Frank W. Kroetz

Effect of the Thyroid State on Myocardial Contractility and Ventricular Ejection Rate in Man

Although the circulatory changes in various thyroid states are well known, the alterations of myocardial contractility of hypothyroidism and hyperthyroidism have remained controversial. The changes in the length of the ejection time (ET) and isovolumic contraction time (ICT) are used as indicative of alterations in inotropic state of the myocardium. Isovolumic contraction time, ejection time, and pre-ejection period were measured externally in 10 normal, 13 hyperthyroid, and five hypothyroid subjects. Cardiac outputs, mean rate of left ventricular ejection index, and predicted ejection times were calculated. More shortening of ICT and ET in hyperthyroid and more prolongation of these intervals in hypothyroid subjects than could be attributed to other factors were interpreted as indicative of increased and decreased myocardial contractility, respectively. Catecholamine depletion in hyperthyroid subjects with adequate administration of intramuscular reserpine induced no changes in cardiac output and oxygen consumption and caused no alteration in different phases of ventricular systole; consequently it had no effect on enhancement of hyperthyroid myocardial contractility.

True isovolumic contraction time

Abstract The relation of true isovolumic contraction time with two external indexes of ventricular performance was studied in intact anesthetized dogs utilizing end-catheter micromanometers in the left ventricle and central aorta. The external indexes studied were (1) the pre-ejection period, the interval from the Q wave of the electrocardiogram to the aortic component of the second sound minus left ventricular ejection time; and (2) external isovolumic contraction time, the interval from the first heart sound to the aortic component of the second sound minus left ventricular ejection time. The isovolumic contraction time was shortened from the resting value by administration of isoproterenol and lengthened by vagal stimulation and administration of methoxamine. Excellent linear correlations were found between absolute values of true isovolumic contraction time and the two indexes during all interventions. When changes from control true isovolumic contraction time were plotted against similar changes in the pre-ejection period and external isovolumic contraction time, better linear correlations were found. In addition, the inverse relation between true isovolumic contraction time and the first derivative of left ventricular pressure (dp/dt) in the intact animal was reflected by the pre-ejection period and external isovolumic contraction time. The two external indexes were therefore shown to reflect reliably changes in true isovolumic contraction time. When changes in diastolic blood pressure are considered, and with only small alterations occurring in left ventricular end-diastolic pressure, they give useful information about changes in ventricular performance including an estimation of changes in left ventricular dp/dt. They relate directly to contractility only when diastolic pressure remains constant.

Left Atrial Rhythm Experimental Production in Man

Various criteria have been proposed for the diagnosis of left atrial rhythm (LAR) in previous experimental and electrocardiographic studies. Differentiation from A-V junctional rhythms remains ill-defined. In order to assess the left atrial (LA) P wave and to define LAR, the P wave and loop were studied by direct LA pacing in 11 patients undergoing diagnostic transseptal left heart catheterization. Experimental LAR produced changes in P-wave configuration and polarity. These changes were most obvious in lead V1 and indicated reversal of the sequence and direction of activation with left atrial preceding right atrial depolarization. A typical dome and dart P wave occurred in two studies. P-wave configuration in leads I and V6 was highly variable; frequent orientation of the LA P vector within the transitional zone of the horizontal electrical axis was thought to be responsible. The LA P loop showed reversal of the direction of inscription of the initial forces, indicating a change in the pattern of atrial depolarization. Stimulation of the appendage produced left-to-right spread of atrial depolarization, whereas activation of the main body was directed primarily anteriorly. Impulse formation in the right side of the posterior wall was usually directed from right to left. When the postero-inferior area was activated, the anterior P vector became directed superiorly, and resembled that of coronary sinus rhythm (CSR) in the frontal plane.This study indicates that the P wave in lead V1 is most important in the diagnosis of LAR; inversion of the P wave in lead V6 is not essential. LAR can usually be differentiated from CSR, since in the horizontal plane, activation of the LA main body is more anteriorly directed than the spatial P vector of CSR.

