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Biomedical subjects

H Boudoulas

Publications and source records attributed to H Boudoulas.

At least 19 recordsLinked to original sources
PubMed1992

Exercise-induced S-wave prolongation in left anterior descending coronary artery stenosis.

Myocardial ischemia may decrease conduction velocity and produce QRS prolongation in the surface electrocardiogram. In cases with normal intraventricular conduction, areas of the myocardium contributing to the development of the S wave receive blood from all 3 major coronary arteries, whereas in left anterior hemiblock or right bundle branch block, most of the blood supply to the areas of the myocardium contributing to the development of the S wave is from the left anterior descending (LAD) coronary artery. To test the hypothesis that the S wave will be prolonged with exercise only in patients with LAD coronary artery stenosis and left anterior hemiblock or right bundle branch block, 88 patients with normal intraventricular conduction, 66 with left anterior hemiblock and 36 with right bundle branch block were studied. Sixty-four, 32 and 21 patients had LAD, right and left circumflex coronary artery stenoses, respectively. In patients with normal coronary arteries, S-wave duration decreased with exercise regardless of the status of ventricular conduction. In patients with coronary artery disease and normal intraventricular conduction, the S wave was prolonged slightly with exercise, but in those with left anterior hemiblock and right bundle branch block, it was prolonged significantly (12.5 +/- 6 and 10.4 ms, respectively) only in those with LAD, but not in those with circumflex or right coronary artery stenosis. S-wave prolongation in patients with LAD coronary artery stenosis and left anterior hemiblock or right bundle branch block most likely is related to exercise-induced ischemia in the areas of the myocardium contributing to the development of the S wave.

Blood Pressure↗
PubMed1992

T-cell receptor gene polymorphisms in familial cardiomyopathy: correlation with anti-beta-receptor autoantibodies.

Cardiac autoantibodies have been detected in a significant proportion of patients with dilated cardiomyopathy, but their relation to the pathogenesis of the disease remains unknown. This issue was examined in 41 members of an Ohio family with a heritable disorder of the cardiac conduction system and the myocardium. In 41.5% of all members studied, serum anti-beta-receptor antibodies were identified by a combination of techniques: ligand binding inhibition assay, enzyme-linked immunoassay of a beta 1-receptor peptide, and adenylate cyclase inhibition. The prevalence of autoantibodies was significantly higher (p < 0.01) in the affected (64.7%) than in the unaffected (25.0%) members. A 10.0 kb restriction fragment length polymorphism of the C beta region of the T-cell receptor gene was also overrepresented in affected males (60% versus 30% unaffected males, p < 0.01). In males, the presence of anti-beta-receptor antibodies was linked to the 10.0 kb C beta polymorphism. In affected males, a BlgII C alpha 2.14 kb polymorphism was also more frequent (62% versus 32% in unaffected, p < 0.01) and was linked to the presence of anti-beta-receptor antibodies. The distribution of haplotypes defined by V beta 8, C alpha, and C beta probes was significantly different between affected and unaffected (p < 0.04) and between antibody-positive and antibody-negative individuals. Since the major function of the T-cell receptor is the recognition of processed autoantigens, these results provide additional support for the role of autoimmunity in dilated cardiomyopathy.

Adult↗
PubMed1992

The Marfan syndrome: cardiovascular physical findings and diagnostic correlates.

Correlations among cardiac symptoms and auscultatory and phonoechocardiographic findings in Marfan syndrome have not been completely defined. A total of 24 patients with Marfan syndrome (16 men and 8 women; mean age 28.2 +/- 8.6 years) were studied. Mitral valve prolapse was noted in 22, of whom 19 had either nonejection systolic click or mitral regurgitation murmur. Mitral regurgitation was noted in 12 patients by Doppler imaging. Aortic root dilatation was noted in 20 patients and aortic regurgitation in six, five of whom had aortic regurgitation murmur (5 of 20 patients had undergone surgery). Proximal aortic dissection was noted in two. Dyspnea (n = 12) was associated with progressive mitral or aortic regurgitation in four, but in the others dyspnea could not be explained by valvular or ventricular abnormalities. Chest pain was related to pneumothorax in five and aortic dissection in two but was not associated with either in 15 patients. Palpitations (n = 12) and lightheadedness (n = 6) were not associated with specific arrhythmias. In conclusion, mitral valve prolapse and aortic root dilatation were the most common cardiovascular abnormalities in Marfan syndrome. Mitral valve prolapse was frequently associated with typical auscultatory findings and symptoms including dyspnea, chest pain, palpitations, and lightheadedness, whereas aortic root dilatation could be clinically silent unless complicated by aortic regurgitation or aortic dissection.

