Aaron B. Shaffer

A Reproducible Model of Cardiogenic Shock in the Dog

An animal model of cardiogenic shock has been developed in the intact unanesthetized dog. Selective embolization of the circumflex coronary artery with 0.2 ml of mercury produces infarction of the posterolateral wall of the left ventricle and a shocklike state in the dog which results in death of the animal in 5 to 48 hr. The syndrome of cardiogenic shock in the animal model simulates closely that observed in man. Systemic blood pressure falls sharply (25 to 30% of control) immediately after embolization, remains low for several hours, then slowly increases toward normal, but never reaches preinfarct levels. The left ventricular end-diastolic pressure (LVEDP) remains within normal limits (5 to 10 mm Hg) during the initial hypotensive state, but increases to values above 10 mm Hg during the period of rising systemic pressures. As left ventricular failure begins to develop as evidenced by the rise in LVEDP, the mean pulmonary artery pressure also rises above control values. The cardiac output falls to 40% of control levels following embolization and never recovers. Peripheral resistance rises to compensate for the reduction of cardiac output and remains above control levels. Electrocardiograms indicate an essentially normal sinus rhythm with short runs (5 to 15 beats) of ventricular tachycardia with A-V dissociation. The hypotensive state does not seem to be related to this arrhythmia. Death of the animal appears to be due to progressive failure of the left ventricular pump to maintain cardiac output and systemic pressures.

Muscular contraction in the infundibular region as a mechanism of pulmonic stenosis in man

Abstract Two discrete types of infundibular pulmonic stenosis were differentiated by an analysis of records of cardiac catheterizations in thirteen patients. In three of these, the right ventricular and infundibular pressure tracings had the same phase relationships, rising together, having simultaneous peaks, and falling together. Since the peaks occurred simultaneously it was assumed that the stenotic orifice between the two chambers had a fixed area. This would correspond to the type of infundibular stenosis characterized anatomically by a fibrous band between right ventricle and infundibulum. In the remaining ten cases, the pressures in the two chambers began to rise together, but the ascending limb of the infundibular pressure tracing was cut off prematurely during early systole. Then the right ventricular pressure continued to rise while the infundibular pressure fell. The peaks of the two curves were, therefore, asynchronous. The pressure gradient between the two curves in this group was wider in late than in early systole. It is postulated that the stenosed opening is narrowed or further narrowed as a result of contraction of a muscular ring during early systole. This group may correspond to those with an enlarged or deformed crista supraventricularis. The presence of such a muscular ring was confirmed at surgery in one patient in this group. Analysis of the pressure tracings provided a basis for bidirectional shunting across associated ventricular septal defects.

Pseudocoarctation of the aorta with bicuspid aortic valve and kinked left subclavian artery: A possible cause of subclavian steal

Abstract This case report concerns a 50-year-old woman with clinical features suggestive of left subclavian steal. In addition to a bicuspid aortic valve, pesudocoarctation of the aorta and a kinking of the proximal left subclavian artery were demonstrated angiographically. The association of kinked left subclavian artery with pseudocoarctation has not been reported previously. The possible basis of this association is discussed, as is the relationship between the kinked subclavian artery and the clinical evidence of subclavian steal. Although subclavian steal was not proved angiographically, the conclusion is that the setting favors its hemodynamic and clinical progression.

Coronary arteriovenous fistula with patent ductus arteriosus

Abstract The first case is reported of coexisting coronary arteriovenous fistula and patent ductus arteriosus in which both lesions were preoperatively diagnosed and successfully corrected during a single operation. An attempt is made to outline the consequences of, and practical approach to, coronary A-V fistula, based on the experience of the present case and a review of the pertinent literature. The problems inherent in the recognition of a patent ductus arteriosus in the presence of a hemodynamically dominant coronary A-V fistula are discussed.

The Apical First Heart Sound as an Aid in the Diagnosis of Atrial Septal Defect

The phonocardiograms of 187 patients were reviewed. In 89 the apical first heart sound was soft or single; in 57 M1 was louder than T1 and in 23 the two components were equal. In only 18 cases was T1 louder than M1 at the mitral area, and of this group five were suspected of having atrial septal defect and 10 were proved cases. In three of the proved cases, this was the only significant finding, the other usual features being absent. Only two proved cases of atrial septal defect in this series did not have T1 louder than M1 at the apex; both had T1 equal to M1. One case suspected of having atrial septal defect also had T1 equal to M1 and in another suspected case the first heart sound was single. This unusual characteristic of the first heart sound may be useful as an indication favoring the diagnosis of uncomplicated atrial septal defect.

Diagnostic value of the left atrial pressure pulse in mitral valvular disease.

