Showing papers by "Eugene Braunwald published in 1968"

Idiopathic Hypertrophic Subaortic Stenosis Clinical Analysis of 126 Patients with Emphasis on the Natural History

Abstract: While considerable information concerning the hemodynamic and angiographic features of idiopathic hypertrophic subaortic stenosis (IHSS) is available, data concerning the natural history of the disease are limited. The clinical courses of 126 patients with hemodynamically documented IHSS, examined repeatedly for up to 12 years, were analyzed. The older patients tended to be more severely symptomatic. Although the course was extremely variable, the patients who were asymptomatic initially tended to remain so, while those who were more disabled generally deteriorated, died, or improved spontaneously. Bacterial endocarditis occurred in three patients. Ten patients died as a consequence of the natural history of IHSS; six of these deaths were unexpected. Sudden deaths occurred usually in patients with no or mild obstruction, and in patients with both the familial and sporadic forms of the disease. Atrial fibrillation was observed in 8% of the patients, and abnormalities of atrioventricular conduction, in 30%....

Oxygen consumption of the heart: Newer concepts of its multifactoral determination

Abstract: The development of tension and the contractile state of the myocardium are the primary determinants of myocardial oxygen consumption. Recognition of these two factors and their interrelation has served to explain a number of apparent discrepancies in the literature. Other factors, including basal myocardial oxygen consumption, activation energy and external work, also contribute to the myocardial oxygen consumption, but to a relatively minor extent. An understanding of these general principles should permit a more rational consideration of the determinants of myocardial oxygen consumption and the implications of these factors in disease states.

A comparison of the effects of vasodilator stimuli on peripheral resistance vessels in normal subjects and in patients with congestive heart failure

Abstract: A B ST R A C T The objective of this investigation was to characterize the mechanism of peripheral vasoconstriction observed in heart failure and to determine whether it can be attributed to the augmented sympathetic nervous activity, characteristic of this state. The response of the resistance bed in the forearm after release of inflow occlusion (reactive hyperemia), to hand exercise, and to local heating and the response of the calf resistance vessels to arterial occlusion and intrararterial sodium nitrite and phentolamine were studied in 23 patients with congestive heart failure and 21 normal subjects. In the normal subjects, reactive hyperemia blood flow after varying periods of arterial occlusion greatly exceeded the values observed in patients with heart failure. Local anesthetic blockade and intra-arterial phentolamine did not significantly alter the reactive hyperemia response in heart failure patients, militating against the possibility that increased sympathetic vasoconstrictor activity is responsible for the reduction of this response. Following compensation, the reactive hyperemia response returned toward normal. The striking elevations of the forearm blood flow observed after hand exercise and heating of the forearm in normal subjects were also markedly attenuated in patients with heart failure. Following intra-arterial phentolamine and/or sodium nitrite, peak calf blood flow was still significantly reduced in heart failure.

Control of myocardial oxygen consumption: relative influence of contractile state and tension development.

Abstract: Myocardial oxygen consumption was measured in 11 anesthetized, open-chest dogs in order to compare in the same heart the relative influence on oxygen usage of tension development and the contractile or inotropic state, as reflected in V(max.) the maximum velocity of shortening of the unloaded contractile elements. The isovolumetrically contracting left ventricle was studied with left ventricular volume, heart rate, and systemic perfusion rate controlled. Wall tension, contractile element velocity, and V(max) were calculated. Peak developed tension was increased at a constant V(max) by increasing ventricular volume, and the effect on oxygen consumption was determined. Oxygen utilization was then redetermined at an increased V(max) but at a constant peak developed tension by infusing norepinephrine (0.76 to 7.6 mug/min) and decreasing ventricular volume to match the tension existing before norepinephrine infusion. Oxygen consumption consistently increased with increases in both developed tension and V(max) with the following multiple regression equation relating these variables: myocardial oxygen consumption (mul/beat per 100 g in LV) = K + 0.25 peak developed tension (g/cm(2)) + 1.43 V(max) (cm/sec). These data indicate that the oxygen cost of augmentation of contractility is substantial, can be independent of any change in fiber shortening, and is similar in order of magnitude to the effect of alterations in tension development

