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Biomedical subjects

J N Bhayana

Publications and source records attributed to J N Bhayana.

At least 19 recordsLinked to original sources
PubMed1997

Heat shock protein 70 expression in native and heterotopically transplanted rat hearts.

Heat shock proteins (hsp) are intracellular proteins that are rapidly synthesized in response to a variety of stress factors. Recent studies in rats have shown that these proteins can elicit a lymphocyte response during cardiac allograft rejection. We studied the expression of the inducible (i) and constitutive (c) forms of hsp70 in rat cardiac allograft and isograft recipients to evaluate their utility as indicators of transplant rejection. Heterotopic transplantation of rat hearts was performed, using Lewis to Lewis isografts and ACI to Lewis allografts. Sham-operated rats were used as controls. Transplanted isograft, allograft, and native hearts of the transplant recipients and their livers and spleens were harvested at 5 days posttransplant and analyzed for hsp70 (i) and (c) expression by Western blots. Seven animals were studied in each group. Isografts at 3 and 60 days and allografts at 8 days were also studied. Quantification of band densities was carried out by laser densitometry. Physiological function of the native hearts of the transplant recipients was studied using Langendorff preparations. High levels of hsp70 (i) were noted in the transplanted and native hearts of the transplant recipients but not in their livers or spleens or in the hearts of the sham-operated control animals. Myocardial function of the native hearts of the transplant recipients was not significantly different from that of the controls. Significantly higher levels of hsp70 (c) were present in mild and severely rejecting allografts compared with controls and nonrejecting isografts. In the rat model of heterotopic cardiac transplantation, high levels of hsp70 (i) in the native hearts of the allograft and isograft recipients suggest a transplant-related, cardiac-specific stress process, not previously described. Heat shock protein 70 (c) expression is significantly increased during early and late allograft rejection and may serve as an indicator of transplant rejection.

Animals↗
PubMed1997

Beneficial effects of fluosol-polyethylene glycol cardioplegia on cold, preserved rabbit heart.

BACKGROUND: Because of its high oxygen-carrying capacity, especially at low temperatures, fluosol may enhance heart preservation. METHODS: Hearts of male New Zealand white rabbits (1.5-2.0 kg) were excised and flushed through the aorta with 0 degree C St. Thomas' Hospital solution, fluosol, or polyethylene glycol or fluosol-polyethylene glycol cardioplegic solution. Hearts were then stored for 12 hours at 0 degree C and reperfused with Krebs-Henseleit buffer at 36.5 degrees C for 60 minutes using a Langendorff system. RESULTS: Myocardial contractile function was significantly greater in the fluosol-polyethylene glycol cardioplegia-preserved group (p < 0.01) and polyethylene glycol-cardioplegia preserved group (p < 0.05) than in the St. Thomas' Hospital solution-preserved group. The myocardial high-energy phosphate content was significantly higher in the fluosol-polyethylene glycol-cardioplegia-preserved group (p < 0.01), with reduced release of lactate dehydrogenase (p < 0.01) in comparison with the St. Thomas' Hospital solution-preserved group. CONCLUSIONS: The addition of fluosol and polyethylene glycol to the cardioplegic solution may enhance long-term cold heart preservation.

Animals↗
PubMed1997

Partial left ventriculectomy to treat end-stage heart disease.

BACKGROUND: It is reasoned that reducing left ventricular diameter (Laplace's law) in patients with dilated cardiomyopathy, will improve ventricular function. METHODS: Partial left ventriculectomy was performed in 120 patients with end-stage dilated cardiomyopathies of varying causes. Most patients were in New York Heart Association functional class IV. The procedure consisted of removal of a wedge of left ventricular muscle from the apex to the base of the heart. Depending on the distance between the two papillary muscles, the mitral valve apparatus was either preserved, repaired, or replaced with a tissue prosthesis. RESULTS: The 30-day mortality was 22% and the 2-year survival was 55%. Although 10% of surviving patients showed no improvement in New York Heart Association functional class, most of the surviving patients were in either class I (57%) or II (33.3%), and the others were in class III and IV. CONCLUSIONS: Partial left ventriculectomy can be used to treat end-stage dilated cardiomyopathy. Further studies and a longer follow-up period are needed to fully assess the effects of this procedure.

