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Biomedical subjects

B S Lewis

Publications and source records attributed to B S Lewis.

At least 181 records · Page 10Linked to original sources
PubMed1982

Cardiac operation during active infective endocarditis: results of aortic, mitral, and double valve replacement in 94 patients.

Cardiac valve replacement was performed in 94 patients (95 operations) in the presence of active infective endocarditis. Most of the patients were extremely ill. The operation was performed as an emergency or semiemergency lifesaving procedure in 88% of them, and more than half received little or no antibiotic treatment prior to the operation. The hospital mortality was 16%--14% for aortic valve replacement (AVR) and 11% for double valve replacement (DVR) but 31% for isolated mitral valve replacement (MVR). The mortality was not higher in patients operated on urgently (emergency or semiemergency), nor was it higher in patients who had aortic annular abscesses or aneurysms. Prosthetic valve endocarditis (PVE) (in each case occurring more than 60 days after the previous valve operation) carried a higher mortality (33%) than native valve endocarditis (NVE) (14%). The relatively high early mortality for MVR may have been related to the fact that we operated upon MVR patients after intensive medical treatment had failed. The late results were good: Sixty-six patients are alive and well, 51 of them in Functional Class I. Six patients were reoperated upon for aortic periprosthetic leaks, and five are now well. Eight patients died late (9%), one of them because of a periprosthetic leak and one because of a clotted valve. In seven of the eight deaths, the cause of death was probably not related to the timing of the original operation. We recommend early valve replacement for patients with infective endocarditis. We believe that early operation reduces mortality, prevents emboli, and is associated with excellent long-term results.

Adolescent↗
PubMed1982

Studies of left-ventricular function in anemia due to beta-thalassemia.

Left-ventricular (LV) function was studied in 23 patients with anemia due to beta-thalassemia, of whom seven had thalassemia intermedia and the remainder thalassemia major. Two-thirds of the patients wih thalassemia intermedia and almost all the patients with thalassemia major were in clinical congestive heart failure. Despite this, resting measurements of ventricular size and systolic ventricular function were normal, indicating high-output cardiac failure. However, effort testing showed a flat response or decrease in the LV shortening fraction in patients with thalassemia major, and serial studies showed a decrease in the shortening fraction over a 4-yr period in some patients. LV diastolic function was studied by calculating peak LV filling rate and the pattern of LV filling in early diastole. Three patient with thalassemia major showed a pattern indicating abnormal LV distension. Since LV end-diastolic dimension was increased, volume overload was present in all patients. The results indicate that the following factors contribute to the genesis of cardiac failure in beta-thalassemia: 1) diminished response of systolic ventricular performance to exercise and later at rest; 2) ventricular volume overload; and 3) abnormal ventricular distension in diastole. Although the ventricular filling suggests abnormal LV compliance, the effect of right-ventricular volume overload or a pericardial factor cannot be excluded.

Adolescent↗
PubMed1982

Association of blood pressure with ethnic origin in 17-year-olds: the Jerusalem Lipid Research Clinic Prevalence Study.

Blood pressure and pulse rate were measured in a random sample of 1,200 17-yr-old Jewish boys and girls examined in 1976-79 during Visit 2 of the Lipid Research Clinic Prevalence Study. Mean systolic pressures were 110.1 and 106.1 mm Hg in boys and girls, respectively, diastolic pressures 69.9 and 70.4, pulse pressure 40.2 and 35.7, pulse rates 73.3 and 77.3 beats/min, and double products 8,082 and 8,228 mm Hg x beat x min-1. Multiple regression analysis showed that there were significant differences in systolic pressures between boys and girls whose fathers had immigrated from different countries, pressures being highest in those of European origin and lowest in those of North African origin. These differences were of the order of 3 to 4 mm Hg and were not explained by the distribution of height, Quetelet index, skinfold thickness, smoking, drinking, social class or education of subject. Pulse pressures followed a similar pattern, but the differences between origin groups were significant only for boys. Diastolic pressures and pulse rates did not vary with origin.

Adolescent↗
PubMed1981

Cardiac rupture and ventricular septal defect in isolated right coronary artery disease.

A patient is described who had both ventricular septal defect and then cardiac rupture with death within 24 hours of the onset of acute posteroinferior myocardial infarction. At autopsy he was found to have single-vessel disease involving the right coronary artery. Isolated disease of the right coronary artery can produce unexpected, fatal mechanical complications.

Aged↗
PubMed1981

Relationship between systolic time interval measurements and the extent of regional ventricular asynergy in coronary artery disease.

Systolic time interval (STI) measurements were made in 44 patients with coronary artery disease: 38 had regional left ventricular (LV) asynergy, and the remaining 6 had normal ventricular contraction patterns on left ventricular angiography. There was a significant correlation between both the preejection period (PEP) (r = 0.70) and the PEP/LVET (LV ejection time) ratio (r = 0.66), with the extent of regional ventricular dysfunction measured quantitatively on the left ventricular angiogram (P less than 0.001). A PEP/LVET ratio greater than 0.50 was associated with ventricular asynergy involving more than 40% of the LV circumference at end diastole. STI measurements also correlated with ejection fraction but not with ventricular end diastolic pressure nor with the number of obstructed coronary arteries.

