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Biomedical subjects

W Harringer

Publications and source records attributed to W Harringer.

88 records · Page 5Linked to original sources
PubMed1992

Acute effects of massive transfusion of a bovine hemoglobin blood substitute in a canine model of hemorrhagic shock.

The capability of stroma-free hemoglobin solutions to act as a plasma expander with oxygen and carbon dioxide transport properties has encouraged the idea of their possible use in settings of massive blood loss. Using a canine hemorrhagic shock model (systolic arterial pressure < or = 50 torr for 60 min), we evaluated the efficacy of an ultra-pure stroma-free bovine hemoglobin solution (PBHg) as a resuscitation fluid in hypovolemic and acidotic animals, using homologous blood (PRBC) and 10% human serum albumin (HSA) as control solutions. Following volume replacement, dogs were studied for 2 h under anesthesia and for 4 h subsequently while awake. Resuscitation with PBHg (30 +/- 3 ml/kg) was able to restore stable hemodynamics and correct acidosis to an extent comparable to that in animals treated with PRBC. Additionally, oxygen transport was maintained at a higher level than that in dogs treated with HSA. Administration of PBHg in this shock model revealed no significant cardiopulmonary toxicity or adverse effects. These short-term results suggest that PBHg may be useful for effective resuscitation after major blood loss.

Animals↗
PubMed1992

Early results of cryopreserved pulmonary allografts as aortic valve substitute.

Excellent clinical results with pulmonary autografts and experimental evidence that the pulmonary valve can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 to March 1991, 45 consecutive patients (59.9 +/- 12.0 years, 25 men and 20 women) received a cryopreserved pulmonary allograft in the aortic position from our hospital based valve bank. All allografts were inserted freehand in the subcoronary position. There were 3 in-hospital deaths (7%) and 1 patient had severe valvular incompetence immediately postoperatively requiring reoperation after 4 weeks. Forty-one patients were followed at 3-6 month interval for 14.7 +/- 7.8 months (3-28 months) and valve performance was assessed routinely by means of color flow Doppler echocardiography: 34 patients (83%) had no or trivial aortic valve regurgitation. Valvular incompetence class II was present in 2 patients (5%) whereas 3 (7%) demonstrated class II-III. Severe aortic regurgitation (class III-IV) could be detected in 2 patients (5%). Both had to undergo reoperation 4 months and 15 months, respectively, postoperatively. Macroscopic and histological evaluation of the explanted valves demonstrated absence of significant degeneration. We assume that a mismatch in size between allograft and aortic annulus could have lead to dilatation of the allograft valve ring and consequently to valvular incompetence. Pulmonary cryopreserved allografts achieve acceptable short-term results which can be improved if initial technical problems can be avoided.

Adult↗
PubMed1992

Aortic valve replacement with the pulmonary autograft--experience of 23 cases.

Since 1988 an intensive homograft-program has existed at the Linz General Hospital. We have installed an own hospital-based homograft bank, where the allografts, after a 24-hour sterilization-period in an antibiotic solution and a controlled freezing procedure, are stored in liquid nitrogen at -196 degrees C. In 1991 for the first time aortic valve replacement was performed by pulmonary autograft in 23, mainly younger, patients. Essentially our technique conforms with that of D. N. Ross, in the course of which 18 autografts were implanted in subcoronary position and 5 aortic-root replacements were performed. 3 patients died perioperatively, 2 times a severe post-operative bleeding with following hypoxemic brain damage being the cause; 3 more patients had to be rethoracotomized because of postoperative bleedings. All these were attributed to a technical difficulty, which was overcome. In one patient a left-ventricular assist device had to be installed due to a left-ventricular failure, a successful heart transplantation followed on the 8th postoperative day. A follow-up was conducted in all patients every 3 months. In 2 patients a substantial valve incompetence of grade II-III and grade III was detected, all other patients showed no regurgitation of clinical relevance. Despite our initial difficulties it is our opinion that the many advantages-no anticoagulation necessary, no valve sound, less incidence of bacterial endocarditis, and longer durability-do justify this operative procedure.

Adolescent↗
PubMed1992

Ultra-pure polymerized bovine hemoglobin blood substitute: effects on the coronary circulation.