Abstract Fifty-four left atrial pressure pulses from 43 patients, all but one of whom had rheumatic mitral valvular disease, were analyzed for features which might be of aid in distinguishing among “pure” mitral stenosis, “pure” mitral insufficiency, or combined significant lesions. All except 5 patients, who presented as classic cases of mitral insufficiency, underwent surgical exploration of the mitral valve. Thirty-six tracings were recorded at surgery and 18 at left heart catheterization. Eleven sets of tracings were obtained under both circumstances in the same patient. These were subjected to additional analysis. Although an end-diastolic gradient across the mitral valve was present in all patients with proved mitral stenosis, such a gradient was also found in half of the patients who clinically or at surgery had pure mitral insufficiency. Numerous features of the contour or pressure level of the left atrial pulse effected poor or no separation of the patients in terms of findings at palpation of the valve. Formulae involving the rate of y descent throughout its entire length were inapplicable because of technical difficulties involved in the accurate measurement of this feature. The most useful feature of the left atrial pulse was the rate of y descent in its initial 0.1 second, related to pressure at the v point (0.1 Ry v ) or to mean left atrial pressure. This resulted in a good separation of patients with mitral stenosis from those without, with the exception of a group of patients with mitral stenosis who had aortic valvular disease in addition. It was found, however, that a degree of mitral stenosis sufficient to significantly slow the rate of the y descent in its initial portion might coexist with a marked degree of mitral insufficiency. The “catheter washout” phenomenon observed during left heart catheterization was of value. This was present in 5 of 8 patients who had mitral insufficiency, with or without mitral stenosis, and in none of 10 patients with mitral stenosis alone. In the 11 patients in whom catheterization and surgical curves from the same individual could be compared, 0.1 Ry v was remarkably constant in 8, despite changes in pressure level, and some alterations in pulse contour. It is concluded that 0.1 Ry v is easily determined and is reproducible. Within its limitations, it is worthy of consideration along with the total picture in evaluating patients for mitral valve surgery.

Right bundle branch system block in healthy young people

Abstract The electrocardiographic patterns of right bundle branch system block was an isolated finding in a group of 4 young individuals who were apparently normal on the basis of clinical and hemodynamic evaluation. Prolongation of the right ventricular electrical-mechanical interval provided evidence that the electrocardiographic abnormality was attributable to a conduction defect in the right side rather than to right ventricular hypertrophy or to a physiologic variant of contour. The significance of the electrocardiographic abnormality in such cases is discussed. It is concluded that the finding of an “isolated” right bundle branch system block in a young and apparently healthy individual cannot, of itself, be taken to indicate prima facie evidence of organic heart disease.

Truncal Inversion with Biventricular Pulmonary Trunk and Aorta from Right Ventricle (Variant of Taussig-Bing Complex)

A heart is described pathologically in which the aorta emerged from the right ventricle and was not related to the ventricular septal defect, while the pulmonary trunk emerged from both ventricles, but mostly the right, and was related to the ventricular septal defect. This Taussig-Bing arrangement of vessels was coupled with the presence of the aortic orifice to the left and the pulmonic orifice to the right, which is an inverted position. The anatomic concept of inversion is an abnormality in position from the standpoint of laterality. A careful study of the conal regions of the left and right ventricles showed that those regions were not inverted. Therefore, this represents a case of Taussig-Bing complex with exclusively truncal inversion, which is unique. This may be explained on the basis of opposite metameric contribution to the development of the truncus.

Estimation of Ventricular Volumes by a Constant Infusion Indicator Dilution Technique

A constant infusion indicator dilution method for estimating ventricular volumes is introduced and its feasibility demonstrated. Using this method, volumes can be calculated by two different approaches, one of which does not assume effective distribution of indicator throughout end diastolic volume (EDV). This offers a means of assessing the effects of nonmixing on the form of the stepwise rise in concentration of the constant infusion curve, which has relevance to the basically related stepwise decline in concentration following sudden injection of indicator. It is suggested that the degree of mixing of diastolic venous return in the previous end systolic volume (ESV) is basic to the distribution of indicator introduced into the ventricle. If mixing is incomplete, the site of origin of stroke volume (SV) from EDV is an important factor in determining the form of an indicator dilution curve and the EDV as calculated from ratios of successive concentrations. The possible range of effects of nonmixing on the form of the constant infusion curve for ventricular volume, as derived from a mathematical model, is outlined. End diastolic volumes, as estimated from ratios of successive concentrations in a series of constant infusion indicator dilution curves obtained experimentally, are tabulated, and as a group do not differ materially from those obtained by the sudden injection method.

Left ventricular constriction due to myocarditis in a child

Abstract A case (followed for six years) is reported of an 8 year old child with syncopal episodes presumed due to acute left ventricular failure. Electrocardiograms showed progressive left ventricular hypertrophy while radiographically there was evidence of left atrial and right ventricular enlargement. Hemodynamic data obtained at left heart catheterization revealed markedly elevated mean left atrial and left ventricular end-diastolic pressure. In the absence of gross left ventricular enlargement this suggested a constrictive phenomenon involving the left ventricle. The etiology of the latter was found at postmortem examination to be due to chronic myocarditis and coronary vasculitis.