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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 127 records · Page 7Linked to original sources
PubMed2000

Pulsatile flow in patients with a novel nonpulsatile implantable ventricular assist device.

BACKGROUND: Ventricular assist devices (VADs) are an accepted therapy for patients with end-stage heart failure. The implantable devices that are available produce a pulsatile flow and are very large. In 6 patients, beginning in November 1998, we started to use the continuous-flow implantable DeBakey VAD device, which weighs 93 g. To detect the flow in peripheral vessels, we measured transcranial Doppler signals in patients after implantation. METHODS AND RESULTS: Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2-MHz probes (for the middle cranial arteries) in 4 patients for up to 12 weeks twice weekly after implantation. The blood velocity was measured, and the pulsation index (PI) calculated. The measured pump flow and rotations per minute were registered. The preoperative echocardiographic assessment values were compared with those acquired 6 weeks after implantation. The PI increased continually in all patients after VAD implantation, left ventricular (LV) ejection fraction did not improve, but right ventricular (RV) ejection fraction after implantation improved compared with preoperative values. The LV end-diastolic diameter after implantation decreased between 11% and 46% intraindividually. There was no correlation between PI and blood pressure or, except in 1 patient, between PI and blood flow through the VAD. CONCLUSIONS: The DeBakey VAD unloads the LV, which leads to a decrease in LV end-diastolic LV diameter and to the restoration of RV function. The unloaded LV and partially recovered RV provide a nearly physiological pulsatile flow despite the continuous flow of the VAD. Pulsatility is independent of peripheral vascular resistance. The first clinical experience with the DeBakey VAD was positive and has resulted in its continued use.

Adult↗
PubMed2000

[Metastasizing malignant germ cell tumor of the testis with infiltration of the thoracic aorta--a case for metastasis surgery].

HISTORY AND FINDINGS: A 33-year-old man was admitted 7 years after a testicular teratomatous carcinoma had first been diagnosed, treated by a right orchiectomy and two-stage radical retroperitoneal lymphadenectomy. Five years later the first mediastinal metastases were treated with high-dosage chemotherapy and autologous germ-cell transplantation, and remaining paraaortic--mediastinal tumour tissue was resected. Two years later another tumour at that site was only partially resected. A curing treatment seemed impossible, because the aortic wall had been invaded. TREATMENT AND COURSE: Five months after re-thoracotomy the metastasis and the invaded aortic segment were resected, the latter replaced by a vascular prosthesis. Histology indicated metastasis of a malignant teratoma of intermediate type. There has been no evident recurrence in the last 20 months. CONCLUSION: Combined orchidectomy, lymphadenectomy, high-dosage chemotherapy with cisplatin and autologous germ-cell transplantation at present constitute the standard treatment of malignant testicular germ-cell tumour. In case of metastatic infiltration of vital structures, such as the aortic wall, special operative procedures can prolong the period of remission when the success of a standard treatment seems limited.

Adult↗
PubMed2000

Changes in surface expression of platelet membrane glycoproteins and progression of heart transplant vasculopathy.

BACKGROUND: Transplant vasculopathy is the main limiting factor of the long-term success of heart transplantation. We sought to establish the role of platelets in the development and progression of transplant vasculopathy. METHODS AND RESULTS: Platelet analysis and intracoronary ultrasound examination were performed in 78 heart transplant recipients. Quantitative intracoronary ultrasound was used to define the severity of disease at baseline (48.8+/-4.5 months after transplantation) and at 1-year follow-up. Platelet activation was assessed with the use of immunological surface markers of activation (ligand-induced binding site 1 [LIBS-1], P-selectin, GPIIb-IIIa) and flow cytometry. We found that LIBS-1 immunoreactivity was significantly increased in patients with diffuse disease when compared with focal transplant disease (median [quartile], 27[14, 64] versus 18[7.9, 47], P=0.04). In a logistic regression model, we found that LIBS-1 was an independent predictor for the presence and progression of diffuse transplant vasculopathy (P=0.04). Patients with enhanced LIBS-1 levels (>75% quartile) had a 3.3-fold increased relative risk (95% CI 1.8 and 18.9, P=0.002) for the presence of diffuse transplant vasculopathy. When a cutoff value of 16.5 for the level of LIBS-1 was used, patients had a 4.8-fold increased relative risk (95% CI 1.9 and 12.5, P<0.01) for the progression of transplant vasculopathy. CONCLUSIONS: Enhanced platelet activation is strongly associated with the development and progression of transplant vasculopathy. Understanding the underlying pathophysiological mechanisms might contribute to the development of treatment strategies to prevent transplant vasculopathy.