Contractile State of the Left Ventricle in Man: Instantaneous Tension-Velocity-Length Relations in Patients With And Without Disease of the Left Ventricular Myocardium

Abstract: The contractile state of the left ventricle in man was analyzed by correlating left ventricular (LV) dimensional changes during contraction determined from cineangiograms, with simultaneous measurements of LV pressure. The mechanical characteristics of ventricular contraction were expressed quantitatively by deriving the extent and velocity of circumferential fiber shortening at the midwall and the time course of LV wall tension (stress); the instantaneous relations between tension, velocity, and length were then examined. In 6 patients without LV disease, wall tension became maximal soon after the onset of ejection, then declined rapidly; in 9 patients with LV disease, tension fell only slightly with continued ejection. The extent of shortening of the minor LV circumference was consistently less in patients with LV disease than in those without such disease. Velocity of circumferential fiber shortening throughout contraction ranged from 0.22 to 1.11 circumferences/sec in patients with LV disease and from 1.66 to 2.71 circumferences/sec in patients without LV disease, at comparable levels of wall tension (137 to 467 g/cm 2 , and 175 to 409 g/cm 2 , respectively). The initial rate of change of velocity of the circumferential fibers at the onset of ejection also was less than in the group without LV disease. The velocity of shortening of the contractile elements at maximum wall tension was 0.11 to 0.87 circumferences/sec in patients with LV disease and 1.46 to 2.04 circumferences/sec in patients without LV disease.

Sympathetic Innervation of the Developing Rabbit Heart: Biochemical and Histochemical Comparisons of Fetal, Neonatal, and Adult Myocardium

Abstract: The sympathetic innervation of the rabbit heart, as a function of age, was studied by measuring the cardiac concentration of catecholamines and observing the anatomic distribution of sympathetic nerves by the monoamine fluorescense technique. The cardiac concentration of norepinephrine in late gestation was quite low; the levels rose progressively after birth to reach adult levels by about three weeks of age. Similar small amounts of epinephrine were found in the hearts at all ages. Substantially less change in adrenal catecholamines accompanied advancing age. At all ages a close correlation was noted between the norepinephrine levels and the histochemical demonstration of sympathetic innervation. Intensely fluorescent, terminal varicosities were observed within large preterminal nerve trunks only in the youngest animals, suggesting that the sympathetic nerves move into, rather than form within, the heart. Chromaffin cells were observed in the hearts at all ages.

Myocardial mechanics in aortic and mitral valvular regurgitation: the concept of instantaneous impedance as a determinant of the performance of the intact heart

Abstract: The effects on myocardial mechanics of acute, artificial aortic and mitral regurgitation were studied in the dog to determine the manner in which the changes in load induced by valvular regurgitation alter ventricular performance. With mitral and aortic regurgitant volumes of approximately the same magnitude as the forward stroke volume, immediate increases occurred in total stroke volume, left ventricular enddiastolic pressure, and peak ejection velocity, whereas contractility remained unchanged. Although calculated myocardial fiber tension rose, the rate of decline of tension during ejection was accelerated with regurgitation due to the more rapid decrease in ventricular size. Average tension therefore decreased relative to average pressure. As a consequence of the increased fiber length and this unloading, contractile element velocity, work, and power were increased. Despite unchanged contractility of the myocardium, the ejection fraction rose with both aortic and mitral regurgitation. When regurgitant beats were compared with control beats at a constant end-diastolic volume, ventricular stroke volume, work, power, and ejection fraction, as well as contractile element velocity, work, and power consistently increased. Thus, reduction of instantaneous impedance to ejection allowed the ventricle to empty further, reducing ventricular wall tension with a resultant increase in the velocity of shortening. External energy output was increased despite unchanged contractility and diastolic fiber length. It is concluded that the impedance to ejection and myocardial fiber tension during ejection govern the velocity and extent of contractile element shortening, and hence affect stroke volume, peak aortic flow rate, and ejection fraction. The alterations of ventricular function accompanying valvular regurgitation can be explained by an evaluation of the effects of these lesions on the instantaneous impedance to left ventricular ejection.

