Showing papers in "Circulation in 1979"

Atherogenesis: a postprandial phenomenon.

Abstract: The hypothesis that plasma chylomicrons in persons who ingest a cholesterol-rich diet are atherogenic is evaluated. Evidence is presented that in humans, and experimental animals, chylomicron remnants as well as low-density lipoproteins are taken up by arterial cells. In persons who do not have familial hyperlipoproteinemia, atherogenesis may occur during the postprandial period. Research directions that may contribute to the evaluation of chylomicron remnants as a risk factor for atherogenesis are discussed. Lipoprotein studies after administration of a test meal containing fat and cholesterol are urgently needed.

Diabetes and cardiovascular risk factors: the Framingham study.

Abstract: The impact of cardiovascular disease was compared in non-diabetics and diabetics in the Framingham cohort. In the first 20 years of the study about 6% of the women and 8% of the men were diagnosed as diabetics. The incidence of cardiovascular disease among diabetic men was twice that among non-diabetic men. Among diabetic women the incidence of cardiovascular disease was three times that among non-diabetic women. Judging from a comparison of standardized coefficients for the regression of incidence of cardiovascular disease on specified risk factors, there is no indication that the relationship of risk factors to the subsequent development of cardiovascular disease is different for diabetics and non-diabetics. This study suggests that the role of diabetes as a cardiovascular risk factor does not derive from an altered ability to contend with known risk factors.

Assessment of left ventricular ejection fraction and volumes by real-time, two-dimensional echocardiography. A comparison of cineangiographic and radionuclide techniques.

Abstract: Five different algorithms for determining left ventricular (LV) ejection fraction (EF) and volumes from two-dimensional echocardiographic examination (TDE) were compared with standard methods for obtaining EF and volume from x-ray cineangiography (cine) and EF from radionuclide ventriculography (RVG) in 35 patients. Although all methods correlated positively, the degree of correlation varied with the algorithm used. For EF determination, TDE algorithms (especially those using multiple planes of section) were superior to unidimensional algorithms commonly used with M-mode echocardiography. The best algorithm (modified Simpson's rule) correlated well enough with cine EF (r = 0.78; SEE 0.097) and RVG EF (r = 0.75; SEE 0.087) to make clinically useful estimates. TDE volumes also correlated meaningfully with cine end-diastolic and end-systole volumes (r = 084; n = 70) but were associated with a large standard error of the estimate (43 ml) and offered less advantage over unidimensional volume estimates. Quantitative application of TDE appears to be a useful noninvasive method of evaluating LVEF, but is not as useful for estimating LV volumes.

Congenital coronary arteriovenous fistula. Report of 13 patients, review of the literature and delineation of management.

Abstract: Thirteen new patients and 174 patients previously reported with coronary arteriovenous fistula (CAVF) were reviewed to delineate the course and management of CAVF and to clarify the role of surgical ligation in the young asymptomatic patient. Patients were grouped according to age: 99 patients (four new and 95 reported) were less than 20 years old and 88 (nine new and 79 reported) were greater than or equal to 20 years old. Of those under 20 years of age, 19% had preoperative symptoms or CAVF-related complications, including congestive heart failure (CHF) in 6%, subacute bacterial endocarditis in 3% and death in one patient. Seventy-six patients younger than 20 years old had CAVF ligation with only one significant complication. In contrast, 63% of the older group and all of our nine older patients had preoperative symptoms or complications, including CHF in 19%, SBE in 4%, myocardial infarction (MI) in 9%, death in 14% and fistula rupture in one patient. Of the 43 ligated older patients, 23% had surgical complications, including MI in three and death in three. Mean pulmonic-to-systemic flow in the entire group was 1.6:1 and did not differ significantly in those with or without symptoms or complications. One of our patients and one previously reported had spontaneous CAVF closure. In summary, early elective ligation of CAVF is indicated in all patients because of the high incidence of late symptoms and complications and the increased morbidity and mortality associated with ligation in older patients.

Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound.

Abstract: The mean pressure drop across the mitral valve and atrioventricular pressure half-time were measured noninvasively by Doppler ultrasound in 40 normal subjects, in 17 patients with mitral regurgitation, 32 patients with mitral stenosis and 12 with combined stenosis and regurgitation. In normal subjects pressure half-times were 20--60 msec, in patients with isolated mitral regurgitation 35--80 msec and in patients with mitral stenosis 90--383 msec. There was no significant change in pressure half-time with exercise or on repeat examinations, indicating relative independence of mitral flow. In 25 patients with mitral stenosis and seven with combined stenosis and regurgitation, pressure half-time was related to mitral valve area calculated from catheterization data. Increasing pressure half-times occurred with decreasing mitral valve area, and this relationship was not influenced by additional mitral regurgitation. Noninvasive measurement of pressure half-time together with mean pressure drop was useful for evaluating patients with mitral valve disease.