Blood Platelets↗
PubMed2000

Electron-beam computed tomography in the assessment of coronary artery disease after heart transplantation.

BACKGROUND: Our aim was to compare the electron-beam CT (EBCT) features of coronary arteries in heart transplant recipients with those of biplane coronary angiography and intracoronary ultrasound (ICUS). METHODS AND RESULTS: We examined 112 heart transplant recipients (25 female; age, 17 to 69 years; median, 52 years) 1 to 153 months (median, 46 months) after surgery by EBCT to detect coronary artery calcifications. Calcifications were quantified by the Agatston scoring system. EBCT scores were compared with coronary angiography in all patients and ICUS of the left anterior descending coronary artery (LAD) in 100 patients. Coronary artery calcifications were found in 84 patients (75%). Angiographically, 16 patients displayed >50% coronary artery stenoses, all of whom had some degree of coronary artery calcification and only 1 of whom had a score of <55 (P<0.0001). With this threshold, EBCT had a sensitivity of 94%, a specificity of 79%, a positive predictive value of 43%, and a negative predictive value of 99% for detecting stenosis. ICUS confirmed the presence of calcified plaques in all patients with an LAD score >9. EBCT total calcium score was associated with the degree of intimal proliferation in that patients without ICUS features of allograft vasculopathy had a median score of 0 (25th percentile, 0; 75th percentile, 0), whereas patients with Stanford class IV vasculopathy had a median score of 41 (9 to 98, P<0.0001). CONCLUSIONS: EBCT is a promising noninvasive test for the detection of coronary heart disease in cardiac transplant recipients.

Adolescent↗
PubMed2000

Cellular allograft rejection affecting the donor aorta after combined heart-lung transplantation.

BACKGROUND: Infectious pseudoaneurysms of the ascending aorta are a recognized major complication after heart-lung transplantation. METHOD: This report describes an unusual and previously unreported complication, that of cellular allograft rejection, which caused a pseudoaneurysm of the donor's ascending aorta in a patient who underwent combined heart-lung transplantation. Repair was performed by primary suture after mobilization of the aortic segments. RESULT: On histological examination the resected aneurysm showed evidence of proliferative vasculitis with perivascular infiltration of the vasa vasorum by mononuclear cells. The mononuclear cells were identified as CD4+ and CD8+ by immunohistological staining. CONCLUSIONS: This report shows that cellular allograft rejection may affect the donor aorta after heart-lung transplantation and may result in pseudoaneurysm formation, even under triple-drug immunosuppression after ABO-compatible allograft transplantation.

Adult↗
PubMed2000

Immunoglobulin adsorption in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Idiopathic dilated cardiomyopathy (IDC) frequently is a progressive disease without causative therapy options. Following the hypothesis that in certain patients autoantibodies against cardiac structures may induce, maintain, or promote the progression of the disease, we investigated whether the elimination of these autoantibodies through immunoadsorption would improve cardiac function. METHODS AND RESULTS: This prospective case-control study included 34 patients with IDC. Each patient presented with moderate to severe heart failure and evidence of autoantibodies directed against beta(1)-adrenoceptors (beta(1)-AABs). Seventeen patients received standard medical therapy (control group), whereas 17 were also treated with immunoadsorption (treatment group) to eliminate beta(1)-AABs. A 1-year follow-up included echocardiographic assessment of left ventricular ejection fraction and internal diameters, beta(1)-AAB levels, and clinical status every 3 months. Within 1 year, the mean+/-SD left ventricular ejection fraction rose from 22.3+/-3.3% to 37.9+/-7.9% (P=0.0001) in the treatment group, with a relative increase of 69.9%. However, in the control group, no overall increase was seen (from 23.8+/-3.0% to 25.2+/-5.9%, P=0. 3154). Left ventricular diameter in diastole decreased by 14.5% from 74.5+/-7.1 to 63.7+/-6.0 mm in the treatment group (P=0.0001) and by 3.8% (P=0.2342) in the control group. In the treatment group, the NYHA functional rating improved after immunoadsorption (P=0.0001). beta(1)-AABs did not increase anew. CONCLUSIONS: In IDC, the use of immunoadsorption is superior to the use of standard medical therapy. It significantly improves cardiac performance and clinical status.