Adult↗
PubMed1992

Ascending aorta distensibility abnormalities in hypertensive patients and response to nifedipine administration.

PURPOSE: The purpose of the present investigation was to study the distensibility of the ascending aorta in patients with arterial hypertension and normal subjects before and after administration of a calcium antagonist, nifedipine. PATIENTS AND METHODS: The distensibility of the ascending aorta was measured before and after nifedipine administration in 22 male hypertensive patients and 12 age-matched male normotensive subjects. Aortic distensibility was calculated as a function of changes in aortic diameter and pulse pressure, using the formula: 2 x (pulsatile change in aortic diameter)/[(diastolic aortic diameter) x (aortic pulse pressure)]. Aortic diameters were measured by echocardiography and aortic pressures were obtained by catheterization of the ascending aorta. RESULTS: In the basal state, the distensibility of the ascending aorta and aortic strain were lower in hypertensive patients than in normotensive subjects (p < 0.001); the lower aortic distensibility, however, was associated with a greater distending pressure. A good inverse correlation (r = -0.81) was found between mean aortic pressure and aortic distensibility. The aortic distensibility was increased after nifedipine administration in both groups; this increase in aortic distensibility, however, was lower in the patients with hypertension compared with normotensive subjects (p < 0.001). CONCLUSIONS: Aortic distensibility is decreased in patients with arterial hypertension. Nifedipine administration increased the distensibility of the ascending aorta both in patients with arterial hypertension and in normotensive subjects. The increase of aortic distensibility after nifedipine administration was lower in hypertensive patients.

Adult↗
PubMed1992

Syncope.

Syncope is a clinical entity of diverse cause. The historical features surrounding the syncopal event and the presence or absence of heart disease are the most important features in establishing the cause for syncope. Passive head-up tilt study provides a means of identifying many patients with vasodepressor syncope. Electrophysiologic study is important in the elucidation of syncope in patients who have syncope undefined after noninvasive evaluation. With proper use of the modalities available, few patients will have an undefined cause for syncope.

Cardiac Pacing, Artificial↗
PubMed1992

Mitral valve prolapse: etiology, clinical presentation and neuroendocrine function.

Based on our experience and the experience of others, the following classification of patients with mitral valve prolapse has been proposed. Mitral valve prolapse - Anatomic includes patients with a wide spectrum of mitral valve abnormalities from mild to severe. Symptoms, physical findings and laboratory abnormalities in these patients are directly related to mitral valve dysfunction and progressive mitral regurgitation. Complications related to abnormal mitral valve include infective endocarditis, thromboembolic events, cardiac arrhythmias, progressive mitral regurgitation, rupture of chordae tendineae and congestive heart failure. Individuals with thick mitral leaflets and mitral systolic murmur are at higher risk of developing complications. The term mitral valve prolapse syndrome refers to the occurrence of symptoms such as palpitation, chest pain, fatigue, poor exercise tolerance, dyspnea, orthostatic phenomena and syncope or presyncope in patients with mitral valve prolapse which cannot be explained on the basis of mitral valve abnormality alone. The pathogenesis of these symptoms in patients with mitral valve prolapse syndrome appears to be related to metabolic neuroendocrine abnormalities. Preventing infective endocarditis is a major consideration in patients with mitral valve prolapse. Significant mitral regurgitation with the development of congestive heart failure often requires mitral valve surgery. The most important therapeutic approach in patients with mitral valve prolapse syndrome is to explain the mechanisms of symptoms and to reassure the patient.

Autonomic Nervous System↗
PubMed1991

Acecainide pharmacokinetics in normal subjects of known acetylator phenotype.