Variables predictive of survival in patients with coronary disease. Selection by univariate and multivariate analyses from the clinical, electrocardiographic, exercise, arteriographic, and quantitative angiographic evaluations.

Abstract: A progression of univariate followed by multivariate analyses was applied to 46 variables selected from the clinical examination, exercise test, coronary arteriography, and quantitative angiographic assessment of left ventricular function in patients with coronary disease to determine those variables most predictive of survival. For the 733 medically treated patients, the final Cox's regression analysis showed that the left ventricular ejection fraction was most predictive of survival, followed by age, number of vessels with stenosis(es) greater than or equal to 70%, and ventricular arrhythmia on the resting electrocardiogram. For the 1870 surgically treated patients, ventricular arrhythmia on the resting electrocardiogram was most predictive of survival followed by ejection fraction, heart murmur, left main coronary artery stenosis greater than or equal to 50%, and use of diuretic agents.

Left ventricular volume from paired biplane two-dimensional echocardiography.

Abstract: To evaluate the applicability of two-dimensional echocardiography to left ventricular volume determination, 30 consecutive patients undergoing biplane left ventricular cineangiography were studied with a wide-angle (84 degrees), phased-array, two-dimensional echocardiographic system. Two echographic projections were used to obtain paired, biplane, tomographic images of the left ventricle. We used the short-axis view (from the precordial window) as an anolog of the left anterior oblique angiogram, and the long-axis, two-chamber view (from the apex impulse window) as a right anterior oblique angiographic equivalent. A modified Simpson's rule formula was used to calculate systolic and diastolic left ventricular volumes from the biplane echogram and the biplane angiogram. These methods correlated well for ejection fraction (r = 0.87) and systolic volume (r = 0.90), but only modestly for diastolic volume (r = 0.80). These correlations are noteworthy because 65% of the patients had significant segmental wall motion abnormalities. The volumes determined from the minor-axis dimensions of M-mode echograms in 23 of the same patients correlated poorly with angiography.

Circadian variation of exercise capacity in patients with Prinzmetal's variant angina: role of exercise-induced coronary arterial spasm.

Abstract: Thirteen patients with Prinzmetal's variant angina performed treadmill exercise tests in the early morning and in the afternoon of the same day. The attacks with ST elevation were induced repeatedly in all 13 patients in the early morning, but in only two patients in the afternoon. Propranolol did not suppress the exercise-induced attacks in all 13 patients. Diltiazem suppressed the attacks in all 13 patients and phentolamine in eight of the nine patients. Coronary arteriograms demonstrated that spasm occluding completely or almost completely the large coronary artery supplying the area of myocardium showing ST elevation appeared during the attacks and disappeared along with the attacks after nitroglycerin administration in all four patients in whom the attacks were induced by arm exercise in the catheterization laboratory. We conclude that there is circadian variation of exercise capacity in patients with Prinzmetal's variant angina caused by coronary arterial spasm induced by exercise in the early morning but not in the afternoon.

Comparative assessment of stimuli that release neuronal and adrenomedullary catecholamines in man.

Abstract: We assessed the release of neuronal and adrenomedullary catecholamines in response to various stimuli of the sympathetic nervous system in normal subjects. Plasma catecholamines and their urinary metabolites, normetanephrine and metanephrine, were measured. Sodium restriction increased supine plasma norepinephrine by 37% and ambulatory plasma norepinephrine by 22%, with urinary normetanephrine excretion increased 29%. The sodium restriction did not elevate plasma epinephrine or urinary metanephrine. The most potent stimuli of norepinephrine were treadmill exercise, orthostasis, caffeine, the cold pressor test, sodium restriction and handgrip exercise, in descending order. Plasma epinephrine was increased by caffeine, treadmill exercise, the cold pressor test, handgrip exercise and the Valsalva maneuver, in that order. Syncope resulted in profound changes in plasma epinephrine but only modest changes in plasma norepinephrine. We conclude that in man, there is frequent dissociation between the effects of different stimuli on neuronal and adrenomedullary catecholamine release.

Endocardial excision: a new surgical technique for the treatment of recurrent ventricular tachycardia.