Autoantibodies↗
PubMed2000

Beta1-adrenoceptor gene variations: a role in idiopathic dilated cardiomyopathy?

A substantial body of evidence suggests involvement of the human beta1-adrenoceptor (beta1-AR) gene in the pathophysiology of dilated cardiomyopathy (DCM), a severe heart disease of significant public health impact. Beta1-AR-mediated signal transduction is dramatically altered due to downregulation, resulting in an impairment of myocardial response. The important role of genetic factors in idiopathic dilated cardiomyopathy (IDCM) recently recognized, we analyzed this prime candidate gene for genetic variation in carefully selected patients and controls. In this preliminary study, 18 single nucleotide polymorphisms were observed, 17 of which were located in the N-terminal and C-terminal region of the coding exon, resulting in 7 amino acid exchanges: Ser-49-Gly, Ala-59-Ser, Gly-389-Arg, Arg-399-Cys, His-402-Arg, Thr-404-Ala, and Pro-418-Ala. These mutations resulted in 11 different beta1-AR genotypes. Importantly, the genotypes carrying the Ser-49-Gly mutation in the N-terminus of the molecule in a heterozygous or homozygous form were observed significantly more frequently in the group of IDCM patients. The present results may provide a clue on the molecular mechanisms involved in IDCM, and add moreover interesting information on nature, distribution, and evolutionary aspects of sequence variation in human adrenergic receptor genes.

Adult↗
PubMed2000

[Iloprost as inhalational and intravenous long-term treatment of patients with primary pulmonary hypertension. Register of the Berlin Study Group for Pulmonary Hypertension]].

Follow-up data for 81 consecutive patients with primary pulmonary hypertension (PPH) and pulmonary hypertension related to connective tissue diseases or liver cirrhosis, entered into a multicenter registry in Berlin between 1/96 and 11/99, are described. At entry into the registry the diagnosis of PPH was known for 22 +/- 32 months. Hemodynamically, these patients were characterized by a right atrial pressure of 8.6 +/- 5 mmHg, a mean pulmonary arterial pressure of 58.9 +/- 17 mmHg, a cardiac index of 1.8 +/- 0.6 l/min/m2 and a pulmonary vascular resistance of 1574 +/- 787 dyn x s x cm-5. In about one third of the patients, a restrictive and/or obstructive pulmonary physiology was found while the majority showed signs compatible with small airway disease. Furthermore, diffusion abnormalities were found in about 65% of the patients. When added to conventional medical therapy the treatment with inhaled or continuously infused prostanoids represents a major improvement in the treatment of patients with PPH. Aerosolized iloprost therapy was started in 51 patients and was continued for 12 and 24 months in 20 and 6 patients, respectively. This therapy was well tolerated without any significant changes in pulmonary function or signs of toxicity. About 25% of these patients had to be switched to continuous intravenous therapy due to progressive clinical and hemodynamic deterioration. About two thirds of these "rescue patients" could be stabilized on intravenous therapy and discharged from the hospital. Based on the currently available evidence, the continuous infusion of prostanoids represents an important part of the standard therapy in the treatment of patients with PPH. These first long-term data on inhaled iloprost therapy in this patient group illustrate the potential value of this well-tolerated and effective treatment within the concept of a differentiated treatment plan for patients with PPH. However, the true importance of prostanoid inhalation in comparison to continuous intravenous therapy in PPH remains to be determined in randomized controlled trials.

Administration, Inhalation↗
PubMed2000

[Artificial heart in terminal stage of dilated cardiomyopathy in childhood].

