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Biomedical subjects

P Venugopal

Publications and source records attributed to P Venugopal.

At least 19 recordsLinked to original sources
PubMed1995

Serial echocardiography for decision making in rapid two-stage arterial switch operation.

BACKGROUND: Rapid two-stage arterial switch operation is advocated in infants with simple transposition presenting late. Accurate assessment of left ventricular preparation is crucial to successful outcome. The role of echocardiography alone in surgical decision making remains unclear. METHODS: Seventeen patients with simple transposition (mean age, 4 months) underwent pulmonary artery banding and modified Blalock-Taussig shunt (first stage) to prepare the left ventricle for the arterial switch operation (second stage). Serial echocardiography was performed in the interval phase to assess left ventricular growth. Sixteen patients underwent arterial switch operation after a mean interval of 10.4 +/- 4 days, with 14 successful conversions. There was one mortality (5.9%) and two conversions to a Senning repair. RESULTS: In all patients a mean increase in left ventricular mass (40.8 +/- 17.8 g/m2 to 81.4 +/- 25.4 g/m2) and posterior wall thickness (3.37 +/- 0.47 mm to 4.63 +/- 0.58 mm) was recorded. Left ventricular end-diastolic internal diameter increased in all except the two switch failures. In all the successful cases the left ventricle had assumed a circular shape on cross-section with the interventricular septum contracting in synergy with the left ventricular mass. In the two failures, however, the interventricular septum had remained flat. CONCLUSIONS: Echocardiography can be used reliably in surgical decision making in rapid two-stage arterial switch operation. Increase in left ventricular mass, left ventricular posterior wall thickness, and left ventricular end-diastolic internal diameter toward normal combined with an acquisition of circular left ventricular configuration with the interventricular septum contracting in synergy with the left ventricular mass appear to best predict successful outcome.

Anastomosis, Surgical↗
PubMed1995

Regrowth resistance in cancer: why has it been largely ignored?

In drug-sensitive malignancies, treatment failure is a complex phenomenon resulting from both drug resistance and the rapid regrowth of malignant cells in between cycles of chemotherapy. This phenomenon has been referred to as regrowth resistance, and has been identified as a common impediment to the successful treatment of many neoplastic diseases. This phenomenon has received little attention in the past. The administration of maximally tolerated individual dosages of chemotherapeutic agents, combined with the use of biological response modifiers to slow the regrowth between courses of therapy, would be an effective approach to reduce the regrowth resistance. This also could reduce the emergence of drug resistant clones.

Antineoplastic Agents↗
PubMed1995

Tree structured wavelet transform segmentation of microcalcifications in digital mammography.

A novel multistage algorithm is proposed for the automatic segmentation of microcalcification clusters (MCCs) in digital mammography. First, a previously reported tree structured nonlinear filter is proposed for suppressing image noise, while preserving image details, to potentially reduce the false positive (FP) detection rate for MCCs. Second, a tree structured wavelet transform (TSWT) is applied to the images for microcalcification segmentation. The TSWT employs quadrature mirror filters as basic subunits for both multiresolution decomposition and reconstruction processes, where selective reconstruction of subimages is used to segment MCCs. Third, automatic linear scaling is then used to display the image of the segmented MCCs on a computer monitor for interpretation. The proposed algorithms were applied to an image database of 100 single view mammograms at a resolution of 105 microns and 12 bits deep (4096 gray levels). The database contained 50 cases of biopsy proven malignant MCCs, 8 benign cases, and 42 normal cases. The measured sensitivity (true positive detection rate) was 94% with a low FP detection rate of 1.6 MCCs/image. The image details of the segmented MCCs were reasonably well preserved, for microcalcification of less than 500 microns, with good delineation of the extent of the microcalcification clusters for each case based on visual criteria.

Calcinosis↗
PubMed1995

Systemic-to-pulmonary artery collateral vessels and surgical shunts in patients with cyanotic congenital heart disease: perioperative treatment by transcatheter embolization.

