Showing papers in "American Journal of Cardiology in 1978"

“Variant” angina: One aspect of a continuous spectrum of vasospastic myocardial ischemia: Pathogenetic Mechanisms, Estimated Incidence and Clinical and Coronary Arteriographic Findings in 138 Patients

Abstract: From January 1970 to December 1977, transient reversible episodes of S-T segment elevation were documented in 138 patients (80 with angina only at rest, 58 with angina both on exertion and at rest). Electrocardiographic monitoring in 33 patients with hemodynamic monitoring revealed that (1) during 6,009 transient episodes of myocardial ischemia, pain was always a late phenomenon and, in some patients, often did not occur; (2) during such transient episodes, ST-T wave behavior was often variable in the same patient with alternation of elevation, depression or only T wave changes with or without pain; (3) independent of the direction of the S-T segment and T wave changes, the episodes were never preceded by an increase of the hemodynamic determinants of myocardial demand but were associated with obvious impairment of left ventricular function. Thallium scintigraphy in 32 patients revealed a regional massive and localized reduction of myocardial perfusion during S-T segment elevation and pseudonormalization of T waves. During S-T segment depression the reduction of thallium uptake was diffuse with fuzzy limits. Coronary angiography revealed no significant stenosis in 8 patients and single, double and triple vessel disease in 38, 34 and 26 patients, respectively. Angiography in all 37 patients studied during angina revealed a severe coronary vasospasm involving vessels with extremely variable extent of atherosclerosis. Severe arrhythmias were recorded in 27 patients, and a myocardial infarction occurred in 28. A total of five patients died within 1 month of hospital admission. Thus, variable intensity and extension of coronary vasospasm and the presence of collateral vessels may result in different degrees of ischemia and various electrocardiographic patterns with or without anginal pain. Vasospastic angina can occur in the presence of extremely variable degrees of coronary atherosclerosis and in any phase of ischemie heart disease. It may evolve into acute myocardial infarction and sudden death: Variant angina appears to be only its most striking electrocardiographic manifestation. When vasospastic angina is appropriately searched for, its incidence rate appears to be high.

Plasma norepinephrine in congestive heart failure

Abstract: Resting plasma concentrations of norepinephrine, dopamine-beta-hydroxylase enzyme activity and peripheral blood lymphocyte beta adrenergic receptor sensitivity to isoproterenol as reflected in cyclic 3′,5′-adenosine monophosphate (cAMP) generation were studied in patients with congestive heart failure due to atherosclerotic heart disease or to congestive cardiomyopathy or hypertensive cardiovascular disease. Systolic time Intervals were also measured in nonhypertensive patients and correlated with the plasma norepinephrine concentration. Control patients were hospital employees without a previous history of heart disease or hypertension, and were matched for age to eliminate the effect of increasing age on the plasma norepinephrine concentration. The results of this study clearly demonstrate that the plasma norepinephrine concentration is directly related to the degree of left ventricular dysfunction in patients with congestive heart failure. When the systolic time intervals were correlated with the plasma norepinephrine levels, a significant prolongation of the preejection period was observed with progressively increasing plasma concentrations of norepinephrine. The reverse was true for the left ventricular ejection time, which demonstrated a significant Inverse relation with the plasma norepinephrine concentration. The ratio of the preejection period to the left ventricular ejection time, which is a reflection of left ventricular function, significantly increased with increasing levels of plasma norepinephrine. In addition, plasma lymphocytes from patients with the greatest degree of left ventricular dysfunction failed to generate normal amounts of cAMP after beta adrenergic receptor stimulation with isoproterenol. It Is suggested that beta adrenergic receptors are desensitized in these patients and that this desensitization contributes to the observed alterations in myocardial contractility.

Noninvasive assessment of coronary stenoses by myocardial imaging during pharmacologic coronary vasodilatation. III. Clinical trial

Abstract: Thallium-201 myocardial imaging was performed at rest, after maximal treadmill exercise and during coronary vasodilatation induced by the intravenous administration of dipyridamole in 62 patients undergoing coronary angiography Myocardial images after dipyridamole infusion were compared with rest and exercise thallium-201 images to determine the utility of pharmacologic stress for detecting coronary artery disease Dipyridamole, 0142 mg/min, was infused for 4 minutes with electrocardiographic and blood pressure monitoring, and thallium-201 was injected intravenously 4 minutes after infusion Myocardial/background count ratios of 23 ± 05 (mean ± 1 standard deviation) after the administration of dipyridamole were higher than similar ratios for exercise images (21 ± 05; P < 0001) The sensitivity of thallium-201 imaging for detecting significant coronary artery disease was equal for dipyridamole and exercise stress In 51 patients with a 50 percent or greater stenosis of one or more coronary arteries, image defects were identified in 34 of 51 (67 percent) exercise and dipyridamole images Twenty of 51 patients (39 percent) had abnormal rest images; in 17 of 20 patients, new or increased image defects were present after exercise and the infusion of dipyridamole One of 11 patients (9 percent) with no stenosis of 50 percent or greater had a defect on exercise and dipyridamole images Six of seven patients with new or enlarged image defects after the intravenous administration of dipyridamole also had new or enlarged defects after the oral administration of dipyridamole After the infusion of dipyridamole, the heart rate increased from 64 ±10 beats/min supine to 88 ± 13 beats/min standing (P < 0001), and blood pressure decreased from 129 ± 1680 ± 9 to 120 ± 1775 ± 9 mm Hg (P < 0001) Angina and S-T depression occurred more frequently with exercise than with dipyridamole S-T depression occurred in only two patients (3 percent) with dipyridamole, suggesting that diagnostic images were often obtained without significant ischemia This study demonstrates that pharmacologic coronary vasodilatation is as effective as maximal treadmill exercise in creating myocardial perfusion abnormalities detectable with thallium-201 imaging in man

