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Biomedical subjects

M Alam

Publications and source records attributed to M Alam.

At least 163 records · Page 9Linked to original sources
PubMed1993

Hemodynamic correlates of the third heart sound during the evolution of chronic heart failure.

OBJECTIVES: The purpose of this study was to examine the temporal relation between the development of a third heart sound during the course of evolving heart failure and associated hemodynamic abnormalities. BACKGROUND: Although various theories have been proposed to explain the origin of the third heart sound, the exact origin of this sound remains unknown. METHODS: Studies were performed in seven dogs in which heart failure was produced by multiple sequential intracoronary micro-embolizations. Hemodynamic studies including ventriculography, pulsed wave Doppler echocardiography and intracardiac phonocardiography were performed at baseline, at the time at third heart sound was first heard and at 6 and 24 weeks after onset of the third heart sound. RESULTS: All dogs developed a third heart sound at 9 +/- 2 weeks after the initial embolization. The onset of the sound was accompanied by an increase in left ventricular chamber stiffness relative to the baseline value (0.25 +/- 0.03 vs. 0.14 +/- 0.01 mm Hg/ml) (p < 0.05) and mean deceleration of early mitral inflow velocity (1,040 +/- 90 vs. 590 +/- 40 cm/s per s) (p < 0.05). CONCLUSIONS: These data indicate that the onset of a third heart sound during the course of evolving heart failure occurs coincident with the development of increased left ventricular chamber stiffness and the manifestation of rapid deceleration of early mitral inflow velocity. These findings are consistent with a myocardial vibratory origin of this sound.

Animals↗
PubMed1993

Disseminated bipolaris infection in an asthmatic patient: case report.

We present the case of a patient with a history of asthma who developed cough and hemoptysis that were unresponsive to antituberculous therapy. Chest roentgenography demonstrated right-sided collapse with consolidation and a pleural effusion. Bronchial biopsy revealed fungal hyphae, and cultures later yielded Bipolaris spicifera. In addition, weight loss and intractable hypotension in association with hyponatremia and elevated potassium levels suggested addisonian crisis, which was confirmed by measurement of serum ACTH and cortisol levels. Computed tomography of the abdomen revealed bilateral adrenal involvement. Tissue obtained on biopsy of the adrenal glands yielded B. spicifera. The patient responded to treatment with 2 g of iv amphotericin B; the adrenal masses and pneumonia resolved, and he remained well until last seen in July 1992. However, he requires replacement therapy with prednisone and fludrocortisone. On review of the available literature, we were unable to find a previously reported case.

Adrenal Gland Diseases↗
PubMed1993

Pitfalls in the echocardiographic diagnosis of intracardiac and extracardiac masses.

Transthoracic and transesophageal two-dimensional (2-D) echocardiography remain the procedures of choice for evaluating cardiac mass lesions. Potential errors in diagnosis can be made, however, if the mass lesion's size, shape, mobility, and attachment to other cardiac structures are not clearly delineated. Usually a left atrial myxoma arises from the interatrial septum at the level of the fossa ovalis. Pitfalls in diagnosis occur when the tumor size is very small, or its attachment site is atypical or ill-defined. Atrial thrombi classically reside in an atrial appendage, but can also form in the body of the left atrium. The presence of atrial fibrillation rhythm, enlarged atrial chamber, prosthetic mitral/tricuspid valves, stenotic mitral/tricuspid valves, low cardiac output state, and spontaneous atrial contrast echoes are all features that favor the mass in question being a thrombus. Ventricular thrombi usually occur with poorly functioning ventricles. The diagnosis of ventricular thrombus should be made with great caution if the systolic function is normal, or if the mass has a band or thread-like appearance. A thorough knowledge of normal anatomical variants that can mimic pathological lesions is also important for reaching a correct diagnosis. Last but not least, as in all testing modalities, the patient's clinical picture should be correlated with the echocardiographic findings.

Artifacts↗
PubMed1993

The role of transesophageal echocardiography in identifying anomalous coronary arteries.