OBJECTIVE: Systemic-to-pulmonary collateral vessels can develop in patients with obstruction of the right ventricular outflow tract or the pulmonary artery. Occlusion of these vessels is necessary before surgical correction of the primary disease. We report the results of transcatheter coil embolization in the treatment of 56 patients. MATERIALS AND METHODS: Seventy-four procedures were done in the perioperative period for treatment of 67 aortopulmonary collateral arteries, five modified Blalock-Taussig shunts, and two enlarged veins. RESULTS: In the "aortopulmonary collateral" group, occlusion was complete in 51 patients (76%), subtotal in seven (10%), partial in four (6%), and failed in five (8%). Inadvertent embolization to the aorta occurred in two procedures, but both coils were retrieved nonsurgically. During follow-up of 1-12 months (n = 32; mean, 6.3 months), the coils remained in position, without any migration. Follow-up angiograms in 14 embolized vessels showed no recanalization (mean, 5.3 months; range, 2-12 months). In the "shunt" group, occlusion was complete in four patients and failed in one. Distal embolization to the pulmonary artery occurred in one patient. This coil was retrieved during surgery. During follow-up of 3-6 months, coils remained in position in all patients. In one patient, a follow-up angiogram at 3 months showed no recanalization. In the "venous embolization" group, occlusion was complete in one patient. The coils were in position 5 months later. The procedure was unsuccessful in the other patient. CONCLUSION: We conclude that transcatheter coil embolization is useful in the treatment of abnormal systemic-to-pulmonary vessels and shunts in patients with obstruction of the right ventricular outflow tract or the pulmonary artery. Homemade coils are safe and effective in obliterating antegrade flow.

Adolescent↗
PubMed1992

Carcinoma of the rectal pouch following restorative proctocolectomy. Report of a case.

A case of adenocarcinoma developing in the pouch following restorative proctocolectomy is presented. This seems to be the third reported in the literature. The carcinoma developed from the remnants of precancerous rectal mucosa left in the muscular rectal cuff. The patient had been suffering from ulcerative colitis for 17 years prior to the development of the malignancy. He presented with features of subacute intestinal obstruction. Diagnosis was by sigmoidoscopic examination of the pouch and biopsy. He was treated with abdominoperineal resection of the pouch and rectum, followed by chemotherapy.

Adenocarcinoma↗
PubMed1992

Thrombolytic therapy for prosthetic valve thrombosis: a study based on serial Doppler echocardiographic evaluation.

Sixteen patients with echocardiographic and cinefluoroscopic evidence of Björk-Shiley prosthetic valve obstruction (13 mitral valves and 3 aortic valves) were treated with intravenous streptokinase. Streptokinase was administered as an initial bolus of 250,000 units for 30 minutes, followed by an infusion of 100,000 units/hr. Serial cinefluoroscopy and echocardiography (M-mode, two-dimensional, and Doppler) were performed at 0, 24, 48, and 72 hours of treatment. The end point of treatment was defined as near normalization of clinical, echocardiographic, and fluoroscopic parameters. Successful thrombolysis was achieved in all patients. The average duration of streptokinase therapy was 43 hours (range 2 to 72 hours). Two of 16 patients had minor systemic embolism during therapy. Short-term follow-up has shown sustained benefit in 14 of 16 patients. Two patients have had rethrombosis of the mitral prosthetic valves and have undergone thrombectomy. Our study demonstrates the feasibility, safety, and efficacy of thrombolytic therapy in the treatment of prosthetic valve thrombosis. It also emphasizes the role of serial Doppler echocardiography in guiding the duration of therapy and assessing its efficacy.

Adult↗
PubMed1992

Prospective controlled study of post-transfusion hepatitis after cardiac surgery in a large referral hospital in India.

