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Biomedical subjects

N Trehan

Publications and source records attributed to N Trehan.

At least 73 records · Page 4Linked to original sources
PubMed1991

Transesophageal echocardiography is superior to transthoracic echocardiography in the diagnosis of sinus venosus atrial septal defect.

The purpose of this study was to compare transthoracic and transesophageal echocardiography in the diagnosis of various types of atrial septal defects. Forty-one adult patients with the clinical diagnosis of atrial septal defect were studied by transthoracic and transesophageal echocardiography (30 women, 11 men; 18 to 81 years of age). Transthoracic echocardiography demonstrated the atrial septal defect in 33 patients (secundum type in 28, primum type in 3 and sinus venosus type in 2). Transesophageal echocardiography demonstrated the defect in all 41 patients. Thus, in 8 (20%) of 41 patients the atrial septal defect was demonstrated by transesophageal and not by transthoracic echocardiography. Six of the eight had a sinus venosus type atrial septal defect; the other two patients had a secundum atrial septal defect (one of these two had a technically poor transthoracic echocardiogram and the other had a small atrial septal defect). Transthoracic echocardiography, therefore, failed to demonstrate the sinus venosus defect in six (75%) of eight patients. An anomalous venous connection associated with the sinus venosus defect was visualized by transesophageal echocardiography in seven of the eight patients but was not seen on transthoracic echocardiography in any patient. Sinus venosus type atrial septal defects are frequently not visualized in adults by conventional transthoracic echocardiography. Transesophageal echocardiography is recommended when an atrial septal defect is clinically suspected but cannot be visualized by transthoracic echocardiography.

Adult↗
PubMed1981

Importance of topical hypothermia to ensure uniform myocardial cooling during coronary artery bypass.

Recent reports have suggested that the delivery of cardioplegia to regional myocardium is impaired in patients with severe coronary artery disease. This study was designed to determine whether or not topical hypothermia is a necessary adjunct to systemic hypothermia and potassium cardioplegia to provide adequate cooling in regional myocardium supplied by stenotic or occluded coronary arteries. Twenty-two patients ranging in age from 47 to 68 years were included in the study. Patients were placed on bypass and cooled to 28 degrees C. Temperature was measured over the right and left coronary artery distributions. The aorta was then cross-clamped and 1,000 cc of potassium blood cardioplegia, 5.7 degrees to 11 degrees C (mean 8.7 degrees), was infused into the aortic root at a mean pressure of 99 mmHg. Temperature was measured and 6 L of cold electrolyte (Plasma-lyte) solution, 2.3 degrees to 5.1 degrees C (mean 3.5) was poured over the heart into the pericardial well. The temperature measurements were then repeated. Myocardial temperature in regional myocardium supplied by normal coronary arteries after the injection of cardioplegia was less than 15 degrees C. However myocardium distal to a severe stenosis or complete occlusion was significantly warmer (p less than 0.001). Topical hypothermia reduced myocardial temperature to less than 15 degrees C in regional myocardium supplied by severely diseased vessels (p less than 0.001). These data demonstrate that the combination of systemic hypothermia and potassium cardioplegia alone does not provide adequate myocardial cooling in patients with severe coronary artery disease and emphasize the need for intraoperative myocardial temperature monitoring to ensure optimal protection during the ischemic period.

Aged↗
PubMed1978

Complications due to cloth wear in cloth-covered Starr-Edwards aortic and mitral valve prostheses--and their management.

Five cases of complications due to cloth wear in cloth-covered composite-seat Starr-Edwards aortic and mitral valvular prostheses are described. The complications of cloth wear were recurrent systemic emboli in three patients, two with aortic and one with mitral prosthesis, and severe hemolytic anemia in two patients with aortic prosthesis. The over-all incidence of clinically significant complications due to cloth wear in aortic and mitral valve prosthesis was 2.5 per cent. The diagnosis of cloth wear is impossible before reoperation and it was made by exclusion of other causes of recurrent transient cerebral ischemic attacks or systemic emboli and by exclusion of other causes of hemolytic anemia. Clinical and laboratory findings suggestive of cloth wear are described. Aggressive management of complications of cloth wear by reoperation is likely to prevent disabling or lethal consequences. Porcine xenograft aortic and mitral bioprostheses were used in these patients to replace the cloth-covered valvular prostheses. The symptoms due to cloth wear were abolished in all patients by reoperation, and all patients are off anticoagulants postoperatively. The operative mortality rate for reoperation in this small group of patients was zero.

Adult↗
PubMedDate not supplied

Coronary artery fistulae without audible murmur in adults.

Retrospective analysis of 4886 adults undergoing coronary arteriography for evaluation of angina between October 1988 and December 1991, revealed coronary artery fistulae in eight patients (all men, aged 36-69 years). No murmur was audible in any of these eight patients. Associated significant coronary artery disease was detected in five patients. The feeder arteries to the fistula were both the left main coronary artery and the left anterior descending artery (LAD) in two, the LAD in six, and the right coronary artery in two patients. The fistula terminated in the pulmonary artery in seven patients and in the right atrium in one patient. Successful operative treatment (coronary artery bypass grafting and ligation of the fistula) was undertaken in four patients with severe obstructive coronary artery disease with satisfactory results. Follow-up for up to 2 years of the three patients with coronary artery fistula and no associated coronary artery disease who did not undergo surgery revealed continuing good prognosis. We conclude that coronary artery fistula in adults is a distinct, though rare (incidence in present series 0.11%) entity, without audible murmur, commonly associated with coronary artery obstructive disease, and that the diagnosis is mostly incidental during routine coronary arteriography.

