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R Hetzer

Publications and source records attributed to R Hetzer.

At least 109 records · Page 6Linked to original sources
PubMed2001

Age-dependent myocardial reinduction of apoptosis inhibitors under VAD in heart failure.

Hemodynamic unloading using the ventricular assist device [VAD] results in partial functional recovery of failing hearts that show increased susceptibility to cardiomyocyte apoptosis. The caspase cascade is the central element of the apoptotic process in cells. We therefore tested expression shifts of left ventricular mRNA of caspases and their endogenous inhibitors from 15 patients with VAD support and successful bridging to transplantation using semiquantitative RT-PCR. Cardiac unloading was shown by the reduction in ventricular Pro-ANP mRNA under VAD. No alteration of mRNA expression under VAD could be observed for initiator caspases, for their selective inhibitors or for apoptotic signal molecules from the mitochondrial intermembrane space. Only two unselective cardiac IAPs (inhibitor of apoptosis protein) were increased under VAD with better recovery in younger patients. In conclusion, our findings indicate that successful hemodynamic unloading by VAD support causes only minor, age-dependent recovery in the expression of IAPs, while presumed alterations in antiapoptotic modulator systems upstream of the caspase cascade still remain to be identified.

Age Factors↗
PubMed2001

Outpatients on biventricular assist devices.

As waiting times for transplants have lengthened, long-term mechanical circulatory support (MCS) has become more common in patients who present with severe cardiogenic shock leading to multiorgan failure. With these patients, we used the biventricular assist device (BVAD, Berlin Heart). In this report, we will describe our 4 years of experience with 11 patients on a BVAD who were discharged home while awaiting transplantation. The 11 patients underwent BVAD implantation from 1997 to 2000. These were 2 women and 9 men. The mean support time was 382 days (range: 156 - 567). The indication for BVAD was cardiomyopathy--six dilated, one restrictive and four ischemic. These patients were monitored for infections, thromboembolic events, bleeding complications, and psychological effects during the time they spent at home. Our experience shows that all of the patients could leave hospital following sufficient training for dressings and anticoagulation after recovering completely from secondary organ dysfunction. The mean time period the patients spent at home was 48 days (range: 3 - 182) days. Seven patients (63 %) had to be readmitted to the hospital--due to transitory ischemic attacks in two cases, hemorrhoidal bleeding in one and wound infections in four cases. One patient died of a traumatic accident during sexual activity. The use of a BVAD is feasible for outpatient use as a bridge to transplantation. It ensures the survival of the patient, enables recovery from multiorgan failure and offers an acceptable quality of life.

Adult↗
PubMed2001

Preliminary analysis of arrhythmias after the Fontan operation with extracardiac conduit compared with intra-atrial lateral tunnel.

BACKGROUND: It is to be expected that avoidance of the atrial suture line during extracardiac Fontan operation (ECFO) decreases the risk of postoperative arrhythmias. METHODS: Two groups of consecutive patients (23 with lateral tunnel (LTFO) and 24 with extracardiac conduit) who underwent successful Fontan operations between 5/93 and 10/98 were comparatively analyzed. All patients had postoperatively standard ECG and 24-hour monitoring. During follow-up, all patients had 2 - 8 (mean 3) standard ECG recordings per year and 76 % of the patients a 24-hour Holter ECG once a year. RESULTS: Median follow-up after ECFO and LTFO was 2.4 years and 4.5 years, respectively. The incidence of supraventricular tachyarrhythmias and bradyarrhythmias after ECFO versus LTFO was lower early after operation and during follow-up (p < 0.05). In follow-up, 20 ECFO patients (91 %) versus 11 patients after LTFO (52 %) remained in sinus rhythm (p < 0.01). Pacemaker insertion was required in 7 (33 %) LTFO patients but none of the ECFO patients (p < 0.01). CONCLUSIONS: The extracardiac Fontan operation decreases the incidence of early and medium-term postoperative arrhythmias. Comparative long-term results are not yet available.

Adolescent↗
PubMed2001

Ministernotomy versus complete sternotomy for coronary bypass operations: no difference in postoperative pulmonary function.