Adolescent↗
PubMed1997

Preoperative and postoperative comparison of patients with univentricular and biventricular support with the thoratec ventricular assist device as a bridge to cardiac transplantation.

OBJECTIVES: The goal of this study was to determine whether there are differences in populations of patients with heart failure who require univentricular or biventricular circulatory support. METHODS: Two hundred thirteen patients who were in imminent risk of dying before donor heart procurement and who received Thoratec left (LVAD) and right (RVAD) ventricular assist devices at 35 hospitals were divided into three groups: group 1 (n = 74), patients adequately supported with isolated LVADs; group 2 (n = 37), patients initially receiving an LVAD and later requiring an RVAD; and group 3 (n = 102), patients who received biventricular assistance (BiVAD) from the beginning. RESULTS: There were no significant differences in any preoperative factors between the two BiVAD groups. In the combined BiVAD groups, pre-VAD cardiac index (BiVAD, 1.4 +/- 0.6 L/min per square meter, vs LVAD, 1.6 +/- 0.6 L/min per square meter) and pulmonary capillary wedge pressure (BiVAD, 27 +/- 8 mm Hg, vs LVAD, 30 +/- 8 mm Hg) were significantly lower than those in the LVAD group, and pre-VAD creatinine levels were significantly higher (BiVAD, 1.9 +/- 1.1 mg/dl, vs LVAD, 1.4 +/- 0.6 mg/dl). In addition, greater proportions of patients in the BiVAD groups required mechanical ventilation before VAD placement (60% vs 35%) and were implanted under emergency conditions than in the LVAD group (22% vs 9%). The survival of patients through heart transplantation was significantly better in patients who had an LVAD (74%) than in those who had BiVADs (58%). However, there were no significant differences in posttransplantation survival through hospital discharge (LVAD, 89%; BiVAD, 81%). CONCLUSION: Patients who received LVADs were less severely ill before the operation and consequently were more likely to survive after the operation. As the severity of illness increases, patients are more likely to require biventricular support.

Heart Transplantation↗
PubMed1997

Concanavalin A, ribose, and adenine resuscitate preserved rat hearts.

Preserved hearts may have cardiac dysfunction associated with inadequate myocardial high-energy phosphates. To resuscitate preserved hearts, hearts from male Wistar adult rats were preserved in 4.0 degrees C cold-modified Krebs-Henseleit buffer (pH 7.40) for 8 h, subjected to 30 min of reperfusion at 36.5 degrees C with the administration of concanavalin A (Con A; 40 mg/L), ribose (0.1 mM), and adenine (0.1 mM). In comparison with the normal control, the preserved group had a decrease in cardiac output (CO; p < 0.001), myocardial adenosine triphosphate (ATP; p < 0.001), and creatine phosphate (CP; p < 0.001), associated with an increase in myocardial Ca2+ (p < 0.01) and release of myocardial adenine nucleosides (ANs; p < 0.001). In comparison with the preserved group, the group reperfused with ribose and adenine had no improvement of these parameters (p > 0.05). The group reperfused with Con A had an increase in CO (p < 0.01) and myocardial CP (p < 0.01), associated with a decrease in myocardial Ca2+ (p < 0.05) and ANs release (p < 0.01), and no change in myocardial ATP. However, the group reperfused with Con A, ribose, and adenine achieved a significant increase in CO (p < 0.005), ATP (p < 0.005), CP (p < 0.005), and a decrease in myocardial Ca2+ (p < 0.01) and ANs release (p < 0.01). Data suggest that the combination of Con A, ribose, and adenine may resuscitate cold-preserved rat hearts.

Adenine↗
PubMed1996

Acute right ventricular failure during aortic valvular operation due to mechanical problem in the right coronary artery.