The Effect of Atrial Contraction on Left Ventricular Performance in Valvular Aortic Stenosis

The instantaneous response of the left ventricle to loss or recovery of effective atrial contraction was studied in 12 patients with valvular aortic stenosis by producing A-V dissociation by electrical pacing of the ventricles so that some ventricular contractions were preceded by an effective atrial contraction while others were not. A conventional hydraulic formula relating size of the aortic valve orifice, pressure gradient, and flow was used to estimate beat to beat stroke volume. A properly timed atrial contraction augmented left ventricular performance in all patients, increasing stroke volume index from 14 to 55% (mean, 27%) and stroke work from 17 to 85% (mean, 45%).The contribution of atrial contraction to integrated cardiac performance was studied in six of the same patients by comparing cardiac performance with right atrial pacing and right ventricular pacing. With right atrial pacing, each ventricular contraction was preceded by an atrial contraction, while with right ventricular pacing many ventricular contractions were not preceded by atrial contraction. Right atrial pacing increased cardiac index in four of six patients: The mean increase for the total group was 13% and the mean increase in left ventricular minute work index was 17%.Although atrial contraction was capable of augmenting left ventricular performance in all patients studied, loss or recovery of effective atrial systole did not always alter integrated cardiac performance. Factors influencing atrial contribution remain poorly understood. Atrial contraction does not appear to have an unusual effect on the performance of the hypertrophied left ventricle.

Candida albicans endocarditis successfully treated with amphotericin b.

MONILIAL endocarditis is almost uniformly fatal. The case reported below was successfully treated with amphotericin B. The patient has remained well in the twenty-one months since the termination of the amphotericin B therapy. In 1958 Merchant et al.,1 in a review of the literature, found 11 proved cases of monilial endocarditis, all of which ended fatally.2 3 4 5 6 7 8 9 10 11 12 Twelve additional fatal cases have been reported since this review.13 14 15 16 17 18 Louria and Dineen17 described a case of disseminated moniliasis with endocarditis that was successfully treated with amphotericin B. Their patient underwent a series of laparotomies and was chronically ill. During recovery from surgery widespread .xa0.xa0.

The experimental production of coronary sinus rhythm in man

Abstract Coronary sinus rhythm was produced experimentally in 8 patients, utilizing the bipolar pacing catheter in the os of the coronary sinus. The distinction between coronary sinus rhythm and upper nodal rhythm is again seen to be an arbitrary one. The value of the P-R interval in coronary sinus rhythm and its relation to A-V block is discussed.

Myocardial Metabolism in Cyanotic Congenital Heart Disease

Eight normal subjects and 7 cyanotic patients, 5 with tetralogy of Fallot, and 2 with Eisenmenger’s syndrome, were studied with coronary sinus catheterization. In the resting state mean coronary flows were lower and myocardial oxygen extractions higher in cyanotic patients so that myocardial oxygen consumption was the same in the 2 groups. Coronary flows appeared to be inversely related to hematocrit in the cyanotic group. Myocardial lactate balance was similar in the 2 groups, but coronary sinus lactate/ pyruvate ratios were frequently higher than arterial ratios in the cyanotic group. The subjects were stressed with supine leg exercise or with an isoproterenol infusion. In cyanotic subjects exercise caused a fall in arterial oxygen and myocardial oxygen extraction so that oxygen delivery tended to be more dependent upon coronary flow. Myocardial oxygen delivery appeared adequate during stress in cyanotic patients and lactate and pyruvate analysis failed to show evidence of myocardial hypoxia. Between the 3rd and 8th min of exercise, cyanotic patients continued to have falling arterial oxygen values and rising arterial lactate and lactate/pyruvate ratios indicating that they had not reached steady metabolic state. Myocardial glucose and free fatty acid uptake were similar in the 2 groups. These results indicate that although the mechanisms of oxygen delivery to the myocardium may differ in normals and some patients with cyanotic congenital heart disease, left ventricular myocardial oxidative metabolism is intact even in the presence of hypoxemia.

EFFECT OF RESPIRATION ON PANSYSTOLIC REGURGITANT MURMURS AS STUDIED BY BIATRIAL INTRACARDIAC PHONOCARDIOGRAPHY.