OBJECTIVES: Less-invasive approaches in cardiac operations offer certain cosmetic advantages, but it is unclear whether there are additional positive effects with regard to the postoperative recovery of patients. The aim of this prospective and randomized study was to ascertain whether partial inferior midline sternotomy can improve pulmonary function, one of the best quantifiable parameters of postoperative recovery, after coronary artery bypass operations when compared with the standard full midline approach. METHODS: One hundred patients scheduled for elective coronary artery bypass grafting were randomized either for a full median sternotomy (standard sternotomy group, n = 50) or for a partial inferior sternotomy (ministernotomy group, n = 50). The following pulmonary features were assessed: vital capacity, forced expiratory volume, percentage of forced expiratory volume from vital capacity, total lung capacity, residual volume, maximum inspiratory pressure, and maximum expiratory pressure. Tests were performed preoperatively and on the fourth and tenth postoperative days. RESULTS: On the fourth postoperative day, both groups had a significant decrease in vital capacity (percentage of predicted values) when compared with preoperative values (preoperative vs fourth day: standard sternotomy group, 87.8% +/- 14.3% vs 42.1% +/- 10.2% [P <.0001]; ministernotomy group, 84.5% +/- 14.3% vs 41.5% +/- 11.8% [P <.0001]), with a significant tendency for recovery from the fourth to the tenth postoperative day (fourth vs tenth postoperative day: standard sternotomy group, 42.1% +/- 10.2% vs 66.3% +/- 12.3% [P =.001]; ministernotomy group, 41.5% +/- 11.8% vs 61.3% +/- 13.1 % [P =.002]). There were no differences in any test results between the groups on either the fourth or the tenth postoperative day. CONCLUSION: A less-invasive approach for coronary artery bypass operations with a partial inferior sternotomy does not improve early postoperative pulmonary function when compared with the conventional approach with a full sternotomy.

Coronary Artery Bypass↗
PubMed2001

Heparin antibodies and thromboembolism in heparin-coated and noncoated ventricular assist devices.

OBJECTIVE: Coating of ventricular assist devices (VADs) with heparin improves the biocompatibility and may reduce the need for systemic anticoagulation. However, heparins are associated with the risk of formation of heparin/platelet factor 4 antibodies (HPF4/A) and the development of heparin-associated thromboemboli. We analyzed the occurrence of HPF4/A and thromboembolism in patients with heparin-coated and noncoated VADs. METHODS: One hundred patients were enrolled in the investigation. Fifty-seven received a heparin-coated (group 1) and 43 a noncoated (group 2) VAD. HPF4/A testing was performed before and 2 and 12 weeks after implantation by the heparin platelet factor 4 enzyme-linked immunosorbent assay. RESULTS: There was no significant difference in the occurrence of HPF4/A in the 2 groups (P =.102). Before the operation, 21 of the patients in group 1 had positive test responses and 25 in group 2. No patient had HPF4/A after termination of systemic heparinization. In group 1 there was no significant difference in the incidence of recurrent pump thromboses in patients who had positive test responses for HPF4/A (n = 11) when compared with those who had negative test responses (n = 9, P =.89). Twenty-one patients had HPF/A but no thromboembolism. However, all 22 patients who had thromboembolism had HPF4/A. CONCLUSIONS: Heparin coating of the VAD surface does not enhance the occurrence of HPF4/A-associated immunologic or thrombogenic reactions. However, the presence of these antibodies is strongly associated with an increased risk of thromboembolism in patients with a VAD.

Adolescent↗
PubMed2001

Detection of myocardial ischemia by electron beam CT. Experimental studies.

PURPOSE: To determine if contrast-enhanced electron beam CT (EBCT) can detect areas of acute myocardial ischemia, and if pharmacological stress testing improves the diagnostic accuracy of EBCT. MATERIAL AND METHODS: We injected 0.5 ml/kg and 1.0 ml/kg b.w. of iopromide at a rate of 4 ml/s into the right atrium of 5 ventilated female minipigs at rest and after occlusion of the left anterior descending (LAD) coronary artery. Both ventricles were examined at six short axis levels with an EBCT unit. Myocardial perfusion was calculated from the time-density curves of four left ventricular myocardial segments and the aorta. We also tested the effect of the contrast agent on myocardial density after i.v. administration of 0.6 mg/kg dipyridamole before and after LAD occlusion. RESULTS: At rest, the contrast agent increased myocardial density by 28+/-2 HU, corresponding to a myocardial perfusion estimate of 67+/-7 ml/min/100 g. After dipyridamole, myocardial density increased by 29+/-4 HU. Following occlusion of the LAD, anteroseptal myocardium displayed 10+/-4 HU density increase. The area of non-enhancement corresponded to ischemic myocardium in stained pathologic sections. CONCLUSION: Contrast-enhanced stress EBCT can be used to detect areas of myocardial ischemia, and EBCT stress perfusion imaging may be necessary to consistently differentiate ischemic from non-ischemic myocardial tissue.