The purpose of this study was to determine the pharmacokinetics of acecainide (formerly N-acetylprocainamide) in six normal subjects of known acetylator phenotype. Three subjects were fast acetylators and three slow acetylators by sulfapyridine phenotyping criteria. Each subject received a 20-min, 3 mg kg-1 intravenous acecainide infusion. Concentrations of acecainide, procainamide, and their deethylated metabolites were measured in serum and urine samples using HPLC. Acecainide renal clearance, nonrenal clearance, steady-state volume of distribution, and other pharmacokinetic parameters were estimated using standard approaches. Acecainide renal clearance and steady-state volume of distribution were (mean +/- SD) 13.6 +/- 1.581 h-1 and 135 +/- 20.31, respectively, and were not significantly different in fast and slow acetylators. Acecainide nonrenal clearance in the six subjects was 3.0 +/- 1.01 h-1; however, nonrenal clearance in slow acetylators was 1.8 times that in fast acetylators (3.9 vs 2.21 h-1, p = 0.012) with clear separation of the subjects into two groups when the data were grouped by acetylator phenotype. The nonrenal clearance of acecainide was inversely correlated with percentage sulfapyridine acetylation. Computer simulations were conducted to explore possible explanations for the observed difference in nonrenal clearance.

Acecainide↗
PubMed1991

The Marfan syndrome: abnormal aortic elastic properties.

Aortic distensibility and aortic stiffness index were measured at the ascending aorta (3 cm above the aortic valve) and the mid-portion of the abdominal aorta from the changes in echocardiographic diameters and pulse pressure in 14 patients with the Marfan syndrome and 15 age- and gender-matched normal control subjects. The following formulas were used: 1) Aortic distensibility = 2(Changes in aortic diameter)/(Diastolic aortic diameter) (Pulse pressure); and 2) Aortic stiffness index = ln(Systolic blood pressure)/(Diastolic blood pressure)(Changes in aortic diameter)/Diastolic aortic diameter. Pulse wave velocity was also measured. Compared with normal subjects, patients with the Marfan syndrome had decreased aortic distensibility in the ascending and the abdominal aorta (2.9 +/- 1.3 vs. 5.6 +/- 1.4 cm2 dynes-1, p less than 0.001 and 4.5 +/- 2.1, vs. 7.7 +/- 2.5, cm2 dynes-1, p less than 0.001, respectively) and had an increased aortic stiffness index in the ascending and the abdominal aorta (10.9 +/- 5.6 vs. 5.9 +/- 2.2, p less than 0.005 and 7.1 +/- 3.1 vs. 3.9 +/- 1.2, p less than 0.005, respectively). Aortic diameters in the ascending aorta were larger in these patients than in normal subjects, but those in the abdominal aorta were similar in the two groups. Linear correlations for both aortic distensibility and stiffness index were found between the ascending and the abdominal aorta (r = 0.85 and 0.71, respectively). Pulse wave velocity was more rapid in the patients than in the normal subjects (11.6 +/- 2.5 vs. 9.5 +/- 1.4 m/s, respectively, p less than 0.01). Thus, aortic elastic properties are abnormal in patients with the Marfan syndrome irrespective of the aortic diameter, which suggests an intrinsic abnormality of the aortic arterial wall.

Adult↗
PubMed1990

Rest and exercise cardiovascular effects of terazosin in congestive heart failure.

This study investigated the acute effects of the alpha 1 antagonist terazosin on myocardial circulatory responses at rest and during exercise. Ten patients with congestive heart failure (class III and IV) underwent hemodynamic evaluation before and after a 5-mg oral dose of terazosin. At rest and during exercise, terazosin significantly decreased pulmonary capillary wedge pressure, systemic vascular resistance and mean arterial pressure while cardiac index increased. Stroke volume index increased (p less than 0.01) during exercise while left ventricular stroke work index remained unchanged in both experimental conditions. Terazosin administration significantly decreased both rest and exercise myocardial oxygen consumption while exercise coronary sinus oxygen content increased and arterial-coronary sinus oxygen difference diminished (p less than 0.05). Parallel with these changes, alpha blockade decreased the ratio of coronary blood flow to total cardiac output. Coronary vascular resistance remained unaltered with alpha blockade both at rest and during exercise. Coronary blood flow tended to diminish with decreased myocardial oxygen demand. Alpha 1 blockade induces systemic vasodilation and improves myocardial circulatory parameters without inducing coronary dilation or altering metabolic autoregulation.

Adrenergic alpha-Antagonists↗
PubMed1990

Comparison of hypersensitivity to adrenergic stimulation after abrupt withdrawal of propranolol and nadolol: influence of half-life differences.