BACKGROUND: The study objective was to evaluate the role of transesophageal echocardiography in identifying the origin of anomalous coronary arteries and confirming their course in relation to the great vessels. The diagnosis of coronary anomalies is made by angiography. The anomalous left main artery with a course between the pulmonary artery and the aorta has been associated with myocardial infarction and sudden death. The course of these anomalous coronary arteries is difficult to demonstrate by angiography alone. METHODS AND RESULTS: Nine patients with angiographically confirmed anomalous coronary arteries were studied by transesophageal echocardiography with color flow Doppler. The abnormal origin of the anomalous coronary arteries was confirmed by transesophageal echocardiography in all nine patients. In four patients, the left main coronary artery originated from the right sinus of Valsalva. In all of these patients, transesophageal echocardiography demonstrated the course of the anomalous left main coronary artery between the aorta and pulmonary artery better than angiography. Other anomalies that were visualized included two patients with origin of the right coronary arteries from the left aortic sinus, one patient with origin of the left anterior descending from the right sinus, one patient with origin of circumflex from the right sinus, and one patient with origin of the left main coronary artery from the pulmonary artery. CONCLUSIONS: Transesophageal echocardiography is a useful noninvasive test for diagnosing anomalous origin of the coronary arteries. Furthermore, it is a valuable adjunct to angiography in demonstrating the abnormal course of the left main coronary artery interposed between the aorta and the pulmonary artery, a potentially life-threatening entity.

Aged↗
PubMed1993

Ball-valve thrombus obstructing a bioprosthetic mitral valve.

We present a patient with a large, left atrial ball valve thrombus that was intermittently obstructing a bioprosthetic mitral valve. The diagnosis was confirmed by transesophageal two-dimensional echocardiogram. The transthoracic study initially had failed to demonstrate the true ball valve nature of the thrombus and instead, suggested two separate mass lesions, one in the left atrium and one in the bioprosthetic mitral valve.

Aged↗
PubMed1993

Transesophageal color flow Doppler features of aorta to right ventricle fistula.

A patient developed aortic-to-right ventricular fistula after aortic valve replacement surgery and infective endocarditis. The fistula was not detected by transthoracic two-dimensional echocardiography and color flow Doppler. The transesophageal study, however, was instrumental in diagnosing this entity and prompting surgical resection of the fistula.

Aortic Diseases↗
PubMed1992

Left ventricular response to submaximal exercise in endurance-trained athletes and sedentary adults.

This investigation examines the hypothesis that athletes increase stroke volume with submaximal exercise through an augmentation of left ventricular (LV) end-diastolic volume and a reduction of LV end-systolic volume, whereas sedentary adults only increase stroke volume modestly, because LV end-diastolic volume does not increase. Upright bicycle exercise was performed by 17 endurance-trained male athletes and 15 sedentary men. M-mode echocardiograms were obtained during submaximal exercise at predetermined heart rates. Athletes, at a heart rate of 130 beats/min, increased their stroke volume 67% from 72 +/- 18 ml to 120 +/- 26 ml (p less than 0.001). This resulted from an increase of LV end-diastolic volume from 119 +/- 23 to 152 +/- 28 ml (p less than 0.001) and a reduction in LV end-systolic volume from 46 +/- 14 to 31 +/- 9 ml (p less than 0.001). Sedentary men at the same heart rate increased stroke volume 22% from 63 +/- 15 to 77 +/- 21 ml (p less than 0.05). LV end-diastolic volume did not change (96 +/- 20 vs 97 +/- 28 ml) (p = not significant), but LV end-systolic volume decreased (33 +/- 11 vs 20 +/- 9 ml) (p less than 0.001). In conclusion, athletes increased cardiac output through a more prominent augmentation of stroke volume than sedentary subjects at submaximal exercise. This was accomplished through an augmentation of LV end-diastolic volume. This may have a conserving effect on myocardial oxygen consumption at these levels of exercise.

