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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 91 records · Page 5Linked to original sources
PubMed2001

Transmyocardial laser revascularization in ischemic cardiomyopathy.

BACKGROUND: In ischemic cardiomyopathy (left ventricular ejection fraction [LVEF] < or = 30%), myocardial revascularization by coronary artery surgery has better results than heart transplantation, provided there is sufficient ischemic but viable myocardium. The mode of action of transmyocardial laser revascularization (TMR) is still being debated, but if the procedure induces improved myocardial perfusion it could be a "bridge," or alternative, to heart transplantation. METHODS: We retrospectively analyzed 194 patients, who underwent TMR between July 1997 and October 1999. Patients with TMR as an adjunct to coronary artery surgery (n = 30) and those who did not provide written consent to the procedure (n = 8) were excluded; 126 patients had normal or moderately reduced left ventricular function, and 30 patients with ischemic cardiomyopathy (LVEF < or = 30%) were included. RESULTS: After 12 months, the Canadian Cardiovascular Society (CCS) score dropped significantly from 3.6 (3 to 4) to 2.4 (1 to 4) and maximum work load increased significantly from 58 W (25 to 100 W) to 73 W (25 to 120 W). However, thallium score and LVEF did not improve significantly (27% [15% to 30%] to 32% [15% to 45%]). Prior to the TMR procedure, all 30 patients had a "low risk" or "medium risk" of death according to the Aaronson classification. The 30-day, 1-year, and 2-year survival rates were 83%, 50%, and 47%, respectively. CONCLUSIONS: We conclude that TMR in ischemic cardiomyopathy (LVEF < or = 30%) has a perioperative risk comparable to that for heart transplantation, but there is no improvement of myocardial performance or life expectancy. Therefore, TMR cannot be regarded as a "bridge," or alternative, to transplantation. However, in individual cases with contraindications for transplantation the anti-anginal effect may justify use of the procedure.

Cardiomyopathies↗
PubMed2001

Revascularization of the occluded right coronary artery during left ventricular assist device implantation.

A 62-year-old man with end-stage ischemic cardiomyopathy and left ventricular function of 20% was evaluated for heart transplantation. Cardiac catheterization revealed proximal occlusion of the dominant right coronary artery (RCA) with collateral blood flow and significant stenosis in the distal part, but no significant re-occlusions of the stented left coronary artery and no significant stenosis of the left circumflex artery. When the patient became catecholamine dependent, Novacor left ventricular assist device (LVAD) implantation, as a bridge to transplantation, was considered and the patient operated upon. To avoid ischemic right heart failure after LVAD implantation, a concomitant re-vascularization of the distal RCA was performed. The post-operative course was uneventful. Five weeks later, a control angiogram showed the patent bypass graft. The distal stenosis of the RCA was treated successfully with dilation and stent implantation. The patient is presently in stable condition on LVAD and awaits transplantation as an outpatient.

Angioplasty, Balloon, Coronary↗
PubMed2001

Postoperative course of S-100B protein and neuron-specific enolase in patients after implantation of continuous and pulsatile flow LVADs.

BACKGROUND: In the early post-operative period after implantation of a continuous flow left ventricular assist device (LVAD) a non-pulsatile flow occurs. We compared the post-operative time-courses of protein S-100B (S100B) and neuron-specific enolase (NSE) as biochemical markers of brain injury in patients after implantation of a continuous flow LVAD and patients receiving a pulsatile flow LVAD. METHODS: Since 1998 the continuous flow DeBakey VAD has been implanted in 8 patients at our institution. For comparison purposes, a group of 7 consecutive patients in whom a pulsatile Novacor N100 LVAD was implanted were investigated. In both groups cardiopulmonary bypass (CPB) with cardiotomy suction was used. S100B and NSE were measured in serum pre-operatively, 4 hours after CPB, and on days 1, 3, 7, and 14 after implantation of the LVAD. A neurologic examination was performed pre-operatively and post-operatively on days 3 and 14. RESULTS: No differences were found between groups in pre-operative characteristics. The analysis of variance with repeated measurements for S-100B and NSE showed significant time effects (p = 0.004, p = 0.009, respectively) but no group effects (p = 0.06, p = 0.26, respectively) and no interaction between groups and time (p = 0.12, p = 0.48, respectively). The pre-operative serum level of S100B was significantly higher (p = 0.03) in the DeBakey VAD group. The pre-operative serum level of NSE was similar in the 2 groups (p = 0.7). In both groups there was a significant increase of S100B and NSE immediately after surgery (S100B: p = 0.006, p = 0.019; NSE: p = 0.01, p = 0.001). The values returned to pre-operative levels in the DeBakey VAD group on day 1 after implantation and in the Novacor group for S100B on day 3 and NSE on day 1. Post-operatively the mean values of S100B and NSE in the DeBakey VAD group compared with the Novacor group were significantly elevated only on day 3 (p = 0.005, p = 0.023).No neurologic complications were noted in patients with a continuous flow LVAD, whereas in the pulsatile LVAD group 2 patients presented neurologic abnormalities during the study period. CONCLUSIONS: The similar course of biochemical markers of brain damage in both groups may indicate that the non-pulsatile flow in the early post-operative period does not lead to increased brain injury or permeability of the brain blood barrier.Elevated levels of S100B and NSE in the post-operative period can be used as diagnostic markers of brain injury in patients after implantation of both types of LVAD.

