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Biomedical subjects

A H Hakki

Publications and source records attributed to A H Hakki.

At least 37 records · Page 2Linked to original sources
PubMed1986

Age-related changes in left ventricular diastolic performance.

Previous studies show that the radionuclide-derived indices of left ventricular (LV) diastolic performance are abnormal at rest in many patients with coronary artery disease (CAD), even in those with normal resting ejection fraction (EF) and no prior myocardial infarction. This study examined the age-related changes in LV peak filling rate and time to peak filling rate in 65 subjects between the ages of 20 and 75 years with a low likelihood of CAD. All subjects had normal resting EF (greater than or equal to 50%), and none had prior infarction. There was a significant age-related decline in resting peak filling rate (r = -0.47, p less than 0.001) and exercise peak filling rate (r = -0.52, p less than 0.001), but no age-related effect in the time to peak filling rate. Of the 29 subjects less than 50 years of age, 26 (90%) had resting peak filling rate greater than or equal to 2.5 EDV/sec (3.1 +/- 0.6, mean +/- SD) compared to 17 of 36 subjects (47%) greater than or equal to 50 years of age (2.6 +/- 0.6) (p = 0.002). In a subgroup of 28 subjects with a history of hypertension, the age-related effect was more marked than in the remaining 37 subjects without such a history (r = -0.66 vs -0.33). Thus, the peak filling rate at rest and during exercise decreases with advancing age; the high frequency of observed abnormality in the peak filling rate at rest in patients with CAD may conceivably be related in part to age differences between patients with CAD and the control group.

Adult↗
PubMed1986

Electrocardiographic diagnosis of posterior myocardial infarction revisited: a new approach using a multivariate discriminant analysis and thallium-201 myocardial scintigraphy.

This study examined the feasibility of using a multivariate discriminant analysis to design a useful electrocardiographic (ECG) model to diagnose posterior myocardial infarction (MI). Thallium-20) scintigraphy was used as a reference standard to identify posterior scar (fixed perfusion defects). The model was derived from 111 patients of whom 37 had fixed posterior defects and 74 had normal images, and its validity was subsequently tested in a separate group of 180 patients. In the initial group of patients, the fixed perfusion defects involved the posterior left ventricular wall alone in 15 patients, and the posterior and inferior walls in 22 patients. Stepwise multivariate discriminant analysis of 26 ECG variables produced a model of two variables (Q-wave duration in a VF and T-wave amplitude in V1) which provided a sensitivity of 78%, a specificity of 89%, and a predictive accuracy of 86% for the diagnosis of posterior MI. This model, when tested in the second group of 180 patients, yielded an overall prediction accuracy of 82% (sensitivity 65%, specificity 85%). Thus, the combination of Q-wave in a VF and upright T wave in V1 is the best ECG predictor of posterior MI. These two variables reflect the frequent association of posterior MI with inferior MI, and the reciprocal repolarization changes in the right precordial leads.

Adult↗
PubMed1986

Limitations of premature ventricular complex morphology in the diagnosis of myocardial infarction.

To determine the diagnostic value of Q-waves (greater than or equal to 0.04 seconds duration) in premature ventricular complexes (PVC's) for the presence of myocardial scar, we examined 12-lead electrocardiograms and multiple lead rhythm strips obtained before and after exercise at the time of thallium-201 myocardial imaging in 970 patients. PVC's were found in 233 patients, 112 of whom had fixed thallium-201 perfusion defects indicative of myocardial scar. PVC's occurring during exercise were excluded from the analysis. Twenty-one patients had Q-wave PVC's in one or more electrocardiographic leads. Of those, 14 patients (67%) had myocardial scar in the suggested location. Myocardial scar was more common among patients with Q-wave PVC's than in patients without (67% vs. 36%, p less than 0.01). However, only 6 of 13 patients (46%) with Q-wave PVC's but no diagnostic sinus beats actually had myocardial scar. The remaining seven patients had Q-wave PVC's, no myocardial scar, and no evidence of myocardial ischemia suggested by angina during exercise, exercise electrocardiogram or thallium-201 imaging. We conclude that although Q-wave PVC's indicate the presence of myocardial scar in 67% of patients, they yield little or no additional diagnostic information to that obtained from the sinus beats

Adult↗
PubMed1986

Plasma norepinephrine in exercise-induced ventricular tachycardia.

