stenosis) are reported. The history, physical examination, and chest x-ray film are not helpful in distinguishing Holmes' heart with pulmonary stenosis from tetralogy of Fallot. Electrocardiogram often provides the first clue to the presence of Holmes' heart; left axis deviation with or without left ventricular hypertrophy is an unusual finding in tetralogy of Fallot, but common in Holmes' heart. Selective ventriculography is diagnostic: the right ventricular outflow chamber overlies the aortic root and aortic valve in the frontal view in Holmes' heart with pulmonary stenosis, but is to the left of the aortic valve in tetralogy of Fallot; no ventricular septum can be identified in Holmes' heart. The diagnosis can be suspected in a child with clinical features of tetralogy of Fallot but atypical electrocardiogram, and can be established by angiography.     

Carotid artery approach for balloon dilation of aortic valve stenosis in the neonate: a preliminary report

Balloon valvuloplasty in neonates with severe aortic valve stenosis is limited by difficulties in catheter manipulation around the arch and across the valve and by the risk of femoral artery complications. A right common carotid artery cutdown was utilized for balloon aortic valvuloplasty in five neonates 1 to 20 days of age, weighing 3.1 to 3.9 kg. Standard balloon valvuloplasty was performed through a 6F sheath inserted in the right carotid artery. The arteriotomy was repaired at the end of the procedure. Mean left ventricular systolic pressure was reduced from 142 to 97 mm Hg, with a decrease in mean peak systolic pressure gradient from 76 to 33 mm Hg. Only one patient developed mild aortic regurgitation. One patient with a hypoplastic left ventricle died, and one patient required open valvotomy. All four survivors have a normal carotid pulse and no neurologic sequelae. Two of these patients required repeat balloon dilation to treat residual aortic valve stenosis at 8 and 10 months of age, respectively. Balloon valvuloplasty using a carotid artery approach is feasible and was safe in five neonates with severe aortic valve stenosis.     

Primitive ventricle with normally related great vessels and stenotic subpulmonary outlet chamber. Angiographic differentiation from tetralogy of Fallot.

Four patients with primitive ventricle and normally related great vessels with stenotic subpulmonary outlet chamber (Holmes' heart with pulmonary stenosis) are reported. The history, physical examination, and chest x-ray film are not helpful in distinguishing Holmes' heart with pulmonary stenosis from tetralogy of Fallot. Electrocardiogram often provides the first clue to the presence of Holmes' heart; left axis deviation with or without left ventricular hypertrophy is an unusual finding in tetralogy of Fallot, but common in Holmes' heart. Selective ventriculography is diagnostic: the right ventricular outflow chamber overlies the aortic root and aortic valve in the frontal view in Holmes' heart with pulmonary stenosis, but is to the left of the aortic valve in tetralogy of Fallot; no ventricular septum can be identified in Holmes' heart. The diagnosis can be suspected in a child with clinical features of tetralogy of Fallot but atypical electrocardiogram, and can be established by angiography.     

Unnatural history of the right ventricle in patients with congenitally malformed hearts

The long-term outcome of patients with congenitally malformed hearts involving abnormal right ventricular morphology and haemodynamics is variable. In most instances, the patients are at risk for right ventricular failure, in part due to morphological differences between the right and left ventricles and their response to chronic volume and pressure overload. In patients after repair of tetralogy of Fallot, and after balloon valvotomy for valvar pulmonary stenosis, pulmonary regurgitation is the most significant risk factor for right ventricular dysfunction. In patients with a dominant right ventricle after Fontan palliation, and in those with systemic right ventricles in association with surgically or congenitally corrected transposition, the right ventricle is not morphologically capable of dealing with chronic exposure to the high afterload of the systemic circulation. In patients with Ebstein's malformation of the tricuspid valve, the degree of atrialisation of the right ventricle determines how well the right ventricle will function as the pump for the pulmonary vascular bed.     

Mechanical determinants of myocardial oxygen consumption with special reference to external work and efficiency.

OBJECTIVE: The aim of the study was to investigate the ambiguous effect of left ventricular afterload on myocardial work, oxygen consumption, and efficiency. METHODS: Myocardial oxygen consumption and mechanical parameters of the left and right ventricle were measured in situ in a modified heart-lung preparation in the rat. Left ventricular afterload was adjusted arbitrarily by means of a Starling resistor mounted in a shunt circuit between the left ventricle and the caudal caval vein. Left and right ventricular pressure and aortic pressure as well as pulmonary flow and the flow in the shunt circuit were measured. The left ventricular pressure and volume values were converted into wall stress and length data assuming a thick walled sphere, and external work was calculated from left ventricular force and shortening. RESULTS: Left ventricular external work ran through a maximum with decreasing aortic pressure. Left ventricular oxygen consumption per gram and beat correlated linearly with left ventricular peak wall stress, tension-time integral, and maximum rate of stress development. Left ventricular force and shortening, the two components of external work, acted differently: force determined left ventricular oxygen consumption, whereas shortening had no direct effect on myocardial oxygen consumption, but was important in determining left ventricular efficiency. CONCLUSIONS: The interplay between left ventricular afterload and coronary perfusion pressure is of special significance for the heart in situ. The decrease in shortening and external work as well as the diminution in efficiency, observed at low aortic pressure values, can be attributed to impaired coronary perfusion. The coronary perfusion pressure must therefore be taken into consideration for the critical examination of the efficiency of the heart in situ.     