Angina Pectoris↗
PubMedDate not supplied

Haemodynamic effects of leg raising in patients undergoing coronary artery bypass grafting.

Twenty patients undergoing elective coronary artery bypass grafting were studied prospectively to evaluate the haemodynamic effects of passive leg raising. The patients were divided into two groups: those having good left ventricular function with ejection fraction of 0.50 or more (group I, n = 10) and those having poor left ventricular function with ejection fraction of upto 0.35 (group II, n = 10). Morphine-based anaesthetic technique was used and standard haemodynamic measurements were obtained at following stages: (1) control--20 to 30 min after induction of anaesthesia; (2) one minute, and (3) five min after raising both the legs; (4) one min, and (5) five min after the legs were repositioned. In group I, heart rate decreased from 71 +/- 9 to 66 +/- 8 beats/min (p < 0.001) at stage 1 and persisted throughout the study period. This was accompanied by a decrease in cardiac index, although, the statistical significance was achieved at stage 3 and 4 only. The haemodynamic changes observed in group II were of more severe magnitude. The heart rate decreased from 90 +/- 13 to 84 +/- 13 beats/min at stage 1 (p < 0.05) and persisted throughout the study with maximum decrease of 14 percent occurring at stage 3. The cardiac index decreased significantly from 2.4 +/- 0.3 to 2.0 +/- 0.5 L/min/m2 (p < 0.05) at stage 1. This persisted throughout the study except that it recovered at stage 4. The maximum decrease in cardiac index (20%) occurred at stage 2. In addition, systemic vascular resistance increased significantly from 1458 +/- 255 to 1830 +/- 420 dyne.sec.cm-5 (p < 0.05) at stage 1 and persisted throughout the study period. We conclude that passive leg raising should be undertaken with caution in patients with coronary artery disease especially in those who have poor left ventricular function.

Aged↗
PubMedDate not supplied

Minimally invasive atrial septal defects repair.

This study reviews the current method of atrial septal defect closure at our institute with a minimally invasive approach without median sternotomy. From September 1997 to August 1998, 37 patients (13 males, 24 females) with mean age 36.5 years (range 18-67 years) underwent atrial septal defect closure by right anterior thoracotomy. Femoral vessels were cannulated through a small groin incision and extracorporeal circulation was established. Venous drainage was assisted with a centrifugal pump. Aortic crossclamping was performed through the intact chest wall using a special transthoracic clamp with sliding rod design inserted through a separate tiny 3 mm incision in the right second intercostal space in the mid clavicular line. Mean duration of cardiopulmonary bypass and aortic crossclamp time was 35 +/- 14 and 23 +/- 7 minutes respectively; mean endotracheal intubation time after surgery 6.2 +/- 3 hours; mean ICU stay 10.6 +/- 2.8 hours; mean length of thoracotomy incision 7.2 +/- 1.8 cm; and, mean hospital stay 4.2 +/- 1.8 days. There was no post-operative neurological dysfunction or femoral cannulation related complication. There was no perioperative or late mortality. No residual atrial septal defect was observed by transoesophageal echocardiography in any patient. The procedure described here provides secure closure of the atrial septal defects in minimally invasive fashion with good results.

Adolescent↗
PubMedDate not supplied

Mechanical ventilation in the prone position: a strategy for acute respiratory failure after cardiac surgery.

Ventilation in the prone position, initially introduced in respiratory therapy to improve the drainage of secretions, has been used in intensive care to improve oxygenation. We report a case of an obese male patient who underwent elective coronary artery bypass grafting and had low PaO2 in the postoperative period. The PaO2 improved whenever the patient was ventilated in the prone position. On each occasion, oxygenation improved without any change in the hemodynamic parameters. The PaO2 increased from 57.8 to 249.7 mmHg on the first occasion, from 48.7 to 194.6 mmHg on the second and 62.5 to 199.7 mmHg on the third at an FIO2 of 1.0. The shunt fraction (Qva/Qt) decreased from 43.6% to 7.2% on the first occasion and from 46.7% to 12.5% on the second. Ventilation in the prone position can be an effective method for improving oxygenation in patients suffering from postoperative acute respiratory failure who are not responding to other ventilatory strategies.

Coronary Artery Bypass↗
PubMedDate not supplied

Is off-pump coronary artery bypass surgery safe for left main coronary artery stenosis?

BACKGROUND: The feasibility of off-pump coronary artery bypass surgery has been well demonstrated. The purpose of the present study was to assess the safety and efficacy of off-pump coronary artery surgery in patients with left main coronary artery disease. METHODS AND RESULTS: Between January 1997 and December 2000, 174 patients with significant left main coronary artery stenosis underwent coronary artery bypass grafting without a pump. During the same period, 991 patients who also had significant left main coronary artery stenosis underwent coronary artery surgery on a pump. The patients in the two groups were matched in preoperative variables except that those in the off-pump group were slightly older, and more required urgent surgery. Hospital mortality was 2/174 and 21/991 in the off-pump and on-pump groups, respectively (p=0.560). The incidence of perioperative myocardial infarction (1.74 v. 14/991, p=0.712), atrial fibrillation (17/174 v 157/991, p=0.050) and blood transfusion requirement (63/174 v. 476/991, p=0.05) were significantly less in the off-pump group. The intubation time (15+/-3 hours v 22+/-4 hours, p=0.001), blood loss (365+/-61 ml v 582+/-76 ml, p<0.001), intensive care unit stay (23+/-10 hours v. 36+/-11 hours, p<0.001) and hospital stay (6+/-4 days v. 9+/-5 days, p <0.001) were also less in the off-pump group. CONCLUSIONS: Off-pump coronary artery bypass surgery is safe and effective for patients with left main coronary artery disease.

Aged↗