The relation between plasma norepinephrine levels and the occurrence of ventricular tachycardia during exercise testing was prospectively evaluated in 17 patients. Ten patients had reproducible ventricular tachycardia exclusively during exercise or recovery, or both; 7 patients had ventricular tachycardia only during ambulatory electrocardiographic monitoring. The two groups did not differ in age, exercise duration, left ventricular ejection fraction at rest, heart rate throughout the exercise protocol, rest QTc interval, change in QTc interval during exercise, the presence of coronary artery disease or exercise-related myocardial ischemia. Furthermore, there was no difference between groups in plasma norepinephrine levels at rest, peak exercise or in the recovery period. Myocardial ischemia was detectable by thallium perfusion scan in only 2 of the 10 patients with exercise-induced ventricular tachycardia. The 10 patients with exercise-induced ventricular tachycardia underwent repeat exercise testing immediately after maximal intravenous beta-adrenergic blockade with propranolol. Although they had no change in exercise duration, ventricular tachycardia did not occur in 9 of these 10 patients. Plasma norepinephrine levels were significantly decreased compared with levels before beta-adrenergic blockade (p less than 0.0002). Thus, plasma norepinephrine levels do not distinguish patients with reproducible exercise-induced ventricular tachycardia from otherwise comparable patients. Propranolol is highly effective in abolishing this arrhythmia and this effect is associated with decreased norepinephrine levels.

Adult↗
PubMed1986

Effects of esmolol on patients with left ventricular dysfunction.

This study examined the effect of esmolol, an ultrashort-acting beta-receptor blocker, in 10 patients with severe left ventricular dysfunction. Simultaneous hemodynamic and radionuclide angiographic measurements were obtained at incremental doses of esmolol (2, 4, 8, 12 and 16 mg/min). At a dose of 4 mg/min, esmolol produced beats blockade: a decrease in heart rate from 91 +/- 4 to 83 +/- 4 beats/min (p less than 0.05) (mean +/- SEM) and a decrease in systolic aortic pressure from 133 +/- 5 to 128 +/- 5 mm Hg (p less than 0.05). At the maximal dose, the heart rate decreased to 79 +/- 3 beats/min (p less than 0.05) and biventricular function was depressed; the left ventricular ejection fraction decreased from 27 +/- 2 to 21 +/- 2% (p less than 0.05) and the right ventricular ejection fraction decreased from 38 +/- 2 to 29 +/- 2% (p less than 0.05). These changes were accompanied by increases in left ventricular end-diastolic volume (p less than 0.05), left ventricular end-systolic volume (p less than 0.05) and pulmonary artery wedge pressure (p less than 0.05), as well as a decrease in cardiac output (p less than 0.05). The hemodynamic abnormalities (which showed considerable interindividual variability) returned to near baseline levels 10 to 30 minutes after infusion was stopped. Thus, esmolol can be administered to patients with severe left ventricular dysfunction. The beneficial effect (beta-adrenergic blockade) is usually achieved with small doses without clinically important hemodynamic changes. At larger doses, however, significant changes in biventricular function may be observed.

Adrenergic beta-Antagonists↗
PubMed1986

Coronary artery cardiomyopathy. Hemodynamic and prognostic implications.

To assess the prevalence and significance of left ventricular dilatation in patients with severe left ventricular dysfunction secondary to coronary artery disease (or coronary artery cardiomyopathy), we studied 70 patients with an ejection fraction of 35 percent or less and one-vessel coronary artery disease (n = 14) or with multivessel coronary artery disease (n = 56). None had had a recent myocardial infarction or valvular heart disease. Patients who underwent myocardial revascularization during follow-up were excluded. The left ventricular end-diastolic volume (measured by contrast ventriculography) was less than 110 ml/sq m in 14 patients (20 percent) (group 1), and was 110 ml/sq m or more in 56 patients (80 percent) (group 2). There were no differences between the two groups in age, sex, diabetes mellitus, hypertension, extent of coronary artery disease, or left ventricular asynergy. Patients in group 1 had lower pulmonary arterial wedge pressure (13 +/- 6 vs 22 +/- 10 mm Hg; p = 0.0008), lower left ventricular end-diastolic pressure (21 +/- 6 vs 27 +/- 9 mm Hg; p = 0.007), and higher left ventricular ejection fraction (31 +/- 2 vs 25 +/- 7 percent; p = 0.001) than patients in group 2. At a mean follow-up of 27 months, 24 patients had died of cardiac causes, all of whom were in group 2. Survival was significantly better in group 1 than in group 2 (Mantel-Cox, p = 0.009). Survival analysis (Cox models) of 20 clinical, hemodynamic, and angiographic variables showed that ejection fraction (chi2 = 13.6; p less than 0.001) and end-diastolic volume chi2 = 4.7; p = 0.03) were the most significant predictors of death. Thus, minimally dilated coronary artery cardiomyopathy is a distinct entity with favorable hemodynamics. Prognostically, the end-diastolic volume adds significant predictive information to the ejection fraction among conservatively treated patients.

