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Biomedical subjects

B S Lewis

Publications and source records attributed to B S Lewis.

At least 19 recordsLinked to original sources
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↗
PubMed1979

Evaluation of the beta-blocking drug acebutolol in angina pectoris.

The effects of the beta-adernergic blocking drug acebutolol were studied in 23 patients with angina pectoris and angiographically documented coronary artery disease. Patients were evaluated clinically, by graded treadmill testing and by 24-hour Holter monitoring in the control state, after 2 weeks treatment with placebo, and after 2 weeks treatment with 600 mg. and then 1,200 mg. of acebutolol. Acebutolol (in a daily dose of 600 mg.) was an effective antianginal drug: the number of clinical attacks of angina pectoris (p less than 0.001) and the consumption of sublingual nitrate decreased (p less than 0.01), there was a significant increase in the treadmill effort tolerance as measured by the time to appearance of ischemic ECG changes (p less than 0.001) and the total work performed (p less than 0.001), and there was also a significant decrease in ischemic ST segment depression on 24-hour Holter monitoring. Treatment with 1,200 mg. acebutolol was associated with a further decrease in heart rate and a further improvement in effort tolerance on treadmill testing (p less than 0.05). On the large dose of the drug, however, there was no further clinical improvement, and no further improvement on 24-hour ECG monitoring; several patients complained of weakness and fatigue. Graded treadmill testing was an excellent objective method for assessing physical effort tolerance and its improvement after treatment with the beta-blocking drug. Twenty-four-hour Holter monitoring was a useful and complementary test, especially in patients who stopped exercising on the treadmill because of fatigue or weakness, and especially for assessing the efficacy of beta-blockade in controlling emotionally induced tachycardia and ischemia in the patient's own daily environment.

Acebutolol↗
PubMed1979

Echocardiography and valve replacement in the critically ill patient with acute rheumatic carditis.

In 4 critically ill patients with acute rheumatic carditis, valve incompetence, and severe life-threatening cardiac failure, medical treatment consisting of bedrest, oxygen, digitalis, diuretics, and steroids produced little or no clinical improvement. Echocardiography showed that in each patient myocardial function was relatively well preserved despite active rheumatic carditis and the critical clinical state. Emergency valve replacement was performed, and a good clinical result was achieved in all 4 patients.

Acute Disease↗
PubMed1979

Selection of saphenous vein bypass gradt diameter to support patency of the stenosed coronary artery.

Injudicious selection of a saphenous vein graft can adversely affect the the late postoperative patency of the proximal coronary artery which it bypasses. The purpose of this investigation was to deduce an upper bound for graft diameter, at small angle of distal anastomosis, below which the stenosed artery will remain patent, from a mathematical model of aortocoronary bypass haemodynamics.

Coronary Artery Bypass↗
PubMed1979

Coronary angiography after traumatic myocardial contusion.

A patient with myocardial trauma following blunt chest injury is presented who returned 4 months later with persistent cardiac symptoms. Left ventriculography showed asynergy of the mid-diaphragmatic surface of the left ventricle while coronary angiography showed normal coronary arteries. The value of cardiac catheterization and coronary angiography in patients in whom symptoms persist after traumatic myocardial contusion and in patients in whom additional coronary artery or other cardiac disease is suspected is emphasized.

Adult↗
PubMed1979

Angina pectoris with normal coronary arteries in Shy-Drager syndrome.

A patient with Shy-Drager syndrome who presented with severe angina pectoris is described. Special investigations of his autonomic nervous system showed sympathetic and parasympathetic dysfunction with supersensitive end-organ response. Sympathetic dysfunction manifested as labile hypertension, severe postural hypotension, and inadequate heart rate response to atropine and the Valsalva manoeuvre. These changes in blood pressure were accompanied by severe disabling angina pectoris. Selective coronary angiography showed normal coronary arteries. It is suggested that angina pectoris resulted from the inadequate circulatory response and is another clinical manifestation of the Shy-Drager syndrome.

Angina Pectoris↗
PubMed1979

Effect of postural changes on pulsus alternans: an echocardiographic study.