The effects of stroma-free hemoglobin (SFHgb) on the coronary circulation remain unclear. An intact canine model utilizing intracoronary adenosine to abolish the confounding effect of autoregulation was used to study maximal myocardial oxygen delivery during progressive hemodilution with polymerized bovine SFHgb. The circumflex coronary artery was instrumented with a flow probe, hydraulic constrictor, and proximal and distal catheters for adenosine infusion and distal pressure measurement, respectively. This preparation was used to generate diastolic coronary pressure-flow relations during maximal vasodilation. Maximal coronary conductance and maximal myocardial oxygen delivery were determined in two groups of 7 dogs each following hemodilution, first with 6% hetastarch (Control), followed by further hemodilution with ultra-pure, polymerized, bovine SFHgb. After hemodilution with SFHgb, maximal coronary flow increased slightly without evidence of coronary vasoconstriction. Since hemodilution with this material increases oxygen carrying capacity, maximal oxygen delivery is greater than Control, despite the very low canine hematocrit. These findings suggest: 1) SFHgb can provide adequate oxygen delivery to the myocardium despite extreme degrees of hemodilution, and 2) in this intact model, there is no evidence of adverse coronary vasomotion.

Animals↗
PubMed1992

[Development of arterial revascularization of the myocardium at the Linz general hospital. Personal experiences with 1000 patients].

Arterial revascularization of the myocardium, particularly the use of the internal mammary artery (IMA) as a bypass graft in coronary artery surgery has become an established procedure over the past decade. From March 1986 to June 1991, of 2070 patients who underwent coronary heart surgery at our department, revascularization of the myocardium was performed with an IMA graft in 1000 cases, whereby the percentage increased from 10.4% in 1986 to 75.0% in 1991 (p less than 0.01). The range of indications gradually widened throughout the period, age no longer being a contradiction today. One reason for this development is the substantial improvement in IMA preparation technique. No increase was found in rethoracotomy rate or in the rate of perioperative infarctions. The mean age of patients receiving an IMA graft increased from 55.2 years (1986) to 64.7 years (1991) and therefore reflects the change in ranges of indication. 54 IMA jump grafts were anastomosed, in 30 cases bilateral IMAs were used and the IMA was implanted as a free graft twice. In the future these successful results with the implementation of IMA grafts will lead to a further displacement of the saphenous vein as main bypass material.

Austria↗
PubMed1991

Risk factors for pancreatic cellular injury after cardiopulmonary bypass.

BACKGROUND: Pancreatitis is a known complication of cardiac surgery with cardiopulmonary bypass. Although ischemia is believed to be a factor, the cause of pancreatitis after cardiopulmonary bypass remains unknown. METHODS: We prospectively studied 300 consecutive patients undergoing cardiac surgery with cardiopulmonary bypass. Serum amylase, pancreatic isoamylase, and serum lipase were measured on postoperative days 1,2,3,7, and 10. Pancreatic cellular injury was defined as the presence of hyperamylasemia (greater than 123 U per liter) with an increase in either the serum level of lipase (greater than 24 U per liter) or the peak level of pancreatic isoamylase. Trypsinogen-activation peptides, which indicate intrapancreatic enzyme activation, were measured in the urine of the last 101 patients studied. RESULTS: Evidence of pancreatic cellular injury was detected in 80 patients (27 percent), of whom 23 had associated abdominal signs or symptoms and 3 had severe pancreatitis (2 with pancreatic abscess and 1 with necrotizing hemorrhagic pancreatitis). Two of 19 postoperative deaths were secondary to pancreatitis. In multivariate analyses, the development of pancreatic cellular injury was significantly associated with preoperative renal insufficiency, valve surgery, postoperative hypotension, and perioperative administration of calcium chloride. The administration of more than 800 mg of calcium chloride per square meter of body-surface area was an independent predictor of pancreatic cellular injury, and the increase in risk was dose-related. No differences were found in the level of trypsinogen-activation peptides between patients who had pancreatic cellular injury and those who did not. CONCLUSIONS: Pancreatic cellular injury, as indicated by hyperamylasemia of pancreatic origin, is common after cardiac surgery. The administration of large doses of calcium chloride is an independent predictor of pancreatic cellular injury and may be a cause of it.

Aged↗
PubMed1991

Importance of coronary spasm for recurrences following percutaneous transluminal coronary angioplasty (PTCA).

