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Biomedical subjects

A M Borkon

Publications and source records attributed to A M Borkon.

At least 19 recordsLinked to original sources
PubMed1999

Is routine postaneurysmectomy hemodynamic assessment of the inferior mesenteric artery circulation helpful?

All patients with an abdominal aortic aneurysm treated during a 27-year period by one surgical group at the MidAmerica Heart Institute were included in this study. A prospective routine postaneurysmectomy hemodynamic assessment of the inferior mesenteric artery (IMA) circulation was performed in a test group of consecutive patients operated on by one surgeon. When a mean IMA stump pressure </= approximately 50 mmHg was found, the IMA was reimplanted. Postoperatively, patients were monitored for clinical evidences of ischemic colitis. The occurrence of ischemic colonic injury was documented by colonoscopy, laparotomy, or autopsy. The incidences of ischemic colitis in the test group, a historical control group, and a concomitant control group were determined and compared. Routine hemodynamic assessment of the postaneurysmectomy IMA circulation did not favorably affect the outcome with regard to the occurrence of clinically evident ischemic colitis.

Aged↗
PubMed1999

An analysis of the effect of age on survival after heart transplant.

BACKGROUND: Advances in immunosuppression and reports of improved survival after cardiac transplantation have led to a liberalization of traditional recipient eligibility criteria, especially age. While age alone is not a contraindication to transplantation, conflicting data exists regarding long-term survival of the older transplant recipient. METHODS: One hundred-fifty three patients undergoing consecutive first time cardiac transplantation from June 7, 1985 through February 1, 1997 were studied. For purposes of analysis, patients were stratified according to age (<55 years vs. >55 years) and hospital and late outcomes determined. RESULTS: The incidence of early and late acute cellular rejection was not different based up on age. The freedom from infection at 12 months was 54+/-5% for patients < or =55 compared to 32+/-8% for patients >55 years old (p = .04). Five year estimated survival for patients >55 years old was only 56+/-9% compared to 78+/-5% for patients < or =55 years old (p = .005). The hazard for death was highest within the first post-transplant year for older patients and was most commonly due to infection. Both advanced age and pre-transplant diagnosis of ischemic cardiomyopathy were found to be independently and additively predictive of reduced late survival. CONCLUSIONS: In the present study, late survival was adversely influenced by advanced age. Older patients (>55 years) with pre-transplant diagnosis of ischemic cardiomyopathy were particularly at high risk (risk ratio 4.6:1) for death. Given little prospect of expanding the number of donor hearts, careful selection of patients over the age of 55 with pre-transplant ischemic cardiomyopathy is warranted.

Adult↗
PubMed1999

The dilemma of too few hearts.

The number of patients being listed for heart transplantation continues to escalate. Despite a variety of attempts to increase organ donation, the number of available donor hearts remains unchanged. This imbalance of supply and demand creates medical rationing of donor organs. When the success of heart transplantation became apparent, selection criteria was relaxed, further increasing the disparity between the numbers of donor hearts and potential recipients. Decreasing the demand by tightening the selection criteria is the most reasonable solution at this time.

Health Care Rationing↗
PubMed1998

25-year trends in resection of abdominal aortic aneurysms.

An attempt was made to document trends that have occured over a 25-year period in clinical presentation, preoperative evaluation, operative management, and patient outcome in patients with an abdominal aortic aneurysm. The experience (574 aneurysmectomies) of one cardiovascular surgical group was analyzed by retrospective review of hospital and office records. Changes over time of patients' ages, aneurysm sizes and statuses, prior myocardial revascularization, operative mortality, and certain other parameters were evaluated. During the period of study, there was a significant decrease in aneurysm size, increase in patients' ages, and an increased incidence of previous coronary artery bypass. No ruptured aneurysm was < 5 cm in diameter. The incidence of rupture and the operative mortality in patients with a ruptured aneurysm did not change significantly. There was a significantly (p = 0.03) lower operative mortality of 0.4% in the latter half of the series for elective aneurysmectomy. Increased utilization of preoperative cardiologic evaluation, and myocardial revascularization, has been associated with a decreased operative mortality in patients undergoing elective aneurysmectomy even though the patients are now older and have more age-related comorbidities. Elective aneurysmectomy should be offered to most patients when an abdominal aortic aneurysm is > or =5 cm in diameter.