Adult↗
PubMed1986

Role of exercise thallium 201 imaging in decision making.

This prospective study examined the impact of results of exercise thallium 201 imaging on the estimation of probability of coronary artery disease (CAD) and patient management among cardiologists and internists in our institution. Before exercise testing, the probability of CAD in the 100 patients enrolled in this study was considered low in 31, intermediate in 28, and high in 41 patients. The probability of CAD after exercise thallium imaging was different in four patients (10%) in the high group, 22 patients (79%) in the intermediate group, and three patients (10%) in the low group. Further, the results of exercise testing resulted in changes in patient management in 29 patients (71%) in the high group, 26 patients (93%) in the intermediate group, and 16 patients (52%) in the low group. Overall, the management changed in 71% of the patients. This change included changes in medications, physical activity, frequency of office visits, need for cardiac catheterization, and need for coronary arterial bypass grafting. Thus, exercise thallium imaging is useful in clinical decision making: the diagnostic certainty is improved in patients with intermediate pretest probability of CAD; and some degree of change in patient management is observed, even in patients in whom the probability of CAD is not altered.

Adrenergic beta-Antagonists↗
PubMed1986

Value of echocardiography and nuclear techniques in assessment of valvular heart lesions.

Assessment of the severity of valvular regurgitation is possible by nuclear techniques, but overlap with mild, moderate, or severe degrees of valvular regurgitation has been reported. For the individual patient, if a baseline correlation is established between RNA measurements and catheterization derived measurements, RNA may then be used serially to follow the patients. Controversy still persists in defining the optimum time for aortic valve replacement. We do not recommend aortic valve replacement in an asymptomatic patient whose end-systolic dimension is greater than 55 mm and fractional shortening is less than 25 percent. No single measurement at one point in time including a greater than or equal to 5 percent decrease in EF during exercise in the presence of a normal resting EF should be used as an indication for aortic valve replacement. It is our belief that these patients can be followed safely and that aortic valve replacement should be recommended only when symptoms appear or resting LV function deteriorates. Conflicting results have been reported with regard to left ventricular function after aortic valve replacement. In the majority of patients with pure AR, a decrease in left ventricular dimensions and improvement in resting EF and exercise EF does occur. However, the improved exercise EF is still lower than that observed in normal subjects. Regression of left ventricular hypertrophy occurs in the vast majority of patients with aortic stenosis in the late postoperative period following aortic valve replacement. In most patients with pure aortic regurgitation, significant regression of hypertrophy has been reported following aortic valve replacement. However, in some patients with isolated aortic regurgitation or mixed aortic stenosis and aortic regurgitation, the increased left ventricular mass and abnormal left ventricular function persist even after successful aortic valve replacement. With regard to patients with mitral regurgitation undergoing mitral valve replacement, a decrease in LVEF occurs early in the postoperative period and the decrease persists in the late postoperative period. In patients undergoing mitral valve replacement and using intraoperative echocardiographic techniques, patients with significant decreases in ejection fraction can be identified in the operating room. These patients can be treated immediately with drug therapy and/or intraaortic balloon counterpulsation support to ensure maximal opportunity for survival.

Aortic Valve Insufficiency↗
PubMed1986

Angina: DDx of atypical presentations in the elderly.

Pretest probability of coronary heart disease should be considered in interpreting exercise test results. In general, 90% of patients with typical angina pectoris, 50% of patients with atypical angina pectoris, and only 10% of patients with nonanginal chest pains have CHD. Marked ST-segment depression in multiple leads is a good indication of extensive coronary artery disease, especially when it occurs early during exercise or at submaximal exercise, and if associated with a blunted or a hypotensive BP response.

Aged↗
PubMed1986

Exercise thallium-201 scintigraphy in men with nondiagnostic exercise electrocardiograms. Prognostic implications.

We studied the prognostic value of exercise thallium-201 imaging in 196 men with suspected or known coronary artery disease who had nondiagnostic exercise electrocardiograms. The perfusion images in each of three projections were divided into three segments; each segment was assessed for perfusion defects (fixed or reversible). There were 12 cardiac events at a mean follow-up of 15 months (range, one to 66 months). Of those, five patients died of cardiac causes and seven had nonfatal acute myocardial infarctions (MIs). Only the number of perfusion defects significantly predicted cardiac events; clinical presentation, history of MI, presence of Q-wave MI, exercise duration, and exercise heart rate and double product did not predict cardiac events or add to information provided by the number of defects. Furthermore, actuarial life-table analysis showed that patients with three or more perfusion defects had significantly worse prognoses than patients with fewer than three defects. Exercise thallium-201 imaging helps in risk stratification of men with nondiagnostic exercise electrocardiograms.

