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Biomedical subjects

V Jeevanandam

Publications and source records attributed to V Jeevanandam.

At least 55 records · Page 3Linked to original sources
PubMed1993

Prevention of acute regional ischemia with endocardial laser channels.

Laser myocardial revascularization has been shown to reduce mortality and infarct size after left anterior descending coronary artery (LAD) ligation in dogs. It has not been shown to improve myocardial contractility in acute ischemia. In this study a holmium-yttrium-aluminum garnet laser (wavelength, 2.14 microns) was used to create nontransmural myocardial channels from the endocardial surface in the ischemic regions of the canine left ventricle. Twelve mongrel dogs (6 controls, 6 laser myocardial revascularizations) underwent 90 minutes of LAD ligation followed by 6 hours of reperfusion. The ischemic region was determined by methylene blue injection during brief LAD occlusion. Laser myocardial revascularization averaged three channels per square centimeter in the ischemic region created using 12 J/channel (600 mJ/pulse, 10 Hz) before LAD ligation. Contractility was assessed from regional preload recruitable stroke work (RPRSW), using pairs of segment length ultrasonic transducers in the ischemic and the nonischemic regions. Two-dimensional echocardiography corroborated with segmental length findings. In control dogs, the ischemic region was dyskinetic during LAD ligation and reperfusion. Dyskinesis of the ischemic region during systole produced negative values for regional stroke work, and RPRSW was considered zero. In 4 of 6 laser-revascularized dogs, RPRSW remained positive in the ischemic region. Two dogs had intermittent dyskinesis. The difference between laser-revascularized and control dogs in ischemic region RPRSW was significant (p < 0.01 by Fischer's exact test).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Novel preservation solution permits 24-hour preservation in rat and baboon cardiac transplant models.

BACKGROUND: Cardiac preservation for transplantation disrupts normal vascular homeostatic mechanisms. Hypoxia and reoxygenation increase endothelial cell permeability, induce procoagulant activity, and alter endothelial cell/leukocyte interactions, with a parallel reduction in endothelial cAMP and nitric oxide levels. Because hypoxia/reoxygenation simulates a significant component of the global ischemia/reperfusion of cardiac transplantation, we hypothesized that preservation failure may be related to these perturbations. This work focuses on repleting the intercellular/intracellular second messengers nitric oxide/cGMP and cAMP in the donor heart to enhance cardiac preservation for transplantation. METHODS AND RESULTS: A heterotopic rat heart transplant model was used to compare lactated Ringer's (LR) and University of Wisconsin (UW) solutions to a novel storage solution (Columbia University solution, CU), which contains a cAMP analogue (dibutyryl cAMP) and nitroglycerin (to enhance nitric oxide-related mechanisms). By 24 to 28 hours of preservation, no LR hearts survived (n = 9), 35% of UW hearts survived (n = 20), and 88% of CU-preserved hearts survived (n = 8; P < .05) versus LR or UW). The viability of preserved hearts was explored by determining whether CU preservation enabled myocytes to maintain resting membrane potentials and preserve their ability to generate an action potential in response to a field stimulus. Of 24 sites explored with a microelectrode in UW-preserved hearts, only 4% were able to generate an action potential, compared with 75% of 36 sites in CU-preserved hearts (P < .001), with corresponding preservation of resting membrane potential in the CU-preserved hearts (-13 mV for UW versus -54 mV for CU, P < .001). Orthotopic baboon cardiac transplantation performed after 24-hour simple hypothermic preservation demonstrated that no UW-preserved heart (n = 4) survived the perioperative period; in contrast, four of five hearts stored for 24 hours in CU solution sustained the recipient with minimal inotropic support, and two animals survived long-term. CONCLUSIONS: Sustaining higher levels of intercellular/intracellular second messengers cAMP and nitric oxide/cGMP provides a new approach to enhancing cardiac preservation.

Adenosine↗
PubMed1992

Normal bronchial healing without bronchial wrapping in canine lung transplantation.