Congenital heart disease in a cohort of 19,502 births with long-term follow-up

Abstract: The Child Health and Development Studies are longitudinal studies of pregnancy and the normal and abnormal development of the offspring. Women who were membres of the Kaiser Foundation Health Plan entered the study in early pregnancy, and their children were examined frequently until the youngest child in the study was 5 years old. This is a more intensive follow-up than hitherto reported. Of the 19,044 live-born children, 163 had definite and another 31 had possible congenital heart disease; the crude incidence rates per 1,000 live births were 8.8 for definite congenital heart disease and 10.4 for definite plus possible congenital heart disease. The incidence rate of congenital heart disease was 7.9 percent among all stillborn fetuses subjected to autopsy and 10.2 percent among those in this group with autopsies evaluated as being detailed enough to detect heart disease. Among the live-born children with congenital heart disease, 21 died in the neonatal period and 22 died in later infancy and childhood; about half the deaths were judged to have been due to heart disease. About 30 percent of the children with congenital heart disease had associated severe anomalies of other systems. In the whole cohort, 50 children had diagnosed chromosomal abnormalities (2.63/1,000 live births) and about 30 percent of them had congenital heart disease. Among the group of 163 children with definite congenital heart disease, the diagnosis was made in 46 percent by age 1 week, in 88.3 percent by age 1 year and 98.8 percent by age 4 years.

Noninvasive assessment of coronary stenoses by myocardial perfusion imaging during pharmacologic coronary vasodilatation. I. Physiologic basis and experimental validation.

Abstract: This study was undertaken to establish the basic hemodynamic conditions necessary to cause abnormalities in external myocardial perfusion images of thallium-201 and technetium-99M-labeled particles as a result of defined coronary stenoses ranging from mild to severe narrowing. Twenty dogs underwent long-term instrumentation with a flow transducer and adjustable constrictor on the left circumflex coronary artery. Catheters were implanted in the aortic root and distal left circumflex coronary artery to measure pressure loss across the stenosis and in the pulmonary artery and left atrium for the injection of drugs or radionuclides, or both. All data were obtained in intact unsedated trained animals. The results from 145 images obtained at rest, during exercise or after coronary vasodilators in dogs with mild to severe coronary stenoses demonstrate the following: (1) The ratio of maximal flow in a normal to stenotic coronary artery must be at least 2:1 before defects appear in the myocardial perfusion image of thallium-201. (2) A diagnostic technique that utilizes a maximal stimulus for increasing coronary flow and an imaging agent that is distributed to the myocardium in linear proportion to coronary flow at flow rates up to 4 or 5 times resting levels will be the most sensitive method for detecting mild coronary stenoses; a diagnostic technique utilizing a submaximal stimulus for coronary flow or an imaging agent whose distribution is not proportional to flow at high flow rates will be least sensitive. (3) Myocardial perfusion imaging during coronary vasodilatation induced with intravenously administered dipyridamole is a better method for identifying moderate coronary stenoses than perfusion imaging during exercise stress in experimental animals. (4) The effect of intravenously administered dipyridamole on the coronary circulation can be closely regulated by adjusting the dose rate of infusion and can be instantaneously reversed with intravenous administration of aminophylline, a dipyridamole antagonist; dipyridamole infusion does not increase myocardial oxygen demands as much as exercise and does not Invoke myocardial ischemia as a diagnostic end point. This stimulus may therefore be more readily controlled than exercise stress and is not subject to the effects on treadmill testing of motivation, chronic lung disease, peripheral vascular disease or musculoskeletal impairment.