We studied the risk of post-transfusion hepatitis (PTH) in recipients of blood collected from voluntary donors screened for HBsAg. Two hundred and fifty patients without any previous history of liver disease or transfusion were followed up for 12 months subsequent to cardiac surgery. Thirty-five of them had closed-heart surgery without receiving transfusion and served as controls. The remaining 215 patients received single-point transfusions (mean 4 +/- 2.4 units). None of the controls and 15 (6.9%) blood recipients developed PTH. Three (20%) patients had hepatitis-B-virus-induced hepatitis while the remainder (80%) had non A, non B (NANB) hepatitis. The number of units of blood transfused and surrogate markers for development of PTH (donor alanine aminotransferase, anti-HBc and anti-HBs antibody) were not associated with the occurrence of PTH (p greater than 0.05). Nine (60%) of the 15 patients developing PTH were asymptomatic. All the patients recovered from the PTH, except one who died of fulminant hepatitis. At the end of 1 year of follow-up, none of the patients had evidence of chronic hepatitis. Only three (25%) of the patients with NANB-PTH developed anti-hepatitis C virus (HCV) antibody during the follow-up. We conclude that the incidence of PTH in India is similar to other parts of the world and NANB virus was the major cause of the PTH. The absence of chronicity and lack of seroconversion to anti-HCV antibody in the majority of the patients after 1 year of follow-up may suggest the possibility of a NANB virus other than HCV as the major cause of PTH in India.

Adolescent↗
PubMed1992

Comparison of immediate hemodynamic response to closed mitral commissurotomy, single-balloon, and double-balloon mitral valvuloplasty in rheumatic mitral stenosis.

The hemodynamic response to closed mitral commissurotomy, single-balloon, and double-balloon mitral valvuloplasty was compared using 20 patients in each group. All patients had symptomatic rheumatic mitral stenosis with a mitral valve area < 1 cm2, without any left atrial clot, mitral valve calcification, or mitral regurgitation. There was a significant improvement in hemodynamics following intervention in all three groups. The mean pulmonary artery pressure decreased from 49.1 +/- 17.5 to 28.6 +/- 8.3 mm Hg (p < 0.001), 48.8 +/- 12.3 to 34.0 +/- 13.9 mm Hg (p < 0.001), and 46.7 +/- 18.0 to 26.3 +/- 13.7 mm Hg (p < 0.001) in the closed mitral commissurotomy, single-balloon, and double-balloon mitral valvuloplasty groups, respectively. The mitral valve area increased from 0.62 +/- 0.27 to 1.5 +/- 0.5 cm2 (p < 0.001), 0.68 +/- 0.24 to 1.5 +/- 0.4 cm2 (p < 0.001), and 0.68 +/- 0.25 to 1.9 +/- 0.8 cm2 (p < 0.001) in the closed mitral commissurotomy, single-balloon, and double-balloon mitral valvuloplasty groups, respectively. The increase in the mitral valve area was maximum in the group with double-balloon mitral valvuloplasty. In the closed mitral commissurotomy group there was a significant rise in left ventricular end-diastolic pressure, from 6.8 +/- 3.9 to 9.3 +/- 3.1 mm Hg (p < 0.001), but this remained unchanged in the single-balloon and double-balloon mitral valvuloplasty groups. Our study shows that single-balloon and double-balloon mitral valvuloplasty are comparable to closed mitral commissurotomy in the immediate hemodynamic response, with a larger valve area in the double-balloon mitral valvuloplasty group.

Adolescent↗
PubMed1991

Profile of coronary arterial disease in diabetic patients undergoing coronary arterial bypass grafting.

Diabetics are believed to have more extensive and diffuse lesions of the coronary arteries in presence of coronary arterial disease. We studied prospectively 52 diabetics with coronary arterial disease who underwent coronary arterial bypass grafting and evaluated their pre-operative symptomatology, angiographic appearance of coronary arteries, coronary arterial dimensions as assessed at surgery, and the post-operative complications. These were compared to 52 age and sex matched non-diabetic controls undergoing surgery during the same period. There was no statistically significant difference in the incidence of pre-operative symptomatology or frequency of myocardial infarction in the two groups. Left ventricular angiographic findings were also comparable, as was the observation on the extent and severity of coronary arterial disease as assessed by angiography and at surgery. Hence, we recommend coronary arterial bypass grafting to diabetics with the same criteria as are applied to non-diabetics, confident that there will be no added morbidity and mortality.