Adult↗
PubMed2001

Hemorheology and renal function during cardiopulmonary bypass in infants.

BACKGROUND: Acute renal failure is an occasional complication after cardiopulmonary bypass in infants. Whereas it is well known that postoperative hemodynamics inflict acute renal failure, the influence of extracorporeal circulation on the kidney is less clear. Moreover, changes in blood viscosity occur during and after surgery, which may influence renal dysfunction. For this reason, we investigated the impact of blood viscosity on renal function during cardiopulmonary bypass. METHODS: In 34 patients weighting less than 10 kg, we performed repeated analysis of urine, blood, and plasma viscosity. RESULTS: Polyuria and proteinuria that appeared during cardiopulmonary bypass indicated an elevated transglomerular filtration gradient, which recovered within 24 hours. The appearance of N-acetyl-beta-D-glucosaminidase in the urine, and elevated excretion of sodium, were additionally indicative of mild tubular damage. Elevation of blood viscosity during hypothermic perfusion showed a statistical correlation with proteinuria and N-acetyl-beta-D-glucosaminidaseuria. With hypothermia, the relation of blood viscosity to plasma viscosity became stronger, while the relation to the hematocrit decreased compared to normothermia. CONCLUSIONS: During cardiopulmonary bypass perfusion, the kidney can be stressed by proteinuria and mild tubular damage. Our data provide evidence that the kidneys can be protected by improved blood viscosity during cardioplegia, but this needs confirmation in a prospective interventional study.

Acetylglucosaminidase↗
PubMed2001

Continuous measurements of renal perfusion in pigs by means of intravascular Doppler.

BACKGROUND: Changes in renal blood flow are considered to play a significant role in the induction and maintenance of kidney failure, but are difficult to monitor with currently available techniques. The objective was to validate renal flow measurements with Doppler guidewires and to apply this technique to assess dose and time dependency of the renal vascular effects of norepinephrine (NE). METHODS: In 10 anesthetized pigs, flow velocity in renal arteries (FVart) and veins (FVvein) and volumetric renal blood flow (VBF) were measured before and after intravenous bolus application of incremental doses of NE (2 to 200 microg). RESULTS: FVart curves exactly reflected the changes in VBF. Beat-to-beat analysis revealed a strong linear correlation over a mean VBF range of less than 0.05 to 0.35 L/min (median correlation coefficient with FVart, r = 0.998), and significant but less close relationships were also found between VBF and FVvein. Ten seconds after the administration of 200 microg NE, FVart dropped from 71 to 6 cm/sec and was 90% reversible after 48 seconds. Similarly, the renal vascular resistance temporarily rose from 988 to 13711 mm Hg. min/L. In contrast, NE-induced increases in systemic vascular resistance were on average a maximum of 1.5-fold but persisted for more than 60 seconds. CONCLUSIONS: Doppler flow measurements in the renal artery provide an excellent surrogate of volumetric blood flow, which may be useful for continuous monitoring of renal hemodynamics. The renal vasculature is more sensitive when compared with the systemic vasculature, but also appears to evoke more efficient counter-regulatory mechanisms in response to NE.

Animals↗
PubMed2001

Prevention of venous graft sclerosis with clopidogrel and aspirin combined with a mesh tubing in a dog model of arteriovenous bypass grafting.