Infarct Expansion Versus Extension: Two Different Complications of Acute Myocardial Infarction

Abstract: Precordial S-T segment mapping studies have suggested that extension of acute transmural myocardial infarcts occurs in up to 80 percent of patients within 6 days. To determine the morphologic nature of extension 76 consecutive acute myocardial infarcts aged 30 days or less were studied. All infarcts had been clinically diagnosed and proved at autopsy. Extension (histologically more recent foci of contraction band necrosis around an infarct) was found in only 13 infarcts (17 percent). However, “expansion” (acute dilatation and thinning of the area of infarction not explained by additional myocardial necrosis) was present in 45 infarcts (59 percent). Severe expansion did not develop until 5 days after infarction and was greater with transmural and first infarcts. Clinically diagnosed extension manifested by new pain, S-T segment elevation, rise in serum creatine kinase level and increased congestive heart failure occurred in 14 of the 76 patients (18 percent). At autopsy these clinical extensions were associated with expansion alone in three patients, with extension alone in two and with both in nine. The study shows that expansion is a common complication of acute myocardial infarction that can worsen cardiac function through left ventricular dilatation and can mimic or possibly cause infarct extension. In contrast, extension with additional myocardial necrosis is an infrequent accompaniment of acute myocardial infarction and is usually a result of hypoperfusion.

Right ventricular infarction complicating left ventricular infarction secondary to coronary heart disease. Frequency, location, associated findings and significance from analysis of 236 necropsy patients with acute or healed myocardial infarction.

Abstract: Right ventricular infarction associated with left ventricular infarction was identified by gross examination at necropsy in 33 (14 percent) of 236 patients with transmural myocardial infarction. Right ventricular infarction occurred exclusively as a complication of posterior left ventricular infarction. Associated right ventricular infarction occurred in none of the 97 patients with isolated anterior wall infarction of the left ventricle, but in 33 (24 percent) of the 139 patients with posterior left ventricular infarction. Transmural infarction of the posterior ventricular septum was an additional prerequisite for right ventricular infarction. Of the 139 patients with infarction of the posterior left ventricular wall, 74 had no transmural infarction of the ventricular septum and none of these 74 had associated right ventricular infarction. In contrast, of the 65 patients with infarction of the posterior left ventricular wall and transmural infarction of the ventricular septum, 33 (50 percent) had associated right ventricular infarction. Among the 33 patients with right ventricular infarction, the infarct was limited to the posterior right ventricular free wall in 27 (82 percent); in the other 6 patients (18 percent) it extended to involve the anterolateral right ventricular free wall. Among patients with a posterior left ventricular infarct, those with a right ventricular infarct had right ventricular dilatation nearly three times (P Hemodynamic data in four patients with a right ventricular infarct disclosed previously reported characteristic hemodynamics of right ventricular infarction in only one patient. Recognition of right ventricular infarction is important because it implies specific therapy, namely, aggressive volume administration. Clinical evidence of posterior left ventricular infarction and right ventricular dilatation should arouse strong suspicion of associated right ventricular infarction.

Noninvasive assessment of coronary stenoses by myocardial imaging during pharmacologic coronary vasodilatation. II. Clinical methodology and feasibility

Abstract: A noninvasive method has been developed utilizing myocardial imaging of thallium-201 injected intravenously at rest and during coronary vasodilatation induced with intravenously administered dipyridamole, a potent selective coronary vasodllator. The method has been validated in experimental animals and shown to be more sensitive than exercise imaging in identifying moderate experimental coronary stenoses. This report describes the clinical feasibility and methodology of applying the technique to man. Study of a total of 162 myocardial perfusion images in 62 patients revealed the following: (1) The quality of myocardial perfusion images of thallium-201 injected during coronary vasodilatation induced with intravenously administered dipyridamole was equal to or better than that of myocardial images of thallium-201 injected during treadmill stress. (2) Myocardial uptake of thallium-201 measured with external imaging was considerably greater during dipyridamole-induced coronary vasodilatation than during treadmill stress. (3) The optimal dose rate of intravenously administered dipyridamole for this imaging technique was 0.142 mg/kg per min for 4 minutes with the thallium injected in the 3rd to 4th minute after completion of infusion while the patient was upright, walking in place. (4) With this dose rate regimen, side effects were minimal except for the occasional development of angina pectoris; the latter was eliminated by intravenous administration of aminophylline, a complete and virtually instantaneous antagonist of dipyridamole, after thallium had been taken up by the myocardium. This new method is therefore applicable to man and the initial results warrant a larger clinical study in order to define the diagnostic sensitivity and specificity of the technique.

Clinical, electrocardiographic and electrophysiologic observations in patients with paroxysmal supraventricular tachycardia.