Impaired Rate of Left Ventricular Filling in Idiopathic Hypertrophic Subaortic Stenosis and Valvular Aortic Stenosis

Abstract: In order to determine whether there is any interference with left atrial emptying or left ventricular filling in idiopathic hypertrophic subaortic stenosis (IHSS) and aortic stenosis, the fall in pressure (y descent) of the left atrial v wave following the opening of the mitral valve was analyzed in 27 patients with IHSS and in 22 patients with valvular aortic stenosis, and the results were compared to those for 13 normal subjects and 24 patients with mitral stenosis. The y descent in 0.1 sec and the mean rate of the y descent, as well as the maximum rate of decline, were reduced in all three groups of patients, as compared to those of the normal group. The changes in IHSS were more marked than those occurring in patients with aortic stenosis or mitral stenosis. These findings in patients with IHSS and valvular aortic stenosis appear to result from reduced left ventricular compliance. It is concluded that there is an impairment of left ventricular filling in IHSS and that obstruction to ventricular inflow, as well as to outflow, contributes to the hemodynamic changes in this condition.

Effects of decreased aortic compliance on performance of the left ventricle.

Abstract: URSCHEL, CHARLES W., JAMES W. COVELL, EDMUND H. SONNENBLICK, JOHN Ross, JR., AND EUGENE BRAUNWALD. Effects of decreased aortic compliance on performance of the left ventricle. Am. J. Physiol. 214(2): 298-304. 1968.-The effects of decreased aortic compliance on the performance of the left ventricle were studied in eight dogs by diverting their aortic blood flow through a rigid bypass. Despite unchanged myocardial contractility, judged by the force-velocity relation during isovolumic systole, direction of blood into the rigid byDass 1. caused increases in peak systolic pressure, duration of ejection, and left ventricular end-diastolic pressure. Stroke volume was unchanged and the ejection fraction therefore declined. Peak and integrated myocardial fiber tension rose as a result of the increases in left ventricular pressure and size and because of the increase in tension, circumferential fiber and contractile element velocities decreased. Further, it was shown that at any instant during ejection, the performance of the ventricle was dependent on the interrelations between myocardial fiber length, tension, velocity, and the impedance to ejection. In other experiments, aortic blood flow was diverted through the rigid bypass while preload was held constant. Under these circumstances, stroke volume fell and left ventricular tension rose to a smaller extent than when preload was allowed to rise. These experiments illustrate that the mechanical performance of the left ventricle is altered by the physical characteristics of the arterial tree. Decreased aortic compliance, as occurs during aging in man, therefore increases the impedance to ejection and the tension load on the myocardium.

Operative Treatment in Idiopathic Hypertrophic Subaortic Stenosis Techniques, and the Results of Preoperative and Postoperative Clinical and Hemodynamic Assessments

Abstract: Operations designed to relieve obstruction to left ventricular outflow were carried out in 25 patients with idiopathic hypertrophic subaortic stenosis (IHSS). All of the patients were symptomatic and 23 were in functional classes III or IV. Preoperatively, a systolic pressure gradient within the left ventricle was demonstrated in every patient (average, 102 mm Hg), and the average left ventricular end-diastolic pressure was 19 mm Hg. Six patients had pulmonary hypertension. During cardiopulmonary bypass, the outflow tract of the left ventricle was exposed through an aortotomy. In five early patients only ventriculomyotomy was carried out, but in all subsequent operations myotomy was combined with a limited resection of the hypertrophied muscular tissue. One patient died, apparently of arrhythmia, on the eighth postoperative day, and another 8 months after operation following cerebral thrombosis. In two other patients complete heart block was produced, and they have implanted pacemakers. Twenty-one of the ...

