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Biomedical subjects

B S Lewis

Publications and source records attributed to B S Lewis.

At least 163 records · Page 9Linked to original sources
PubMed1983

Nonsurgical myocardial revascularization: initial experience with percutaneous transluminal coronary angioplasty.

Coronary artery atheromata obstruct coronary blood flow and produce myocardial ischemia. Percutaneous transluminal coronary angioplasty (PTCA) was performed to dilate narrowed coronary arteries on 16 occasions in 15 patients with severe proximal coronary artery narrowings and significant clinical angina pectoris. The lesions involved the left-anterior descending (LAD) coronary artery in nine patients (10 dilatation procedures), the right coronary artery (RCA) in five, and the circumflex coronary artery in one. Successful dilatation was achieved on nine occasions (56%): in 7 of the 10 LAD lesions (70%), in 2 of the 5 RCA lesions (40%), but not in the patient with circumflex disease. Successful dilatation was accompanied by a significant improvement in symptoms and in myocardial performance, as judged by atrial pacing MUGA (multigated) ventriculography. The ischemic response of the ventricle to stress the significantly reduced or abolished. PTCA is a useful, nonoperative method for dilating obstructed coronary arteries and for improving myocardial blood flow.

Adult↗
PubMed1983

Atrial pacing thallium scintigraphy in the evaluation of coronary artery disease.

A study was undertaken to examine the value of rapid atrial pacing and thallium-201 scintigraphy in the evaluation of ischemic heart disease. Ten subjects with angiographically normal coronary arteries and 31 patients with coronary artery disease were studied. Six of these patients were studied after coronary artery bypass surgery. Coronary ischemia or infarction could be diagnosed from the ECG alone (rest and atrial pacing) in 87% of the patients with a greater than or equal to 50% narrowing of a coronary artery. The ECG and scintiscan (at rest and pacing) together had a sensitivity of 100%. The ECG could not identify the site of stress-induced ischemia. Rapid atrial pacing with scintigraphy identified 91% of those patients with a right coronary artery narrowing (greater than 50%), 85% with a narrowing of the left anterior descending coronary artery, but only 33% with a narrowing of the circumflex coronary artery. The scintiscan correctly identified 40% of arteries with a 50 to 89% narrowing, 75% with a 90 to 99% narrowing and 88% with a complete obstruction. The scintiscan predicted single- and double-vessel disease, but underestimated the number of vessels involved in patients with triple-vessel disease. This technique was also useful in assessing the patency of implanted coronary artery bypass grafts. Rapid atrial pacing is a simple and safe method of inducing ischemia, while thallium scintigraphy shows the site, extent and severity of coronary artery disease.

Adult↗
PubMed1983

Nuclear left ventriculography at rest and during atrial pacing in the evaluation of coronary artery disease.

This study was undertaken to examine the value of rapid atrial pacing (RAP) combined with left-ventricular nuclear (LVN) angiography in the diagnosis of ischemic heart disease. It included 32 patients: 12 normal subjects and 20 with clinical coronary artery disease (CAD) and greater than 50% narrowing of a coronary artery (significant CAD). The ECG and an LVN angiogram (LVNA) were recorded at rest and during graded RAP. In the normal subjects, left-ventricular wall motion was normal at rest and during atrial pacing, but a wall motion abnormality (WMA) appeared in one subject. Left-ventricular ejection fraction (EF) did not change significantly. In the 20 patients with significant CAD, the diagnostic sensitivity of the ECG during RAP was 100% and 90% for the nuclear angiogram (presence or appearance of WMA at rest and during RAP). The mean EF in this group decreased from 0.38 to 0.31. WMA on the LVNA was present in 79% of patients with significant left-anterior descending, in 44% of those with right, and in 33% of those with circumflex coronary artery disease. WMA (at rest or on pacing) occurred in 17% of patients with 50 to 89% narrowing of an artery, in 50% with 90 to 99% narrowing and in 68% with total obstructions. The LVNA (rest and/or RAP) identified patients with significant single-vessel disease, but underestimated the extent of double-and triple-vessel disease. The LVNA at rest and during atrial pacing was an excellent method of evaluating significant coronary artery disease.

Adult↗
PubMed1983

Electrocardiographic patterns in diabetics without clinical ischemic heart disease.

Resting ECG patterns were studied in 42 young diabetic patients and in 40 matched control subjects. There was no clinical ischemic heart disease in either group. Discriminant analysis showed significant differences between the two groups: diabetics typically had a higher heart rate, a leftward frontal QRS axis, a prolonged corrected QT interval and ST segment and T wave changes. Using resting ECG variables we were able to correctly classify 62 (75%) of the 82 patients studied. The findings support the existence of a nonischemic diabetic cardiopathy.