Abstract: Twelve patients with medically refractory ventricular tachycardia secondary to ischemic heart disease underwent surgery for cure of their arrhythmia. Preoperatively, the tachycardia could be reproducibly initiated and terminated in each patient by programmed stimulation. In all instances, intraoperative mapping localized the tachycardia to the border of the aneurysm, a site not routinely resected during aneurysmectomy. In nine instances, the area of origin involved the septum. During bypass the tachycardia could still be induced after standard aneurysmectomy or ventriculotomy in 11 of 12 patients. On the basis of intraoperative mapping, resection of endocardium in the area of origin (25--40% the circumference of the aneurysmectomy) up to normal muscle was performed. In one patient without a discrete aneurysm, endocardial excision alone through a ventriculotomy was performed. There was one operative death due to cardiogenic shock (preoperative ejection fraction 5%) and one late death due to rupture of a mycotic aneurysm in the pulmonary artery. Before discharge, all patients underwent a repeat relectrophysiologic study off antiarrhythmic agents and in none could ventricular tachycardia be initiated. Hemodynamic and angiographic catheterization showed improved hemodynamics and ejection fractions in all. The 10 survivors remained free of sustained ventricular tachycardia for 9--20 months, with one late nonarrhythmic death.

Ventricular ectopic beats and their relation to sudden and nonsudden cardiac death after myocardial infarction.

Abstract: The role of ventricular ectopic beats (VEBs) in identifying patients who die of cardiac cause in the posthospital phase of myocardial infarction was evaluated in 940 patients who survived an acute coronary event. Six-hour Holter ECG recordings were obtained before hospital discharge, and VEBs were classified as complex (bigeminal, multiform, repetitive or R on T), simple (one or more VEBs that did not have complex patterns), or not present. Patients were followed 1-60 months (average 36 months) and cardiac mortality was categorized as sudden (less than or equal to 1 hour) or nonsudden (greater than 1 hour) among 98 witnessed cardiac deaths. Complex VEBs were associated with a significantly increased cardiac death rate, but did not discriminate between sudden and nonsudden death. Simple VEBs were associated with a 3-year cardiac mortality rate intermediate between those with complex and those with no VEBs. The relationship between complex VEBs and cardiac mortality was independent of 10 relevant clinical variables.

Survival in medically treated coronary artery disease.

Abstract: SUMMARY In1214symptomatic medically treated patients with coronaryartery disease, 57noninvasive baseline clinical characteristics and24catheterization descriptors wereanalyzed byamultivariable analysis technique todetermine thecharacteristics that wereindependent predictors ofsurvival and,inparticular, to determine whether noninvasive characteristics contributed prognostic information inaddition tocatheterizationfindings. Whenthenoninvasive characteristics were analyzed, 31characteristics were significant (p< 0.05) univariate predictors ofsurvival, butonly12contained significant independent prognostic information. Five- and7-year survival ratesin197patients whohadnone oftheindependently significant noninvasive characteristics wereboth90%.Nineteen variables weresignificant whenthecatheterization descriptors were analyzed individually. Onlysevenwereindependently significant whenthey wereanalyzed jointly. Whenall81 baseline characteristics wereanalyzed jointly, sevennoninvasive characteristics (history ofperipheral vascular disease, NewYorkHeartAssociation class IVheart failure, nonspecific intraventricular conduction defect, progressive chest pain, nocturnal pain, premature ventricular complexes on theresting ECG,andleft bundle branch block) andsixinvasive characteristics (left-main stenosis, arteriovenous oxygen difference, number of diseased vessels, abnormal left ventricular contraction, left ventricular end-diastolic pressureandanterior asynergy) wereindependently significant. Different survival rates may occurinsubsets that areuniform with respect toonly oneortwoimportant characteristics (e.g., coronaryanatomyandventricular function) because ofdifferences inother important baseline characteristics. Bothnoninvasive andinvasive characteristics mustbe takeninto account todefine prognosisincoronarydisease fully. EARLY STUDIESofpatients withclinically diagnosed coronary artery disease identified clinical characteristics suchasage,sex, previous myocardial

Cross-sectional echocardiography. I. Analysis of mathematic models for quantifying mass of the left ventricle in dogs.

Abstract: Cross-sectional echocardiography was used to quantify left ventricular mass noninvasively in 21 dogs. Short- and long-axis cross-sectional images of the left ventricle were reproducibly traced at endocardial and epicardial borders during stop-motion video-tape replay. We used area, length and diameter measurements to calculate left ventricular mass by seven mathematic models, including the standard formulas used with M-mode echocardiography and cineangiography. Calculated mass was compared with excised weight of the left ventricle by regression and percent error analyses. Formulas using short-axis areas and long-axis length resulted in higher correlation coefficients (0.94--0.95) and lower mean errors (6--7%) than for standard formulas. Since short-axis areas account for regional left ventricular irregularities, noninvasive quantification of left ventricular mass by cross-sectional echocardiography in dogs is most accurate with formulas using short-axis areas.

Echocardiographic assessment of cardiac anatomy and function in hypertensive subjects.