Aged↗
PubMed1998

Coronary artery bypass for isolated disease of the left anterior descending artery. Late survival of 648 patients.

We studied a series of 648 consecutive patients who underwent coronary artery bypass grafting for isolated primary disease of the anterior descending coronary artery. We evaluated the patients periodically during a long-term follow-up period of up to 17 years. We studied factors such as survival, survival without acute event (i.e., acute myocardial infarction, repeat coronary artery bypass, and percutaneous transluminal coronary angioplasty), and asymptomatic survival (i.e., survival without acute event or angina). We further analyzed these factors as they occurred in patients who received only saphenous vein grafts versus their occurrence in patients who received internal mammary artery grafts. There was 1 death in the early postoperative period (defined as 30 days or earlier after the operation). The 5-, 10-, and 15-year survival rates were 94.8%, 86.6%, and 72.2%, respectively. These survival rates are slightly better than those of an age- and sex-matched United States census population. In our series, the rates of survival, event-free survival, and asymptomatic survival were better, although not significantly so, in the group of 108 patients in whom the internal mammary artery was used as the bypass conduit. We conclude that patients who undergo coronary artery bypass grafting for isolated disease of the left anterior descending coronary artery enjoy normal survival rates, in comparison with the survival rates of an age- and sex-matched United States census population, through at least the 1st 16 postoperative years. Additionally, patients who receive an internal mammary artery bypass graft have slightly better rates of survival, event-free survival, and asymptomatic survival than do those who receive only saphenous vein grafts.

Angioplasty, Balloon, Coronary↗
PubMed1997

Bypass surgery versus coronary angioplasty for revascularization of treated diabetic patients.

BACKGROUND: The purpose of this study was to evaluate outcomes after coronary bypass surgery versus coronary angioplasty in 525 patients with pharmacologically treated diabetes. Diabetic patients constitute a significant portion of patients considered for coronary revascularization. Some studies have shown no difference in long-term outcome when comparing revascularization mode. Recently, the Bypass Angioplasty Revascularization Investigation reported better survival with bypass surgery over angioplasty in treated diabetic patients. However, the above studies have been limited by small cohorts of diabetic patients. METHODS AND RESULTS: By using a single-institution comprehensive database, a retrospective cohort design was used to study 525 consecutive pharmacologically treated diabetic patients who underwent coronary revascularization. Patients treated with surgery (n=246) were statistically similar when comparing age, gender, angina class, and ejection fraction to patients (n=279) treated with angioplasty. Follow-up was complete in 95% of bypass patients and 99% of angioplasty patients. Mean follow-up was 55.5 months. Complete revascularization was accomplished more often in the surgery group (79%) than in the angioplasty group (42%; P<.001). During a 6-year follow-up, repeat revascularization (8% versus 64%; P=.001), cardiac events (32% versus 41%; P=.04), and death (30% versus 37%; P=.08) occurred less in the bypass patients than the angioplasty patients. Multivariable analysis identified age >70 years, ejection fraction <40%, class IV angina, and incomplete revascularization, but not mode of revascularization, as correlates of late mortality. CONCLUSIONS: For most pharmacologically treated diabetic patients, freedom from death, myocardial infarction, and subsequent revascularization during long-term follow-up is superior with bypass surgery compared with angioplasty. This worse outcome was mediated in part by the frequent occurrence of incomplete revascularization with angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1997

Early repair of postinfarction ventricular septal rupture.

BACKGROUND: Postinfarction rupture of the interventricular septum is usually fatal without surgical intervention. The optimal timing and the most appropriate technique of surgical repair remain unsettled. METHODS: The results of surgical closure of postinfarction ventricular septal defect in a consecutive series of patients seen over a 24-year period were reviewed and analyzed. Late follow-up was obtained in all patients who survived the operation. RESULTS: Sixty of 76 patients treated surgically exhibited cardiogenic shock, low cardiac output syndrome, or both at the time of operation. A plan of early operative intervention was followed in these unstable patients, with 60% of them undergoing repair within 24 hours of septal rupture. For the entire series of patients, the hospital mortality rate was 40.8%; survival was 41.5% at 5 years and 25.6% at 10 years postoperatively. CONCLUSIONS: Significant trends observed during the period of study were a more aggressive stance regarding surgical intervention in all patients who presented with hemodynamic instability and improved survival in those patients who presented with septal rupture complicating an inferior myocardial infarction.