Abstract: Seventy-nine patients without ventricular preexcitation but with documented paroxysmal supraventricular tachycardia were analyzed. Electrophysiologic studies suggested atrioventricular (A-V) nodal reentrance in 50 patients, reentrance utilizing a concealed extranodal pathway in 9, sinus or atrial reentrance in 7 and ectopic automatic tachycardia in 3. A definite mechanism of tachycardia could not be defined in 10 patients (including 7 whose tachycardia was not inducible). The three largest groups with inducible tachycardias were compared in regard to age, presence of organic heart disease, rate of tachycardia, functional bundle branch block during tachycardia and relation of the P wave and QRS complex during tachycardia. A-V nodal reentrance was characterized by a narrow QRS complex and a P wave occurring simultaneously with the QRS complex during tachycardia. Reentrance utilizing a concealed extranodal pathway was characterized by young age, absence of organic heart disease, fast heart rate, presence of bundle branch block during tachycardia and a P wave following the QRS complex during tachycardia. Sinoatrial reentrance was characterized by frequent organic heart disease, a narrow QRS complex and a P wave in front of the QRS complex during tachycardia. In conclusion, a mechanism of paroxysmal supraventricular tachycardia could be defined in most patients. Observations of clinical and electrocardiographic features in these patients should allow prediction of the mechanism of the tachycardia.

Ergonovine maleate provocative test for coronary arterial spasm.

Abstract: Ergonovine maleate was evaluated as a provocative agent for inducing coronary spasm during coronary arteriography. The study group consisted of 98 patients with either mild fixed obstructions of coronary luminal diameter (less than 50 percent) or normal coronary arteriograms. The test was considered positive if the drug precipitated severe coronary spasm. A positive ergonovine test occurred in 10 of 11 patients with Prinzmetal's variant angina (P < 0.02). Two of these patients had a transmural myocardial infarction in the distribution of the spastic artery. Ergonovine tests were negative in (1) the 15 control patients with no clinically suspected coronary artery disease (P < 0.001), (2) 63 of 66 patients with angina-like chest pain (P < 0.001), and (3) all 6 patients with myocardial infarction and no history of Prinzmetal's variant angina (P < 0.05). No major complications occurred as a result of this test. Thus, ergonovine maleate test is a safe, sensitive and specific method for reproducing coronary spasm in patients with Prinzmetal's variant angina and no major coronary obstructions. The results suggest that coronary spasm can be implicated as a cause of myocardial infarction in patients with normal coronary arteriograms who also have Prinzmetal's variant angina. Coronary spasm was not demonstrated in patients who had normal coronary arteriograms and a history of myocardial infarction as an isolated clinical event. Also, coronary spasm could not be demonstrated in the majority of patients who had angina-like chest pain and no major coronary obstruction.

Bruce treadmill test in children: normal values in a clinic population.

Abstract: The Bruce treadmill protocol is suitable for children as young as age 4 years. Maximal endurance time may be used as the sole criterion of exercise capacity, and normal values were established with 327 children having an innocent heart murmur. Mean endurance time in boys increased from 10.4 minutes at age 4 to 5 years, to 14.1 minutes at age 13 to 15 years. Mean endurance time in girls increased from 9.5 minutes at age 4 to 5 years to 12.3 minutes at age 10 to 12 years. Mean maximal heart rate ranged from 193 to 206 beats/min. Age differences in mean maximal and submaximal heart rates were small. There were negative correlations between endurance time and the ratio of weight to height. There were negative correlations between heart rates at treadmill stages 1 to 3 and the endurance times. The correlation coefficient of endurance time with maximal oxygen uptake was 0.88, but for clinical purposes endurance time alone is a satisfactory indicator of exercise performance.

Recording from the body surface of arrhythmogenic ventricular activity during the S-T segment.

Abstract: Recent experimental reports have documented the delay of epicardial potentials beyond the QRS complex as a result of infarction, and the degree of delay was directly associated with the onset of ventricular arrhythmias. This study describes a method using high amplification, band pass filtering and signal averaging for recording from the body surface these delayed potentials presaging ventricular arrhythmias. This technique, has been used for recording low level cardiac potentials masked by noise. In 10 dogs control records of the electrocardiogram and surface averaged lead were obtained during sinus rhythm, atrial pacing and premature atrial beats. Subsequently, the left anterior descending coronary artery was ligated in each dog. Nine dogs survived the surgical procedure and underwent similar recordings 3 to 6 days after infarction. Electrocardiographic changes were consistent with a recent infarction. During the pacing protocol discrete multiphasic wave forms appeared during the S-T segment of the surface averaged lead, and concomitant changes in the terminal portions of the QRS complex were observed in seven dogs. In five of these dogs ventricular arrhythmias were observed at the faster pacing rates or after closely coupled premature atrial beats. The chest was then reopened and the pacing procedure repeated during recording of direct epicardial electrograms with a multicontact bipolar electrode. This electrogram validated the existence of potentials during the S-T segment in all but one dog and late activity that was not repeatable on a beat to beat basis in another. Thus, when late activity was confirmed with the epicardial electrogram, seven of eight dogs showed a corresponding change in the surface averaged lead. This technique may prove to be a sensitive indicator of abnormal electrical activity preceding ventricular arrhythmias.