Animals↗
PubMed2001

Extent of myocardial tissue damage during transmyocardial laser revascularization with the CO2 Heart Laser.

OBJECTIVE AND BACKGROUND: Transmyocardial laser revascularization (TMR) is the only surgical treatment for patients with severe diffuse coronary artery disease, who are not candidates for bypass grafting or percutaneous angioplasty. However, vaporization of tissue during the creation of channels leads to a certain loss of viable myocardium during every TMR procedure. METHODS: We analyzed serum levels of creatine kinase and creatine kinase MB subtype in 163 patients after sole TMR with a CO2 laser (wave length 10.6 microm, 800-watt power). The control group consisted of 35 consecutive CABG patients and 30 consecutive redo-CABG patients. Additionally, in the TMR group we measured echocardiographically the left ventricular ejection fraction before and after TMR. We recorded the total amount of laser energy applied, average and maximum energy per channel, and the number of created channels, in order to calculate the correlation between these parameters and postoperative enzyme levels or changes in the LVEF. RESULTS: After TMR, we measured higher creatine kinase levels compared to those in CABG patients (607.8+/-558.4 U/L vs. 285.0+/-292.3 U/L, p < 0.01). The relative proportion of CK-MB of total CK, however, was significantly lower after TMR, compared to that of the control group (4.5+/-3.0% vs. 10.1+/-6.4%, p < 0.01). Patients with a pronounced postoperative increase in CK-MB levels or a higher percentage of CK-MB of total CK also after TMR operations show a decline in left ventricular contractility. In the laser group, the maximum enzyme levels were detected significantly later than in the control group (25.0+/-19.4 h postoperatively vs. 8.7+/-9.1 h, p < 0.01). There was no significant correlation between the technical laser parameters or the number of created channels and the percentage of CK-MB of total CK or changes in left ventricular ejection fraction. CONCLUSIONS: CO2 laser TMR does not result in significant injury to the myocardium. Cardiac enzymes play an important role in the detection of perioperative myocardial infarction in TMR patients.

Carbon Dioxide↗
PubMed2001

Anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and renal impairment using heparin and the platelet glycoprotein IIb-IIIa antagonist tirofiban.

BACKGROUND: Patients with heparin-induced thrombocytopenia type II require an alternative to standard heparin anticoagulation. However, in patients with renal impairment, anticoagulation during cardiopulmonary bypass with agents such as danaparoid sodium or r-hirudin are associated with hemorrhage. Anticoagulation with unfractionated heparins combined with prostacyclin, a potent platelet aggregation inhibitor, is associated with severe hypotension. The authors investigated a new concept using unfractionated heparins after platelet inhibition with the short-acting platelet glycoprotein IIb-IIIa antagonist tirofiban. METHODS: Ten patients with heparin-induced thrombocytopenia type II and renal impairment were enrolled in the investigation. All had heparin-induced thrombocytopenia type II antibodies present as proved by the heparin-induced platelet aggregation assay, the heparin-platelet factor 4 enzyme-linked immunosorbent assay, or both. In all patients, preoperative anticoagulation to an activated partial thromboplastin time of 40-60 s was performed with r-hirudin. Anticoagulation during cardiopulmonary bypass was achieved with a bolus of 400 IU/kg unfractionated heparins after a bolus of tirofiban 10 microg/kg followed by an infusion of tirofiban at a rate of 0.15 microg x kg(-1) x min(-1) until 1 h before conclusion of cardiopulmonary bypass. Additional unfractionated heparins were only administered if activated clotting time decreased below 480 s. Coagulation was monitored by a abciximab-modified TEG and the adenosine diphosphate-stimulated (20 microm) platelet aggregometry. D-dimer concentrations, as a marker of venous thromboembolism, were measured before and 12, 24, and 48 h after surgery. Postoperative antithrombotic therapy was started immediately with r-hirudin to anticoagulation to an activated partial thromboplastin time of 40-60 s. RESULTS: The postoperative blood loss ranged from 110 to 520 ml. No patient needed reexploration. In no patient was there clinical evidence of thrombosis or embolism in the postoperative period or of a critical increase of the D-dimer concentrations, suggesting venous thromboembolism. Transfusion of platelets was necessary in only two patients. CONCLUSIONS: The protocol is easy to perform and no increased postoperative bleeding and no thromboembolic complications occurred. The combination of unfractionated heparins and tirofiban may be an alternative to other anticoagulation strategies in patients with heparin-induced thrombocytopenia.

