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The keynote to understanding cardiac function is recognizing the underlying architecture responsible for the contractile mechanisms that produce the narrowing, shortening, lengthening, widening, and twisting disclosed by echocardiographic and magnetic resonance technology. Despite background knowledge of a spiral clockwise and counterclockwise arrangement of muscle fibers, issues about the exact architecture, interrelationships, and function of the different sets of muscle fibers remain to be resolved. This report (1) details observed patterns of cardiac dynamic directional and twisting motions via multiple imaging sources; (2) summarizes the deficiencies of correlations between ventricular function and known ventricular muscle architecture; (3) correlates known cardiac motions with the functional anatomy within the helical ventricular myocardial band; and (4) defines an innovative muscular systolic mechanism that challenges the previously described concept of “isovolumic relaxation.” This new knowledge may open new doors to treating heart failure due to diastolic dysfunction.

In deriving clinically used hemodynamic indices such as fractional flow reserve and coronary flow velocity reserve, simplified models of the coronary circulation are used. In particular, myocardial resistance is assumed to be independent of factors such as heart contraction and driving pressure. These simplifying assumptions are not always justified. In this review we focus on distensibility of resistance vessels, the shape of coronary pressure-flow lines, and the influence of collateral flow on these lines. We show that (1) the coronary system is intrinsically nonlinear because resistance vessels at maximal vasodilation change diameter with pressure and cardiac function; (2) the assumption of collateral flow is not needed to explain the difference between pressure-derived and flow-derived fractional flow reserve; and (3) collateral flow plays a role only at low distal pressures. We conclude that traditional hemodynamic indices are valuable for clinical decision making but that clinical studies of coronary physiology will benefit greatly from combined measurements of coronary flow or velocity and pressure.

One of the fastest growing fields in medicine is the care of adults with congenital heart disease (adult CHD or ACHD). This is mainly a consequence of much longer survival due to advances in pediatric cardiology, interventional catheterization, cardiac surgery, and intensive care. Fifty years ago we could diagnose most forms of moderate and severe CHD, but some anomalies were untreatable and others had relatively low survival after treatment. Today, in-hospital mortality is low for almost all forms of CHD, and most of the survivors can be expected to reach adult life. In addition, a medical system with greater focus on CHD now detects many lesions such as coarctation of the aorta and atrial septal defects that previously went unnoticed. Patients with ACHD need adequate resources, facilities and manpower to care for them, and we in turn need accurate estimates of how many patients have each type and severity of ACHD in order to plan effectively. These estimates are moving targets, because improvements in preoperative, intraoperative, and postoperative care occur continuously. What was good yesterday may not be adequate today. Articles see pp 2254 and 2264 The classic dilemma in studying this problem is how to obtain accurate data on a large number of patients. Studies based on registries showing the incidence of CHD at birth and mortality from CHD may show the big picture, but the details are inaccurate.1 On the other hand, following a smaller population intensively gives accurate data but runs the risk of being unrepresentative of the population as whole as well as risking excessive stochastic variation, especially for complex anomalies with a low birth incidence. Several attempts have been made to derive these data. A landmark report of Task Force I of the 32nd Bethesda Conference set up by the American College of …

In order to assess the influence of recent modifications in cardiac catheterization technique and patient management, a prospective study of all complications in a series of 1160 cardiac catheterizations of neonates, infants, and children was performed. Thirty-four major and 136 minor complications were recorded. Fatal complications were rare in all age groups (0.26%); however, postcatheterization deaths not attributable to the procedure were common in critically ill neonates with nonremediable lesions. Arrhythmias and arterial complications accounted for 78% of all complications. Although the incidence of arrhythmias was high (8.3% of all cases), particularly in infants, almost all responded to simple therapeutic measures. Five arrhythmias resulted in clinical deterioration and two contributed to death. The incidence of arterial complications varied considerably with the method of arterial entry. Percutaneous catheterization by the sheath method was associated with fewer complications than with the Seldinger technique, arteriotomy, or insertion of a teflon cannula into an exposed artery. Complications were particularly common after brachial arteriotomy in patients with coarctation of the aorta (16.1%). Complications of contrast media and perforation of the heart were infrequent, each occurring once. Although the total number of major complications was only moderately less frequent than in patients of comparable age in the Cooperative Study on Cardiac Catheterization, 1 there was a considerable reduction in the most severe complications and deaths. The changes in catheterization technique and patient management that contributed to decreased mortality and morbidity are discussed.