OBJECTIVE: to investigate the effect of clopidogrel combined with aspirin or aspirin alone on fibromyointimal hyperplasia (FIMH) in a bypass model with native vein grafts (NVG) and biocompound grafts (BCG). DESIGN: twelve Beagle dogs were randomised into two equal groups. In each animal NVG and a BCG were interposed in the common carotid arteries. Postoperatively, Group 1 received clopidogrel (200 mg/d) and aspirin (100 mg/d) and Group 2 received aspirin (100 mg/d) alone. METHODS: the BCG was constructed by sheathing the ipsilateral jugular vein with highly flexible metal mesh tubing. After 30 days the grafts were harvested and pressure fixed. FIMH was determined by morphometry. RESULTS: the average wall thickness of the BCG was significantly lower than that of the NVG in both groups (0.26 (SD)0.02 mm vs 0.47 (SD)0.15 mm, p = 0.04 and 0.28 (SD)0.05 mm vs 0.70 (SD)0.29 mm, p = 0.01, respectively). For BCG treated with aspirin, the wall cross section area was lower (5.0 (SD)0.6 mm(2)vs 9.1 (SD)3.3 mm(2), p = 0.02) and the lumen larger (25.2 (SD)5.9 mm(2)vs 9.7 (SD)3.4 mm(2), p < 0.01) than for the NVG. There was also a difference in the lumen cross section area of the NVG, which was larger after combined therapy with clopidogrel and aspirin (17.9 (SD)7.8 mm(2)vs 9.7 (SD)3.4 mm(2), p = 0.04). CONCLUSIONS: in this dog model the sheathing of vein grafts effectively prevents FIMH following bypass surgery. Clopidogrel is effective in NVG.

Animals↗
PubMed2001

Ventricular assist device in severe heart failure: effects on cytokines, complement and body weight.

AIMS: Inflammatory and immune activation and body wasting are important features of end-stage chronic heart failure. It is not known whether restoration of cardiac output by assist device implantation can improve these abnormalities. METHODS: We studied 48 patients (39 males; age 45+/-2 years) with NYHA class IV heart failure. All patients underwent ventricular assist device implantation for end-stage heart failure as a bridge to cardiac transplantation. Plasma levels of tumour necrosis factor alpha, and its receptors, interleukin-6, elastase, activated complement, and soluble CD14 receptors were measured at the time of operation and in survivors at 1 week (n=46), 40 days (n=35) and 90 days (n=26). Follow-up was for a minimum of 1 year. RESULTS: One-year survival was 35% (95% CI: 22-49%). Body mass index was the only predictor of survival (body mass index >25 (n=16); survival 63 (39-86) %; body mass index <25 (n=32); survival 22 (7.5-36) %: P=0.003). Tumour necrosis factor alpha fell from 9.66+/-1.33 pg x ml(-1) to 4.2+/-1.0 at 1 week (P=0.008), but returned to pre-operative levels at 90 days. Interleukin-6, activated complement and elastase fell progressively to 40 days, but were rising at 90 days. There was no change in tumour necrosis factor receptor. There was a gradual rise in CD14 (3.99+/-0.15 microg x ml(-1) at baseline, 5.02+/-0.39 at 90 days, P=0.006). After surgery, body weight fell from 80+/-2 to 73+/-2 kg by 1 month (P<0.001) and to 72+/-2 kg at 90 days. CONCLUSIONS: Ventricular assist device implantation results in a short-term fall in tumour necrosis factor alpha and interleukin-6, but no change in CD14 or tumour necrosis factor receptor, suggesting that the pathophysiological process resulting in inflammation was not altered by left ventricular assist device implantation. Low body mass index is related to poor outcome after assist device implantation, and no weight gain.

Body Weight↗
PubMed2001

Risk scores currently used in German heart surgery.

BACKGROUND: Risk scores (RS) in heart surgery assess mortality and morbidity and mirror the degree of severity of disease of the patients when presented for surgery. We examined the use and dissemination of RS in Germany. MATERIAL AND METHODS: Our survey included 79 German heart surgery institutes in Fall 1999 and Winter 2000. RESULTS: Four institutes did not respond. Out of 75 (ad 100 %) responders 56 (75 %) institutes did not use RS, 17 (22 %) institutes used one RS method and 2 (3 %) institutes used two RS methods. The most frequently applied RS methods were the Cleveland Clinic Score and the Euro Score (n = 7, each) followed by institution-specific, internally developed RS methods (n = 5), Parsonnet's RS (n = 1) and the RS from the STS database (n = 1). Fourteen institutes used RS for internal quality control. Of these, 2 institutes publish their RS data for external quality control. The patient-related individual procedure risk was used in 6 institutes. CONCLUSIONS: A quarter of the German heart surgery institutes use one or more RS methods. The most commonly used were the Cleveland Clinic Score and the Euro Score, followed by internally developed RS methods. RS methods were most frequently used for internal quality control. The degree of the severity of disease of the patients who presented for surgery could only be compared between a small number of institutes using the same RS.

Cause of Death↗