Adult↗
PubMed2001

A rare complication of laparoscopic surgery: iatrogenic arteriovenous fistula with high-output cardiac failure.

SUMMARY: The authors report a 19-year-old man with cardiomegaly and high-output cardiac failure resulting from a hemodynamically significant arteriovenous fistula that was diagnosed 18 months after laparoscopic surgery for an inguinal hernia. The diagnosis was established on clinical examination and by ultrasonography and was confirmed by cardiac catheterization and angiography. The fistula was closed surgically by direct venous suture and reconstruction of the iliac artery with a polytetrafluoroethylene patch. The surgical repair achieved complete closure of the fistula with rapid normalization of cardiac size and function within 8 days.

Adult↗
PubMed2001

Endothelialization of PTFE vascular grafts under flow induces significant cell changes.

BACKGROUND: To minimize thrombogeneity of small diameter PTFE grafts they are usually coated in vitro with endothelial cells under static culture conditions. The disadvantage of this technique is that a cell layer is formed that fails to withstand shear stress typical in normal blood flow. METHOD: Since the in vivo functional and structural status of endothelial cells correlates with the applied shear stress, we developed a computer-controlled perfusion system to seed and culture cells on PTFE-grafts up to a confluent monolayer under the influence of increasing shear stress. The confluence of endothelial coating was defined by immunohistological staining of cross sections, and by upper light microscopy of flattened graft samples. In addition, the expression of fibronectin as an important adhesion molecule was estimated. RESULTS AND DISCUSSION: The application of pulsatile shear stress (6.6 dyn/cm2, 5 min) to grafts endothelialized under perfusion (n = 7) did not lead to a disruption of the confluent cell layer. In contrast, a 5 min long shear stress of 3 dyn/cm2 was sufficient to wash more than 50% of cells off the PTFE-graft cultured under static conditions (n = 6). The perfusion cultures showed a significantly higher proliferation rate in comparison with static cultures. This effect was reproducibile in both serum-containing and serum-free culture media. The expression of fibronectin by endothelial cells was significantly higher in the perfused graft compared to the static one. These results suggest the practicability of endothelialized PTFE vascular grafts, preconditioned to shear rates similar to the in vivo situation, as an alternative bypass material in cardiac surgery.

Blood Vessel Prosthesis↗
PubMed2001

Right pulmonary artery-to-left atrium communication: a rare cause of systemic cyanosis.

Direct communication between the right pulmonary artery and the left atrium is a rare congenital vascular malformation. The clinical diagnosis is difficult, and preoperative angiography is essential. We treated this anomaly successfully with surgery and the use of cardiopulmonary bypass in an 11-year-old boy. Surgery provides a complete cure for this anomaly.

Abnormalities, Multiple↗
PubMed2001

Evaluation of post-cardiopulmonary bypass coagulation disorders by differential diagnosis with a multichannel modified thromboelastogram: a pilot investigation.

We assessed a modified multichannel thromboelastogram for differentiation of the causes of coagulopathy after cardiopulmonary bypass and its suitability as a therapy guide. Thirty adult patients undergoing surgery with cardiopulmonary bypass, who revealed a coagulopathy as observed by a prolonged activated clotting time of >150 sec after the application of protamine, were enrolled. Therapy was based on the results obtained by the computerized four-channel thromboelastogram with baseline, heparinase (2 IU/mL), heparinase/abciximab (5 microg/mL), and heparinase/fresh frozen plasma (25%) channels. The mean activated clotting time before therapy was 162.2+/-7.8 sec. Based on differential diagnosis with the modified multichannel thromboelastogram, two patients received protamine (30 mg), five desmopressin (0.4 microg/kg), 19 patients three units of fresh frozen plasma, two patients platelet transfusions, and two patients both protamine (30 mg) and three units of fresh frozen plasma. After therapy, there was a significant (p < .01) decrease of the activated clotting time to a mean value of 127+/-8.3 sec. Therapy based on the synoptic modified multichannel thromboelastogram analysis provides a guide for effective therapy of coagulopathy. However, elaboration is desirable, and larger clinical trials are necessary for a final evaluation of the protocol.