Unstable angina pectoris: National cooperative study group to compare surgical and medical therapy: II. In-Hospital experience and initial follow-up results in patients with one, two and three vessel disease

Abstract: A prospective randomized study comparing intensive medical therapy with urgent coronary bypass surgery for the acute management of patients with unstable angina pectoris was carried out by nine cooperating medical centers under the auspices of the National Heart, Lung, and Blood Institute. Between 1972 and 1976, a total of 288 patients were entered into the study. All patients had transient S-T or T wave changes, or both, in the electrocardiogram during pain; 90 percent had pain at rest in the hospital, and 76 percent had multivessel coronary disease. The medically and surgically treated patients were comparable with respect to clinical, electrocardiographic and angiographic characteristics and left ventricular function. During the total study period, the hospital mortality rate was 5 percent in the surgical group and 3 percent in the medical group (difference not significant). The rate of in-hospital myocardial infarction was 17 and 8 percent in the respective groups (P In the 1st year after hospital discharge class III or IV angina (New York Heart Association criteria) was more common in medically than in surgically treated patients with one vessel disease (22 percent versus 3 percent, P The results indicate that patients with unstable angina pectoris can be managed acutely with intensive medical therapy, including the administration of propranolol and long-acting nitrates in pharmacologic doses, with adequate control of pain in most patients and no increase in early mortality or myocardial infarction rates. Later, elective surgery can be performed with a low risk and good clinical results if the patient's angina fails to respond to intensive medical therapy.

Noninvasive assessment of coronary stenoses with myocardial perfusion imaging during pharmacologic coronary vasodilatation. V. Detection of 47 percent diameter coronary stenosis with intravenous nitrogen-13 ammonia and emission-computed tomography in intact dogs.

Abstract: To determine the minimal coronary lesions detectable with perfusion imaging, 16 stenoses of 43 to 66 percent diameter narrowing were applied to the left circumflex coronary artery of three chronically instrumented intact dogs. Orthogonal diastolic coronary arteriograms, obtained on cut film by triggering X-ray exposures from the electrocardiogram while injecting contrast medium through a chronically implanted coronary arterial catheter, were analyzed quantitatively by computer. Fifteen millicuries of nitrogen-13 ammonia was injected intravenously during resting conditions, and emission-computed tomography was performed without electrocardiographic gating. One hour later, after residual nitrogen-13 ammonia had decayed, 15 mg of intravenous dipyridamole was given followed by a second dose of intravenous nitrogen-13 ammonia and repeat performance of emission-computed tomography. The cross-sectional tomographs of the heart were of high quality and revealed in the images obtained with dipyridamole definite perfusion defects with coronary stenoses of 47 percent or greater diameter narrowing. Stenoses of 45 percent diameter narrowing or less did not produce perfusion defects. Quantitative perfusion abnormalities approximated the quantitative severity of stenoses. It is concluded that noninvasive myocardial emission-computed tomography with nitrogen-13 ammonia during dipyridamole-induced coronary vasodilatation detects mild coronary stenoses for purposes of potential medical intervention.

Structural changes in glutaraldehyde-treated porcine heterografts used as substitute cardiac valves: Transmission and scanning electron microscopic observations in 12 patients

Abstract: Scanning and transmission electron microscopic studies were made of (1) 12 glutaraldehyde-treated porcine valvular heterografts that had been implanted in patients for 2 days to 76 months; (2) 3 unimplanted commercially processed porcine aortic valves; and (3) 1 unprocessed porcine aortic valve. Comparison of unprocessed porcine valves and unimplanted commercially processed valves showed loss of endothelium and acid mucopolysaccharides during preimplantation processing. Short-term (less than 2 months) changes after implantation consisted of insudation of plasma proteins, penetration of erythrocytes into surface crevices, formation of a thin surface layer of fibrin, and deposition of macrophages, giant cells and a few platelets. Longer-term (more than 2 months) changes were proportional to the time interval after implantation and consisted of progressive disruption of collagen, erosion of the valve surfaces, formation of aggregates of platelets and accumulation of lipid. The surfaces of the leaflets did not become covered with endothelium or with a fibrous sheath. Calcific deposits were found in one valve and bacterial organisms in another. Thus, progressive breakdown of collagen appears to be a critical factor in determining the long-term durability of glutaraldehydetreated porcine valvular heterografts.

Life expectancy without surgery in tetralogy of fallot

Abstract: All published autopsy cases of patients with tetralogy of Fallot who died without surgical treatment were studied to determine the life expectancy of such persons. In addition, the data from a study of persons with tetralogy alive in Denmark in 1949 were reanalyzed. The survival data from these two sources were remarkably similar, indicating that 66 percent of persons with tetralogy of Fallot not treated surgically live to age 1 year, 49 percent to age 3 years and 24 percent to age 10 years; thereafter, the hazard function (or Instantaneous risk of death) remains constant. The chance of survival is significantly less when pulmonary atresia, rather than stenosis, is present.