Abstract: Cardiovascular complications are a major source of morbidity and mortality in hypertensive patients. To assess the prevalence of anatomic and functional abnormalities of the heart in such patients, we studied 234 asymptomatic subjects with mild-to-moderate systemic hypertension by echocardiography. After adjusting the echocardiographic values for age and body surface area, we found abnormally increased ventricular septal and/or posterobasal free-wall thickness in 61% of the hypertensive subjects. We found increased left atrial, aortic root, and left ventricular internal dimension (at end-diastole) in 5-7%, and decreased mitral valve closing velocity (E-F slope) and left ventricular ejection fraction were noted in six and 15% of the subjects, respectively. Four percent of the patients had disproportionate septal thickening (i.e., ventricular septal-to-left ventricular free-wall thickness ratio greater than or equal to 1.3). In contrast to the high prevalence of cardiac abnormalities detected by echocardiography, less than 10% of the hypertensive subjects had abnormal 12-lead ECGs or abnormal chest x-rays. These findings demonstrate a high prevalence of cardiac abnormalities in a population of asymptomatic hypertensive subjects. These abnormalities can be detected by echocardiography before they are otherwise apparent.

Plasma lipid distributions in selected North American populations: the Lipid Research Clinics Program Prevalence Study. The Lipid Research Clinics Program Epidemiology Committee.

Abstract: Cross-sectional age- and sex-specific plasma lipid distributions (means, medians and selected percentiles) are given for 48,431 white participants in visit 1 of the Lipid Research Clinics (LRC) Prevalence Study. This study consisted of two visits in which 10 LRCs screened participants selected from well-defined North American target populations that included a broad range of sociodemographic subgroups. These data confirm findings from earlier studies in developed countries, showing age-related differences in plasma lipid levels. However, for overall distributions, the LRC data showed slightly lower cholesterol and markedly higher triglyceride values than those previously reported for North America. Some variation in plasma lipid values was evident among the clinic populations. The large number of participants within most subgroups permitted a variety of analytic and comparative studies. For example, data from the large pediatric population revealed a drop in plasma cholesterol levels in adolescent males and females. Males aged 20--50 years had higher cholesterol levels than females in the same age group, and higher triglyceride levels between ages 20--70 years. Numbers were also sufficient for meaningful comparisons between lipid distributions of females who were taking sex hormones and those who were not: In females taking sex hormones, cholesterol and triglyceride levels were higher for subjects younger than 45 years, but slightly lower after age 45, than lipid levels in females not taking hormones.

Treatment of hypertension with nifedipine, a calcium antagonistic agent.

Abstract: Hemodynamic monitoring after a single dose (10 mg) of nifedipine in 27 primary hypertensive subjects (diastolic pressure greater than 110 mm Hg) documented that this calcium antagonistic agent exerts a potent arteriolar vasodilating action, which results in prompt (-21% of control at 30 minutes) and persistent (-16% of control at 120 minutes) fall in mean arterial pressure associated with a rise in cardiac output and pulse rate. The same patients received oral treatment for 3 weeks. Hourly pressure readings showed that 1) the antihypertensive response to each dose lasts 8--12 hours; and 2) nifedipine every 6 hours significantly reduced blood pressure throughout the 24 hours, without postural hypotension. Side effect were short-lasting (headache in five patients, palpitation without arrhythmias in eight patients, burning sensation in the face and legs in five patients and sporadic extrasystoles in five patients) and tended to disappear with continued treatment. Development of drug resistance, sodium retention, plasma volume expansion, renin release or angina pectoris were not observed during the study. Although these findings seem to differentiate nifedipine from other vasodilators currently used in the treatment of hypertension, broader experience and more prolonged trials with nifedipine as an antihypertensive agent will be needed before conclusions can be drawn on these particular aspects.

Determinants of ventricular function in pressure-overload hypertrophy in man.

Abstract: To test the hypothesis that impaired cardiac performance in some patients with pressureoverload hypertrophy is due to inappropriately high wall stress, rather than depressed contractility, the importance of hemodynamic and geometric factors was assessed in 14 patients with isolated aortic stenosis and various degrees of left ventricular failure (ejection fraction range 0.19-0.85). There was poor correlation between either aortic valve area, peak left ventricular systolic pressure, or left ventricular mass, and measures of ventricular function. In contrast, there were close correlations between circumferential wall stress and both ejection fraction (r= 0.96) and velocity of fiber shortening (r = 0.91) in patients with aortic stenosis. Forcevelocity- shortening relationships in six normal control subjects fell on the same regression line as that defined by the patients with aortic stenosis, while force-velocity-shortening relationships of patients with primary myocardial failure clearly differed. A major determinant of wall stress was the ratio of left ventricular wall thickness to cavity radius (h/R). Patients with h/R ratios > 0.36 had higher values for ejection fraction (0.61 ± 0.06 vs 0.36 i 0.07, p>0.05), Vcf (0.79 ± 0.10 vs 0.39 ± 0.04 sec ', p>0.05) and stroke work index (71 ± 10 vs 45 9 g-m/m2, p>0.005) than those with lower ratios.The results indicate that left ventricular wall thickness and geometry are closely correlated with ventricular performance in patients with pressure-overload hypertrophy due to aortic stenosis. Poor cardiac performance in some such patients may be due to inadequate hypertrophy (or inappropriate geometry) rather than to depression of myocardial contractility.