We have reviewed the clinical and catheterization data and pathologic findings in ten infants under one month of age with isolated severe aortic valve stenosis. All presented with evidence of progressive cardiac failure and diminished cardiac output. A hyperdynamic right ventricular impulse was present in nine infants who were subsequently shown to have a left-to-right atrial shunt, through a stretched patent foramen ovale. Calculated aortic valve area ranged from 0.12 cm 2 /m 2 to 0.29 cm 2 /m 2 . Three patients died prior to surgical intervention because of low cardiac output and refractory metabolic acidosis. Aortic valvotomy was attempted in the remaining seven. Five died intraoperatively or in the immediate postoperative period and one other died six months after surgery. Necropsy was obtained in all nine patients who died. We believe that, in this group, the clinical course reflects fetal and postnatal hemodynamics. We have discussed the probable hemodynamic factors which occur and have related them to the morphological development of aortic stenosis in these infants. The poor prognosis of these patients probably results from a combination of factors which include left ventricular outflow obstruction, often associated with a small aortic annulus, a markedly thickened left ventricle, and left ventricular malfunction secondary to subendocardial ischemia and/or endocardial fibroelastosis.

An index of myocardial oxygen supply/demand was calculated from the left ventricular and aortic pressure tracings in 80 infants and children with isolated valvar aortic stenosis. Supply was estimated by multiplying the area between aortic and left ventricular pressures during diastole (DPTI) by arterial oxygen content (C). Demand was estimated from the area under the left ventricular tracing during systole (SPTI). The oxygen supply/demand ratio was expressed as: DPTI X C/SPTI. A ratio 2 /m 2 , an increasing number of patients develop ratios 2 /m 2 but heart rates 100/minute and severe stenosis all have ratios consistent with subendocardial ischemia. Supply/demand ratios 10. It is concluded that in severe valvar aortic stenosis heart rate is a critical factor in the development of a reduction in the oxygen supply/demand ratio consistent with subendocardial ischemia. Exercise induced tachycardia may be useful in identifying patients with severe valvar aortic stenosis and borderline ischemia who have normal T waves at rest.

Sotalol is a beta-adrenergic blocker that also prolongs action potential duration and myocardial refractoriness over the short term (class III effect). Its short-term antiarrhythmic effects were compared with those of metoprolol, which has neither short-term class III nor membrane-stabilizing action, on reentrant ventricular arrhythmias produced by programmed stimulation in 17 conscious dogs 3 to 8 days after myocardial infarction. Ventricular arrhythmias were prevented or significantly slowed by sotalol in 11 of 19 studies (58%) compared with in one of 14 (7%) studies with metoprolol. Sotalol prolonged refractoriness in the infarct zone, measured from an implanted "composite" electrode, by 41 +/- 45% (mean +/- SD, p less than .01), which was significantly greater than the increases it produced in effective refractory period of the normal ventricle (14.0 +/- 5.5%) or QT interval (12.5 +/- 7.8%). Metoprolol had no effect on infarct-zone refractoriness. Sotalol differentially increases refractoriness in potential reentry circuits in ischemic myocardium. Its antiarrhythmic effect in this model is not due to beta-blockade, and is presumably related to prolongation of action potential duration.

Since May 1957 cardiac catheterization has been carried out in 46 patients with pulmonic stenosis and an intact ventricular septum (pulmonic stenosis) and 42 patients with pulmonic stenosis and a right-to-left shunt through a septal defect (tetralogy of Fallot). Right atrial pressures were usually higher in pulmonic stenosis. Average pulmonary arterial and left atrial mean pressures were similar in the 2 groups, as were the pulmonary blood flows. Although significant differences between right ventricular and systemic arterial systolic pressures may be demonstrated in tetralogy of Fallot, simultaneous right ventricular and left ventricular or aortic systolic pressures were always within a few mm. Hg of each other. The postectopic right ventricular systolic pressure was always at least 10 mm. Hg above its previous level in pulmonic stenosis, whereas in tetralogy of Fallot it almost never exceeded its previous level by more than 10 mm. Hg. All patients with tetralogy of Fallot had flat-topped right ventricular pressure curves, whereas 31 of 46 patients with pulmonic stenosis had triangular right ventricular pressure curves. The phonocardiogram was found to be among the most useful tools in differentiating the 2 groups. Auscultatory phenomena of severe pulmonic stenosis with a widely split second heart sound, late crescendic diamond-shaped systolic murmur, and persistence of this murmur beyond the sound of aortic closure differed strongly from tetralogy of Fallot of equal severity. At cardiac catheterization proof of the presence of a ventricular septal defect may be gained by passing the catheter through it. If this is not done, the presence of a ventricular septal defect may be strongly inferred if the right ventricular pressure curve has almost parallel sides and a flat or rounded top, if the right ventricular systolic pressure is near that in the systemic circulation, and if it does not rise after ectopic beats more than 10 mm. Hg above its previous level. For greater certainty in diagnosis indicator-dilution curves or angiocardiography should be done. The accurate preoperative diagnosis of the presence or absence of a ventricular septal defect is extremely important, for at open-heart operation it is essential not to miss the ventricular septal defect after completely relieving the obstruction to right ventricular outflow; it is just as important not to do unnecessary right ventriculotomies.