In children with dilated cardiomyopathy the disease may progress so rapidly that they die during the waiting period before a suitable donor organ is found. Fifteen children of 4 months to 15 years of age had been in congestive heart failure with multiorgan failure due to dilated cardiomyopathy, where intensive medical treatment had failed. After resuscitation, a miniaturized pulsatile ventricular assist device for the mechanical replacement of heart function was implanted. The biventricular assist device ("Berlin Heart") consists of two extracorporeal pneumatically driven polyurethane blood pumps, with a multi-layer flexible membrane that separates a blood and an air chamber. Four silicon cannulae connect the blood pumps to the patient. A three-leaflet valve prevents blood reflux. The pumps are driven by a pulsatile electropneumatic system. In 12 of the 15 children the bridging to transplantation was successful with a support time of 1 to 98 days (mean 24 days). Nine of them were extubated and mobilized while assisted. Three children died during the support time due to hemorrhage, sepsis, and pulmonary failure. In addition, there was one infarction of the arteria cerebri media. To date seven of the transplanted children are in good condition on follow-up. The beneficial effects of ventricular assist device use are well known in adult patients and with special devices it can be transferred to infants and children in whom longer need for support is anticipated. Even in small infants it is an effective method for bridging to cardiac transplantation.

Adolescent↗
PubMed2000

[Ventricular septal aneurysm in a patient with Marfan syndrome].

This is the first description of a patient with Marfan syndrome and an aneurysm of the ventricular septum. Apart from a borderline dilatation of the ascending aorta, there were no cardiovascular manifestations of Marfan syndrome. A transesophageal echocardiographic examination showed a large aneurysm of the ventricular septum. To prevent the imminent rupture and the acute occurrence of a significant left-to-right-shunt on the ventricular level, as well as increasing irritation of tricuspid valve, an elective operation was performed. Besides the routine cardiological diagnostics, the search for intracardial defects is also necessary in patients with Marfan syndrome.

Adult↗
PubMed2000

Impersonation of a ruptured thoracic aneurysm by a transdiaphragmatic pancreatic cyst.

Pancreatic cysts can, in rare cases, expand into the posterior mediastinum and may require surgical resection. We present the case of a patient with a thoracic aneurysm, in whom the mediastinal involvement of a chronic pancreatic cyst masqueraded as a ruptured aneurysm. Surgery was undertaken: first, the initial resection and drainage of the thoracic portion of the pseudocyst, and second, a thorough cleansing of the entire cyst through median laparotomy 15 days later.

Aged↗
PubMed2000

Surgical treatment of a chest-wall penetrating left ventricular pseudoaneurysm.

This report describes the treatment of a patient who developed a chest-wall penetrating pseudoaneurysm 3 years after coronary bypass grafting and after the resection of a lateral wall left ventricular aneurysm twice. The patient presented with a pulsatile tumor in the left submammilar region. Surgery was done in deep hypothermia, with femoro-femoral cannulation and via a left anterolateral thoracotomy. The perioperative course was uneventful and the patient is still well 5 years after surgery.

Aged↗
PubMed2000

Pseudoaneurysm of the outflow graft in a patient with Novacor N100 LVAD system.

Six months after implantation of a wearable Novacor N100 left ventricular assist device, a 47-year-old patient developed a swelling that overlay the body of sternum. Computed tomographic scan of the chest revealed a pseudoaneurysm of the Novacor outflow graft. The patient was taken back to surgery and the diagnosis was confirmed at operation. Repair was performed by direct sutures via right anterolateral thoracotomy, under deep hypothermia and low flow technique. The postoperative course was uneventful.

Aneurysm, False↗
PubMed2000

Reinforcing the conventional sternal closure.

Sternal infection is a devastating complication of heart surgery. It may be the result of unstable osteosynthesis, caused by the sternal wires cutting into the cortical layers, which results in tension loss and gap formation. We describe a technique that prevents the cerclages from cutting into the sternal plates and covers the sternum with a well-capillarized barrier of major pectoralis muscle.

Aged↗
PubMed2000

Alterations in coagulation after implantation of a pulsatile Novacor LVAD and the axial flow MicroMed DeBakey LVAD.