Cardiovascular and humoral responses to extremes of sodium intake in normal black and white men.

Abstract: To examine possible racial differences in the relationship between urinary sodium excretion (UNaV) and blood pressure in whites and blacks, and to characterize cardiovascular, renal and humoral responses, we studied 14 normotensive men (seven white and seven black) at six levels of sodium intake from 10–1500 mEq/24 hrs. Systolic and diastolic pressure increased from 113 ± 2/69 ± 2 mm Hg (SEM) at the 10 mEq/24 hr level of sodium intake to 131 ± 4/85 ± 3 mm Hg at the 1500 mEq/24 hr level of sodium intake (p < 0.001). Cardiac index increased concomitantly from 2.6 ± 0.1 to 3.6 ± 0.3 I/min/M2 (p < 0.001). Linear and quadratic regression analysis of the relationship of UNaV and blood pressure revealed that blacks had higher blood pressures with sodium loading than whites. Sodium loading caused a significant kaliuresis that was greater in whites than blacks. Six subjects were restudied while receiving potassium replacement. Compared with initial responses, blood pressure was elevated to a lesser degree (p < 0.02) and a greater natriuresis appeared at a level of 1500 mEq/24 hr of sodium intake (p < 0.02). The data suggest that blacks have an intrinsic reduction in the ability to excrete sodium compared with whites. The increases in blood pressure with acute sodium loading can be attributed to an increase in cardiac index. Potassium balance appears to influence the responses in blood pressure that occur with sodium loading

Complications of coronary arteriography from the Collaborative Study of Coronary Artery Surgery (CASS).

Abstract: Data were collected prospectively on 7553 consecutive patients undergoing coronary arteriography. The studies were performed at 13 clinics of the Collaborative Study of Coronary Artery Surgery (CASS) using brachial and femoral techniques. There were eight deaths 0--24 hours and seven deaths 24--48 hours after arteriography (2/1000). There were 15 non-fatal myocardial infarctions (MIs) 0--24 hours and four MIs 24--48 hours after arteriography (2.5/1000). Of 657 cases with left main stenosis greater than or equal to 50%, five died and three had MI. Left main disease increased risk of death by 6.8 times (p less than 0.001). Other factors increasing risk were unstable angina, congestive heart failure, multiple premature ventricular contractions, and hypertension. Of the 1187 patients studied from the brachial artery, six died (0.51%) and five had MIs (0.42%). In 6328 patients studied from the femoral artery, nine died (0.14%) and 14 had MIs (0.22%). The brachial artery technique increased the risk of death 3.6 times compared with the femoral approach (p less than 0.05). This result did not apply when analysis was restricted to laboratories with 80% or more brachial procedures. Risk was not altered by heparin. Thus, a prospective, multicenter analysis of complications reveals low risk of coronary arteriography but significant difference between two techniques.

Quantitative analysis of cardiac muscle cell disorganization in the ventricular septum of patients with hypertrophic cardiomyopathy.

Abstract: The presence of numerous abnormally arranged cardiac muscle cells in the ventricular septum has been considered a characteristic anatomic feature of patients with hypertrophic cardiomyopathy. To determine the specificity of this histologic marker for patients with hypertrophic cardiomyopathy, we used a quantitative method to determine the area of myocardium occupied by disorganized cells. In hypertrophic cardiomyopathy, septal disorganization was present in 94% of the 54 patients studied at necropsy. Furthermore, disorganization was extensive in most of these patients, involving 5% or more of the transverse plane tissue section in 89% of the patients and 25% or more of the section in 56% of the patients. Septal disorganization was best identified in tissue sections cut perpendicular to the long axis of the left ventricle. Septal disorganization was present in only 26% of the 144 control patients with other heart diseases or normal hearts. Most important, when present in these patients, disorganization was usually limited in extent. In only 7% of the controls studied did abnormally arranged cells occupy 5% or more of the tissue section. The average area of septum disorganized was 31 ± 3% (mean i SEM) in patients with hypertrophic cardiomyopathy and only 1.5 ± 0.6% in the controls (p>0.001). Hence, while the presence of ventricular septal disorganization is not pathognomonic of hypertrophic cardiomyopathy, widespread distribution of this abnormality is a very sensitive and specific histologic marker for this disease.