Assessment of cardiac performance with quantitative radionuclide angiocardiography: Right ventricular ejection fraction with reference to findings in chronic obstructive pulmonary disease

Abstract: A reproducible noninvasive technique for measuring right ventricular ejection fraction was developed using first pass quantitative radionuclide angiocardiography. Studies were obtained in the anterior position with a computerized multicrystal scintillation camera with high count rate capabilities. Right ventricular ejection fraction was calculated on a beat to beat basis from the high frequency components of the background-corrected right ventricular time-activity curve. In 50 normal adults, right ventricular ejection fraction averaged 55 percent (range of 45 to 65 percent). This radionuclide measure of right ventricular function was reproducible, with minimal inter- and intraobserver variability and was sensitive to changes in inotropic state induced with isoproterenol. In 36 patients with chronic obstructive pulmonary disease, right ventricular ejection fraction ranged from 19 to 71 percent. All 10 patients with cor pulmonale, as well as 9 additional patients, had an abnormal right ventricular ejection fraction. Arterial oxygen tension and forced expiratory volume were depressed significantly more in patients with abnormal right ventricular ejection fraction than in subjects with normal right ventricular function. There was no relation between abnormalities in right and left ventricular ejection fraction.

Rapid changes in left ventricular dimensions and mass in response to physical conditioning and deconditioning.

Abstract: To determine the influence of training and detraining on left ventricular dimensions, echocardiographic estimates of left ventricular indexes were undertaken in two groups of young healthy subjects. The training group consisted of eight competitive swimmers who were studied serially for 9 weeks. Left ventricular end-diastolic dimension in this group increased from the pretraining value of 48.7 ± 1.7 (mean ± standard error) to 53 ± 0.2 mm by the 1st week and to 52 ± 1.7 mm by the 9th week of training (P The results indicate that (1) exercise training-induced adaptive changes in left ventricular dimensions occur rapidly and mimic the pattern of chronic volume overload; and (2) modest degrees of exercise-induced left ventricular enlargement are reversible after cessation of training.

Hemodynamics at rest and during supine and sitting bicycle exercise in normal subjects

Abstract: To assess left ventricular function and to compare mean pulmonary wedge pressure and left ventricular end-diastolic pressure in the supine and sitting positions, 10 patients without demonstrable cardiovascular disease underwent hemodynamic studies at rest and during exercise In the two positions. At rest the values for heart rate were higher and the values for cardiac index, stroke index, left ventricular stroke work Index, mean pulmonary capillary wedge pressure and left ventricular end-diastolic pressure were lower in the sitting position. During both supine and sitting exercise left ventricular end-diastolic pressure, cardiac index, stroke index and left ventricular stroke work index increased significantly from the resting values. Comparison of data during exercise revealed higher values for heart rate and rate-pressure product and lower values for pulmonary capillary wedge pressure, left ventricular end-dlastollc pressure and stroke index in the sitting position; systolic and mean systemic pressure, cardiac index and left ventricular stroke work Index were similar during the two exercise periods. When absolute changes from rest to exercise were compared, the Increase In heart rate, systolic blood pressure, pulmonary capillary wedge pressure, left ventricular end-dlastollc pressure, cardiac index, stroke index, and left ventricular stroke work index were similar In the two positions. There was a good correlation between left ventricular end-diastolic pressure and pulmonary capillary wedge pressure at rest and during exercise in the two postures.

New antiarrhythmic agents: amiodarone, aprindine, disopyramide, ethmozin, mexiletine, tocainide, verapamil.

Abstract: The present status, clinical experience, side effects, clinical pharmacology and electrophysiologic actions of seven new antiarrhythmic agents are reviewed. The drugs selected for comment are amiodarone, aprindine, disopyramide, ethmozin, mexiletine, tocainide and verapamil. Each drug has been shown to have clinical efficacy in suppressing cardiac arrhythmias.

Thallium-201 myocardial perfusion scintigraphy for the clinical clarification of normal, abnormal and equivocal electrocardiographic stress tests

Abstract: Sixty-five patients were studied with stress electrocardiography and thallium-201 relative myocardial perfusion scintigraphy. Results were correlated with selective coronary angiography. Scintigraphy was more sensitive (85 versus 67 percent), more specific (89 versus 63 percent) and significantly more accurate (87 versus 65 percent) than stress electrocardiography for the diagnosis of significant coronary arterial lesions in patients with isoelectric S-T segments at rest. Stress scintigraphy helped clarify the equivocal stress test due to left bundle branch block, left ventricular hypertrophy, drugs, hyperventilation and other conditions and was more accurate than the stress electrocardiogram (89 versus 53 percent) even in the presence of a depressed S-T segment at rest. Thallium-201 scintigraphy is a safe and simple noninvasive method for identifying abnormal myocardial perfusion, stress-induced ischemia and, indirectly, significant coronary arterial lesions.