To test whether a beta-blocker's pharmacokinetics has an effect on the development of the beta-blocker withdrawal syndrome, we compared response to exercise and isoproterenol after abrupt withdrawal of two beta-blockers, one with a short half-life (propranolol) and one with a long half-life (nadolol). Eight normal males participated in the randomized cross-over trial. They took propranolol, 40 mg every 6 hours for 6 days, and nadolol, 80 mg daily for 7 days. Exercise- and isoproterenol-induced changes in heart rate and pulse pressure were significantly less than control values during treatment with both drugs (p less than 0.05). Significant hypersensitivity of heart rate response was seen on days 2, 3, and 7 after propranolol withdrawal (p less than 0.05) and on day 6 after nadolol withdrawal (p less than 0.005). Hypersensitive responses to isoproterenol were seen after propranolol withdrawal; no evidence of hypersensitivity to isoproterenol was seen after nadolol withdrawal. The area under the heart rate response, time curve after nadolol withdrawal was significantly less than that after propranolol withdrawal (20.3 beats/min.day vs 44.9 beats/min.day, respectively, (p less than 0.05). There was a significant inverse correlation between the degree of hypersensitivity and nadolol pharmacokinetic half-life (r = -0.80, p less than 0.02). We conclude that abrupt withdrawal of a beta-blocker with a long half-life may protect against the development of the beta-blocker withdrawal syndrome.

Adult↗
PubMed1990

New coronary artery disease index based on exercise-induced QRS changes.

Exercise-induced changes in Q, R, and S wave amplitudes have been reported to detect coronary artery disease but with low specificity, low sensitivity, or both; it was hypothesized that their incorporation into a composite index (Athens QRS score) might improve specificity and sensitivity. For this purpose 246 patients were analyzed retrospectively and 160 prospectively. All patients underwent maximal exercise testing with a standard Bruce protocol and coronary arteriography as part of the diagnostic evaluation for possible or definite coronary artery disease. The Athens QRS score was decreased as the number of obstructed coronary arteries increased (normal coronary arteries = 7.85 +/- 5.23 mm, one-vessel disease = 5.2 +/- 5.3 mm, two-vessel disease = -0.85 +/- 5.4 mm, three-vessel disease = -3.5 +/- 5.8 mm; p less than 0.0001); the score was unrelated to exercise-induced ST segment depression, and negative (less than 0) scores were always associated with coronary artery disease. An Athens QRS score of 5 mm predicted coronary artery disease with sensitivity ranging from 75% to 86% and a specificity ranging from 73% to 79%, values higher than those of the Q wave (75% and 50%, respectively), R wave (65% and 55%), and S wave (70% and 10%) and of the ST segment depression (62% and 70%). It is concluded that exercise-induced changes in the QRS complex provide a useful index not only for the diagnosis but also for the assessment of severity of coronary artery disease.

Angiography↗
PubMed1990

Mitral stenosis: left atrial dynamics reflect altered passive and active emptying.

To assess the passive and the active phases of left atrial (LA) emptying, LA volumes and function were studied in 15 patients with mitral stenosis (MS) in sinus rhythm and in 11 normal subjects (NL) with two-dimensional echocardiography with simultaneous electrocardiograms. LA and left ventricular (LV) volumes were measured with the biplane area-length method. LA maximal and minimal volumes were measured at mitral valve opening and closure, respectively. In addition, LA volume was measured at onset of atrial systole (beginning of the P wave on the electrocardiogram). LA volumes were larger in MS compared with NL; Maximal 122 +/- 65 cm3 versus 46 +/- 12 cm3, p less than 0.001; onset of atrial systole 108 +/- 63 cm3 versus 29 +/- 12 cm3, p less than 0.001; minimal 90 +/- 60 cm3 versus 18 +/- 7 cm3, p less than 0.001. LA passive emptying volume (maximal minus volume at onset of atrial systole) was not statistically different in MS compared with NL, while LA active emptying volume (volume at onset of atrial systole minus minimal) was larger in MS compared with NL (17 +/- 5 cm3 versus 11 +/- 5 cm3, p less than 0.05). The net result was normal LA total emptying volume (maximal minus minimal) MS 32 +/- 11 cm3, NL 28 +/- 5 cm3. In contrast, the LA emptying fractions were significantly decreased in MS compared with NL (passive 0.13 +/- 0.08 versus 0.39 +/- 0.1, p less than 0.0001, active 0.19 +/- 0.08 versus 0.38 +/- 0.07, p less than 0.0001, total 0.30 +/- 0.1 versus 0.62 +/- 0.07, p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