Augmented Sympathetic Neurotransmitter Activity in the Peripheral Vascular Bed of Patients with Congestive Heart Failure and Cardiac Norepinephrine Depletion

Abstract: Since there is an overall augmentation of sympathetic nervous activity in patients with congestive heart failure while adrenal medullary function is normal and neurotransmitter stores are diminished in the heart, investigation was directed to the functional status of adrenergic receptors and available norepinephrine stores in the peripheral vascular beds Blood flow, determined plethysmographically, and vascular resistance, calculated in the calf, following intra-arterial injections of tyramine and norepinephrine in eight patients with congestive heart failure were compared to the responses in nine patients with heart disease but without heart failure The absolute increase in vascular resistance produced by graded doses of norepinephrine was greater in patients with heart failure However, the relative augmentation of vascular resistance produced by any dose of norepinephrine was essentially identical in the two groups In contrast, the vasoconstrictor response to a standard dose of the indirectly acting

Hemodynamic Effects of Diuresis at Rest and During Intense Upright Exercise in Patients with Impaired Cardiac Function

Abstract: Although diuretic therapy appears to improve the exercise capacity of patients with moderately impaired cardiac function, the hemodynamic basis for this improvement is not clear. It is also unknown to what extent the moderate diuresis that often occurs during the first few days of hospitalization contributes to the normal or nearly normal hemodynamic measurements obtained in certain patients with cardiac impairment who are thought clinically to have signs and symptoms of pulmonary congestion. Accordingly, the circulatory response to moderate diuresis resulting in a loss of weight averaging 3.4 kg was investigated in 15 patients with heart disease. At rest in the supine position mean pulmonary arterial wedge pressure fell after diuresis from an average of 24 to 13 mm Hg. Reductions also occurred in mean pulmonary arterial pressure (42 to 26 mm Hg), mean right atrial pressure (9 to 4 mm Hg), and right ventricular end-diastolic pressure (11 to 6 mm Hg). Cardiac output decreased by an average of 20%, mean systemic arterial pressure by 12%, right ventricular stroke work by 44%, and left ventricular stroke work by 25%. Diuresis also caused similar reductions in these values in the sitting position at rest and during mild and intense levels of treadmill exercise. Despite the reductions in cardiac output, all but one of the patients studied achieved substantial clinical improvement from the diuresis. Such improvement probably resulted from the fact that the beneficial effects of lower pulmonary vascular pressures outweighed the deleterious effect of a reduction in cardiac output. Thus, moderate changes in body weight brought about by either fluid retention or fluid loss may result in substantial alterations in circulatory dynamics. These changes, if unrecognized, can lead to considerable confusion when attempts are made to correlate the hemodynamic findings with the degree of cardiac decompensation as judged clinically.

Role of the venous system in baroreceptor-mediated reflexes in man

Abstract: Although baroreceptor stimulation produced by marked alterations in arterial pressure has been shown to produce reflex changes in venous tone in animals, the effects on venous tone in man of altering arterial pressure within the physiologic range have not been clear. In six subjects, venous tone did not change when mean arterial pressure was raised by 25-40 mm Hg, although heart rate fell reflexly by 40%. Venous tone remained constant in 10 subjects when arterial pressure was lowered. This contrasted to the sustained rise in forearm vascular resistance and the persistent tachycardia that occurred. However, 12 subjects continued to respond to these interventions by transient venoconstriction. To eliminate possible emotional influences on venous tone due to the experimental intervention, venous responses were studied before and during general anesthesia in five of these subjects. In contrast to the response before anesthesia, an equivalent fall in arterial pressure during anesthesia no longer evoked a venoconstrictor response. Venous reactivity and the baroreceptor reflex arc remained intact during anesthesia, since venous tone always rose after a deep inspiration, and tachycardia always accompanied the fall in arterial pressure. It is concluded that changes in arterial pressure in the physiologic range in man do not induce measurable reflex alterations in venous tone, and that the increases sometimes seen with decreases in arterial pressure appear to be due to extraneous psychic factors.