It is difficult to make prognoses and decisions on therapy of individuals with congenital heart disease (CHD) and plan efficiently for medical services and training programs because studies on the incidence and relative frequency of different types of CHD at birth, mortality rates, times of death, and prevalence rates in children and adults are incomplete or unrepresentative. The present study assesses the merits of previous surveys and attempts to indicate the best information about these rates. Specific attention has been directed to data on ventricular septal defect (VSD), with an estimated incidence of at least 20/10,000 live births; about 10% of these children died before 15 years of age. There should thus be about 18/10,000 surviving school children with VSD, yet the most intensive school surveys show only about half this number. This supports the suggestion that there is a high incidence (perhaps 50%) of spontaneous closure of VSD during childhood. Spontaneous closure may also occur frequently after childhood, but this conclusion needs to be confirmed by better surveys.

Ten patients with pulmonic stenosis are reported who, despite having right ventricular systolic pressures much above systemic levels, had ventricular septal defects proved at operation in 9 and suggested by indicator-dilution curves in the other. Because of the high right ventricular systolic pressures these patients had clinical and electrocardiographic evidence of marked right ventricular hypertrophy and were initially thought to have severe pulmonic stenosis with an intact ventricular septum. One patient had an almost single ventricle with pulmonic and aortic stenosis. In all the others the right ventricular systolic pressure failed to equilibrate with pressures in the systemic circulation. In 2 patients this was probably due to obstruction of the ventricular septal defect by the septal leaflet of the tricuspid valve. In the others the suggestion that the ventricular septal defect was closed off during systole by muscular contraction was confirmed in 1 patient at operation. This syndrome has been reported in other series and may occur in as many as 5 to 10 per cent of patients diagnosed as having severe pulmonic stenosis. It is important to know before operation whether or not there is a ventricular septal defect associated with the pulmonic stenosis, for this influences the decision about doing a right ventriculotomy. The preoperative diagnosis of this variant of tetralogy of Fallot may be made by phonocardiography and cardiac catheterization.

Sixty-one critically ill infants with congenital heart disease had operative treatment within 6 weeks of birth. Anatomic and physiologic diagnoses were established preoperatively by cardiac catheterization and angiography in all. A variety of palliative or corrective operations was performed to relieve specific hemodynamic burdens. Thirty-seven (61%) survived hospitalization, but 18 had one or more postoperative complications. At the present time, 29 (48%) are alive 9-45 months after operation. Although operative mortality and morbidity rates are high, none of these patients was expected to survive early infancy without operation.

Acute right ventricular (RV) hypertension and failure occur clinically. In this study we examined the mechanism of RV failure. Adult dogs were studied acutely under anesthesia; dogs were instrumented for measurement of pressures and right coronary artery blood flow. Myocardial blood flow and cardiac output were determined with radionuclide-labeled microspheres, and the presence of ischemia was determined by biochemical analysis of ventricular biopsies. RV hypertension was produced by constricting the pulmonary artery and was increased until RV failure occurred, as evidenced by decreased aortic pressure and cardiac output and increased RV end-diastolic pressure. With increasing RV systolic pressure, RV myocardial blood flow failed to increase in proportion to demand. At the onset of RV failure, there was no reactive hyperemia of right coronary flow compared with control, indicating the absence of further coronary vascular reserve; biochemical analysis demonstrated that the RV free wall was ischemic; the LV free wall was not. Infusion of phenylephrine raised aortic pressure and hence, myocardial perfusion pressure; RV failure reversed as shown by decreased RV end-diastolic pressure and increased cardiac output and RV systolic pressure; reactive hyperemia of right coronary flow was restored and the biochemical indexes of ischemia were reversed, demonstrating that ischemia is the cause of failure in acute RV hypertension.

Increased inspiratory right ventricular filling with a consequent shift of the ventricular septum to the left, thereby decreasing left ventricular filling, has been suggested as a mechanism of pulsus paradoxus. We recently saw a patient with tricuspid atresia and hypoplastic right ventricle who developed pulsus paradoxus. His course may help clarify the contribution of this mechanism.

