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Biomedical subjects

M P Macris

Publications and source records attributed to M P Macris.

At least 19 recordsLinked to original sources
PubMed1996

Improved left ventricular function after chronic left ventricular unloading.

BACKGROUND: This study assessed the effect of prolonged left ventricular unloading on native ventricular function. METHODS: We reviewed data from 31 patients (30 men, 1 woman) supported more than 30 days (mean, 137 days; range, 31 to 505 days) with the HeartMate left ventricular assist system. The patients' mean age was 46 years (range, 22 to 64 years); 17 had idiopathic and 14 had ischemic cardiomyopathy. Data (anatomic, physiologic, hemodynamic, histologic, and biochemical) were collected at the time of HeartMate implantation, during support with the device temporarily off, and at the time of device explantation. RESULTS: Routine chest roentgenogram showed improvement in cardiothoracic ratio (0.62 +/- 0.04 to 0.55 +/- 0.03; p < 0.0001). Echocardiography performed with the pump off showed a significant decrease in left ventricular end-diastolic dimension (6.81 +/- 0.87 cm to 5.39 +/- 1.08 cm; p < 0.0005) and a significant improvement in ejection fraction (0.11 +/- 0.05 to 0.22 +/- 0.17; p < 0.02). Cardiac index increased (1.96 +/- 0.52 L.min-1.m-2 to 2.93 +/- 0.73 L.min-1.m-2; p < 0.0001), mean aortic pressure increased (71.40 +/- 10.63 mm Hg to 76.33 +/- 16.84 mm Hg; p = 0.48), pulmonary capillary wedge pressure decreased (24.18 +/- 6.27 mm Hg to 14.48 +/- 3.01 mm Hg; p < 0.0001), and pulmonary vascular resistance decreased (3.34 +/- 2.00 Wood units to 2.51 +/- 0.88 Wood units; p < 0.05). Comparisons of tissue samples taken at the time of implantation and at the time of transplantation showed a marked reduction in myocytolysis. Calcium uptake, calcium-binding rates, and lipid levels normalized in patients studied. Plasma norepinephrine levels decreased to near normal levels. CONCLUSION: Prospective studies are now indicated to determine whether device removal without transplantation may be beneficial in selected patients.

Adult↗
PubMed1996

Localized administration of sodium nitroprusside enhances its protection against platelet aggregation in stenosed and injured coronary arteries.

Sodium nitroprusside, a potent vasodilator, was evaluated for its effect on platelet aggregation in stenosed and endothelium-injured coronary arteries in a canine model. Twenty-five anesthetized dogs were studied; coronary blood flow velocity was continuously monitored. Recurrent intracoronary platelet aggregation and dislodgment (indicated by cyclic variations in coronary blood flow) were induced by mechanically injuring and stenosing the left anterior descending coronary artery. Sodium nitroprusside was administered either intrapericardially or intravenously 30 min after cyclic flow variations were established. Intrapericardial administration of saline (control) did not affect cyclic flow variations in any of 6 tested dogs. Sodium nitroprusside abolished cyclic flow variations in all 7 dogs (100%) when given intrapericardially and in 5 to 7 dogs (71%) when given intravenously (compared to intrapericardial salines, p < 0.01). A smaller dose of sodium nitroprusside was required to abolish cyclic flow variations when given intrapericardially than when given intravenously (1.6 +/- 0.5 micrograms.kg-1.min-1 vs 4.8 +/- 0.8 micrograms.kg-1.min-1, p < 0.01). The mean aortic pressure was reduced by 10 to 20 mmHg after intrapericardial sodium nitroprusside administration and by 30 to 40 mmHg after intravenous sodium nitroprusside administration. To investigate the mechanism of protection by sodium nitroprusside, NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthetase, was used to induce cyclic flow variations in mildly injured and stenosed left anterior descending coronary arteries in 5 dogs. Intrapericardial sodium nitroprusside abolished the cyclic flow variations in all 5 dogs. Then oxyhemoglobin, an inhibitor of nitric oxide, was administered into the left anterior descending coronary arteries of these dogs, and it restored the sodium nitroprusside-abolished cyclic flow variations in all 5 dogs. Thus, sodium nitroprusside protects against platelet aggregation and cyclic flow variations in stenosed and endothelium-injured canine coronary arteries, probably by the action of nitric oxide, and it is more effective and hemodynamically safer when administered intrapericardially than when administered intravenously.

Administration, Topical↗
PubMed1995

Permanent mechanical replacement of the left ventricle.

Patients with congestive heart failure have a poor prognosis and their care is expensive. Treatment with the HeartMate left ventricular assist device (Thermo Cardiosystems Inc, Woburn, MA) has indicated that life for such patients can be prolonged, quality of life increased, and cost of care decreased. Although currently approved only as a bridge to transplantation, the HeartMate and other such devices may one day offer permanent support of the left ventricle as an alternative to cardiac transplantation.

Cardiopulmonary Bypass↗
PubMed1994

Improved survival after extended bridge to cardiac transplantation.