Severe Mitral Regurgitation Following Acute Myocardial Infarction and Ruptured Papillary Muscle Hemodynamic Findings and Results of Operative Treatment in Four Patients

Abstract: The results of operative treatment are described in four patients who sustained myocardial infarctions and in whom ruptured left ventricular papillary muscles caused severe mitral regurgitation. All were men between 51 and 69 years of age, and the intervals between myocardial infarction and operation were 3 to 15 months. Each patient manifested severe congestive heart failure. All were in sinus rhythm and had an apical holosystolic murmur and an atrial gallop sound. Three of the four had severe pulmonary hypertension (60 to 80 mm Hg systolic), grossly elevated mean left atrial pressure, and v waves 37 to 45 mm Hg. In all the cardiac index was abnormally low (average 1.8 L/min/m2). In all four patients the mitral valve was replaced with a 2M Starr-Edwards prosthesis. In two of the excised valves, one head of the posterior papillary muscle was infarcted and had ruptured, and in the other two the anterior papillary muscle was similarly involved. All patients survived, and all have derived distinct symptomati...

Effects of Acute Valvular Regurgitation on the Oxygen Consumption of the Canine Heart

Abstract: The effects on myocardial oxygen consumption and mechanics of acute, simulated aortic and mitral regurgitation were studied in open-chest, anesthetized dogs to determine how changes in the mechanical performance of the ventricle alter oxygen consumption. When regurgitation was induced acutely with effective stroke volume (total stroke volume less regurgitant volume) and heart rate held constant, left ventricular end-diastolic volume, total stroke volume, the ejection fraction, left ventricular wall tension, and the extent of shortening of the contractile element and the circumferential fibers all increased. With volumes of regurgitation approaching effective systemic blood flow, oxygen consumption increased only moderately, despite the increases in tension and shortening. When valvular regurgitation was induced while peak ventricular wall tension was held relatively constant, stroke volume doubled and the extent of both contractile element and circumferential fiber shortening increased. Contractile element work in generating tension was unchanged; that which led to fiber shortening increased substantially. Myocardial oxygen consumption did not increase significantly. Thus, marked increases in the efficiency of the contractile elements and myocardial fibers occurred. The low energy cost per unit of work expended in shortening as opposed to that used for tension development therefore allows the excess stroke volume of valvular regurgitation to be maintained at only a small added oxygen cost to the ventricle.

Influence of aortic pressure-induced homeometric autoregulation on myocardial performance.

Abstract: CLANCY, RICHARD L., THOMAS P. GRAHAM, JR., JOHN Ross, JR., EDMUND H. SONNENBLICK,AND EUGENE BRAUNWALD. InJuence of aortic pressure-induced homeometric autoregulation on myocardialperformance. Am. J. Physiol. 214(5) : 1186-l 192. 1968.The alteration in left ventricular (LV) performance following aortic pressure-induced homeometric autoregulation, defined by a fall in LV end-diastolic pressure after a sudden increase in aortic pressure (AP), was assessed in terms of the mechanics of LV contraction. The relative contributions of the accompanying Frank-Starling mechanism and altered contractility, or inotropic state, were measured from the force-velocity (F-V) relations of single isovolumic contractions in a dog right-heart bypass preparation, the relations during homeometric autoregulation and during increased LV filling at constant aortic ‘pressure being compared at equal LV end-diastolic circumferences (LVEDC). Mean values following the homeometric autoregulatory response and during increased LV filling were, respectively : mean AP 113 and 78 mm Hg, LVEDC 20.2 and 20.2 cm, LVEDP 8.7 and 9.9 mm Hg, and stroke volume Il.3 and 18.9 ml. The isovolumic F-V curves were shifted to the right following AP elevation, maximum stress and contractile element velocity being 7.4 and 7.3% larger than during increased LV filling. These results suggest that the increase in LV performance during the steady state after pressure-induced homeometric autoregulation has occurred is associated with a small augmentation of LV contractility, but that the major effect results from the operation of the Frank-Starling mechanism.