To examine the importance of coronary spasm for recurrences following coronary angioplasty, the incidence of spontaneous and ergonivine-provoked coronary spasm was studied, during initial and 6 months follow-up coronary angiography, in a consecutive series of 102 patients with single-vessel disease and successful coronary angioplasty. Repeat angiography demonstrated restenosis in 35 patients (34%). In patients with no demonstrable coronary spasm before and 6 months after PTCA, restenosis occurred in 23% (14/61). The recurrence rate for patients with spasms only before PTCA was similar (29%; 6/21). An increase of recurrences was observed in patients with coronary spasm before and 6 months after PTCA (69%; 9/13) and was extremely high in patients with detectable spasms only after PTCA (86%; 6/7). The importance of the severity of underlying coronary stenosis as regards the ergonovine testing result, demonstrated no relationship between the degree of underlying stenosis and the incidence of provokable coronary spasms. Thus, coronary spasms provokable only before PTCA do not increase the risk for recurrences. Spasms persisting after PTCA or seen only after the procedure are associated with a significantly higher rate of restenoses.

Angina Pectoris, Variant↗
PubMed1991

[Risk of complications of early coronary angioplasty after thrombolysis in acute myocardial infarct].

The present study reports on the complication rates in 143 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) within 4 weeks after thrombolysis for acute myocardial infarction. The results were analyzed with respect to the time between thrombolysis and PTCA. PTCA was successful in 130 patients (91%). The mortality was 0.7% (1 patient). Severe complications occurred in 9 further patients (7%): 8 reinfarctions (6%) and one patient with a large haematoma of the groin requiring surgical treatment (0.7%). The total complication rate, including milder was 24%. A comparison of patients treated with PTCA within the first 4 days after thrombolysis (group I, n = 67) with patients dilated between 5 and 28 days after thrombolysis (group II, n = 76) resulted in a complication rate of 33% in group I and 16% in group II (p less than 0.01). This important difference was due to the higher frequency of ischaemic complications in group I than in group II (28% versus 12%). Besides reinfarction (7.5% in group I versus 4% in group II), prolonged ischaemic episodes were the most frequent cause of complications. Our results demonstrate a very high risk of complications if PTCA is performed within the first 4 days after thrombolysis for acute myocardial infarction.

Adult↗
PubMed1990

Coronary angioplasty after intravenous streptokinase in acute myocardial infarction: influence of restenosis on clinical outcome and left ventricular function.

The importance of recurrence of stenosis on clinical outcome and left ventricular function was studied in a consecutive series of patients with acute evolving myocardial infarction (maximal duration of pain 4 h) and thrombolysis (1.5 x 10(6) units of streptokinase intravenously over 60 min) with recanalized single-vessel disease and subsequent successful coronary angioplasty. Coronary angioplasty was performed in 76 patients between 24 hours and 8 days (mean interval 3.3 days) after thrombolysis and was successful in 86% (65/76). The in-hospital reinfarction rate was 5.2% (2 acute and 2 in-hospital reinfarctions). Repeat angiography after a mean interval of 5.9 months revealed a 39% (24/62) restenosis rate (21 restenoses, 3 reocclusions). Restenoses were associated with significantly more clinical complaints (21% vs. 62%; p less than 0.001). Left ventricular function analysis showed significant improvement in the mean global ejection fraction (6.6 +/- 6.0%; p less than 0.001) and mean regional wall motion of the infarct zone (6.2 +/- 8.2%; p less than 0.01) only in patients without restenosis. Recovery of left ventricular function was more evident in inferior than in anterior wall infarctions. In contrast, patients with restenosis had no change in left ventricular function. Thus, the present study demonstrates the adverse influence of restenosis on recovery of left ventricular function and clinical outcome.

Angioplasty, Balloon, Coronary↗
PubMed1989

Clinical efficacy of intravenous amiodarone in the short term treatment of recurrent sustained ventricular tachycardia and ventricular fibrillation.