In the past, left ventricular assist device (LVAD) support was frequently plagued by complications; thus, bridge to transplantation times were kept short. Increasing evidence suggests that extended bridging provides greater benefit due to improved end-organ perfusion and, thus, generally improved physical condition. To assess whether extended bridging translates into improved long-term survival after transplantation, we reviewed our experience with the HeartMate 1000 IP LVAD (Thermo Cardiosystems, Inc, Woburn, MA). Since January 1988, 19 patients (mean age, 45 +/- 9 years) have undergone extended bridging (mean time, 106 +/- 57 days). Their mean weight was 82 +/- 16 kg, and their mean body surface area was 2.0 +/- 0.2 m2. We define "extended" as the length of support necessary for systemic organ recovery after prolonged heart failure. During support, average pump flow indices ranged from 2.3 to 3.3 L.min-1.m-2, and all patients underwent physical rehabilitation. Between the time of LVAD implantation and explantation, the mean serum creatinine value decreased from 1.63 +/- 0.6 to 1.25 +/- 0.6 mg/dL (p = not significant), and the mean serum total bilirubin value decreased from 2.8 +/- 2.0 to 0.63 +/- 0.11 mg/dL (p < 0.05). All but 1 patient improved from New York Heart Association class IV to class I. Device-related complications were minimal. Twelve control patients ("de facto randomized") who did not receive the LVAD also were evaluated: actuarial survival at 1 year was 0% (p < 0.05); 3 (25%) underwent transplantation and died within 2 months; 9 (75%) died before transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Current methods for circulatory support.

Although the concept of artificial circulatory support has existed for almost 200 years, it has only been within the last 4 decades that engineers and physicians have developed mechanical devices that can 1) temporarily support the circulation in a patient until the heart recovers or a new heart can be transplanted, or 2) permanently replace a failed heart. In this paper, we briefly describe the devices and techniques that are in current clinical use and speculate on the use of such devices in the future.

Counterpulsation↗
PubMed1994

Progress in cardiac transplantation.

This article summarizes general practices in cardiac transplantation, including the selection of recipients and pretransplant management, selection of donors, surgical technique, management of perioperative complications, and induction and maintenance protocols for immunosuppression. Advancements in the management of rejection and infection also are included. Coronary artery disease is the most frequent cause of late death in spite of improved immunosuppressive regimens, antiplatelet agents, and lipid-controlling drugs. Still, long-term survival has improved markedly. A brief description of the Texas Heart Institute experience with 532 cardiac transplants is provided.

Cause of Death↗
PubMed1990

First human use of the Hemopump, a catheter-mounted ventricular assist device.

The Hemopump, a catheter-mounted, temporary ventricular assist device, consists of an external electromechanical drive console and a disposable, intraarterial axial-flow pump (21F). Power is transmitted percutaneously to the pump by a flexible drive shaft within the catheter. The device is positioned in the left ventricle by way of the femoral artery approach or through the ascending aorta. Blood is drawn from the left ventricle through the transvalvular inlet cannula and pumped into the aorta. As of December 1988, the Hemopump had successfully supported the circulation of 7 patients (5 men, 2 women) ranging in age from 44 to 72 years (mean age, 59 years) and suffering from cardiogenic shock (cardiac index less than 2.0 L/min/m2). Indications for use included failure to be weaned from cardiopulmonary bypass in 4 patients, acute myocardial infarction in 1, severe cardiac allograft rejection in 1, and donor heart failure in 1. Duration of support ranged from 26 to 113 hours (mean, 66 hours). Although 5 patients demonstrated transient hemolysis, none experienced infection, thrombosis, or vascular injury. Hemodynamic variables improved in all patients during support by the device. As of December 1988, 5 of the 7 patients were alive more than 30 days after support had been discontinued, and 3 of these patients were discharged from the hospital. On the basis of our initial clinical results, the Hemopump, which does not require a major surgical procedure for insertion, provides effective, temporary circulatory support in patients with potentially reversible cardiac failure.

Adult↗
PubMed1989

Effect of prior cardiac surgery on survival after heart transplantation.

We conducted a retrospective analysis of 182 adult orthotopic heart transplant patients who underwent operations at our institution between July 1982 and October 1987 to determine whether prior cardiac operation affects survival. Group I included the 72 patients (39.6%) who had undergone a previous cardiac operation or operations and group II, the 110 (60.4%) who had not. The mean age of the patients in group I was 52.1 +/- 8.1 years and in group II, 46.1 +/- 10.2 years (p less than 0.01). The incidence of ischemic heart disease was 86.1% in group I and 29.1% in group II (p less than 0.01). All patients received cyclosporine-based immunosuppression. More patients in group I than in group II required reoperation for bleeding after transplantation: 18 (25.0%) versus 9 (8.2%) (p less than 0.01). The actuarial 1-year and 3-year survival rates were 77.6% and 66.5%, respectively, for group I and 77.1% and 66.3%, respectively, for group II. Because both groups had similar survival rates, we believe that prior cardiac operation in heart transplant recipients does not compromise long-term survival.