Alterations in Regional Pulmonary Blood Flow in Patients with Congenital Heart Disease Studied by Radioisotope Scanning

Abstract: External scintillation scanning of intravenously administered 131I-labeled macro-aggregates of human serum albumin (131I-MAA) was employed to evaluate the distribution of pulmonary arterial blood flow in 61 normal subjects and in 100 patients with various congenital cardiovascular malformations. Intra-aortic administration of 131I-MAA demonstrated that blood flow through subclavian-pulmonary artery anastomoses is directed principally to the lung on the side of the anastomosis; the relative concentration of 131I-MAA in each lung after intravenous injection provided an index of the patency of the anastomosis or of the development of pulmonary atresia or pulmonary hypertension. In contrast to the findings in patients with a patent subclavian-pulmonary shunt, scans obtained from patients with a patent ductus arteriosus did not reveal a separation of the systemic arterial and systemic venous inflows to the lungs. The patency of superior vena caval-right pulmonary arterial anastomosis could be assessed after in...

Digitalis: New facts about an old drug∗

Abstract: Present evidence suggests that the fundamental hemodynamic property of the digitalis glycosides to improve the contractile state of the myocardium rests upon the cellular action of the drugs to potentiate excitation-contraction coupling. This effect appears to be mediated by glycoside-induced enhancement of the concentration of calcium ions in the endoplasm surrounding the myofibrils at the time of cardiac contraction. It is likely that the arrhythmiaprovoking properties of digitalis are related to the loss of intracellular potassium and the inhibition by the drug of the membrane pump ATPase system required for maintaining intracellular potassium concentrations. The postulation that the inotropic and certain toxic actions of digitalis are mediated by different mechanisms is helpful clinically since the two properties of the glycoside can be dissociated by the administration of potassium. The over-all metabolic and hemodynamic effects of the glycosides are closely dependent on the state of the circulation at the time the agent is employed. Thus, the drugs have the direct property of increasing the oxygen utilization of the myocardium while producing their inotropic effect, manifested by a rise in the velocity of contraction, and in this respect they possess no unique ability to improve the efficiency of the heart. However, this action to increase myocardial oxygen requirements is masked and offset in the presence of heart failure, since the reduction of myocardial systolic wall tension by the drug diminishes the oxygen demand of the heart more than the direct inotropic effect tends to augment it. Similarly, the alterations of cardiocirculatory dynamics produced by the drug are related to the hemodynamic condition of the patient. Thus, in the absence of heart failure, the inotropic effect is not translated into an increase in cardiac output. In contrast, in patients with congestive heart failure, the improvement of the contractile state of the failing myocardium by the glycoside elevates the cardiac output to a marked degree, allowing a diminution of the elevated adrenergically-induced arteriolar resistance and venous tone and a shift of venous blood out of the portal into the systemic venous compartment. Thus, digitalis possesses both direct and indirect cardiac and extracardiac actions, and the over-all alterations of circulatory dynamics depend on the hemodynamic status of the patient.

Calcific Pulmonic Stenosis

Abstract: Seven patients are described in whom calcium deposits occurred in stenotic pulmonary valves. In five the calcific deposits were visible on chest roentgenogram. Survival into adulthood and severe pulmonic stenosis appeared to be the prerequisites for the development of large deposits of calcium in this valve.

