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Biomedical subjects

O H Frazier

Publications and source records attributed to O H Frazier.

At least 19 recordsLinked to original sources
PubMed1997

Report of the National Heart, Lung, and Blood Institute Special Emphasis Panel on Heart Failure Research.

The SEP identified priorities to support in future basic and clinical research and pointed out directions likely to result in advances against heart failure. The list is not intended to be all-encompassing and does not address, for example, exciting lines of work already under way. Rather, the recommendations are designed to point out gaps in current knowledge not being adequately addressed and highly promising new directions. Although the incidence of heart failure continues to grow, emerging lines of research provide hope that research advances will eventually lead to more effective treatment and ultimately to prevention. This research will be well served by bringing the latest multidisciplinary approaches and the best investigators to focus on the problems of heart failure. It is hoped the efforts of distinguished expert entities such as the task force and SEP will be a useful guide in addressing the needs of the biomedical community and assisting in its success.

Animals↗
PubMed1997

Long- and short-term effects of transmyocardial laser revascularization in acute myocardial ischemia.

BACKGROUND AND OBJECTIVE: This study examined the effect of transmyocardial laser revascularization (TMLR) on infarct size and global and regional left ventricular (LV) function. STUDY DESIGN/MATERIALS AND METHODS: Acute ischemia was induced in 24 dogs by ligating the left anterior descending artery. TMLR was done through a left thoracotomy in 12 dogs. The 12 control dogs had ligation only. Global and regional LV function were measured before ligation, then at 6 hours or 3 months after ligation. We calculated the volumetric ratio of damaged myocardium to myocardium at risk (Vd/Vr). RESULTS: At 6 hours, global compensation despite regional dyskinesia was universal; Vd/Vr was the same in control and TMLR dogs. At 3 months, global function during stress was significantly higher in TMLR dogs than in control dogs (P < .05); regional contractions were synergic only in TMLR dogs; mean Vd/Vr was significantly lower in TMLR dogs. CONCLUSION: TMLR limits infarct expansion and improves long-term global and regional function after acute ischemia.

Animals↗
PubMed1997

Development of an implantable ventricular assist system.

BACKGROUND: This study describes the present state of progress in the development of the Jarvik 2000 ventricular assist system. METHODS: Designed for implantation in the human thorax, the system consists of a small (25 cm3, 90 g) intraventricular axial-flow blood pump that transmits power and data via internal electronics and a transcutaneous energy transfer system. The pump is powered by portable internal and external polymer lithium ion batteries. The only moving part, the pump rotor, contains a permanent magnet of a brushless direct-current motor that mounts an axial-flow impeller and partial magnetic thrust support, with blood-immersed radial and thrust bearings. The motor uses a redundant coil and electric lead design, which permits continued operation in case of wire breakage. RESULTS: Seven calves have been supported for an average of 107 days (range, 40 to 162 days) with prototypes of the Jarvik 2000 ventricular assist system. No physiologic complications have occurred. When its user is at rest, the pump produces flows of 5 to 6 L/min with a decreased arterial pulse contour. Renal and hepatic functions have remained normal throughout the duration of all studies. Mean plasma free hemoglobin levels ranged from 4.3 to 11.4 mg/dL (mean, 6.3 mg/dL) for each study. Pathologic analyses of the heart and kidneys revealed no damage related to the device. CONCLUSIONS: These studies indicate that the Jarvik 2000 ventricular assist system is feasible in animals and holds promise for long-term support of patients.

Animals↗
PubMed1997

Transmyocardial laser revascularization: results of a multicenter trial with transmyocardial laser revascularization used as sole therapy for end-stage coronary artery disease.