BACKGROUND: The MicroMed DeBakey left ventricular assist device (LVAD) is a chamber and valveless axial flow blood pump. We investigated parameters of the coagulation system in patients after implantation of the axial flow LVAD and patients following implantation of a pulsatile Novacor LVAD. METHODS: Six consecutive patients of both groups were investigated over a period of 6 weeks after implantation. beta-Thromboglobulin, platelet factor 4, factor XIIa, thrombin/antithrombin complexes, plasmin/alpha2-antiplasmin complexes, and D-Dimer levels were measured. RESULTS: With the exception of the plasmin/alpha2-antiplasmin levels in the Novacor group, all parameters were elevated in both groups. The levels of beta-thromboglobulin, platelet factor 4, factor XIIa, and plasmin/alpha2-antiplasmin were significantly increased in the axial flow LVAD group. CONCLUSIONS: The axial flow LVAD strongly influences the systems of contact activation and fibrinolysis. The elevation of platelet proteins appears to follow platelet damage. Although no thromboembolic events were observed in both groups, elevation of thrombin/antithrombin complexes provides convincing evidence of an increased activation of the coagulation system and the concomitant risk for the development of thromboembolism.

Adult↗
PubMed2000

Intramyocardial impedance measurements for diagnosis of acute cardiac allograft rejection.

BACKGROUND: Measurements of intramyocardial impedance at high frequencies can indicate alterations in cell membranes and intracellular spaces during acute cardiac allograft rejection. METHODS: Fifteen beagle dogs underwent heterotopic heart transplantation and were immunosuppressed with cyclosporine and methyl prednisolone (MP). Impedance was determined twice daily by means of four screw-in electrodes in the right and left ventricle. Transmyocardial biopsies and the intramyocardial electrogram (IMEG) were performed as reference methods. A total of 23 rejection episodes were induced. When acute rejection was recognized histologically and through IMEG readings, the animals were treated with a bolus of 125 mg of methyl prednisolone over 5 consecutive days. Treatment of rejection was controlled by biopsy and IMEG. RESULTS: All hearts showed a uniform decrease in impedance of about 28.3%+/-5.5% immediately after transplantation, which subsequently reached a stable plateau after 7 to 8 days. Impedance values then remained unchanged as long as rejection was absent. Biopsy findings of grades 1A to 1B (ISHLT) were accompanied by a statistically significant increase in impedance of 12.2%+/-2.5%; of grades 2 to 3A of 19.2%+/-3.2% and of grades 3B to 4 of 27.0%+/-2.9%. Sensitivity was 96%, specificity 91%. Successful treatment of rejection led to a decrease of impedance to the initial levels. CONCLUSIONS: The amount of increase in impedance of high frequencies is a method to stratify acute cardiac allograft rejection into grades like histologically grading. The effectiveness of rejection treatment can also be monitored through impedance measurement. The method is also applicable for telemetric rejection monitoring by means of an implantable device.

Acute Disease↗
PubMed2000

Comparison of porcine xenografts and homografts for pulmonary valve replacement in children.

BACKGROUND: Due to the limited availability of homografts, different alternatives are used for replacement of the pulmonary valve. This study investigates the value of porcine stentless pulmonary xenografts in pediatric cardiac patients. METHODS: Twenty-three pediatric xenograft (size 10 to 21 mm) recipients were compared with 23 homograft (size 9 to 21 mm) recipients. RESULTS: Hospital mortality was 2 of 23 patients in the xenograft group and 3 of 23 in the homograft group (NS). Six out of 20 xenografts and 1 of 19 homografts were stenotic after 1 year (p = 0.011). Xenograft stenoses were mainly located at the distal anastomosis, while the leaflets were preserved. Homografts showed valvular stenoses and wall calcification. The 1 year freedom from reoperation was 77% in the xenograft and 93% in homograft recipients (NS), and from transcatheter intervention 84% and 100% (p = 0.004), respectively. Transcatheter intervention in 7 xenograft patients and 1 homograft recipient improved stenosis gradients from 65 to 40 mm Hg (mean) in 6 out of 8 patients. Explanted xenografts showed a loss of elastic membranes and proliferating connective tissue scars coated with activated endothelium. CONCLUSIONS: Xenografts demonstrated a higher incidence of supravalvular obstructions, which were possibly due to unfavorable hemodynamics at the distal anastomosis. Histological findings additionally indicated a pronounced immunological response. Interventional angioplasty lowered the rate of reoperation. Thus, the use of xenografts in children can be accepted as a second choice when a homograft is unavailable.

Animals↗