James J. Leonard

Direct Correlation of External Systolic Time Intervals with Internal Indices of Left Ventricular Function in Man

Direct correlation of externally measured systolic time intervals with internally measured indices was obtained using catheter-tip micromanometers in six patients who had normal coronary arteriograms. Simultaneous recordings were made of central aorta and left ventricular pressure, maximum rate of rise in left ventricular pressure (dp/dt), external carotid pulse, external and internal sound, and electrocardiogram. Acute interventions were used to vary the indices by a variety of mechanisms including changes in contractility, preload, afterload, and heart rate. The initial values and the changes in these values produced by acute interventions are identical for left ventricular ejection time (LVET) whether measured externally (range 175 to 385 msec) or internally (range 169 to 392), r = 0.99. Although the absolute values differed for internally measured isovolumic contraction time (internal ICT), externally measured ICT, and preejection time (PEP), there was good linear correlation between the changes obser...

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.

Reflex heart rate control in man.

Abstract In summary, the relative roles of the parasympathetic and sympathetic nervous systems in baroreceptor reflex heart rate control have been studied in eleven normal young men. These data have been compared to the results of similar studies in a heart transplant subject. The findings indicate that in normal conscious men, reflex parasympathetic stimulation and withdrawal primarily control heart rate responses to changes in blood pressure. Beta-adrenergic activity, while influencing basal heart rate plays little, if any, role in baroreceptor reflex heart rate control. The Valsalva maneuver may be used as an effective measure of parasympathetic integrity but it may not be used as a reliable index of sympathetic integrity. The pharmacologically denervated heart is similar in terms of reflex responses to the surgically denervated heart in conscious man. The heart rate responses to Valsalva maneuver, amyl nitrite inhalation, and phenylephrine infusion should be reliable indices of parasympathetic reinnervation of the transplanted heart should reinnervation occur.

Hyperthyroidism as a high cardiac output state.

Abstract Hyperthyroidism is the most common cause of hyperkinetic circulatory disease. Thyroid hormone probably produces this high output state by inducing vasodilatation of the circulatory beds supplying muscle and skin. This hormone induced effect lowers the total peripheral resistance which increases cardiac output. The heart responds to the low peripheral resistance by accelerating the heart rate and augmenting stroke volume. In addition, the thyroid hormone enhances ventricular contractility. These cardiac responses are generated by a direct effect of thyroid hormone on the cardiovascular system and are essentially independent of autonomic influence. Thyrotoxicosis can induce congestive heart failure without complicating influences. Present information does not allow a full explanation of this phenomenon, but improper utilization of energy by an oversized heart may be a contributing factor. Adequate treatment of this high cardiac output state, whether or not it is accompanied by congestive heart failure, cannot be properly accomplished without vigorous treatment of the underlying endocrine disorder. Most adjunctive therapeutic measures presently recommended are of only slight and temporary benefit. Digitalis and diuretics can help control the manifestations of heart failure and should be used when these symptoms are present. Bed rest in a quiet environment is certainly more important in reducing the circulatory load of an already overstressed heart. Reserpine and other autonomic-blocking drugs cannot be recommended on a rational scientific basis. There is little evidence that these agents have any salutory effect on the circulatory disease of hyperthyroidism.

Familial Heart Block and Sinus Bradycardia Classification and Natural History

Abstract Study of 1 family and review of 18 revealed a spectrum of inherited bradycardia from pure familial heart block (10 families), through combined familial heart block and sinus bradycardia (6 families), to pure familial sinus bradycardia (3 families). Familial heart block occurs in 2 forms, congenital (8 families) and of adult onset (8 families). Either may be associated with sinus bradycardia. Complete heart block appeared to be congenital in all 20 affected members of families with congenital block, resulting in 10 deaths, 8 within the first 10 days of life. A narrow QRS complex did not improve the prognosis of members with complete heart block. Of 17 patients with familial complete heart block of adult onset, 8 died from heart block at a mean age of 47 years. Since partial block preceded complete block in 11 subjects who had prior electrocardiograms, it may be possible to identify family members in whom complete block is likely to develop. In families with pure sinus bradycardia, sinus bradycardia was inherited with a high degree of penetrance. It resulted in nodal rhythm in all 16 affected members and in atrial fibrillation in 9. Atrial fibrillation may be protective in these circumstances, not requiring cardioversion. Sinus bradycardia in families with heart block was usually benign. Various features of formation of the conduction system may provide an embryologie basis for the combined inheritance of sinus nodal disease and heart block. Although the lesions may reside in the sinoatrial node and atrioventricular node-His bundle junction, pathologic correlates of the familial bradycardias require further elucidation.

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.

Left Atrial Transport in Mitral Stenosis

Active left atrial transport was examined acutely in five patients with mitral stenosis and sinus rhythm. To observe the effect of active left atrial contraction on subsequent left ventricular output, the timing of atrial contraction with respect to ventricular contraction was varied. Atrioventricular (A-V) dissociation produced by right ventricular pacing was used to change continually the relationship of left atrial (LA) to left ventricular (LV) contraction. Measurements of each beat included mitral valve gradient, left ventricular ejection time (LVET), and left ventricular peak-systolic pressure (LVPSP). The diastolic gradient was used to calculate diastolic flow per beat after the area of the stenotic mitral orifice had been previously determined. Calculated diastolic flow increased significantly (24%) as did the parameters of left ventricular output, LVPSP and LVET (P < 0.005 for both), when atrial contraction was optimally timed. Cumulative effects were observed when a series of well-placed or poorly placed atrial contractions occurred. The method documents change in LV output which depends on appropriate timing of LA contraction that may not have been seen with a steady-state approach.

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.