BACKGROUND: Transmyocardial laser revascularization was used as the sole therapy for patients with ischemic heart disease not amenable to percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. This technique uses a carbon dioxide laser to create transmyocardial channels for direct perfusion of the ischemic heart. METHODS: Since 1992, 200 patients, at eight hospitals in the United States, have undergone transmyocardial laser revascularization. The patients have a combined 1560 months of follow-up for an average of 10 +/- 3 months per patient. Their age was 63 +/- 10 years and their ejection fraction was 47% +/- 12%. Eighty-two percent had at least one previous bypass graft operation and 38% had a prior angioplasty. Preoperatively, the patients underwent nuclear single photon emission computed tomography perfusion scans to identify the extent and severity of their ischemia. These scans were repeated at 3, 6, and 12 months. Angina class, admissions for angina, and medications were recorded. RESULTS: The perioperative mortality was 9%. Angina class decreased significantly from before treatment to 3, 6, and 12 months (p < 0.001). Likewise, there was a significant decrease in the number of perfusion defects in the treated left ventricular free wall. Concomitantly, there was a significant decrease in the number of admissions for angina in the year after the procedure when compared with the year before treatment (2.5 vs 0.5 admissions per patient-year). CONCLUSION: These combined results indicate that transmyocardial laser revascularization provides angina relief, decreases hospital admissions, and improves perfusion in patients with severe coronary artery disease.

Adult↗
PubMed1996

Sudden cardiac death in cardiac transplant recipients.

BACKGROUND: Sudden cardiac death (SCD) remains a significant cause of mortality in the general population. Its role in cardiac transplant patients-including its incidence, mechanism, potential risk factors, or influence on survival in this patient population-has not been well described. METHODS AND RESULTS: We undertook a retrospective analysis of the clinical and autopsy records of 257 patient deaths. SCD was analyzed in relation to severity and frequency of rejection episodes, clinical history of arrhythmias, coronary artery disease (CAD), hypertension, diabetes, left ventricular dysfunction, and clinical history of premorbid symptoms. A total of 25 patients were identified as having died of SCD, an incidence of 9.7%: 20% died < or = 12 months after transplantation, 80% died after > 12 months, and 20% died after > or = 60 months. Patient survival ranged from 2.5 to 138 months (mean, 45.7 months). The mean number of rejection episodes per patient was 2.6, most occurring within 12 months after transplantation. Echocardiography or multigated acquisition scan revealed an ejection fraction (EF) > or = 50% in 68% of patients; however, the presence of arrhythmias, primarily atrial, was evident in 68% of patients and was equally distributed between patients with EFs > or = 50% and EFs < 50%. CAD was present in 53% of patients (10 of 19) whose angiograms were available, and the appearance of CAD after transplantation was between 29 and 85 months (mean, 51.4 months). Of the 9 patients with normal cardiac catheterization studies, 6 with available autopsy reports had documented CAD. Autopsy data in 13 of 25 patients revealed CAD in 92% and rejection in 15% (International Society for Heart and Lung Transplantation grade > 3A). Of the deaths, 64% occurred within 3 months of the last endomyocardial biopsy, 96% had normal biopsies, and the only rejection was without hemodynamic compromise. CONCLUSIONS: SCD occurs relatively frequently in the cardiac transplant population, and CAD is present in most of the patients. Because the frequency of arrhythmias is relatively high in this group, more aggressive antiarrhythmic therapy may be beneficial for patients with allograft CAD in the prevention of SCD.

Adult↗
PubMed1996

The paradox of cytokine monitoring-predictor of immunologic activity as well as immunologic silence following cardiac transplantation.

The utility of cytokine monitoring to predict the onset of significant rejection was evaluated in 34 patients following heart transplantation. Serial blood levels of 5 cytokines involved in inflammation and immune activation(IL-1, IL-2, IL-6, IL-8, and TNF) were correlated with clinical outcome and endomyocardial biopsy scores. The majority of patients (68%) experienced a significant rejection during the study period. IL-6 and IL-8 levels were effective markers of significant rejection 2-4 days before diagnosis with EMBX. IL-6 and IL-8 levels of 15 and 1000 pg/ml predicted the onset of rejection with sensitivities of 75% and 66% and specificities of 86% and 76%, respectively. In contrast, IL-6 and IL-8 levels less than 15 and 400 pg/ml predicted a rejection-free course with sensitivities of 91% and 91% and specificities of 81% and 68%, respectively. The remaining cytokines differentiated patients experiencing a clinically unremarkable course from those experiencing mild-to-moderate rejection but did not discriminate rejection severity. IL-6 levels identified steroid and OKT3 resistance within 48 hr of antirejection therapy. IL-6 levels elevated to 197 +/- 20 pg/ml among steroid-resistant patients and normalized to 20 +/- 5 pg/ml among responders. IL-8 levels delineated OKT3 resistance. IL-8 levels rose to 3496 +/- 500 pg/ml among nonresponders, whereas levels fell to 152 +/- 50 pg/ml among responders. This study demonstrates that IL-6 and IL-8 are useful markers of rejection and therapeutic efficacy following heart transplation.