Aged↗
PubMed1995

Detection of HLA IgG antibodies by two enzyme-linked immunoassays, solubilized HLA class I and PRA-STAT. Comparison with the AHG PRA.

HLA class I-directed IgG antibodies have traditionally been detected with a complement-dependent lymphocytotoxicity (CDL) technique. We have evaluated two solid-phase enzyme-linked immunoassays (EIA) and compared them with the CDL antihuman globulin (AHG) dithiothreitol-treated (DTT) PRA in their ability to discriminate between the presence or absence of HLA class I-directed IgG antibodies in serum from patients awaiting transplantation. The EIA were: (1) an EIA that uses solubilized HLA class I antigens (sHLA-I) isolated from a 240-member platelet donor pool, and (2) the PRA-STAT ELISA kit. For the first comparison, we used 691 serum samples from 272 patients taken before they had been transplanted. The data show a significant (P < 0.0001) linear correlation (r = 0.77 between the AHG DTT PRA and the sHLA EIA. They also demonstrate that the mean sHLA-I EIA ratio significantly increases (P < 0.01) above background levels with each stepwise increase in AHG DTT PRA level. Discordant results were 1.0% (7/691) for sHLA-I EIA+ PRA- and 6.3% (44/691) for PRA+ sHLA-I EIA-. However, a lower correlation was noted between the AHG DTT PRA and the PRA-STAT (Nextran) PRA results (n = 230; r = 0.42). The sHLA-I EIA is able to determine whether or not HLA Class I IgG antibodies are present in serum from transplant candidates and is an appropriate adjunct to the traditional CDL PRA assay, whereas the PRA-STAT is not.

Enzyme-Linked Immunosorbent Assay↗
PubMed1995

Right atrial compression related to defibrillator patches.

Acceptable function of an internal defibrillator can be achieved with different patch orientations. For patients requiring defibrillator patches concomitant with a cardiac procedure requiring extracorporeal circulation, application of one of the patches within the pericardium adjacent to the right atrium has provided excellent defibrillation thresholds. We describe 4 such patients in whom a compressing thrombus subsequently developed between the patch and the atrium. The thrombus was small and asymptomatic in 1 patient, but caused localized tamponade requiring reexploration in 2 patients and a fatal superior vena caval obstruction in 1. The precise etiology of this serious complication remains unclear, but its occurrence argues against the application of intrapericardial defibrillator patches in this orientation.

Aged↗
PubMed1993

Mitral valve repair using a flexible and adjustable annuloplasty ring.

Initial experience with a new flexible and adjustable mitral annuloplasty ring is described. Used in conjunction with standard techniques of mitral valve repair, this ring was implanted in 21 consecutive patients undergoing elective operation for mitral regurgitation. Satisfactory valve repair was feasible in 20 of these patients. Once the ring was sewn in place, adjustment of the ring to reduce or eliminate residual regurgitation was beneficial in 9 patients. Excellent results were achieved as determined by intraoperative transesophageal echocardiography. Comparable late results were found in all but 1 patient up to 1 year after repair. This patient required mitral valve replacement 6 months after repair due to failure of papillary muscle reconstruction. The BiFlex ring has the merits of a flexible prosthesis with the advantage of easy adjustment once secured in place.

Aged↗
PubMed1992

Risk analysis of operative intervention for failed coronary angioplasty.

To assess the outcome of emergency coronary artery bypass grafting (CABG) after failed percutaneous transluminal coronary angioplasty (PTCA), 91 patients undergoing emergency CABG after failed PTCA over a 30-month period ending July 31, 1991, were studied. For reference, a cohort of patients (91) concurrently undergoing elective CABG equally matched for age, sex, number of grafts, ventricular function, and reoperative status was compared. Specific outcomes including death, hospital length of stay, use of blood products, and development of myocardial infarction were analyzed. More than half the patients undergoing emergency CABG for failed PTCA required three or more grafts. Operative mortality was 12.1% (11/99) for emergency CABG compared with 1% (1/91) for elective case-matched CABG patients (p = 0.007). Emergency CABG patients required frequent use of postoperative inotropes (p = 0.02) and intraaortic balloon counterpulsation (p = 0.001). Length of hospital stay (p = 0.005), administration of blood products (p = 0.009), postoperative myocardial infarction (p = 0.0005), and ventricular arrhythmias (p = 0.0004) were increased after emergency compared with elective CABG. The presence of multivessel disease or use of a reperfusion catheter had no influence on clinical outcome. Despite accumulated experience and improved operative management, patients requiring emergency CABG for failed PTCA remain at increased risk for postoperative complications and death.