Adult↗
PubMed2001

Some new perspectives in heparin-induced thrombocytopenia type II.

We conclude that HIT II is a serious complication, particularly in patients undergoing cardiovascular surgery that involves CPB. New tests might contribute to the earlier diagnosis of this disease. However, the reduction of immunization by the use of alternative anticoagulants whenever possible seems to be the most effective strategy for the reduction of HIT II-associated complications. If HIT II is diagnosed. r-hirudin is effective as an acute therapy (especially in combination with GP IIb/IIIa inhibitors) and also for further anticoagulation. If patients must undergo CPB, all current alternative anticoagulation concepts are associated with relevant drawbacks that put the patient at an increased risk for post-operative bleeding and/or CPB thrombosis. Currently, r-hirudin is most probably the best option for this purpose. However, when there is impaired renal function, the persistent anticoagulant effect is associated with hemorrhage. Further studies must evaluate whether extracorporeal elimination procedures, such as hemofiltration or plasmapheresis, are effective in avoiding such complications. Otherwise, the combination of UFH with a potent antiplatelet agent, especially with short-acting GP IIb/IIIa antagonists, is an attractive alternative.

Anticoagulants↗
PubMed2001

[Marfan syndrome and heart valve diseases].

Marfan syndrome is a hereditary disease of the connective tissue with increased mortality mostly due to changes of the cardiovascular system. We describe our experience with the surgical treatment of 243 patients with Marfan syndrome and cardiovascular complications. We report the results of treatment of annulo-aortal ectasia using the classical surgical methods of Bentall DeBono and Cabrol and the method for preservation of the native aortic valve and concomitant surgery of the mitral valve. Reconstruction or replacement of the mitral valve is mainly based on the classical indications. Preservation of the native aortic valve and reconstruction of the mitral valve in patients with Marfan syndrome is possible but the long-term results are still unknown.

Adolescent↗
PubMed2001

[The use of cross-sectional imaging modalities in the diagnosis of heart valve diseases].

Exact visualization of valve morphology seems to be possible with the cross-sectional imaging modalities, magnetic resonance imaging (MRI) and the recently introduced technique of multi-detector computed tomography (MDCT). These techniques are used, if other non-invasive imaging modalities, like echocardiography, fail or provide only insufficient information. This commonly occurs in the assessment of right ventricular valves. Quantification of valve stenosis is possible by calculating valve orifice area, which can be performed with MRI and MDCT. An estimation of the instantaneous peak gradient can only be achieved by MR flow measurements. MR flow measurement is a reliable method to quantify the degree of mild to moderate stenoses. Quantification of valve regurgitation is possible by measurement of the regurgitation fraction with MR flow measurements as well as with MR volumetry/CT volumetry. But only the MR flow measurement is suitable for the quantification of valve regurgitation in patients with multiple valves involved or cardiac shunting. MRI and probably MDCT are the most reliable methods in the evaluation of ventricular volumes and therefore suitable for the follow-up in patients with valvular heart disease, because changes in volumes are important for therapeutic decisions in these patients. The crucial advantages of MRI compared to CT in the diagnostic of valvular heart diseases however are the absence of radiation exposure, the possibility of quantitative evaluation of valves function using flow measurements and the higher temporal resolution as compared to MDCT.

Adolescent↗
PubMed2001

[Surgery in terminal mitral valve diseases].

In the past few years both the spectrum of mitral valve diseases leading to surgery and the surgical techniques have changed. We present our experience with the preservation of the subvalvular apparatus when mitral valve replacement is performed. In addition to preservation of the subvalvular apparatus of the posterior mitral leaflet, five techniques of subvalvular preservation are described. We conclude that mitral valve replacement should always aim at preservation of the subvalvular structures. The surgical method of choice in cases of isolated mitral valve insufficiency is mitral valve reconstruction. Treatment of associated atrial fibrillation, preferably by radiofrequency ablation, should always be performed concomitantly. Surgery of the mitral valve represents a palliative operation in selected patients with terminal cardiomyopathy.

Atrial Fibrillation↗