Sensitivity, specificity and predictive accuracy of radionuclide cineangiography during exercise in patients with coronary artery disease. Comparison with exercise electrocardiography.

Abstract: Noninvasive radionuclide cineangiography permits the assessment of global and regional left ventricular function during intense exercise. To assess the sensitivity of the technique in detecting coronary artery disease, we studied 63 consecutive patients with ≥ 50% stenosis of at least one coronary artery. Fiftynine (94%) had regional dysfunction with exercise; 56 (89%) developed lower-than-normal ejection fractions during exercise. When both regional dysfunction and subnormal ejection fractions are considered together, the sensitivity was 95%. Each patient also underwent exercise electrocardiography to either angina or 85% of predicted maximal heart rate. Of the 42 patients who developed angina during exercise electrocardiography, 26 (62%) developed ≥1 mm ST-segment depression; four additional patients (10%) had Q waves diagnostic of previous myocardial infarction. In contrast, 39 (93%, p < 0.001) developed regional dysfunction during radionuclide study, and one additional patient developed a subnormal ejection fraction without regional dysfunction. To assess specificity, we studied 21 consecutive patients with chest pain who had normal coronary arteries. None developed regional dysfunction; ejection fraction increased in all to levels within the range previously defined as normal. The predictive accuracy in this symptomatic population was 100%. We conclude that radionuclide cineangiography is highly sensitive (more so than exercise electrocardiography), predictive and specific in detecting patients with coronary artery disease.

The influence of location and extent of myocardial infarction on long-term ventricular dysrhythmia and mortality.

Abstract: SUMMARY Although theextent ofenzymatically estimated infarct size appearstobeanimportant determinant ofmorbidity andmortality early after infarction, itsinfluences on long-term survival andlate ventricular dysrhythmia havenotyetbeencharacterized. Accordingly, we prospectively studied 173patients youngerthan66yearsofagewithout evidence ofprior myocardial infarction, whosurvived acutemyocardial infarction foratleast 24hours. Infarct size was estimated enzymatically anddysrhythmia quantified bycomputerfromtwo-channel, 24-hour ambulatory ECGs.Themean infarct size index (ISI) ofthose whodied was significantly larger thanthat ofsurvivors (46.5 ± 5.8(SEM) vs21.1i 1.4CK-g-Eq/m2, p < 0.001). Overall survival was significantly better after small (ISI < 15CK-g-Eq/m2) ormodest infarcts (15< ISI< 30)than after large infarcts (ISI30)(p< 0.01, p < 0.05, respectively). Regardless ofthelocus oftheinfarction, patients withsmall infarcts hada better prognosis thanthose withlarger infarcts. Latemortality was comparable after transmural andsubendocardial infarction, buthigher after anterior thanafter inferior infarction (15%vs 6%;p < 0.05). Amongthe10clinical andhemodynamic variables evaluated withmultivariate analysis, ISI(but notinfarct locus), peakplasma creatine kinase, congestive failure atthetimeofadmission, ageandgender weresignificantly related tomortality. Premature ventricular complexes were more frequent among patients withmodest orlarge infarcts (ISI15)throughout thefollow-up (p< 0.05), regardless ofinfarct locus. Thus, theextent ofinfarction isa strong determinant ofbothventricular dysrhythmia andmortality, late aswell asearly after acutemyocardial infarction. MORTALITY EARLY after acutemyocardial infarction isrelated toage,thepresence orabsence of oldmyocardial infarction, andthesite andextent of myocardial infarction sustained.1-5 Inaddition, theincidence andseverity ofventricular dysrhythmia during thefirst 24hours after infarction reflect theamountof myocardium damaged.6 7Long-term survival appears toreflect inpart theseverity oftheinfarct based onindirect criteria, such asthepresence ofcongestive heart failure, depressed ejection fraction anddyskinesis. Further, late ventricular dysrhythmia appears tocorrelate notonly with theseverity ofcoronary artery diseasebutalsowithleft ventricular contraction abnormalities, which inturnreflect theextent ofinjury.'2' 13 Thisstudy wasdesigned todetermine whether the extent ofinfarction isanimportant determinant ofthe incidence andseverity ofventricular dysrhythmia and mortality lateafter infarction. Becausepotential relationships might beobscured byadvanced ageor oldinfarcts,3 onlypatients aged65years oryounger andwithout historical or electrocardiographic evidence ofprevious myocardial infarction were studied.