The deleterious effect of steroids on bronchial healing in lung transplantation has led to the development of techniques to protect the anastomosis and to the exclusion of steroid-dependent patients from transplantation. The effect of steroids on bronchial healing was tested in a canine single-lung allotransplantation model. Twenty size-matched mongrel dogs (20 to 30 kg) underwent left lung transplantation without anastomotic wrap or direct revascularization. Postoperatively, all received daily doses of cyclosporine (15 mg/kg) and azathioprine (1 mg/kg) and were subdivided into three steroid dosage groups. Group A (n = 10) animals received 1.5 mg/kg of prednisone per day whereas groups B (n = 5) and C (n = 5) received 5.0 mg/kg of prednisone per day for 28 postoperative days. In addition, group C received prednisone (5.0 mg.kg-1.day-1) for 1 month preoperatively. In group A, 8 of 10 dogs survived 28 days without evidence of respiratory compromise, with anastomotic bursting pressure greater than 510 mm Hg. In group B, all 5 dogs survived to 28 days without evidence of respiratory compromise and with intact bronchial anastomoses (bursting pressures greater than 510 mm Hg). In group C, 3 of 5 animals survived to 28 days with intact anastomoses. Histological examination demonstrated normal bronchial healing in all anastomoses. These data suggest that preoperative steroid dependence should not be a contraindication to lung transplantation and that bronchial anastomotic wrapping with vascular tissue may not be essential.

Anastomosis, Surgical↗
PubMed1992

The effects of heparin bound surface modification (Carmeda Bioactive Surface) on human platelet alterations during simulated extracorporeal circulation.

To determine if treatment with covalently bound heparin (Carmeda Bioactive Surface (CBAS)) to the synthetic surface of the extracorporeal circuit (ECC) would alter the stereotypic pattern of adverse platelet alterations, 450 ml of heparinized blood (lU/ml) was recirculated at a flow rate of twice the circulating volume (L/min) for 2 hrs at 37 degrees C through either untreated (CONT,n=7) or treated (CBAS,n=7) circuits constructed of identical components including a pediatric (0.8m 2) reversed hollow fiber membrane oxygenator. In CONT circuits, platelet count maintained 88+1% (x+/-SEM) of its initial level in the circuit prime sample, dropped to 36+/-6% after 5 min, and returned to 56+/-2% following 2 hrs of ECC. In CBAS circuits, platelet count in the circuit prime sample demonstrated 90+/-4%, decreased to 68+/-10% after 5 min (p less than 0.05) and declined further to 45+/-5% after 2 hrs (NS). Although platelets from both groups retained reactivity to ADP after priming the circuit, only at 5 min of recirculation did CBAS circuits significantly preserve this responsiveness. In CONT circuits, baseline plasma levels of platelet factor 4 rose from 24+/-3 to 581+/-82 ng/ml in the primed circuit and continued to rise to 2933+/-276 ng/ml by 2 hrs of ECC. In contrast, CBAS circuits markedly reduced this release after 2 hrs (577+/-165 ng/ml). Furthermore by 2 hrs of ECC, plasma levels of thromboxane B 2 in the CBAS circuits were significantly reduced when compared to CONT circuits (3035+/-1529 vs 29916+/-16293 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1992

The implantable defibrillator: an electronic bridge to cardiac transplantation.