Effects of left ventricular loading by negative intrathoracic pressure in dogs

There are many factors, both intrinsic and extrinsic to the left ventricle, that can affect its function when negative intrathoracic pressure is imposed. In this study, we examined whether the left ventricular response to the afterload imposed by negative intrathoracic pressure was similar to that imposed by partial aortic constriction. We used steady-state right heart bypass to control pulmonary venous return to the left ventricle and reflex blockade to maintain constant heart rate and contractility. To impose negative intrathoracic pressure we used a pressure chamber fitted over a midsternal thoracotomy, which allowed steady negative pressure to be applied to all intrathoracic surfaces. Left ventricular volumes were measured from biplane cineradiograms of multiple 1-mm markers implanted in the left ventricular midwall. With cardiac output and heart rate constant, we compared the left ventricular response to two different levels of negative intrathoracic pressure and to increasing aortic pressure by partial aortic constriction. In each case, negative intrathoracic pressure produced a rise in the left ventricular end-systolic and end-diastolic volumes as well as transmural pressures similar to the effects of partial aortic occlusion. Thus, when cardiac output, heart rate, and contractility are maintained constant and all external restraints on the left ventricle are removed, the left ventricle responds in a similar manner to an increase in hydraulic load whether produced by a decrease in intrathoracic pressure or by partial aortic occlusion.     

Bedeutung und Einsatz der Beatmung bei akut dekompensierter Herzinsuffizienz

Acutely decompensated chronic heart failure causes increased left ventricular preload and afterload. Increasing preload manifests itself in conditions ranging from increasing degrees of pulmonary congestion to lung edema. The resulting disturbances of lung function affect oxygen diffusion, the ventilation/perfusion ratio, airway resistance, and lung compliance. Mechanical ventilation with positive endexpiratory pressure (PEEP), which can be applied using a CPAP or BiPAP mask, is then required depending on the severity of disturbed oxygenation. Beside the importance for oxygenation, PEEP has hemodynamic consequences. It reduces the preload of both ventricles and represents for the left ventricle a nearly causal treatment. Reduced preload reduces myocardial oxygen demand and increases myocardial oxygen supply. Simultaneously, PEEP reduces the systolic left ventricular wall tension. This reduction of afterload again implies increased oxygen supply and decreased myocardial oxygen demand. Artificial ventilation is an important treatment option of acutely decompensated chronic heart failure, acute left heart failure, and cardiogenic shock.     

Cardiovascular disturbances in chronic respiratory insufficiency

The mechanical factors by which chronic respiratory insufficiency may influence right and left ventricular performance during both spontaneous and mechanical ventilation are reviewed. During a spontaneous inspiration the right heart distends because of increased inflow and increased pulmonary vascular resistance. This decreases the effective left ventricular compliance, through ventricular interdependence, reducing the gradient for pulmonary venous return. The inspiratory decrease in pleural pressure also effectively increases the impedance to left ventricular ejection. An inspiratory increase in abdominal pressure further increases the left ventricular afterload. These factors combine to impair left ventricular performance. During intermittent positive pressure ventilation, left ventricular stroke volume increases early in inspiration. This increased inspiratory flow cannot be attributed to a phase lag in the right heart output reaching the left heart chambers because, even with a constant pulmonary arterial inflow, aortic flow increases during inspiration. Several factors may act in concert to improve left ventricular performance, despite the adverse effects of intermittent positive pressure ventilation on the right ventricle. These include (1) a decrease in right heart volume, increasing left ventricular compliance and hence the gradient for pulmonary venous return; (2) anterograde emptying of the alveolar capillary bed with lung inflation; (3) the increase in pleural pressure decreasing impedance to left ventricular emptying; and (4) physical compression of the heart by the lungs.     

Percutaneous balloon valvuloplasty in neonates with critical aortic stenosis

Percutaneous balloon valvuloplasty was attempted in 10 newborn infants with critical aortic valve stenosis and severe congestive heart failure. Three had a very small left ventricle and aortic anulus. In one infant, the aortic valve could not be passed, and in another infant, a technical error resulted in severe valvular damage, aortic insufficiency and death. Among the eight patients who had effective dilation, the stenosis was relieved in seven as assessed by a significant decrease in transvalvular pressure gradient, improvement of left ventricular contraction and eventual inversion of the ductal shunting. The procedure failed in the only patient whose dilation was performed with an undersized balloon. Aortic insufficiency occurred in three infants and was severe (perforated cusp) in one, moderate in one whose valve was dilated with an excessively large balloon and mild and transient in one. None of the three infants with a very small left ventricle recovered (two died and one underwent cardiac transplantation). Among the seven infants with a left ventricle of acceptable size, three underwent subsequent aortic valvotomy; one of these died and two bad good results. The remaining four are doing well 16 +/- 5 months later (mean +/- SD) with mild to moderate residual aortic stenosis and normal left ventricular function. In conclusion, percutaneous balloon valvuloplasty is an acceptable alternative to surgery in neonates with critical aortic valve stenosis. Incidence of complications and good relief of the obstruction depend on a careful technique. Immediate results are similar to those of surgery. Late prognosis depends on the quality of the left heart structures.