Effect of moderate physical exercise on serum lipoproteins. A controlled clinical trial with special reference to serum high-density lipoproteins.

Abstract: A controlled trial is reported on the effects of mild-to-moderate physical activity on serum lipoproteins. After two baseline examinations 100 asymptomatic middle-aged men were randomly assigned to exercise and control groups. The exercise group participated in a 4-month exercise program that consisted of 3-4 weekly sessions. The control group was advised to maintain their previous exercise habits. The success of the program was corroborated by the increase in VO2 in the training group, but not in the control group. Serum triglycerides decreased from 1.54 +/- 0.10 to 1.27 +/- 0.08 mmol/1 (p less than 0.001) and high-density lipoprotein (HDL) cholesterol increased from 1.27 +/- 0.04 to 1.41 +/- 0.04 mmol/1 (p less than 0.01) in the exercise group during the trial. No change was seen in the control group. As the concentration of apolipoprotein AI stayed constant in both groups, the ratio HDL cholesterol/apolipoprotein AI increased only in the exercise group. The level of low-density lipoprotein (LDL) cholesterol and apolipoprotein AII decreased in both groups during the trial. The alterations in serum triglycerides and HDL cholesterol in the exercise group were not dependent on weight reduction; similar changes were also seen in subjects with constant body weight during the intervention.

A new technique for assessing right ventricular ejection fraction using rapid multiple-gated equilibrium cardiac blood pool scintigraphy. Description, validation and findings in chronic coronary artery disease.

Abstract: A reproducible, noninvasive technique for determining right ventricular ejection fraction (RVEF) was developed using multiple-gated equilibrium blood pool scintigraphy, which allows serial rapid measurements without reinjection of radioactivity. Studies were obtained using in vitro labeled technetium- 99m red blood cells, gamma camera and computer. In 20 patients, RVEF determined by multiple-gated equilibrium imaging in the left anterior oblique view was compared with RVEF measured by first-pass scintigraphy. For both types of imaging, multiple regions of interest (ROIs) were used for RVEF. The accuracy of RVEF using equilibrium scintigraphy was also evaluated using a single ROI. In 20 additional patients, rapid (2-minute) equilibrium scintigraphy for RVEF was compared with standard (6-minute) imaging. Excellent correlation (r = 0.94) for RVEF was found between multiple-gated equilibrium scintigraphy and the first-pass technique when multiple ROIs were used. Inter- and intraobserver variations for the equilibrium method were small (r = 0.91 and r = 0.98, respectively). RVEF with the 2-minute equilibrium technique correlated well with the 6-minute method (r = 0.98). In contrast to the high correlation when multiple ROIs were used, analysis of equilibrium scintigraphy by single ROI severely underestimated first-pass RVEF and showed poor correlation (r = 0.60).In 15 normal subjects and 21 patients with significant coronary artery disease and different degrees of right coronary artery stenosis, simultaneous left ventricular ejection fraction (LVEF) and RVEF were measured. RVEF was less than LVEF in normal subjects (0.48 ± 0.05 vs 0.63 ± 0.08, mean ± SD). In patients with coronary artery disease, RVEF was not significantly different from that in the normal group, regardless of the degree of stenosis of the right coronary artery. We conclude that 1) multiple-gated equilibrium scintigraphy is a very accurate and reproducible new technique for determining RVEF; 2) the technique may be performed rapidly, and is therefore well suited to serial assessment of right ventricular function during exercise; 3) multiple ROIs are necessary for accurate measurement with this technique; and 4) RVEF is normally less than LVEF and is not significantly affected at rest by right coronary artery disease.

Two periods of early ventricular arrhythmia in the canine acute myocardial infarction model.

Abstract: The time course of ventricular arrhythmias in the early period (0--30 minutes) after ligation of the left anterior descending coronary artery was studied in 41 open-chest mongrel dogs anesthetized with pentobarbital sodium (Nembutal). ECGs and seven single and composite electrograms from various regions in and around the ischemic zone were recorded throughout the experiments. Two periods of ventricular arrhythmias were clearly seen. The first occurred 2--10 minutes after coronary ligation, peaking at 5--6 minutes, and was designated as immediate ventricular arrhythmias (IVAs). There was a distinct correlation between incidence, severity, onset and termination of IVA and the degree of local delay and fragmentation of the normal sinus activation spread in the ischemic subepicardial zone. The second wave of ventricular arrhythmias occurred 12--30 minutes after ligation independently of the previous increased delay and fragmentation of activation in the ischemic subepicardium. Delayed ventricular arrhythmias (DVAs) were as severe as IVAs--there were nine instances of ventricular fibrillation during DVA and seven during IVA. While the mechanism of IVA is most probably related to reentry accompanied by delay and fragmentation of ischemic subepicardial activation, the mechanism of DVA remains unclear. Our evidence suggests that DVAs are also reentrant, with the reentry pathways located in deep myocardial structures or involving microscopic pathways at the Purkinje muscle junction.