Adrenergic beta-Antagonists↗
PubMed1981

Hydralazine in the management of symptomatic sinus bradycardia.

Hydralazine (Apresoline) was used to increase heart rate in 21 patients (14 hypertensive and 7 normotensive) suffering from symptomatic sinus bradycardia (SSB). Patients were assessed clinically and by 24-h ECG analysis before and after tailored increasing doses of the drug. Heart rates measured were resting (basal) rate, minimum rate during sleep, maximal rate during the day, and mean rate during the 24-h period (from hourly strips). The longest sinus pause or period of sinus arrest (when present) was also measured. Hydralazine ameliorated symptoms and produced a 20% or greater increase in heart rate in just under two-thirds of the hypertensive and half of the normotensive patients. Blood pressure decreased slightly in hypertensive but not in normotensive patients, and there were no important side-effects. Hydralazine appears to be a useful and effective drug to increase heart rate in patients with SSB.

Adult↗
PubMed1981

Regional ejection fraction of the normal left ventricle.

Regional ventricular function is important in assessing the functional significance of muscle fibrosis and ischemia in coronary artery disease. We have investigated three different methods of computerized quantification of the regional left ventricular function in 20 normal subjects. Method 1 divided the left ventricle into eight rectangular regions and corrected for rotatory and translational movement of the heart during systole. Method 2 was similar to Method 1, but corrected for shortening of the long axis of the left ventricle. Method 3 assumed radial inward contraction using a polar system of coordinates after correcting for rotatory and translational movement. The values obtained for the regional ejection fraction and regional volumes were calculated and compared for each region.

Cardiac Catheterization↗
PubMed1981

Echocardiographic diagnosis of left anterior descending coronary artery disease and left ventricular asynergy.

Interventricular septal (IVS) motion was studied by M-mode echocardiography in 60 patients to review the value of the technique in identifying left anterior descending (LAD) coronary artery disease. Abnormalities of IVS thickening and excursion were presented in 90% of patients with proximal LAD disease, whereas septal function was essentially normal in patients with distal LAD disease and in patients with disease of the right and/or circumflex coronary arteries. Abnormalities of IVS motion were greater in patients with a history of previous anterior wall infarction and/or the presence of angiographic left ventricular (LV) asynergy. There was no difference between patients with isolated or combined LAD disease, nor was there a difference between patients with complete or partial obstruction of the LAD, when more than 75% of the lumen was occluded. The echo was also useful in identification of anterior LV asynergy. Abnormal widening of the LV near the apex and abnormal septal movement in this area detected, with high sensitivity and specificity, patients with angiographic anterior wall asynergy.

Arrhythmias, Cardiac↗
PubMed1980

Isovolumic relaxation period in man.

Isovolumic relaxation period (IRP) was measured noninvasively from the onset of the aortic component of the second heart sound on the phonocardiogram to the point of separation of the mitral leaflets on the echocardiogram. IRP was measured in 83 patients with different cardiac diseases. The duration of IRP was 58 +/- 11 msec. in normal subjects. It was prolonged in hypertension (p < 0.001), HOCM (p < 0.001), in aortic stenosis (p < 0.05), and aortic incompetence (p < 0.001), and was shortened in congestive cardiomyopathyl (p < 0.05) and mitral stenosis (p < 0.01). In patients with coronary artery disease and normal over-all systolic LV function, IRP was prolonged (p < 0.001); IRP was shortened in four patients with coronary disease who had severe LV dysfunction and severe additional mitral incompetence. IRP was related to systemic blood pressure, percentage shortening of the LV in systole, and to the mitral EF slope. It tended to increase with increasing heart rate and a regression equation was developed for predicting IRP in relation to blood pressure and heart rate in normal sbjects. There was no relation to the PR-Ac time or to isovolumic contraction time. IRP is a useful measurement of LV dynamics in early diastole.

Aortic Valve Insufficiency↗
PubMed1980

Early calcification and obstruction of a mitral porcine bioprosthesis.

A patient is described in whom severe prosthetic valvular stenosis developed ten months after mitral valve replacement with an Angell-Shiley porcine heterograft. At emergency operation, calcification of the prosthesis was revealed. Early calcification and stenosis of a porcine heterograft valve is a life-threatening complication that must be recognized promptly and treated by emergency valve replacement.

Adolescent↗
PubMed1980

Left ventricular function in liver cirrhosis: an echocardiographic study.

Left ventricular (LV) size and function were studied by echocardiography and measurement of systolic time intervals in 14 patients with liver cirrhosis. There was a small increase in LV end-diastolic dimension, and an increase in systolic ventricular performance, calculated stroke dimension and stroke and cardiac indices. Mean blood pressure was low normal. Preejection period was shortened and the preejection period/LV ejection time ratio, decreased. The data indicate that patients with liver cirrhosis have mild LV enlargment, reduced peripheral resistance and an increase in mesurements of systolic LV performance.