BACKGROUND: Sudden cardiac death (SCD) is common among patients awaiting heart transplantation. Medical management of SCD may fail due to lack of efficacy or adverse side effects. The implantable cardioverter-defibrillator (ICD) may extend patient survival until a donor heart is available. METHODS AND RESULTS: We reviewed 16 patients listed for transplantation between November 1988 and October 1991 who underwent ICD implantation for ventricular arrhythmias refractory to medical management. Mean age was 51.4 +/- 11.4 years (range, 19-66 years), mean ejection fraction was 15.4 +/- 3.0% (range, 10-21%), and underlying cardiomyopathy was ischemic (12 patients), valvular (one patient), or dilated (three patients). There was no mortality from ICD insertion. Fourteen patients were discharged before transplantation, and two patients remained in the hospital until transplantation. Twelve patients underwent transplantation after a mean of 155.7 +/- 113.7 days (range, 3-319) on the transplant list. The ICD delivered shocks for tachyarrhythmia associated with near syncope in 15 of 16 patients. ICD shocks numbered > 10 in five patients, 5-9 in three patients, and 1-4 in seven patients. There was no morbidity or mortality attributed to patch electrode removal. CONCLUSIONS: We conclude that the ICD can be implanted with minimal morbidity in transplant candidates, allowing the patients to be ambulatory and to leave the hospital while awaiting heart transplantation. In patients at risk of SCD, the ICD is an effective electronic bridge to transplantation.

Anti-Arrhythmia Agents↗
PubMed1992

Cardiac transplantation after prolonged graft preservation with the University of Wisconsin solution.

We tested the ability of University of Wisconsin solution to extend hypothermic preservation of the nonperfused heart during orthotopic baboon allotransplantation. Seven baboons received hearts after cardioplegia and storage (4 degrees C) with University of Wisconsin solution, with a preservation time of 14.2 +/- 1.6 hours. One animal died as a result of a technical error. Six survivors were immunosuppressed for 45 days and then put to death. Preservation did not alter heart weight or histologic features according to light and electron microscopy. Animals were weaned from bypass and returned to their cages without intravenous support within 3.9 +/- 0.8 hours. Weekly biopsies, electrocardiograms, enzyme analyses, echocardiograms, and right heart catheterizations demonstrated excellent cardiac function. University of Wisconsin solution can extend hypothermic cardiac preservation and has no deleterious effects on long-term myocardial function (up to 45 days). This study validates the rationale for human trials with preservation and storage in University of Wisconsin solution toward the goal of improving and prolonging donor heart preservation.

Adenosine↗
PubMed1992

Laser activation of tissue sealant in hand-sewn canine esophageal closure.

UNLABELLED: Dehiscence rates of esophageal anastomoses are between 5% and 20%. Because small leaks between sutures might promote microabscess formation and lead to dehiscence, we postulated that a better initial physical seal might be beneficial. Reinforcement with laser activation of tissue sealant (LATS) is a new technique that has been shown to increase the bursting strength of anastomoses in other tissues. The tissue sealant is composed of 0.4 ml of hyaluronic acid and 0.2 ml of albumin, to which 3 drops of indocyanine green dye are added to give the sealant a peak absorbance of 805 nm, matching the wavelength (808 nm) of a small, hand-held diode laser. Since tissues do not absorb at this wavelength, laser energy is focused in the sealant, minimizing collateral thermal damage. To extend this concept, we assessed LATS in a canine model of esophageal closure. The esophagus was exposed via a right thoracotomy in 20 dogs, and two transverse incisions, 2 cm in length, were made in each esophagus (n = 40 closures). Both sites were closed with a single layer of interrupted 4-0 polyglycolic acid suture. Either the proximal or distal incision was randomly chosen to receive laser activation of tissue sealant. Tissue sealant was applied to the reapproximated edges of the hand-sewn closure, which was then exposed to diode laser energy. The end point was visible shrinking and desiccation of the sealant, which required about 2 minutes. Each esophagus was recovered at 0, 2, or 7 days postoperatively (n = 10, 5, and 5 dogs, respectively), bursting pressure was measured, and the closures were examined histologically. At all three time points LATS closures had significantly higher bursting pressures than control closures (time 0: 251 +/- 87 versus 105 +/- 46, p less than 0.0001; time 2 days: 296 +/- 36 versus 121 +/- 14, p less than 0.0013; time 7 days: 318 +/- 72 versus 197 +/- 60, p less than 0.0021). Histologic study revealed trace thermal injury, with regeneration of intact mucosal lining by 7 days. CONCLUSION: laser activation of tissue sealant is a simple technique that significantly increases the strength of esophageal closure and may reduce the prevalence of dehiscence.