Adult↗
PubMed1982

Permanent cardiac pacing in South African Blacks.

Fifty-seven Black patients received permanent cardiac pacemakers at Baragwanath Hospital, Johannesburg, over a 7 1/2-year period. Most patients had established complete heart block (77%), while very few had intermittent conduction disorders or sinus node dysfunction. In most patients the cause of the conduction disease was unknown but was probably primary degeneration of the conducting pathways (Lenègre's disease); 2 patients underwent insertion of a pacemaker after myocardial infarction, 4 had congestive cardiomyopathy and 4 had valve disease and/or had previously undergone valve replacement. Seventeen patients (30%) were hypertensive. The results of cardiac pacing have been very good and the complication rate is low. Cardiac conduction disorders requiring insertion of a permanent cardiac pacemaker are not infrequent in South African Blacks, despite the absence or rarity of coronary artery disease in this population.

Adolescent↗
PubMed1982

An unusual case of mitral valve aneurysm: two dimensional echocardiographic and cineangiocardiographic features.

A patient is described in whom an aneurysm of the posterior mitral leaflet caused severe mitral incompetence and cardiac failure. The aneurysm was seen as an additional echo-free space within the left atrium in the real time two dimensional echocardiogram. Both echocardiographic and cineangiocardiographic appearances were misinterpreted initially because the aneurysmal leaflet did not more into the left ventricle during diastole. This feature was explained during the successful surgical repair of the valve by the observation that the aneurysm was adherent to the left atrial wall.

Adult↗
PubMed1982

High-quality imaging of a left atrial tumour using real-time two-dimensional echocardiography.

A patient with a large left atrial mass is described in whom real-time two-dimensional (2-D) echocardiography provided images of exceptionally high quality. The mass was pedunculated, attached to the lower interatrial septum, appeared jelly-like in consistency and prolapsed into the mitral orifice during diastole. These features are characteristic of a left atrial myxoma. The importance of real-time 2-D echocardiography in the diagnosis of atrial tumours, and especially that of the subxiphoid view, is discussed.

Echocardiography↗
PubMed1982

Verapamil in effort-induced angina pectoris in patients with normal coronary arteries.

Two patients with classical effort-induced angina pectoris associated with abnormal ST-segment depression on graded exercise testing and normal coronary arteriograms are described. Both patients deteriorated during treatment with propranolol, and became asymptomatic during treatment with verapamil with normal graded exercise tests. Verapamil may thus improve an inadequate vasodilatatory response of the coronary vascular bed to effort.

Angina Pectoris↗
PubMed1982

Real time two dimensional echocardiography in constrictive pericarditis.

Real time two dimensional echocardiography was performed in five patients with constrictive pericarditis. The echocardiogram showed several typical features: (1) The heart was normal in size or decreased; the ventricles were small and the atria enlarged. (2) The pericardium was seen as a single or double dense rigid shell surrounding both ventricles and the apex; its immobility was striking. (3) The inferior vena cava and hepatic veins were greatly dilated in keeping with the severe clinical venous congestion. (4) Both interventricular and interatrial septa bulged into the left side of the heart on inspiration. (5) The atrioventricular valves were hypermobile. (6) A prominent ventricular diastolic filling half was seen. The two dimensional echocardiogram excluded other causes of severe cardiac failure such as congestive cardiomyopathy and valvular heart disease, while the dense immobile pericardial echo or echoes and the "normal" texture of the myocardial echoes made the diagnosis of restrictive cardiomyopathy unlikely.

Adolescent↗
PubMed1982

Regional left ventricular ejection fraction from real-time two-dimensional echocardiography.

We studied regional left ventricular contraction patterns and ejection fraction from real-time two-dimensional echocardiograms in 8 normal subjects, 11 patients with coronary artery disease and 2 with congestive cardiomyopathy. The ventricle was divided into 12 regions and for each region, we calculated ejection fraction using a method which integrated the incremental volumes of a series of hemicylinders constructed within that region. The data obtained were displayed graphically to provide a detailed picture of regional ventricular function. Normal subjects had a uniform regional ventricular pattern (regional ejection fraction 54-74%). In patients with coronary disease, we found varying degrees of regional ventricular contraction abnormalities. In congestive cardiomyopathy global hypokinesis was present, and regional ejection fraction was reduced in all areas (11-39%). The study showed that two-dimensional echocardiography is a useful non-invasive bedside technique which may provide detailed quantitative information relating to regional left ventricular contraction abnormalities.

Adolescent↗
PubMed1982

Long-term effect of verapamil in hypertrophic cardiomyopathy.