BACKGROUND: When right ventricular failure occurs during aortic valvular operation, inadequate myocardial protection may be the culprit. However, other causes of right ventricular failure should be considered, such as air or particulate matter embolization. Right ventricular failure unexpectedly occurred during an aortic valvular operation, and the cause was found to be a mechanical problem with the right coronary ostium. METHODS: A mechanical problem with the right coronary artery (RCA) occurred in 9 patients undergoing aortic valvular procedures, which included isolated aortic valve replacement (4 patients), aortic valve replacement and coronary artery bypass (1 patient), Bentall procedure (2 patients), aortic valve reconstruction (1 patient), and double valve replacement and coronary artery bypass (1 patient). Although myocardial protection was considered to be the cause, a mechanical problem was subsequently identified in the RCA, leading that artery to be bypassed with a segment of saphenous vein. RESULTS: The 1 patient in whom the condition was not recognized at time of aortic valve operation died; at autopsy, a damaged and occluded right ostium was confirmed. The other 8 patients who had the RCA bypassed survived. CONCLUSIONS: We conclude that when right ventricular failure unexpectedly occurs during an aortic valvular operation and does not improve with reperfusion, a mechanical problem in the RCA should be considered. In this situation we recommend that the RCA be bypassed with a segment of saphenous vein graft.

Acute Disease↗
PubMed1995

Direct coronary sinus cannulation during cardioplegic infusion.

Retrograde cardioplegia has gained popularity as an improved method of myocardial protection. Cannulation of the coronary sinus, at times, may be difficult or impossible when the transatrial approach is used. We herein report a technique of direct cannulation of the coronary sinus, which appears to be safe and effective.

Cardiac Catheterization↗
PubMed1991

Use of duplex imaging to assess suitability of the internal mammary artery for coronary artery surgery.

The internal mammary artery is the preferred conduit for coronary artery surgery. To determine the role, if any, of preoperative duplex imaging in assessing the suitability of this vessel, preoperative noninvasive measurements of internal mammary artery diameter and blood flow were performed in 243 patients. The left internal mammary artery was insonated through the third intercostal space by use of duplex scanner (5.0 MHz probe) before coronary artery surgery. Internal mammary artery diameter (millimeters), peak systolic velocity (centimeters/second), and mean velocity (centimeters/second) were measured, and internal mammary artery flow was calculated from velocity and cross-sectional area. In 45 of these patients the internal mammary artery diameter also was measured during surgery with a sterile caliper, and blood was collected for 30 seconds from the transected internal mammary artery to measure flow. These findings were compared to the preoperative values. In 243 patients the mean internal mammary artery diameter was 2.34 +/- 0.03 mm, and mean peak systolic blood flow was 226.7 +/- 6.3 ml/min. In the 45 patients in whom intraoperative measurements were obtained, preoperative mean internal mammary artery diameter was 2.39 +/- 0.05 mm and was not significantly different from the intraoperative mean internal mammary artery diameter of 2.36 +/- 0.04 mm. Preoperative peak systolic flow was 231.3 +/- 8.1 ml/min, and mean flow was 110.3 +/- 7.1 ml/min; intraoperative flow measured 136 +/- 3.6 ml/min. Noninvasive determinations correlated with operative findings for internal mammary artery diameter (r = 0.87) (p less than 0.05), peak systolic blood flow (r = 0.70) (p less than 0.05), and mean blood flow (r = 0.60) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Pulmonary resection combined with cardiac operations.

Surgical management of patients with concomitant critical cardiac disease and resectable lung lesions is controversial. During a 7-year period (1982 to 1988), 21 patients underwent combined cardiac and pulmonary operations. Patients had cardiac symptoms only; the lung lesions were found on preoperative chest roentgenograms. The pathological diagnosis was established in only 2 of the patients before operation. All underwent concurrent pulmonary resection during cardiac operations requiring extracorporeal circulation. The pulmonary operations included 17 wedge resections and four lobectomies. The final diagnoses in 8 patients with stage I non-small cell lung cancer included epidermoid carcinoma (4), adenocarcinoma (3), and bronchoalveolar carcinoma (1). Postoperatively, 1 patient required a permanent pacemaker and 1 patient died. The actuarial survival at 5 years for all patients who underwent combined procedures was 95%. The 5-year survival for the 8 patients with lung cancer was 88% compared with 100% for those with benign pulmonary pathology (p = 0.172). This experience suggests that combining pulmonary resection with cardiac operations is safe and offers a favorable prognosis to a select group of patients.

Adult↗
PubMed1989

Cardioplegia delivery by combined aortic root and coronary sinus perfusion.