Adult↗
PubMed1996

Evolution of battery-powdered, vented left ventricular assist devices.

Battery-powered, vented left ventricular assist devices are designed to provide long-term circulatory support and an enhanced qualify of life. Their ongoing evolution into an effective clinical tool to treat patients with severe heart failure has resulted from the efforts of many, the open communication among researchers involved in the program, and the strong support from the National Institutes of Health.

Equipment Design↗
PubMed1996

Surgical treatment of multiple coronary aneurysms in an elderly man.

We report an unusual case involving a 70-year-old man with multiple coronary aneurysms, including a 5-cm aneurysm of the right coronary artery. The precise size was determined with magnetic resonance imaging, although the aneurysms were diagnosed initially on angiography. Multiple coronary aneurysms are rare in adults, The cause may have been atherosclerosis, syphilis, or collagen vascular disease, all of which cause weakening of the media. The patient underwent successful operation, including coronary artery bypass grafting.

Aged↗
PubMed1996

Complete resection of a right atrial intracavitary metastatic melanoma.

We report a case of complete resection of a very large intracavitary metastatic melanoma of the right atrium. We describe a technique for resecting without damaging the atrium and for preventing the narrowing of the right atrium. In such cases, complete resection may be indicated despite widespread disease.

Female↗
PubMed1996

Low thromboembolic risk without anticoagulation using advanced-design left ventricular assist devices.

BACKGROUND: A major limitation of cardiac assist devices has been the high incidence of thromboembolic events and their requirement for systemic anticoagulation. The Thermo Cardiosystems HeartMate 1000 IP left ventricular assist device (LVAD) employs a design that may reduce thromboembolic risk and obviate the need for systemic anticoagulation. METHODS: Two hundred twenty-three patients with nonreversible heart failure were supported with the HeartMate LVAD as a bridge to heart transplantation. All patients were monitored prospectively for thromboembolic events. Anticoagulation regimens and occurrence of subclinical thromboembolic events, including those seen by transcranial Doppler examinations in selected patients, were also recorded. RESULTS: Total time of LVAD support use was 531.2 patient-months. Twenty-three patients (10%) received warfarin postoperatively for 42.4 patient-months (8.2% of total support time). Six patients (2.7%) had thromboembolic events, representing 0.011 events per patient-month of device use. CONCLUSIONS: The thromboembolic complication rate associated with this LVAD is acceptably low despite the minimal anticoagulation employed in this series, allowing consideration of long-term device use for the treatment of heart failure.

Adolescent↗
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

Transmyocardial laser revascularization: clinical experience with twelve-month follow-up.

We are investigating a new technique for myocardial revascularization in which an 800 W carbon dioxide laser is used to drill 1 mm diameter channels into a beating heart after left thoracotomy. Clotting occludes the channels on the subepicardium, and in the long-term setting, blood from the left ventricular cavity flows through these channels to perfuse the ischemic subendocardium. To test the efficacy of this technique in a preliminary clinical trial, we used it as sole therapy for 21 consecutive patients. All patients had hibernating myocardium, reduced coronary flow reserve, or both, had distal diffuse coronary artery disease, and had angina refractory to normal therapy. Eight patients were excluded from follow-up because of death (n=5), rerevascularization (n=2), or diaphragmatic paralysis resulting in postoperative respiratory incapacity (n=1). In the remaining 13 patients available for follow-up, the mean angina class (Canadian Cardiovascular Society) was 3.7 +/- 0.4 before operation and 1.8 +/- 0.6 12 months after operation (p < 0.01). Mean resting left ventricular ejection fraction was 48% +/- 10% before operation and 50% +/- 8% at 12-month follow-up. At 12 months, resting mean subendocardial/subepicardial perfusion ratio had increased by 20% +/- 9% in septal regions treated by laser but decreased by 2% +/- 5% in untreated regions (n=11, p <.001). These results suggest that revascularization by this laser technique positively affects subregional myocardial perfusion and may result in clinical benefits for patients with reversible myocardial ischemia. Studies to date have not demonstrated significant changes in global and regional ventricular contractile function.