Temporal response of left ventricular performance to mitral valve surgery.

Abstract: We separated MR patients into two subgroups. In 12 subjects (group 1) with preoperative EDD = 5.94 0.42 cm, ESD = 3.55 ± 0.43 cm, and EF = 0.70 ± 0.05, EF fell slightly by 6 months after surgery to 0.59 ± 0.10 (p < 0.01), but remained within the normal range. Concomitantly, left ventricular hypertrophy regressed, as CSA was 24.2 6.5 cm2 before and 18.6 ± 2.4 cm2 after surgery (p < 0.01). contrast, in four subjects (group 2) with preoperative EDD = 8.07 ± 0.35 cm, ESD = 5.69 ± 0.70 cm, and EF = 0.57 ± 0.05, left ventricular function progressively deteriorated after surgery, with EF falling 0.26 ± 0.06 (p < 0.01). In the latter group left ventricular hypertrophy did not regress (CSA = 31.5 ± 4.5 cm2 before and 31.9 ± 3.4 cm2 after surgery, NS). Techniques for myocardial preservation during mitral valve surgery did not differ between the MR and MS groups. In group 2 MR subjects, there was no evidence of intraoperative myocardial infarction.

Determination of right atrial and right ventricular size by two-dimensional echocardiography.

Abstract: No data are available on determining right atrial and right ventricular size by two-dimensional echocardiography. We performed two-dimensional echocardiograms on eight human right-heart casts obtained at autopsy and on 50 patients who underwent complete left- and right-heart catheterization. Measurement of individual dimensions of the long and short axes of the right atrium and ventricle from right heart casts closely correlated with the volume of these structures as determined by water displacement. Further, individual dimensions by cross-sectional echo correlated well with actual casts dimensions. Subsequently, echocardiographic measurements of right atrial and ventricular long and short axes were obtained in the apical four-chambered view in a group of normals and compared with a group of patients with right ventricular volume overload states. Mean values for right atrial short-axis and long-axis measurements were greater in right ventricular volume overload patients than in normals: 6.5 +/- 0.3 vs 3.6 +/- 0.1 cm, and 6.0 +/- 0.3 vs 4.2 +/- 0.1 cm, respectively (both p less than 0.001). In addition, measurements of both individual dimensions as well as planed area of the right ventricle were greater in right ventricular volume overload patients than in normals: maximal short axis 6.1 +/- 0.3 vs 3.5 +/- 0.2 cm, mid-short axis 6.1 %/- 0.4 vs 2.8 +/- 0.2 cm, and area 40 +/- 2.6 vs 18 +/- 1.2 cm2 (all p less than 0.001). There were no differences in right ventricular long-axis measurement. Two-dimensional echocardiography provided better separation of normals from right ventricular volume overload patients than did M-mode techniques. Thus, two-dimensional echocardiography, with the apical four-chambered view, enables accurate visualization of the right atrium and ventricle in almost all patients. Futher, measurements of right atrial and right ventricular size by two-dimensional echocardiography readily distinguish normal patients from those with right ventricular volume overload.

Cross-sectional echocardiography in acute myocardial infarction: detection and localization of regional left ventricular asynergy.

Abstract: Left ventricular asynergy associated with acute myocardial infarction was evaluated by crosssectional echocardiography. Patients with acute infarction were studied within 48 hours of admission, and a segmental analysis of left ventricular wall motion was performed using nine segments obtained by short- and long-axis recordings of the left ventricle. By this segmental approach, analysis of wall motion in the entire left ventricle was possible. Complete studies were recorded in 37 of 44 original patients. Segmental wall motion abnormalities were recorded and localized in each of the 37 study patients. Asynergy was detected in 142 segments, and 29 patients had multiple segment involvement. Asynergy was most common in the apical segments of the left ventricle, but the cross-sectional scans permitted detection of asynergy in all segments. Correlation between the ECG and the cross-sectional echocardiogram revealed that 19 of 20 patients with inferior infarction had asynergy in posterior segments, 14 of 14 patients with anterior infarction had asynergy in anterior segments, and three of three patients with anteroinferior infarction had asynergy both anterior and posterior segments. In addition, the location of segmental asynergy followed specific patterns for each ECG subgroup of infarction. In four patients with postmortem examination, 21 of 22 segments that had asynergy by cross-sectional echocardiography also had pathologic evidence of infarction. Therefore, the cross-sectional echocardiogram provides a reliable method for detecting the presence and location of regional asynergy associated with acute myocardial infarction.