Adhesives↗
PubMed1992

University of Wisconsin solution versus crystalloid cardioplegia for human donor heart preservation. A randomized blinded prospective clinical trial.

We have previously shown the safety and efficacy of University of Wisconsin solution for hypothermic preservation of the human donor heart in a pilot group of 16 transplant recipients. The present study is a randomized clinical trial comparing University of Wisconsin solution to conventional preservation using crystalloid cardioplegia and saline storage within a 4-hour limit of ischemia. Heart transplant recipients (n = 42) were randomized into two groups: those receiving hearts preserved by University of Wisconsin solution, the UWS group (n = 22), and those receiving hearts preserved in the conventional manner, the CCS group (n = 20). Recipient age, gender, heart disease, and preoperative inotropic support and donor age, gender, and mean ischemic time in hours (UWS 2 hours 36 minutes, range 1 hour 36 minutes to 2 hours 53 minutes; CCS 2 hours 20 minutes, range 1 hour 20 minutes to 2 hours 44 minutes; p = not significant) were similar. Significant differences observed between the two groups included (1) mean time (minutes) from reperfusion to achieve a stable rhythm, (2) need for intraoperative defibrillations, (3) need for transient cardiac pacing, and (4) integrated postoperative creatinine kinase and aspartate aminotransferase release over 48 hours. There was no difference in postoperative electrocardiogram, endomyocardial biopsy, or hemodynamics. One UWS patient died of sepsis and another of a ruptured cerebral aneurysm. UWS is safe for donor organ arrest and preservation despite high viscosity and potassium concentration. When compared with CCS hearts, hearts preserved in UWS regained electrical activity more rapidly and had better myocardial protection as demonstrated by enzymatic analysis. Further investigation is required to determine the effects of UWS preservation on long-term survival, to determine the prevalence of rejection and graft atherosclerosis, and to test the ability of UWS to extend donor ischemic time in human cardiac transplantation.

Adenosine↗
PubMed1991

University of Wisconsin solution for human donor heart preservation: initial clinical experience.

Although in vitro and primate orthotopic transplant experiments have suggested the superiority of University of Wisconsin solution (UWS) compared with crystalloid cardioplegia and saline solution storage for hypothermic heart preservation, concerns about the viscosity and the high potassium concentration of UWS have precluded its use in human cardiac transplantation. To test the safety and efficacy of UWS, 16 patients received hearts arrested with, flushed with, and stored in UWS at 4 degrees C for a mean ischemic time of 153.3 +/- 30.7 minutes. After reperfusion, the hearts contracted vigorously and attained a stable sinus rhythm within 4.0 +/- 2.4 minutes, and the patients were weaned from bypass in 24.5 +/- 8.0 minutes. There was no evidence of acute or chronic ischemic myocardial injury by enzymatic analysis, electrocardiography, or biopsy specimen histology. The results suggest UWS can be safely used, within currently accepted limits of donor ischemic time, to arrest and preserve human hearts for transplantation. Further studies of preservation are required to compare UWS with crystalloid cardioplegia and saline solution storage and to test the ability of UWS to prolong the period of safe donor hypothermic ischemia in clinical heart transplantation.

Adenosine↗
PubMed1991

Effect of AICD patch electrodes on the diastolic pressure-volume curve in pigs.

Although the automatic implantable cardioverter defibrillator (AICD) is effective against malignant ventricular arrhythmias, the effects of AICD patches on left ventricular diastolic properties have not been defined. Accordingly, extrapericardial (group E, n = 5) or intrapericardial (group I, n = 6) AICD patches were implanted through a median sternotomy in 11 anesthetized pigs. Six weeks later, using a left thoracotomy, the hearts were arrested with hypothermic cardioplegia. A balloon catheter was inserted into the left ventricle through the aortic root, and pressure-volume curves were measured before and after sequential removal of patches and pericardium. A dense intrapericardial fibrotic reaction in group I was not present in group E. Normalized left ventricular filling volumes in group E were significantly larger at pressures of 5.1 to 10, 15.1 to 20, and 20.1 to 28 mm Hg compared with group I (p less than 0.05). We conclude that intrapericardial AICD patches adversely affect left ventricular diastolic pressure-volume relations and recommend that AICD patches be placed in the extrapericardial location clinically whenever possible.