Exercise-Induced Left Ventricular Dysfunction in Symptomatic And Asymptomatic Patients With Aortic Regurgitation: Assessment With Radionuclide Cineangiography

Abstract: In patients with aortic regurgitation, left ventricular dysfunction at rest, which is associated with a poor long-term prognosis, often develops before severe symptoms. To determine whether evidence of left ventricular dysfunction could be detected before if appeared at rest, 43 patients with severe aortic regurgitation were studied using radionuclide cineanglography during exercise. In 30 normal subjects, left ventricular ejection fraction increased during exercise (57 ± 1 percent [mean ± standard error] at rest, 71 ± 2 percent during exercise, P

Natural and evoked atrial flutter due to circus movement in dogs

Abstract: Natural atrial flutter was discovered In a dog. Two forms of the arrhythmia resembling the human counterparts of typical and atypical atrial flutter were noted. The Observations in this dog led to studies in a series of normal dogs in which the extrastimulus technique was used to evoke runs of repetitive activity simulating but unlike true atrial flutter. Epicardial atrial activation maps were made from 72 to 96 bipolar complexes recorded during the arrhythmias. Multiple effective refractory periods were determined and these values were used to construct maps of the refractory period distribution. Dog 1, with true atrial flutter, demonstrated a complex form of circus motion characterized by unidirectional block and one-way conduction. Abnormal slowing of the unblocked circus wave stabilized and maintained the repetition by permitting more time for recovery of a uniform state of excitability ahead of the wave. The slow conduction in this dog was associated with right atrial hypoplasia and discontinuity in the preferential atrial conduction pathways. The circus activation patterns in the dogs with evoked flutter were similar to those in true flutter; however, the cycle lengths were shorter and the circus wave conducted faster. In evoked flutter the regional differences in refractory period duration determined the one-way block and circus conduction patterns. The circus pattern was caused by a nonuniform bimodal refractory state of the atrium that simultaneously exerted a blocking effect while permitting conduction and complex shaping of the unblocked wave, which was routed back to its site of origin. Thus atrial flutter was the result of three Interacting factors: (1) an atrial premature beat, (2) nonuniform distribution of atrial refractory periods, and (3) slow conduction of the circus wave initiated by factors 1 and 2.

Techniques for right and left ventricular endomyocardial biopsy

Abstract: Right ventricular endomyocardial biopsy using percutaneous right internal jugular approach proved a safe and easily performed technique in more than 1,300 procedures. Adequate tissue was obtained in more than 98 percent of patients and morbidity rate was remarkably low. Other approaches to the right ventricle may be used, but retrograde left ventricular endomyocardial biopsy appears to be the safest and most reliable alternative to transjugular right ventricular biopsy. The safety and success of the techniques for right and left heart biopsy described depend on meticulous attention to methodologic detail.

The myocardial supply:demand ratio--a critical review.

Abstract: Myocardial ischemia occurs when there is an imbalance between myocardial oxygen demand and supply, and it is usually entirely or predominantly subendocardial. Animal experiments have shown that relative subendocardial ischemia (a reduced inner:outer flow ratio) can be predicted quite accurately from the ratio of two pressure-time areas: DPTI, the area between diastolic aortic and left ventricular pressures, and SPTI, the area beneath the systolic left ventricular pressure curve. Although the importance of relating supply and demand is obvious, care is needed in applying the results of these animal experiments to man. Recent work has shown that the critical DPTI:SPTI ratio below which subendocardial ischemia occurs is about 0.4 to 0.5 rather than 0.7 to 0.8, as originally reported. On the other hand, the critical ratio may be raised to an unknown extent by myocardial edema or hypertrophy, or by thickened or narrowed coronary arteries. Furthermore, the critical ratio is not independent of absolute coronary diastolic pressure: It is much lower than 0.4 when coronary pressures are high, perhaps because intramyocardial diastolic pressures are much higher than once thought. Further work is required to allow an important physiologic concept to be used in making decisions about patients with heart disease.

Estimation of left ventricular volumes in man from biplane cineangiograms filmed in oblique projections

Abstract: In patients with coronary artery disease, right and left anterior oblique views of the left ventricle are considered optimal for assessment of regional wall motion, but the accuracy of ventricular volumes determined from these projections has not been validated. Eleven postmortem left ventricular casts were filmed with the 35 mm cine technique in the 30 ° right anterior oblique and 60 ° left anterior oblique positions, and volumes were calculated using the area-length method. True volume, assessed from volume displacement, ranged from 15 to 185 cc. Calculated volume (V oblique ) slightly but consistently overestimated true volume (V T ), with close correlation and a small standard error of the estimate (SEE):V T = 0.989 V oblique − 8.1 cc, r = 0.99, SEE = 8 cc. With use of this regression equation, values for left ventricular volumes and ejection fraction were calculated from biplane oblique (30 ° right anterior oblique/60 ° left anterior oblique) cineanglograms In 17 normal adults. Values for end-diastolic volume index (72 ± 15 cc/m 2 [mean ± standard deviation]), end-systolic volume index (20 ± 8 cc/m 2 ), stroke volume Index (51 ± 10 cc/m 2 ) and ejection fraction (0.72 ± 0.08) were similar to those reported by others. Examination of the effects of variable obliquity suggests that strict standardization of the degree of obliquity is necessary to offset variation In the long axis in the left anterior oblique projection caused by foreshortening.