Aged↗
PubMed1996

Transmyocardial laser revascularization.

Transmyocardial laser revascularization is currently being tested in randomized clinical trials as an alternative technique for relieving angina in patients with ischemic myocardium. In this technique, an 800-W carbon dioxide laser is used to create channels in the myocardium that open directly into the left ventricular cavity. Although the exact mechanism by which tissue revascularization occurs is not yet known, initial results from an earlier clinical trial were promising: a significant number of patients were relieved of angina symptoms, exercise tolerance was improved, complications were minimal, and the safety of the technique seems established. A controlled, randomized trial is now underway, and initial results appear promising.

Female↗
PubMed1996

Cardiac devices.

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Animals↗
PubMed1996

Increased expression of ICAM-1 in a case of accelerated coronary artery disease after heart transplantation.

The development of accelerated coronary artery disease after heart transplantation remains the limiting factor for long-term survival. The most widely accepted hypothesis to explain the development of this vascular lesion is chronic immunologic injury to the vessel wall, which leads to recruitment of monocytes and lymphocytes into the intima and to subsequent neointimal proliferation. In this report, we describe a case of accelerated coronary artery disease that led to allograft failure and repeat heart transplantation 3 years after the initial procedure. Pathologic examination showed striking intimal proliferation with abundant expression of intercellular adhesion molecule-1 in both endothelial cells and cells deep within the intima. Cardiac myocytes also stained for intercellular adhesion molecule-1, with the most intense staining noted in intercalated disks, whereas staining for E-selectin was restricted to endothelial cells. These findings are similar to those we observed in a canine model of transplant arteriopathy and highlight the need for further studies to examine whether inhibitors of endothelial cell adhesion molecules or their leukocyte ligands can successfully ameliorate transplant vasculopathy.

Coronary Disease↗
PubMed1995

Myocardial revascularization with laser. Preliminary findings.

BACKGROUND: We assessed the transmyocardial laser revascularization (TMLR) as sole therapy in patients with symptomatic coronary artery disease refractory to interventional or medical treatment. METHODS AND RESULTS: Thirty-one patients were evaluated with positron emission tomography (PET), dobutamine echocardiography, 201Tl single-photon emission computed tomography (201Tl-SPECT), and multigated acquisition radionuclide ventriculography (MUGA). TMLR was performed in 21 patients who had demonstrable ischemia in viable myocardium. The mean Canadian Cardiovascular Society (CCS) angina class was 3.70 +/- 0.7 (4 patients with unstable angina). Untreated septal segments were used as controls. At 3 months, (n = 15 patients), the mean CCS angina class was to 2.43 +/- 0.9 (P < .05). On dobutamine echocardiography, the mean resting wall motion score index was improved by 16% in lased segments (P < .03 vs control), and mean LVEF at peak stress increased by 19% (P = NS vs baseline). On 201Tl-SPECT, perfusion of lased and nonlased segments did not change. On PET, the mean ratio of subendocardial to subepicardial perfusion (SEn/SEp) increased 14% over baseline (P < .001 vs control). At 6 months (n = 15 patients), the mean CCS angina class was 1.7 +/- 0.8 (P < .05). The mean resting wall motion score index was up by 13% in lased segments (P < .05 vs control). Resting LVEF was unchanged. Stress LVEF increased 21% (P = NS vs baseline). Myocardial perfusion remained unchanged by 201Tl-SPECT. On PET, 36% of the lased segments were better, and 25% were worse compared with baseline. The resting SEn/SEp by PET was up 21% (P < .001 vs control). All deaths (two perioperative and three late) occurred in patients with preoperative congestive heart failure. Two patients required repeat revascularization of new coronary lesions. CONCLUSIONS: These results suggest that TMLR improves anginal status, relative endocardial perfusion, and cardiac function in patients who do not have preoperative congestive heart failure.

Aged↗
PubMed1995

Overseas transport of a patient with an extracorporeal left ventricular assist device.

An 18-year-old boy with end-stage cardiomyopathy who was undergoing support with an extracorporeal pneumatic left ventricular assist device was transported from Japan to the United States. During the 17-hour flight, the patient's condition was stable, and the pneumatic assist device worked well under low atmospheric pressure in the cabin. Subsequently, he had a successful heart transplantation after 119 days of left ventricular assist device support.

Adolescent↗