Angioplasty, Balloon, Coronary↗
PubMed1991

Bio-medicus ventricular assist device for salvage of cardiac surgical patients.

Over a 5-year period, 41 (1%) of 4,193 patients undergoing cardiac operations underwent intraoperative or early postoperative insertion of a Bio-Medicus ventricular assist device when it became apparent that the patient could not otherwise survive. Fourteen patients were in cardiogenic shock and 7 were in cardiac arrest at the time of initiation of their primary cardiac surgical procedure, and in no instance was the device planned as a bridge to cardiac transplantation. Bleeding, sepsis, and thromboembolism were frequent postoperative complications. Central nervous system deficits were observed in 16 patients during their postoperative course. Eight patients (19.5%) were long-term survivors. Of the preoperative risk factors evaluated only age was significantly associated with survival, with 7 (33%) of the 21 younger (39 to 63 years) patients surviving. Blood product usage and hospital cost were analyzed in an attempt to assess cost/effectiveness of use of this device for attempted salvage of such desperately ill patients.

Adult↗
PubMed1991

Mechanisms of blood flow during pneumatic vest cardiopulmonary resuscitation.

Mechanisms of blood flow during cardiopulmonary resuscitation (CPR) were studied in a canine model with implanted mitral and aortic flow probes and by use of cineangiography. Intrathoracic pressure (ITP) fluctuations were induced by a circumferential pneumatic vest, with and without simultaneous ventilation, and by use of positive-pressure ventilation alone. Vascular volume and compression rate were altered with each CPR mode. Antegrade mitral flow was interpreted as left ventricular (LV) inflow, and antegrade aortic flow was interpreted as LV outflow. The pneumatic vest was expected to elevate ITP uniformly and thus produce simultaneous LV inflow and LV outflow throughout compression. This pattern, the passive conduit of "thoracic pump" physiology, was unequivocally demonstrated only during ITP elevation with positive-pressure ventilation alone at slow rates. During vest CPR, LV outflow started promptly with the onset of compression, whereas LV inflow was delayed. At compression rates of 50 times/min and normal vascular filling pressures, the delay was sufficiently long that all LV filling occurred with release of compression. This is the pattern that would be expected with direct LV compression or "cardiac pump" physiology. During the early part of the compression phase, catheter tip transducer LV and left atrial pressure measurements demonstrated gradients necessitating mitral valve closure, while cineangiography showed dye droplets moving from the large pulmonary veins retrograde to the small pulmonary veins. When the compression rate was reduced and/or when intravascular pressures were raised with volume infusion, LV inflow was observed at some point during the compressive phase. Thus, under these conditions, features of both thoracic pump and cardiac pump physiology occurred within the same compression. Our findings are not explained by the conventional conceptions of either thoracic pump or cardiac compression CPR mechanisms alone.

Animals↗
PubMed1988

Donor core-cooling provides improved static preservation for heart-lung transplantation.

Twenty-three dairy calves underwent heart-lung allotransplantation after donor organs were procured using either donor core-cooling through cardiopulmonary bypass (CPB) or pulmonary artery flush (PAF) to assess which method provides optimal graft preservation. In Groups 1 (control) and 2, donors were cooled to 15 degrees C on CPB and organs were either immediately transplanted (Group 1) or stored in saline solution (4 degrees C) for 4 hours (Group 2) prior to transplantation. In Group 3, donors were pretreated with prostaglandin E1 prior to PAF with modified Euro-Collins solution. Organs were stored in saline solution (4 degrees C) for 4 hours and were then transplanted. Acute cardiopulmonary function following transplantation was assessed by the ratio of end-systolic pressure to end-systolic dimension, extravascular lung water (EVLW), lung compliance, arterial oxygenation, and lung biopsy. Cardiac function after the transplantation procedure was similar in all groups, but EVLW values and lung biopsy scores were worse after PAF. Arterial O2 tension appeared lower after PAF, but not significantly so. Core-cooling provides superior static preservation and thus improved graft function in the acute bovine model.

Animals↗