Adult↗
PubMed1980

Influence of intracoronary meglumine diatrizoate on regional myocardial contractility and the protective effect of hydrocortisone.

The effects of direct intracoronary injection of meglumine diatrizoate (RENOGRAFIN) on regional myocardial contractility were studied in 11 open-chested dogs. The left anterior descending or circumflex artery was cannulated selectively from the ascending aorta and the changes in myocardial contractile force and its first derivative were measured by an epicardial strain gauge sutured to the myocardium supplied by the cannulated artery. The myocardium perfused by the non-cannulated artery served as the control area. Direct intracoronary injection of meglumine diatrizoate, 1 ml, caused regional depression of myocardial function, with a significant decrease in contractile force and its first derivative in the study area; there was no change in the control area, nor were there changes in the first derivative of left ventricular pressure, heart rate or systemic blood pressure. There was no additive depressant effect after multiple injections. Local pretreatment with hydrocortisone (4 mg/kg, by slow intracoronary infusion) ameliorated the myocardial depressant effect of meglumine diatrizoate so that there was a smaller decrease in contractile force and its first derivative. The results may have clinical significance in patients undergoing coronary arteriography.

Animals↗
PubMed1980

Isolated circumflex coronary artery obstruction.

Isolated obstruction of the circumflex branch of the left coronary artery was present in 10 of 1,000 patients undergoing selective coronary angiography for suspected coronary artery disease. The clinical syndrome consisted of typical angina pectoris (six patients), atypical chest pain (three patients) and episodes of myocardial infarction (three patients). Left ventricular damage was mild, never involving more than 20% of the left ventricular circumference as measured during angiography. Left axis deviation was very common on the ECG. In eight patients, the ECG showed a mean frontal QRS axis of 0 degrees or less and in two, an axis of less than -30 degrees. The circumflex lesion typically occurred toward the end of the proximal third of the artery, often immediately after its major anterolateral marginal branch. Two patients had complete obstruction and eight had subtotal circumflex narrowing: the clinical picture was not differnet in these two subgroups. Overall left ventricular function, as measured by ejection fraction and left ventricular diastolic pressure, was normal in most of the patients. End-diastolic pressure was slightly increased in five patients, two of whom also had systemic hypertension.

Angina Pectoris↗
PubMed1980

Effect of standing and squatting on echocardiographic left ventricular function.

The effects of changes in posture on left ventricular (LV) diameter and function were studied by echocardiography in 14 healthy children. On changing from the supine to the standing position, enddiastolic LV diameter decreased by 13 +/- 5% (P < 0.001), heart rate increased (P < 0.05) and calculated stroke index (-37 +/- 11%, P < 0.001) and cardiac index (-32 +/- 14%, P < 0.001) fell. There was not a significant change in the echocardiographic measurement. % delta s, mean Vcf and max Vpwm (ns) but mean Vcf increased in relation to mean blood pressure in 3 patients, suggesting an increase in LV contractility. Squatting was accompanied by an increase in LV cavity dimension (P < 0.001), while heart rate fell slightly and calculated stroke index (%35 +/- 28%, P < 0.001) and cardiac index (+33 +/- 27%, P < 0.001) increased. Mean blood pressure increased by 19 +/- 18% (P < 0.01). There was again no significant change in % delta s, mean Vcf and max Vpwm. Most patients fell on the control (supine) blood pressure--mean Fcf curve; in 2 patients there was a residual increase in sympathetic tone and LV contractility.

Adolescent↗
PubMed1979

Echocardiographic diagnosis of pulmonary atresia with intact ventricular septum.

The echocardiographic features of pulmonary valvar atresia with intact ventricular septum are described. The pulmonary valve fails to open during systole: there is a large pre-systolic 'a' wave dip, but the pulmonary valve membrane then returns to its closed diastolic position where it remains for the remainder of the cardiac cycle. The echocardiogram also provides valuable information about right ventricular size, the tricuspid valve, and aorta-mitral and aorta-septal relations.

Cardiomegaly↗
PubMed1979

Relationship between extent of coronary artery disease and correlative risk factors.

An analysis was made of correlative factors which might be related to the angiographically measured extent of coronary artery disease in 140 patients. All patients presented with clinically important chest pain. Thirty-three had a normal coronary arteriogram. The extent of the atheromatous process was measured precisely at angiography by three different techniques. A coronary score, based on the percentage of luminal narrowing, was found to be best suited for the analysis. The most important contributory factors to the severity of atherosclerosis was duration of clinical history, number of previous myocardial infarctions, and male sex, but more specifically elevation of serum cholesterol and diabetes mellitus. Cigarette smoking, obesity, hypertension, a family history of atherosclerosis, and elevated serum triglycerides had a positive influence but this was not statistically significant.

Angina Pectoris↗