Termination of ventricular tachycardia with bursts of rapid ventricular pacing

Abstract: Bursts of rapid ventricular pacing used during 573 episodes of ventricular tachycardia in 23 patients terminated 5 12 episodes (89 percent), with burst rates averaging 56 beats/min above the ventricular tachycardia rate, for 5 to 10 captures. Tachycardia was accelerated by pacing bursts to rates below 300 beats/min in 16 episodes (3 percent); 10 of these terminated spontaneously or responded to further bursts. Acceleration of heart rate to more than 300 beats/min or ventricular fibrillation occurred six times (1 percent), each episode requiring direct current cardioversion. Pacing bursts had no effect in 38 instances (7 percent), mostly in patients with terminal cardiogenic shock. Implantable pacemakers delivering bursts of rapid ventricular pacing were placed in two patients who have used these units at home. No deaths were associated with bursts of rapid ventricular pacing, which is an effective, rapid, pleasant alternative to repeated direct current cardioversion and a useful tool during electrophysiologic testing in patients with recurrent tachycardia.

Myocardial imaging with thallium-201: A multicenter study in patients with angina pectoris or acute myocardial infarction

Abstract: A multicenter study of rest and exercise thallium-201 myocardial Imaging in 190 patients from five centers was performed. Exercise images were obtained after graded treadmill or bicycle stress with use of five different gamma camera models and were interpreted by the originating investigator without knowledge of other clinical data. Of 42 patients with less than 50 percent coronary stenosis, 4 (10 percent) had a resting image defect, 1 (2 percent) a new exercise defect and 5 (12 percent) either a resting or an exercise Image defect, or both. Of 148 patients with coronary stenosis of 50 percent or greater, 64 (45 percent) had an image defect in the study at rest, 90 (61 percent) had new or increased defects after exercise, and 115 (78 percent) had resting or exercise defects, or both. New exercise image defects were more common than exercise S-T depression (90 of 148 [61 percent] versus 62 of 148 [42 percent]; P

Risk stratification after acute myocardial infarction

Abstract: One hundred patients admitted to the hospital with acute myocardial infarction who lived 10 days and agreed to enroll were studied. Data from the history, hospital course and a 24 hour Holter electrocardiographic recording were related to cardiac mortality in the 6 months after enrollment. Fifteen cardiac deaths occurred during this period; 12 of these were sudden. The univariates with the strongest association with mortality were (in descending order): blood urea nitrogen level, serum creatinine level, serum uric acid level, enlarged heart 2 weeks after infarction, ventricular tachycardia 2 weeks after infarction, peak creatine kinase level and left ventricular failure in the coronary care unit. The odds of dying if one of these factors was present rather than absent ranged from 3.6 to 11.5. Groups with two or three of these univariates had up to 20 times the odds of dying in 6 months. A period of greatly enhanced risk for cardiac death persists for about 6 months after acute myocardial infarction. Relatively simple clinical variables can identify the groups at highest and lowest risk. This information is useful for designing management strategies.

Sudden death in patients with hypertrophic cardiomyopathy: Characterization of 26 patients without functional limitation

Abstract: Sudden death is a recognized complication in symptomatic patients with hypertrophic cardiomyopathy. However, its occurrence in patients with no or transient previous cardiac symptoms presents a particularly challenging diagnostic and therapeutic dilemma. Therefore, 26 patients with hypertrophic cardiomyopathy whose death was the first definitive manifestation of cardiac disease were evaluated. Their ages ranged from 8 to 49 years (mean 18) and 23 were less than 25 years of age; 19 were male and 7 female. Of the 26 patients, 13 died during or immediately after moderate or severe physical exertion. Of 12 patients with previous cardiac catheterization, 6 had no or a small left ventricular outflow tract gradient under basal conditions and 6 had an outflow gradient of 50 mm Hg or greater. Left ventricular end-diastolic pressure was elevated in nine patients, and the ventricular septum was moderately to severely thickened (17 mm or more) in all patients. The electrocardiogram was abnormal in all 19 patients studied before death. Thus, sudden death may be the first definitive manifestation of cardiac disease in some patients with hypertrophic cardiomyopathy. Although the effects of patient selection in this study group cannot be excluded, sudden death was common in children and young adults and was often related to physical exertion; each patient showed a distinctly abnormal electrocardiogram and moderate to severe ventricular septal thickening.