Adult↗
PubMed1991

The morphology of coronary arterial dissection occurring subsequent to angioplasty and its influence on acute complications.

We reviewed the records of 402 patients undergoing percutaneous transluminal coronary angioplasty to identify factors predicting an ischemic event with arterial disruption during an otherwise uncomplicated angioplasty. Major dissection of the coronary arteries without immediate occlusion was found in 25 patients, who exhibited 28 dissected lesions. Dissections were classified into 2 types: those producing a continuous extraluminal and parallel filling tract, and those with a continuous parallel filling tract extending into and compromising the lumen. Ischemic complications (defined as myocardial infarction, the need for repeat angioplasty, or coronary arterial bypass surgery) occurred in 6 patients (24%) within 24 hours of the completion of the procedure. The remaining 19 patients had an uncomplicated hospital course. Acute ischemic complications following dissection correlated with the percentage of luminal compromise 50 +/- 0% in those with complications as opposed to 17 +/- 21% in those without: P less than 0.001) and the development of dissection producing a filling tract which compromised at least half the lumen (100% in those with complications versus 9.1% in those without: P less than 0.001). There was a trend towards an increase in ischemic complications in patients with proximal and eccentric lesions. We conclude that patients who develop dissections which produce significant luminal compromise after an otherwise uncomplicated angioplasty are at a high risk of developing an acute ischemic complication within 24 hours of the procedure.

Acute Disease↗
PubMed1991

Comparison of left coronary and laevo-phase pulmonary angiograms in detecting left atrial thrombi in rheumatic mitral stenosis.

We have compared the diagnostic accuracy of left coronary and laevo-phase pulmonary angiograms in detecting left atrial thrombi in 27 consecutive patients with rheumatic mitral stenosis who underwent both these procedures prior to open-heart surgery. In 10 patients, both procedures were 'positive' for thrombus, confirmed at subsequent surgery in all instances (true positive). Both procedures were negative for thrombus in 11 patients, and none of these patients showed thrombi at subsequent surgery (true negative). Left coronary angiography only was positive for thrombus in one patient in whom no thrombus was found at surgery. Laevo-phase pulmonary angiography only was positive for thrombus in five patients, two of whom had thrombus at subsequent surgery. The sensitivity, specificity and predictive accuracy of left coronary angiogram were 83.3% and 93.3% and 90.9% and that of laevo-phase pulmonary angiogram 100%, 80% and 80% respectively. Laevo-phase pulmonary angiograms showed higher sensitivity and left coronary angiograms showed higher specificity for angiographic diagnosis. However, the differences were found to be statistically insignificant. Angiography is a reliable method for detecting left atrial thrombi if both left coronary and pulmonary angiograms are performed and both procedures are positive or negative for thrombus.

Adolescent↗
PubMed1991

Chest radiographs are unreliable in predicting thrombi in the left atrium or its appendage in rheumatic mitral stenosis.

We have assessed the diagnostic accuracy of a flat or concave left mid-cardiac border (the region of the left atrial appendage) on conventional postero-anterior chest radiographs as a predictor of the presence of thrombi in the left atrium or its appendage in 80 patients with rheumatic mitral stenosis who subsequently underwent open-heart surgery. Forty-six patients (Group I) were found to have left atrial thrombus at surgery whereas 34 patients (Group II) showed no evidence of thrombosis. Only 22 of 46 patients in Group I showed a flat or concave left mid-cardiac border (sensitivity, 48%; specificity, 53%; positive predictive value, 58%). Furthermore in Group 1, the thrombus involved the left atrial appendage in 33 patients. In this subgroup only 14 patients showed a flat or concave left mid-cardiac border (sensitivity, 42%; specificity, 49%; positive predictive value, 37%). The presence of flatness or concavity in the left mid-cardiac border on conventional posterior-anterior chest radiographs in patients with rheumatic mitral stenosis is an unreliable indicator of the presence of thrombi in the left atrium or its appendage.