Retrograde coronary sinus perfusion for the administration of cardioplegic solutions has recently been the subject of renewed interest. A method is described for the administration of bolus antegrade cardioplegia followed by continuous retrograde coronary sinus perfusion, particularly for patients with left main artery disease, left main equivalent, or aortic root/aortic valve disease. Advantages of the technique are discussed, as well as its limitations and its use for myocardial preservation in heart transplantation.

Aorta↗
PubMed1989

Combined antegrade/retrograde cardioplegia for myocardial protection: a clinical trial.

The role of retrograde coronary sinus perfusion in the preservation of ischemic myocardium is controversial. We evaluated the use of combined antegrade and retrograde cardioplegia in 59 patients undergoing coronary artery bypass surgery. Nineteen patients were administered antegrade cardioplegia, whereas 40 patients were administered antegrade plus retrograde cardioplegia. Hemodynamic data were obtained before the onset of cardiopulmonary bypass and at 1, 2, 4, 8, 16, and 24 hours after cessation of cardiopulmonary bypass. Myocardial function was assessed by measuring systemic blood pressure, heart rate, cardiac index, pulmonary artery pressure, and capillary wedge pressure. Both cohorts were similar in age, incidence of hypertension, diabetes, and previous myocardial infarction. No significant differences were noted in the need for postoperative inotropic support, the incidence of postoperative arrhythmias, myocardial infarction, heart block, or death. The two groups were similar with respect to cardiac index and systemic and pulmonary vascular resistance. However, the left ventricular stroke work index, when expressed as a function of its prebypass control value, was significantly improved (p less than 0.01) in the cohort administered combined cardioplegia. In the combined group recovery of left ventricular stroke work index occurred earlier and was more complete. These results suggest that the use of combined antegrade/retrograde cardioplegia is safe and may provide superior protection.

Aged↗
PubMed1988

Circumferential intimal tear causing obstruction of the aortic arch: an unusual complication of aortic dissection.

A 66-year-old man was first seen because of occlusive disease of the aortic arch vessels secondary to a Type I aortic dissection. At operation, circumferential detachment of the intima was found with intussusception of this flap into the descending aorta causing obliteration of the arch vessels. There has been only one previous report of circumferential intimal intussusception complicating aortic dissection.

Aged↗
PubMed1984

Improved cardiovascular hemodynamics with atrioventricular sequential pacing compared with ventricular demand pacing.

To determine the advantages of atrioventricular (AV) sequential pacing over ventricular demand pacing, paired cardiovascular hemodynamic studies were performed in each pacing mode at a constant heart rate. The paired studies included determination of ejection fraction (EF) by echocardiography and gated blood pool radionuclide scanning, and of cardiac output (CO) by the indicator-dilution method. There was no significant difference in EF with either pacing mode. Determined by echocardiography, EF with AV sequential pacing was 57% compared with 56% with ventricular demand pacing; by the gated blood pool method, EF with AV sequential pacing was 58% compared with 57% in the ventricular mode. Significant improvement with AV sequential pacing was seen in CO (4.75 L/min from 3.75 L/min; p less than 0.01); stroke volume (58 ml from 48 ml; p less than 0.02); arteriovenous oxygen content difference (4.9 vol% from 5.6 vol%; p less than 0.01); total peripheral resistance (1,724 dynes sec cm-5 from 2,025 dynes sec cm-5; p less than 0.01); and cardiac contractility, as reflected by mixing time (6.9 seconds from 8.0 seconds; p less than 0.02). No significant changes were noted in mean arterial or atrial pressure or in systemic oxygen consumption. In a second group of 6 patients, similar paired studies were done in AV sequential pacing modes before and after therapeutic reduction of total peripheral resistance. A significant increase in CO (43%) was observed following reduction in total peripheral resistance. We conclude that AV sequential pacing improves CO more effectively than ventricular demand pacing. Cardiac output can be further enhanced in patients with congestive heart failure by pretreatment with agents to reduce total peripheral resistance.

Adult↗
PubMed1984

Preparation of venous allografts. A comparison of techniques.