The clinical efficacy of intravenous amiodarone in terminating sustained ventricular tachycardia and in preventing recurrences of ventricular tachycardia and ventricular fibrillation was evaluated in 26 patients. All of them presented with organic heart disease accompanied by depressed left ventricular function. Intravenous amiodarone terminated spontaneous ventricular tachycardia in eight of 19 patients. Fifteen of the 26 patients had had at least one episode of ventricular tachycardia or ventricular fibrillation each day in the period immediately before the intravenous administration of amiodarone. Amiodarone controlled ventricular tachycardia or ventricular fibrillation in nine of these 15 patients; in three further cases it was successful when supplemented by additional administration of a previously ineffective antiarrhythmic drug and ventricular pacing. Two patients died despite these measures. In one, the amiodarone infusion had to be stopped because of an arrhythmogenic effect. Sustained deterioration of haemodynamic function or of pre-existing intraventricular conduction disturbances was never seen. Intravenous amiodarone was effective in terminating sustained ventricular tachycardia and in preventing frequent episodes of ventricular arrhythmia that were refractory to other antiarrhythmic drugs.

Amiodarone↗
PubMed1989

[Hyperlipidemia and coronary heart disease].

The relationships between total serum cholesterol levels greater than 200 mg/dl or LDL-cholesterol levels greater than 155 mg/dl (135 mg/dl) and the incidence of coronary heart disease is well established. In contrast an inverse relationship could be shown between HDL-cholesterol levels and the frequency of cardiac death and non fatal myocardial infarction. It also seems to be possible that elevated triglyceride levels (greater than 200 mg) may represent an additional risk factor. Subsequent studies with a large number of patients and longterm observation proved, that fat-modified diets or drug treatment of hyperlipidemia results in a reduction of morbidity and mortality due to coronary heart disease, whereby the reduction of coronary events correlates directly to the degree of reduction of total cholesterol or LDL-cholesterol, respectively. This knowledge allows the clinician to identify persons at high risk for coronary heart disease and to start effective individual therapy in accordance with the recommendations of the European Atherosclerosis Society.

Cholesterol↗
PubMed1987

[Intravenous thrombolysis in acute myocardial infarct. Clinical and angiography results in 124 patients and the significance of early revascularization].

124 patients with evolving acute myocardial infarction received high-dose intravenous streptokinase (1.5 Mio U within 60 min i.v.). Hospital mortality was 4% and 11% of the patients suffered from a streptokinase-related complication (most frequent bleeding problems). All complications could be treated medically. The angiographic control in 111 patients (90%) after a mean of 11 +/- 8 days after thrombolysis demonstrated a patent antegrade perfused infarct-artery in 85 patients (77%). From the first 55 patients only 16% had a revascularization procedure. An early revascularization in 39 patients (57%) of the last 69 patients reduced the reinfarction rate from 15 to 7%. The hospital mortality was not influenced (3.6 vs 4.3%). High-dose i.v. streptokinase-application is associated with low treatable complication rates and clinically relevant reperfusion rates. An early revascularization (coronary angioplasty, bypass-surgery) reduces the reinfarction rate to about 50% and improves left ventricular function.

Aged↗
PubMedDate not supplied

Determinants of maximal right ventricular function.

After heart transplantation, right ventricular failure can occur because of increased afterload. Previous studies have suggested that the maximal pressure the right ventricle can develop is determined primarily by right ventricular perfusion pressure. However, the interaction of the left ventricle and the pericardium as functional co-determinants of maximal right ventricular function is unknown. This study was undertaken to determine the interaction of the pericardium, left ventricular pressure, and right coronary artery perfusion pressure as potential determinants of maximal right ventricular function. In an acute canine preparation, with progressive pulmonary artery constriction, maximal generated right ventricular pressure was determined over a range of left ventricular systolic pressures. Additional groups of dogs were studied with the right coronary artery cannulated and were maintained at constant perfusion pressure. In all preparations, the maximal pressure the right ventricle could generate was linearly related to left ventricular systolic pressure. Having a closed pericardium markedly enhanced this effect; some effect was present with an open pericardium, although the magnitude of the influence of left ventricular pressure on maximal right ventricular pressure was much less. Maintaining constancy of right coronary artery perfusion pressure, either at high or low values, did not alter these findings nor did it alter the influence of the pericardium. These results suggest that right ventricular perfusion may not be the sole determinant of maximal right ventricular function. Furthermore, with the pericardium open, such as in the posttransplantation state, the left ventricular contribution to maximal right ventricular function may be diminished, increasing vulnerability for right ventricular failure caused by increased afterload.

Animals↗