We describe a patient who had severe left ventricular dysfunction and pulsus alternans following an episode of severe viral myocarditis. Pulsus alternans was mild with the patient in the supine and squatting positions but increased dramatically on standing. Echocardiograms were used to study changes in left ventricular dimension and function with changes in posture. On standing, there was a decrease in the left ventricular diameter and an increase in the absolute and relative shortening fraction and the velocity of shortening on the strong beats, and there was a decrease in end-diastolic dimension and the measurements of ventricular contractility on the weak beats. The marked increase in pulsus alternans during standing may have been induced by increased sympathetic stimulation following the decrease in ventricular loading conditions, while the great beat-to-beat differences in end-diastolic dimension suggest, in addition, the importance of Starling's mechanism.

Adult↗
PubMed1979

Effect of acebutolol on dynamic ischemic ECG changes: a study using ambulatory twenty-four-hour ECG monitoring.

The clinical effect of the beta-adrenergic blocking drug acebutolol hydrochloride (SECTRAL) was studied in 18 patients with angina pectoris. Ambulatory 24-h ECG monitoring proved to be a useful method for assessing the efficacy of this drug in individual patients in their own daily stresses and environment. Patients were studied in the control state, after two weeks' treatment with placebo, and after two weeks' constant oral dose of the drug. It was found that acebutolol produced a significant decrease in ischemic ST segment depression in patients in whom good beta-blockade was achieved. The drug was less effective in patients in whom the heart rate response to exercise was not suppressed and in those with critical coronary artery obstructions.

Acebutolol↗
PubMed1979

Diagnostic value of cross-sectional echocardiography in left atrial myxoma.

Atrial myxoma is a rare condition that may have unusual clinical manifestations. Two patients with left atrial myxoma are described. One presented with paroxysmal nocturnal dyspnea and no abnormal physical signs on clinical examination; the second presented with palpitations and physical findings suggestive of mild mixed mitral valve disease. Echocardiography and cross-sectional echocardiography confirmed the diagnosis of atrial myxoma in both patients, and the tumors were successfully removed by operation. Cross-sectional echocardiography may obviate the need for cardiac catheterization in patients with left atrial tumors.

Echocardiography↗
PubMed1979

Serial echocardiography during the first 3 mth of life in normal neonates.

Echocardiography was performed in 13 normal neonates on the first day of life and repeated after 1 wk, 1 mth and 3 mth. Measurements were made of cardiac chamber size and wall thickness, mitral, tricuspid and pulmonary valve motion, right and left ventricular systolic time intervals, and of fractional left ventricular shortening (%deltaS) and mean velocity of circumferential fibre shortening (mean Vcf). During the study there was a relative decrease in right ventricular cavity size and wall thickness with an increase in the pulmonary valve EF slope, indicating a fall in pulmonary artery pressure with regression of the right ventricle. Left ventricular size and thickness increased while LVET became longer, possibly the consequence of an increasing left ventricular afterload. There was not a significant change in %deltaS and mean Vcf during the study period. The greatest change from right to left ventricular preponderance occurred between 1 wk and 1 mth of life and was accompanied by changes in the mean frontal QRS axis of the electrocardiogram. The study shows that significant changes occur in the echocardiogram during the first 3 mth of life; neonatal echocardiograms should be interpreted not only in relation to the baby's weight, but also to its age.

Atrial Function↗
PubMed1979

Effect of respiration on echocardiographic ventricular dimensions and relationship to the second heart sound.

The effects of normal respiration on echocardiographic right and left ventricular dimensions were studied in 8 normal subjects (group 1) and in 10 patients with ventricular volume overload due to anaemia (group 2). Right ventricular internal diameter (RVID) increased on inspiration in both groups of patients (group 1, 0.3 +/- 0.1 cm; group 2, 0.6 +/- 0.4 cm), while left ventricular internal diameter (LVID) decreased (group 1, 0.3 +/- 0.2 cm; group 2, 0.4 +/- 0.3 cm). The changes in echocardiographic diameter were related to the duration of electromechanical systole and to the changes in the splitting of the second heart sound; there was a linear relationship between RVID and Q--P2 (P less than 0.001) and A2--P2 (P less than 0.001). Echocardiographic measurements of cardiac chamber size should take into account the changes which occur during respiration.