Abstract Twelve patients have been studied in an attempt to delineate the effect of continuous accentuated respiration on the intracardiac murmurs of mitral and tricuspid insufficiency. External phonocardiographic and stethoscopic observations have been made in order to demonstrate the correlation between internal and external acoustical events and to derive some knowledge regarding the validity of Carvallos observations. Of the eleven patients with mitral insufficiency, eight were studied by left atrial phonocardiography. In none did respiration result in an altered intensity of the murmur of mitral insufficiency when recorded in the left atrium. In eight patients with mitral insufficiency and associated tricuspid insufficiency, marked inspiratory augmentation of the regurgitant murmur was recorded in the right atrium. Thus, the two premises upon which Carvallos sign rest are valid, namely, that respiration does not affect the intensity of the murmur of mitral insufficiency while inspiration results in augmentation of the tricuspid regurgitant murmur in every case when these murmurs are recorded at their source. The external phonocardiogram clearly demonstrated inspiratory augmentation of the tricuspid regurgitant murmur in four patients with tricuspid insufficiency. A less obvious but similar response was noted in an additional three patients. However, stethoscopic examination of these seven patients clearly demonstrated inspiratory augmentation of the systolic regurgitant murmur in every case. Thus, careful auscultatory examination may be more reliable than external phonocardiography in detecting changes in intensity of the tricuspid regurgitant murmur. In the eighth case of combined mitral and tricuspid insufficiency, neither the external phonocardiogram nor the stethoscopic observation demonstrated external augmentation of the regurgitant murmur. In this instance, the diagnostic value of intracardiac phonocardiography is clearly demonstrated. In addition, observations concerning the importance of selective augmentation of the regurgitant murmur in the diagnosis of tricuspid insufficiency have been discussed and an additional pitfall of confusing a long ejection murmur with a regurgitant murmur has been demonstrated. It is apparent from these studies that selective inspiratory augmentation of a pansystolic regurgitant murmur, when present, continues to be a useful sign of tricuspid insufficiency.

Congenital pulmonary valvular insufficiency complicating tetralogy of fallot: Intracardiac sound and pressure correlates

Abstract A case of tetralogy of Fallot with organic pulmonic insufficiency is presented with confirmation by cardiac catheterization with angiocardiography and simultaneous intracardiac phonocardiography and pressure measurements. Simultaneous intracardiac sound and pressure correlates proved valuable in elucidating the mechanism for the production of the unusual murmur of organic pulmonic insufficiency. The murmur occurs simultaneously with the low diastolic pressure gradient between the pulmonary artery and the right ventricle during low velocity regurgitation, and is delayed in onset following aortic closure. The silent interval in this study represents the period during isometric relaxation of the hemodynamically functioning “single” ventricle and during early diastole when the respective systolic and diastolic gradients are insufficient to generate audible sound. This case occupies a unique position in the spectrum of pulmonic insufficiency, with hypertensive pulmonic insufficiency and the Graham Steell murmur at one end, and nonhypertensive, isolated congenital pulmonic valvular insufficiency at the other end.

The diagnosis of acute circulatory failure: Shock and syncope

Abstract Shock, syncope and even sudden death are manifestations of acute circulatory failure. Shock is a clinical complex resulting from a circulatory transport system which is inadequate to support tissue metabolic needs. The typical clinical picture is one of a patient manifesting distrubed mentation, pallor, diaphoresis, cool, occasionally cyanotic skin, paradoxical pulse, absence of Korotkoff sounds with or without hypotension, tachycardia and collapsed veins. Advanced shock may exist in the absence of some of these findings. In these unusual cases, hemodynamic evaluation of the pathophysiology seems advisable. Syncope is a sudden loss of consciousness usually due to interruption of cerebral blood flow. It may be caused by one or a combination of factors including cardiac, circulatory, metabolic, neurologic or psychic disturbances. An etiological diagnosis can usually be made with a careful history and physical examination, together with a few simple bedside tests. In some instances special tests such as electroencephalography, electrocardiography, or metabolic studies may be necessary to confirm the suspected etiology.