Adult↗
PubMed1989

Improved immunosuppression for heart transplant patients using intravenous doses of cyclosporine.

Inducing immunosuppression in heart transplant patients with intravenous doses of CsA may decrease the incidence of severe rejection in the 1st month after operation. In our initial series, 16 consecutive patients (group A) who had no contraindications to this type of therapy received an i.v. dose of CsA, 1 mg/kg/day, postoperatively, which was then increased by 1 mg/kg every 24 hr until a full maintenance dose of 4 mg/kg/day was achieved (total time, 72 hr). The gradual increase in dosage was designed to prevent nephrotoxicity associated with higher doses of CsA. Intravenous administration was continued for 2 weeks, at which time oral administration of CsA, 14 mg/kg/day, was begun. In a subsequent series, 21 similar patients (group B) received the same amount of CsA, except that doses were increased every 12 hr, so that the full maintenance dose was achieved 36 hr postoperatively. In group B, the i.v. dose of CsA was continued for only 1 week, at which time oral administration of CsA, 14 mg/kg/day, was begun. All patients received the same standard steroid taper (30 mg/day by day 10). Patients from both groups who were greater than or equal to 55 years old and had serum creatinine greater than or equal to 1.5 mg/dl and patients from group B who had creatinine clearance less than or equal to 55 ml/min also received azathioprine, 2 mg/day, which was adjusted to maintain the white blood cell count at a level greater than or equal to 5000/cc. There was a similar number of such patients in both groups. Severe rejection was defined by endomyocardial biopsy with frequent foci of myocyte degeneration. Three (18.7%) patients in group A experienced severe rejection, and 2 (9.4%) in group B did. No patients developed renal failure. All patients survived the 1st month. The overall survival rate for group A at 12.2 +/- 1.5 months was 94%, and for group B it was 86% at 7.5 +/- 1.4 months. Both these groups compared favorably with our historical control group of patients who received oral doses of CsA to induce immunosuppression, in which 59 of 165 (35.8%) had severe rejection in the 1st month, with a 1-year actuarial survival rate of 76%. Based on this experience, we believe that i.v. administration of CsA enhances the induction of immunosuppression, thereby reducing the incidence of severe rejection. This protocol is likely to be effective because it minimizes the problems of oral absorption in the perioperative period.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

Cardiac transplantation in patients over 60 years of age.

Cardiac transplant programs have routinely excluded patients over 55 years of age from consideration as transplant candidates. The Texas Heart Institute modified this policy of using age as a contraindication to transplantation. Between July, 1982, and August, 1987, a total of 200 cardiac transplants were performed, 28 (14%) of which were in patients over 60 years of age, the eldest being 66 years old at the time of transplant. Our immunosuppressive regimen consisted primarily of cyclosporine and prednisone. In 1985, azathioprine was added in an effort to decrease dosages of cyclosporine, thereby decreasing its associated nephrotoxicity. The incidences of rejection and infection were 1.2 and 1.4 episodes/patient, respectively, for those over 60 years of age versus 1.7 and 1.3 episodes/patient, respectively, for those less than 60 years of age. Of the 28 patients, 23 are alive and well. Four deaths were caused by infection, and the other by diffuse coronary arteritis. The one-year actuarial survival for patients over 60 years of age was 83%, compared with 75% for the other transplant patients. We conclude that persons over 60 years of age can undergo cardiac transplantation with results equal to or perhaps better than those of other heart transplant patients. Our experience suggests that advanced age should not be considered a major contraindication to cardiac transplantation.

Actuarial Analysis↗
PubMed1988

The treatment of advanced cardiac allograft rejection.

Severe cardiac allograft rejection remains a serious problem despite the advances of cyclosporine-based immunosuppression. This study analyzes our experience with 202 recipients of cardiac allografts who were treated primarily with cyclosporine and prednisone. Failure of such therapy in 86 patients (43%) resulted in 105 episodes of advanced cardiac allograft rejection as diagnosed by endomyocardial biopsy. Of 101 rejection episodes that were initially treated with intravenous pulse therapy, 48 (48%) were successfully resolved, yet 60% of these successes were associated with major infections. Patients in whom steroid therapy failed or was contra-indicated received intravenous antithymocyte globulin (ATG) or intravenous monoclonal antibody (OKT3). ATG and OKT3 successfully reversed severe rejection in 26 (81%) of 32 and in 13 (93%) of 14 episodes, respectively. Infectious complication rates were 54% and 21%, respectively. Because the majority (87%) of these rejection episodes occurred within the first 30 days after treatment, many of them may have resulted from inadequate immunosuppressive induction therapy. Based on our results, we believe that advanced cardiac allograft rejection may be managed best by individualizing immunosuppressive therapy, thus enhancing prevention, and by adding OKT3 to the regimen when rejection occurs.

Adolescent↗