Adolescent↗
PubMed1979

Echocardiographic aortic root motion in ventricular volume overload and the effect of mitral incompetence.

Echocardiographic aortic root motion in systole was studied in 57 patients: 13 normal subjects, 4 patients with left ventricular (LV) volume overload due to anaemia, 16 patients with mitral incompetence, 13 with aortic incompetence and 11 with mitral stenosis. In normal subjects, patients with mitral stenosis and in patients with LV volume overload, in whom the increased stroke volume was ejected forwards into the ascending aorta (anaemia, aortic incompetence) the amplitude of motion of the posterior aortic wall (vp), the aortic widening fraction (AWF) and total aortic motion (TAM) were increased. In mitral incompetence, however, despite the large increase in total LV stroke index, there was a decrease in vp (P less than 0.01), AWF (P less than 0.001) and TAM (P less than 0.001), and the decrease in aortic motion for a given stroke index was related to the mitral regurgitant fraction, indicating that aortic wall movement in systole depended predominantly on forward ejection of the LV stroke volume. Reduced echocardiographic aortic root motion and widening during systole are useful echocardiographic signs of mitral regurgitation.

Anemia↗
PubMed1978

Left ventricular function in beta-thalassemia and the effect of multiple transfusions.

Left ventricular performance was studied in 23 young patients with severe chronic anemia due to beta-thalassemia major and intermedia. The patients were divided into three groups according to the number of blood transfusions they had received. The left ventricle (LV) was enlarged in patients who had not received blood and larger still in patients who had received multiple transfusions. Echocardiography and systolic time interval measurements showed that systolic function of the LV was good in all the patients and that there was no statistical difference in systolic function in patients who had and those who had not received multiple transfusions. Heart rate was increased in the latter group. Stroke index and cardiac index were high, especially in patients in Group 3. The diastolic closure rate (EF slope) of the anterior mitral leaflet and its amplitude of movement were increased, but less so in Group 3; this may reflect an alteration in diastolic LV distensibility. The results indicate that despite the presence of cardiomegaly and severe clinical congestive heart failure, LV performance is well preserved in patients with beta-thalassemia, even in those who have received repeated blood transfusions. Clinical cardiac failure is the consequence of volume overload and abnormal chamber compliance. There was no evidence in this of a congestive cardiomyopathy.

Adolescent↗
PubMed1978

Ventricular ectopic rhythms due to rapid runaway pacemaker.

A patient initially had syncope due to a runaway pacemaker firing at an unusually rapid rate (30 impulses per second). The ventricular arrhythmia was characterized by numerous ectopic beats, with coupling intervals related to the length of the preceding cycle and runs of ventricular tachycardia with slight variations in the intervals between beats. This case demonstrates the clinical characteristics of a very rapidly firing, low-intensity, ventricular parasystolic focus.

Arrhythmias, Cardiac↗
PubMed1978

Acebutolol in angina pectoris: objective assessment using graded treadmill testing.

The clinical effects of a new cardioselective beta-adrenergic blocking drug, acebutolol hydrochloride (SECTRAL), were studied in 18 patients with angina pectoris, using graded treadmill testing according to a modified Bruce protocol. Measurements were made in the control state, after two weeks' treatment with placebo and after two more weeks of constant oral dose of the drug. Acebutolol produced a significant increase in the treadmill work performed before the onset of ischemic ECG changes and chest pain. The heart rate and blood pressure responses to exercise were depressed, so that the greater work load was achieved at a lower double product. Graded treadmill testing is a useful method for assessing the efficacy of treatment with a beta-blocking drug.

Acebutolol↗
PubMed1978

Selective coronary angiography in patients with conduction disturbances of the heart.

Selective coronary angiography and left ventriculography was performed in 14 patients with conduction disturbances of the heart or chronic complete heart block. Occlusive coronary arterial diseas was present in 3 patients: 2 of these had had extensive previous myocardial infarction and 1 complained of angina pectoris. The other patients gave no history of coronary artery disease and conduction abnormalities were the consequence of idiopathic fibrosis of the conducting system. The coronary arteries were normal or dilated and were remarkably free of atheroma in this group of older patients. Left ventricular function, as measured by ejection fraction, was normal except in the 2 patients who had had previous myocardial infarction.

Adult↗