Animals↗
PubMed1991

Improved heart preservation with University of Wisconsin solution: experimental and preliminary human experience.

We tested the ability of University of Wisconsin solution (UWS) to extend hypothermic nonperfused heart preservation in baboons and then proceeded to human transplantation. Orthotopic transplantation was performed in five baboons (UWS cardioplegia and storage [4 degrees C]; preservation time 10.3 +/- 0.6 hours). Four survivors were immunosuppressed for 45 days and killed. One animal died from disruption of the aortic anastomosis due to technical error. Preservation did not alter histology under light and electron microscopy or heart weight (at harvest, 51.4 +/- 11.6 g; before implant, 52.5 +/- 11.1 g). Animals were weaned from bypass (mean, 23 +/- 12 minutes) and returned to their cages without intravenous support within 3.6 +/- 0.6 hours. Weekly biopsy, electrocardiogram, enzyme analysis, echocardiogram, and right heart catheterization demonstrated excellent cardiac function. Following success in baboons, UWS was applied to human transplantation (n = 2, UWS cardioplegia and storage [4 degrees C]; preservation time 4.2 and 2.1 hours). The hearts returned to sinus rhythm within 4 minutes of reperfusion without defibrillation, and enzymatic and hemodynamic data reveal excellent heart preservation. Preliminary data suggest the ability of UWS to prolong heart preservation in baboons and be used safely in humans. Further studies are required to compare UWS with crystalloid cardioplegia and saline storage and to prolong donor heart preservation in humans.

Adenosine↗
PubMed1990

Single-stage management of sternal wound infections.

Deep median sternotomy wound infection is a significant source of morbidity after cardiac operations. Accepted approaches in treating this complication include débridement with either sternal closure over an irrigation system or open dressings and closure by secondary intention. Muscle flaps are often used in subsequent procedures for wound closure. A single-stage procedure was developed to eliminate irrigation, open wound management, or reoperation for muscle flap closure. This approach consists of débridement and immediate closure with a pectoral musculocutaneous flap. The following report describes 31 patients treated by such a method. Compared with results of previous techniques in treating sternal wound infections, hospital study is decreased, fewer reoperations are needed, and patient management is simplified.

Cardiac Surgical Procedures↗
PubMed1987

A comparison of direct brush cytology and biopsy in the diagnosis of colorectal cancer.

Direct brush cytology has been underutilized as compared with direct biopsy in the endoscopic diagnosis of colorectal lesions. We report on a large series of patients in whom biopsy and brush cytology were compared with each other and with the pathology of the specimen. Our results show that cytology should be used with biopsy to get maximal yield (97% accuracy), especially in areas of strictures or obstruction.

Biopsy↗
PubMed1985

Preparation of fibrin glue from single-donor fresh-frozen plasma.

Fibrin glue is used widely in Europe as a tissue sealant and hemostatic agent. The European glue is prepared commercially from pooled human blood. It is not available in this country because of the risk of transmission of hepatitis B, acquired immune deficiency syndrome, and other blood-transmitted diseases. We describe a cryoprecipitation technique for preparation of fibrin glue from single-donor fresh-frozen plasma. This technique enables the glue to be made in large quantities with no greater risk of disease transmission than with that from the transfusion of single-unit fresh-frozen plasma. We have found that the glue is a useful tool in surgery. By helping to control difficult bleeding, its use can decrease the need for blood transfusions and shorten operating room time. It also is effective as a means to pretreat highly porous vascular prostheses that currently are used infrequently because of bleeding. These porous grafts offer potential advantages in handling, suturing, and long-term patency. This new technique of fibrin glue preparation may make this useful surgical adjunct as readily available in this country as it is in Europe.

Chemical Precipitation↗