Fundamental mechanisms in congestive heart failure

Abstract: The state of congestive heart failure is associated with clear-cut depressions of intrinsic myocardial function. The production and storage of energy in the failing heart are normal, and although the failing heart converts energy to work at a normal efficiency, the rate of this process is decreased. This decreased rate may be caused by a reduction of the activity of myofibrillar adenosine triphosphatase, which in turn may be causally related to the depression of cardiac function. In considering the efficiency of the failing heart, the translation of myocardial tension into useful circulatory work must also be considered. In this case, efficiency could be reduced by geometric factors such as ventricular size and shape and wall thickness or asynchrony of contraction. Finally, the failing heart must depend on supporting mechanisms, such as adrenergic stimulation, for normal function, and in the presence of reduced intrinsic norepinephrine stores, the presence of circulating catecholamines may be important.

Integrity of Energy Stores in Cat Papillary Muscle

Abstract: Although isolated cat papillary muscles have proved useful in a variety of physiologic and pharmacologic studies, the energy integrity of this preparation has been questioned. Accordingly, papillary muscles (avg diam = 1.3 mm) were either placed in oxygenated Krebs solution for 1 hour at 26°C at rest or were made to contract at various frequencies and temperatures and for various durations. In addition, samples of right ventricular muscle were obtained from living cats. Specimens were frozen in liquid nitrogen-cooled isopentane for determination of ATP and creatine phosphate (CP). In vivo CP + ATP of right ventricular muscle was 12.9±0.8 µmoles/g. In papillary muscles at rest, CP + ATP was 16.7±0.6 µmoles/g, significantly higher than right ventricular muscle in vivo ( P <.01). In vitro at 12 contractions/minute, CP + ATP was 16.0±1.0 µmoles/g, not different from resting papillary muscles but higher than in vivo stores in right ventricular muscle. At 30 or 60 contractions/minute, CP + ATP was reduced to 13.7±1.1 and 11.1±0.7 µmole/g. Neither increasing the in vitro temperature from 26° to 37°C, nor extending the duration of stimulation from 1 to 3 hours at 12/minute significantly altered CP + ATP. It is concluded that the energy stores in papillary muscles, even of moderately large diameter, are intact for at least 3 hours while contracting at frequencies of 12/minute at 26°C. Further, energy stores of papillary muscle are even greater than those found in right ventricular muscle in vivo. While muscle is contracting at 30 or 60/minute, its energy stores may be slightly limited.

Heart motion video-tracking (radarkymography) in diagnosis of congenital and acquired heart disease

Abstract: Heart motion video-tracking (radarkymography) is a technic for recording the movements of cardiovascular structures. Over 100 patients with a variety of congenital and rheumatic heart lesions were studied. Characteristic graphic linear tracings were obtained in patients with mitral valve disease, obstruction to the aortic outflow tract, ventricular aneurysms and coarctation of the aorta. Radarkymography offers certain advantages over electrokymography, which to date has been the major technic for recording motion of the cardiac silhouette.

Effect of Thyroid State on Myocardial Contractility

Abstract: The mechanical properties of papillary muscles isolated from hyperthyroid, euthyroid and hypothyroid cats were compared and the relationship between hyperthyroidism and endogenous as well as exogenous catecholamines was studied. Changes in the level of thyroid activity profoundly affected the intrinsic contractile state of cardiac muscle primarily byaltering the speed of shortening of the contractile elements, while total force production was not modified markedly. Muscles from hyperthyroid animals were not supersensitive to exogenous norepinephrine and the increased speed of shortening associated with hyperthyroidism was independent of endogenous norepinephrine stores. {Endocrinology 82: 191, 1968)

Chapter 4: Deaths Related to Cardiac Catheterization

Abstract: were reported, 12.4% of the major complications ended fatally. Whenever possible, the specific complication responsible for the patient's death was determined; accordingly, many patients discussed in this chapter are also discussed under the specific complication or technique, described elsewhere in this volume. The 55 deaths have been divided into various categories, as shown in table 1. Although it was possible to subdivide the cause of the deaths, there were sufficient differences among individual patients to require a brief description of each case.