Adolescent↗
PubMed1990

Left coronary angiography in the pre-operative diagnosis of thrombosis of the left atrium or its appendage in rheumatic mitral stenosis.

We studied the utility of pre-operative selective left coronary angiograms for detecting thrombosis in the left atrium or its appendage in 81 patients with rheumatic mitral stenosis, who subsequently underwent open-heart surgery. Thrombus was predicted by the angiographic demonstration of neovascularity seen as a bunch of small vessels arising from the circumflex branch of the left coronary artery coursing superiorly to the region of the left atrial appendage and terminating in a network of smaller vascular channels with a blush of contrast medium coalescing into small 'lakes'. This pooling of contrast medium was considered essential for positive angiographic diagnosis. Based on these criteria, the angiographic diagnosis of thrombus was made in 27 patients. Thrombus was found in 33 patients at surgery. Selective left coronary angiography had a sensitivity of 72.7%, specificity of 92.7% and predictive value of 88.8% for detecting thrombi in the left atrium or its appendage. Coronary angiography should be performed in all the patients with mitral stenosis who are undergoing cardiac catheterization especially if balloon mitral valvoplasty or closed mitral valvotomy are planned.

Adolescent↗
PubMed1990

Cardiac injuries--a clinical and autopsy profile.

One hundred two patients sustaining cardiac injuries over a 4-year period were analysed to highlight the natural history of the cardiac injuries. There were 45 blunt, 36 stab, and 21 gunshot injuries. The injury involved the ventricle in 85, atrium in seven, pulmonary artery in five cases, and resulted in crush injury to the heart in the remaining five cases. Thirty-three patients (32.3%) died on the scene and 58 (56.9%) died during the transportation. Only 11 patients (10.8%) reached the hospital alive, and ten of these patients survived following thoracotomy and repair of the cardiac injury. The factors influencing the natural course of cardiac injury were analysed: 2.2% of patients with blunt cardiac trauma reached the hospital alive compared to 19.4% with stab and 14.3% with gunshot injuries; ventricular injuries had a greater prehospital mortality compared to atrial or pulmonary artery injuries; 11.3% of patients sustaining injury to right ventricle reached the hospital alive compared to 3% of those with left ventricular injuries. These data emphasize the need for rapid transport, immediate recognition, and aggressive surgical management, to make a favourable impact on the natural history of cardiac injuries.

Adolescent↗
PubMed1990

Effect of hydroxyurea on foetal haemoglobin in myeloproliferative & myelodysplastic syndromes.

The effect of hydroxyurea on foetal haemoglobin (HbF) levels was evaluated in 36 patients of myeloproliferative and myelodysplastic disorders. In 17 (47.2%) patients, HbF levels increased from 1.40 +/- 1.17 to 3.03 +/- 1.97 per cent after 4 wk therapy with hydroxyurea. In the responders this increase was highly significant (P less than 0.001). The rise in the HbF levels after hydroxyurea therapy was significant in patients with chronic myeloid leukaemia but not in the other groups.

Adolescent↗
PubMed1990

Changes in the lipid composition of red blood cells in hyperglycemic rats.

The effects of hyperglycemia (experimental diabetes) and insulin treatment were studied on cholesterol and total as well as individual components of phospholipids in red cell membrane from adult rats. While total phospholipid content did not change significantly, the individual components were selectively affected. Cholesterol content was reduced markedly during hyperglycemia. Insulin administration to hyperglycemic rats in general appeared to cause a reversal of the diabetic effects. A direct action of insulin on the red cell phospholipids and cholesterol metabolism was observed.

Animals↗