Pulmonary vascular disease, a serious complication of many congenital heart lesions, has three major components: increased muscularity of small pulmonary arteries; intimal hyperplasia, scarring and thrombosis; and reduced numbers of intraacinar arteries. The muscularity is due to increased stress on the vessel wall, and is reversible. The intimal changes may be due to endothelial damage, causing an imbalance between prostacyclin and thromboxane A2 production and leading to local platelet aggregation. This, in turn, may stimulate migration and division of myointimal cells, which thicken the intima and lead to scarring and thrombosis. Extensive intimal changes are probably irreversible, but the possibility of preventing them by use of agents that inhibit platelet aggregation needs to be considered. The mechanism of a decrease in numbers of intraacinar arteries is unexplained. The potential for growth of new vessels after corrective surgery of the cardiac defect is an important factor in restoring pulmonary vascular resistance to normal. Available evidence suggests that this growth potential is reduced after 2 years of age and argues for early surgical relief of pulmonary vascular stresses.

Absent or hypoplastic pulmonary valve is an uncommon condition usually associated with a ventricular septal defect and an obstructive pulmonary valve ring. Secondary abnormalities involving the pulmonary arteries and major bronchi are common, and many result in severe pulmonary complications. Eight patients with absent pulmonary valve, ventricular septal defect and obstructed pulmonary valve ring are herein described. The clinical features, cardiac catheterization, cineangiographic and postmortem findings are presented. Possible fetal hemodynamics and their influences are discussed, as are postnatal hemodynamics and their clinical consequences. Patients with this combination of lesions have been regarded as having a very poor prognosis, and recent publications have advocated early surgical intervention; however, most published series are small, and only 106 cases have been documented. These cases have been reviewed for clinical and anatomic features as well as an overview of prognosis and results of surgical intervention.

Systolic pressure differences of 6 to 45 mm Hg were found between the main and branch pulmonary arteries in 37 of 242 infants undergoing diagnostic cardiac catheterization. Eleven of these 37 infants were restudied, and all had lost the pressure difference regardless of the underlying cardiac defect. A similar pressure difference was noted in lambs studied at thoracotomy with direct measurement of main and branch pulmonary arterial pressures. Increasing pulmonary blood flow caused a rise in pressure differences and also evoked a difference in some older lambs when none was originally present. Cineangiography in infants with a pressure difference showed no discrete narrowing or poststenotic dilatation of the pulmonary arteries. The main pulmonary artery was a large domed structure from which relatively small right and left branches arose at sharp angles from the inferior and posterior surfaces. The size, disparity, and angulation probably caused turbulence with, at times, a loss of pressure. Systolic flow murmurs may be common. In assessment of pulmonary vascular resistance, it is therefore important to recognize that a portion of the total pressure drop across the lungs after birth reflects maturational changes of the larger pulmonary arteries as well as of the muscular arterioles.

Severe valvar aortic stenosis (VAS) and supravalvar aortic stenosis (SVAS) each may cause left ventricular (LV) subendocardial ischemia and infarction, even with patent coronary arteries. LV ischemia in VAS has been related to reduced coronary perfusion relative to raised metabolic requirements, whereas this mechanism of ischemia has not been widely accepted in SVAS because coronary perfusion pressure is higher than normal. LV subendocardial coronary blood flow (CBF) occurs predominantly in diastole and a diastolic pressure-time index (DPTI) was used to estimate it. LV oxygen requirements were estimated from the systolic pressure-time index (SPTI). The ratio DPTI:SPTI (supply:demand) was evaluated as an estimate of the adequacy of subendocardial flow. SVAS was produced acutely in nine dogs and phasic left CBF and distribution of CBF to the LV myocardium were measured. Although mean CBF always rose with aortic constriction, flow in diastole fell from a control of 80% to 34% ( P < 0.001) and LV myocardial flow distribution became inhomogeneous with the proportion of flow to subendocardial muscle decreasing 63% ( P < 0.001). Departure from the normal homogeneous flow distribution to the LV was predictable from the ratio DPTI:SPTI; values below 0.7 were always associated with relative subendocardial underperfusion. DPTI:SPTI ratios in two patients, one with severe VAS (0.25) and one with SVAS (0.39) were well below values obtained in 18 control patients (1.03 ± 0.23), and were similar to the ratios in dogs with SVAS (0.27 ± 0.08). Both patients had ECG changes suggesting LV ischemia. The mechanism of subendocardial ischemia is thought to be the same in both types of stenosis and its presence is predictable from pressure measurements available at cardiac catheterization.