Aged↗
PubMed1985

Effects of esmolol on cardiac function: evaluation by noninvasive techniques.

In a double-blind, randomized, crossover study, the effects of esmolol and propranolol were examined at rest and during peak upright exercise in 15 patients. At rest, both esmolol and propranolol significantly decreased heart rate, systolic blood pressure, rate-pressure product, left ventricular ejection fraction, cardiac index and right ventricular ejection fraction. During exercise, significant decreases were also found in heart rate, systolic blood pressure and cardiac index in both treatment groups. No significant differences were found between mean esmolol and mean propranolol measurements at rest and during exercise, except for the exercise systolic blood pressure, which was lower during esmolol infusion. Blood levels of esmolol decreased markedly by 30 minutes postinfusion, as did its beta-blocking action. Esmolol was well tolerated with no important local, systemic or laboratory abnormalities. Thus, the effects of esmolol on cardiovascular performance at rest and during exercise are similar to those of propranolol.

Adrenergic beta-Antagonists↗
PubMed1985

Effects of intravenous infusion of esmolol and propranolol on biventricular performance at rest and during exercise as assessed by quantitative radionuclide angiography.

This double-blind, randomized, crossover study examined the effects of intravenous infusion of esmolol (a new ultra-short-acting beta-receptor blocking agent) and propranolol on cardiovascular performance at rest and during peak upright exercise in 15 patients. Biventricular function was assessed by means of first-pass radionuclide ventriculography with a computerized multicrystal camera. At rest, significant treatment differences between esmolol and propranolol vs baseline were found for the heart rate, systolic blood pressure, double product, left ventricular ejection fraction (EF), systolic blood pressure to end-systolic volume ratio, cardiac index and right ventricular EF. During exercise, significant treatment differences were also found for the heart rate, systolic blood pressure, double product, right ventricular EF and cardiac index. The mean baseline measurements were higher than the mean treatment measurements, but no significant differences were found between mean esmolol and mean propranolol measurements at rest and during exercise except for the exercise systolic blood pressure, which was lower during esmolol infusion. The magnitude of drug effect was greater at the time of exercise than at rest. The blood level of esmolol decreased markedly by 30 minutes after infusion. Esmolol was well tolerated, with no important local, systemic or laboratory abnormalities. Thus, the effects of esmolol on cardiovascular performance at rest and exercise are similar to those of propranolol.

Aged↗
PubMed1985

Percutaneous left heart catheterization and coronary arteriography with and without an arterial sheath in patients without peripheral vascular disease.

The advantages and disadvantages of an arterial sheath to introduce catheters percutaneously through the femoral artery were prospectively studied in 184 consecutive patients without peripheral vascular disease undergoing routine diagnostic left heart catheterization and coronary arteriography. The arterial sheath was used randomly in 91 patients (sheath group) and the standard Seldinger technique in 93 (control group). There were no differences in age or sex between the two groups. All patients were studied with no premedication and had the same dose of lidocaine local anesthesia and heparin. No major complication occurred in any of the patients in the sheath or control groups. There were no significant differences in groin hematomas between the two groups. The patients in the control group more commonly had severe or moderately severe discomfort requiring additional local anesthesia. We conclude that the use of an arterial sheath percutaneously for introduction of catheters for left heart catheterization and coronary arteriography is advisable, particularly for anxious patients who have a low pain threshold.

Aged↗
PubMed1985

Quantitation of regional left ventricular function by two-dimensional echocardiography in normals and patients with coronary artery disease.

Regional endocardial motion and wall thickening of the left ventricle were quantitatively assessed in nine normal subjects and in 21 patients with coronary artery disease using two-dimensional echocardiography (2DE) and a computerized light pen system. Eight equal sectors of a cross-sectional image from parasternal short-axis, apical four-and two-chamber views were used for measuring sector area difference of endocardial motion and wall thickness between end diastole and end systole. In 13 patients with anterior wall motion abnormalities, area difference of wall thickening found by 2DE was abnormal in 12 of 13 (92%) patients, and only in 6 of 13 (46%) patients by endocardial motion. In 10 patients with dyskinetic regions in apex or anterior wall, dyskinesia by wall thickening was found in all patients, but only in 6 of 10 (60%) by endocardial motion. Thus, wall thickening assessed by 2DE is a more sensitive technique than analysis of endocardial motion in evaluating regional wall motion abnormalities in patients with coronary artery disease.

Adolescent↗