We studied the long-term effects of oral verapamil (240-720 mg) daily on 10 patients with hypertrophic cardiomyopathy. Symptomatic improvement of chest pain or shortness of breath occurred in all the patients although 4 deteriorated after 1 year. Side effects occurred in 3 patients. The electrocardiogram improved in 4 subjects. Quantitative echocardiography showed a significant (P less than 0.05) decrease in left ventricular contractility (% delta S decreased from 44 +/- 9 to 38 +/- 9, mean +/- SD), septal hypertrophy (1.6 +/- 0.5 to 1.4 +/- 0.5 cm) and % thickening of the left ventricular free wall (79 +/- 29 to 57 +/- 22). There was also moderate evidence of improvement in left ventricular compliance; mitral valve EF slope increased from 38 to 55 mm/sec and left atrial diameter decreased.

Adult↗
PubMed1982

Platelet studies in patients with hypertrophic cardiomyopathy.

Because of a shared abnormality of platelet and muscle in some neuromuscular diseases, platelets were investigated in five cases of hypertrophic cardiomyopathy, a disease likely to be primarily myogenic. Morphometric and chemical differences from normal were found consisting of increased cell size, decreased phosphorus concentrations and increased permeability to cations. The findings suggest membrane and energy metabolism aberrations.

Adult↗
PubMed1982

Left ventricular filling and emptying patterns in anemia due to beta thalassemia. A computer-assisted echocardiographic study.

Patterns of left ventricular (LV) filling and emptying were studied in 17 patients with chronic anemia due to beta thalassemia and in 8 normal subjects. M-mode echocardiograms were recorded in each patient and digitization and computer analysis of the tracings provided data relating to the systolic and diastolic performance of the LV. LV diameter was increased. The rate, pattern and time relationships of LV systolic emptying were normal or increased in patients with thalassemia especially in those with thalassemia major requiring a large number of blood transfusions. Peak LV filling rate and the time course of early diastolic ventricular filling were also normal or increased in most patients but an abnormality of diastole was present in 3; this may have been due to abnormal early diastolic relaxation or to right-sided overload altering the LV filling pattern.

Adolescent↗
PubMed1982

Mitral valve prolapse and panic attacks.

Patients complaining of recurrent spontaneous panic attacks (RSPA) are frequently seen in emergency rooms and psychiatric outpatient services. The symptomatology of RSPA suggests some underlying cardiac pathology. Recent publications in the psychiatric literature have reported a high incidence of mitral valve prolapse (MVP) in patients complaining of RSPA. In our study we report a 39% incidence of MVP in a psychiatric population with RSPA. The importance of this finding is yet to be determined.

Adult↗
PubMed1982

Quantitation of regional ventricular asynergy using real-time two-dimensional echocardiography.

Real-time two-dimensional echocardiography was used to identify and quantitate regional left ventricular dysfunction in 12 patients with coronary artery disease. THe extent of regional ventricular asynergy was expressed as the percentage of the left ventricular circumference contracting abnormally. The findings were compared with those obtained from cardiac catheterization and left ventriculography. The severity and extent of echocardiographic asynergy correlated closely with that observed on the angiocardiogram (r = 0.96, P less than 0.001). There was also a significant relationship between echocardiographic and angiocardiographic ventricular volume (r = 0.81, P less than 0.001) and ejection fraction (r = 0.79, P less than 0.01). Real-time two-dimensional echocardiography provided a useful noninvasive technique for the identification and quantitation of the extent of regional ventricular dysfunction.

Aged↗
PubMed1982

Echocardiography of the inferior vena cava in healthy subjects and in patients with cardiac disease.

Echocardiograms were recorded from the inferior vena cava (IVC) in 45 subjects: 10 normal subjects, 8 patients with cardiac volume overload due to anemia, 4 with severe right heart failure, 6 with significant tricuspid incompetence (TI), 7 with pericardial effusion (PE) and 10 with left-sided cardiac disease. The IVC was readily identified on the echo recordings made 1 to 2 cm below the junction of the hepatic veins. In normal subjects a double wave form was present on the IVC echogram for each beat: the waves corresponded to the "a' and "v' waves of the IVC pressure pulse tracing. The IVC diameter decreased on inspiration (P less than 0.01), particularly of the "x' descent (P less than 0.001). In patients with severe right heart dysfuction, the IVC was dilated (TI: P less than 0.02; PE: P less thaN 0.003; CMO: P less than 0.001), having lost its waveform and with diminished respiratory variation. There was, however, considerable overlap between the normal subjects and the different patient groups. In two of the patients with tamponade, the IVC did not empty upon inspiration, and pericardiocentesis was followed by a return of the waveform and normal respiratory changes. IVC dimensions were normal in patients with anemia and in those with left heart disease. The results of the study showed that the echogram may provide simple and useful measurements of IVC size and function.

Adolescent↗