In order to evaluate alternate techniques of preparing veins for use as homografts, 102 femoral veins were harvested from adult mongrel dogs. The veins were treated in four different ways, then transplanted into recipient animals bypassing their ligated femoral arteries. Group I--24 veins (6 cm each) were harvested and immediately transplanted. Group II--24 veins were stored in 15% dimethyl sulfoxide (DMSO) solution at -120 C for 21 days prior to transplantation. Group III--26 veins were stored for 21 days in plasminate solution at -60 C prior to use as allografts. Group IV--28 veins were stored in 0.5% gluteraldehyde solution for 21 days prior to implantation. Animals were randomly sacrificed at 1-month, 2-month, 6-month, and 12-month intervals. Patency of the transplant was determined weekly by ultrasound. Specimens were sent for light and scanning electron microscopy at the time of harvest, prior to implantation, and at sacrifice. Endothelial damage was graded on a scale of 0-16. Veins in Group II had a significantly higher patency rate (68% at 1 year) than Group III (35%) and Group IV (11%) (p less than 0.05). The intimal layer of all patent vessels was replaced by an organized mural thrombus. Partial endothelialization of the luminal surface was most prevalent in Group II. Intimal damage related to storage technique was significant in Group III (p less than 0.01). At sacrifice, severe endothelial damage was present in all groups (p less than 0.01). In conclusion, veins stored in 15% dimethylsulphoxide (DMSO) solution at -120 C have immunologic and physical characteristics that yield patency rates acceptable for clinical use when autogenous tissue is not available.

Animals↗
PubMed1983

Noninvasive screening for asymptomatic carotid artery disease prior to cardiac operation. Experience with 500 patients.

Five hundred patients scheduled for cardiac operations underwent preoperative screening for asymptomatic carotid artery disease by means of the Gee ocular pneumoplethysmograph (OPG). Only patients with abnormal OPG measurements (5 mm Hg difference or greater in ophthalmic artery pressures or 0.69 or less ophthalmic artery/brachial artery pressure ratio) had cerebral angiography regardless of the presence or absence of a carotid bruit. Thirty-two patients (6.4%) were found to have carotid bruits. Nine patients had abnormal OPG measurements. Cerebral angiograms disclosed that six of these patients had significant (greater than 50%) carotid artery stenosis, and endarterectomy was performed prior to cardiac operation without incident. Nine other patients without carotid bruits had abnormal OPG measurements, and they also underwent cerebral angiography. Angiograms revealed significant carotid artery stenosis in three patients and prophylactic endarterectomy was performed. Twenty-three patients with carotid artery bruits and normal OPG measurements did not have cerebral angiography prior to the cardiac procedure. The incidence of stroke in this series of 500 patients was 0.4% (two patients). The clinical management of patients with asymptomatic carotid artery disease and coronary artery disease was facilitated by the use of noninvasive screening for the evaluation of carotid artery bruits. Patients with hemodynamically insignificant carotid disease, verified by OPG measurements, can be spared the risk and cost of cerebral angiography. Patients without clinical signs of carotid artery disease can also be identified.

Arterial Occlusive Diseases↗
PubMed1982

Perioperative protection of the myocardium in patients with impaired ventricular function.

Seventeen patients with poor ventricular function and severe coronary artery obstruction were operated on employing hypothermic potassium cardioplegic solution for myocardial preservation. Preoperatively and postoperatively, serial hemodynamics, electrocardiograms (ECG), MB-CPK studies, and technetium pyrophosphate scans were obtained for all patients. All ECGs and scans were negative for perioperative infarction. Peak MB-CPK levels were 40 +/- 25 units per liter. Two patients had MB-CPK levels suggestive of perioperative myocardial infarction. The preoperative cardiac index was 2.8 +/- 0.8 L/min/m2 and remained the same in the perioperative period. Stroke work index and total peripheral resistance were within normal range and remained constant throughout the period of study. Three patients required epinephrine (0.5 micrograms per minute) during the first 6 hours postoperatively, and in 2 patients an intraaortic balloon was inserted prophylactically and removed on the second postoperative day. Good myocardial preservation can be achieved in patients with severe coronary artery obstruction and preexisting left ventricular dysfunction using hypothermic potassium cardioplegic solution.

Aged↗