Adult↗
PubMed1992

Synthesis and antiviral activity of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine.

A number of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG, 1) have been synthesized and tested in vitro for anti-herpes and anti-human immunodeficiency virus (HIV) activity. Among these analogues, (R)-2'-methyl-PMEG [(R)-3] and 2',2'-dimethyl-PMEG (7) demonstrated potent anti-HIV activity in the XTT assay with EC50 values of 1.0 and 2.6 microM, respectively. The corresponding (S)-2'-methyl-PMEG [(S)-3] was found to be less potent against HIV. In addition, the (R) and (S) enantiomers of 9-[3-hydroxy-2-(phosphonomethoxy)propyl]guanine (HPMPG, 8) were prepared for comparison of biological activity, and shown to be active and equipotent against herpesviruses, but inactive against HIV.

Antiviral Agents↗
PubMed1992

Serial echocardiographic studies following thrombolytic treatment in myocardial infarction with special reference to the atrioventricular valve plane displacement.

Echocardiographic recording of the atrioventricular (AV) valve plane displacement was used for serial studies of left ventricular (LV) function in 27 patients with first-time acute myocardial infarction (MI) treated with a thrombolytic agent within 4 h of the onset of symptoms and showing noninvasive signs of early reperfusion. The recordings were made immediately before or during thrombolytic therapy and 24 h, 1 week, 1 month, and 2 months after attempted reperfusion. Regional LV function was assessed by recording the amplitude of systolic descent of the AV plane toward the apex at 4 different sites on left ventricle corresponding to the septal, anterior, lateral, and posterior walls from apical 4- and 2-chamber views. Global LV function was assessed using the mean value of the AV plane displacement from the above 4 sites (AV mean). In 15 patients with anterior MI, the displacement at the septum and anterior wall was significantly decreased compared with the posterior and lateral walls at baseline. The displacement had increased significantly after 1 week, 1 month, and 2 months (p less than 0.01, p less than 0.01, and p less than 0.001). The AV mean also increased significantly (p less than 0.01) during the study period. A corresponding regional increase was observed in inferior MI. The AV mean remained unchanged, however, during the follow-up period. It is concluded that the easy visualization and the simplicity of recording the AV plane displacement makes the method a valuable non-invasive tool for serial echocardiographic studies following acute MI treated with a thrombolytic agent.

Echocardiography↗
PubMed1992

Mechanism of functional mitral regurgitation during acute myocardial ischemia.

The mechanism and temporal manifestation of functional mitral regurgitation after acute myocardial ischemia were examined in eight dogs. Regional ischemia was produced by selective microembolization of the left circumflex coronary artery. Mitral regurgitation and regional left ventricular wall motion abnormalities were evaluated with use of Doppler color flow mapping and two-dimensional echocardiography, respectively. Measurements were made at baseline (before embolization) and were repeated at 30 min and 3 weeks after embolization. Mitral regurgitation developed in all dogs 30 min after embolization and completely subsided 3 weeks later. There was no evidence of mitral valve prolapse, mitral anulus dilation or left ventricular segmental dyskinesia at any time during the study. Regional wall motion analysis showed only hypokinesia of the left ventricular segment overlying the papillary muscle at 30 min with subsequent normalization of the segment at 3 weeks. Mitral regurgitation was accompanied by an increase of the end-systolic distance between the mitral anulus plane and the point of coaptation of the mitral leaflets. This distance was 0.5 +/- 0.1 cm at baseline, increased to 0.9 +/- 0.1 cm 30 min after the embolization (p less than 0.001) and returned to near baseline (0.6 +/- 0.1 cm) 3 weeks after the embolization. These data indicate that mitral valve prolapse, mitral anulus dilation and regional left ventricular dyskinesia are not necessary conditions for the development of functional mitral regurgitation after acute myocardial ischemia. Instead, hypokinesia of the ventricular segment overlying the papillary muscle and leading to retraction of the mitral leaflets toward the apex appears to be a sufficient condition for incomplete leaflet coaptation.

Animals↗