Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 289 records · Page 16Linked to original sources

PubMed1995

Infected ascending aortic prosthesis: successful treatment by thoracic transposition of the greater omentum.

A patient who developed a prosthetic infection with purulent mediastinitis after replacement of the ascending aorta for acute type A dissection was successfully treated with thoracic transposition of a pedicle of the greater omentum. The patient's further postoperative course was free from infection and, 30 months later, he has not developed any complications from the graft. We consider thoracic transposition of the greater omentum to be an excellent procedure for treating mediastinitis or deep sternal wound infections after cardiac surgery.

Acute Disease↗

PubMed1995

Blunted humoral responses to mental stress and physical exercise in cardiac transplant recipients.

Since recent results have suggested that the relative neuroendocrine response to physical activity is exaggerated following cardiac transplantation, we studied the haemodynamic-neuroendocrine responses to mental stress, and to physical exercise, in heart transplant recipients free of antihypertensive medication. Ten patients were studied 1.7 years (mean) after transplantation and compared with 10 age-matched controls. Plasma levels of catecholamines, renin activity, aldosterone, atrial natriuretic factor, calcitonin gene-related peptide (CGRP), and endothelin were measured, together with blood pressure and heart rate, during mental stress and graded, submaximal ergometry. Mental stress increased blood pressure in both groups (P < 0.02), but heart rate in controls only (P < 0.05). Noradrenaline did not change. Adrenaline rose in controls only (P < 0.05). Plasma renin activity increased in both groups (P < 0.02), while aldosterone increased in controls only P < 0.02). Atrial natriuretic factor, and endothelin were higher in patients (P < 0.01). Mental stress, however, did not induce any changes. No significant differences were found in relative changes (delta %), except for plasma renin activity which was greater in controls (P < 0.05). During ergometry, only delta % noradrenaline was greater in patients (P < 0.05). delta % for all other parameters were either of the same order as in controls, or blunted. Thus, apart from noradrenaline, cardiac transplant recipients, not receiving antihypertensive medication, do not show an exaggeration in the relative neuroendocrine response to mental or physical stress.

Adolescent↗

PubMed1995

Treating poststernotomy mediastinitis by transposition of the greater omentum: late angiographic findings.

Transposition of the greater omentum to the thorax for treatment of severe mediastinal infections due to the anatomical structure and physiological properties of the omental tissue is a proven and safe procedure. From 1987 to 1993, thoracic omentoplasty was performed in 112 cases at our facility. In order to attempt to visualize the vascularization of an omental graft by the right or left gastroepiploic artery via the coeliac trunk, a small group of patients (n = 7) underwent left heart catheterization followed by angiography of the gastroepiploic arteries. Visualization of the gastroepiploic arteries was successful in six patients. Furthermore, anastomoses with adjacent vessels were observed in individual cases. The omental vessels remain open for a long period after transposition to the thorax, and additionally, appear to create anastomoses with surrounding vessels.

Aged↗

PubMed1995

Anomalous origin of the left coronary artery from the pulmonary artery in adults.

Between March 1986 and December 1994, four adult patients underwent surgery for anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) at the German Heart Institute Berlin. The patients, aged 27, 35, 54, and 60, were all females. ALCAPA was diagnosed 3 to 8 months before surgery. The patients presented with cardiac murmur (two patients), abnormal ECG pattern (two patients), arrhythmia (one patient), and acute myocardial infarction (one patient). During surgery a two coronary system was established either by Takeuchi operation (one patient), interruption of the anomalous vessel and aortocoronary saphenous vein bypass (two patients), or internal mammary artery bypass (one patient). There were no postoperative deaths, however, one patient had to be reoperated because of a recurrent shunt. Clinical improvement was observed in all four patients with disappearance of fatigue, angina, dyspnea, and ischemic ECG changes. Despite having this long-standing congenital heart defect, adult and elderly patients with ALCAPA may benefit from surgical intervention to establish a two coronary system.

Adult↗

PubMed1995

Poststernotomy mediastinitis treated by transposition of the greater omentum.

Due to its anatomical structure and physiological properties, omental tissue has proven to be beneficial when transposed to the thorax to treat severe mediastinal infections. Between April 1987 and July 1994, 17,005 open heart operations were performed at our institution. One hundred and forty patients who developed mediastinitis or serious wound infections postoperatively were treated by transposition of the greater omentum into the retrosternal space. These patients were compared with a control group of 100 patients operated in the same period, who did not develop infectious complications postoperatively. Significant differences were found in several risk factors, such as obesity, type, and duration of primary operation, ejection fraction < 30% (< 0.01), as well as the incidence of low cardiac output syndrome treated by insertion of an intra-aortic balloon pump (p < 0.05). However, no significant differences were observed in factors such as diabetes mellitus, emergency operation, reoperation, degree of postoperative bleeding, and duration of aortic cross-clamp time. The mortality of mediastinitis largely depended on the type of primary operation. It was 19.2% in patients who underwent coronary surgery, and 52.2% in patients who underwent transplantation (overall mortality 35.7%). Only in 2% of the patients did we find complications related to the creation of the omental pedicle and its translocation. Today, serious disturbances in sternal wound healing, especially involving mediastinitis, are rare complications in cardiac surgery. Nevertheless, they continue to be associated with high mortality and prolonged hospitalization.

Humans↗

PubMed1995

Performance of aortic and pulmonary homografts in the right ventricular outflow tract in children.

Cryopreserved homografts have been used at the German Heart Institute Berlin since October 1986. Until 31st May 1994, cryopreserved aortic (AA) or pulmonary (PA) homografts were implanted in the pulmonary position and followed up in 104 patients. The mean age at operation was 5.5 years. The patients were treated with 3-5 mg/kg aspirin daily after the operation for three months. They all had routine echocardiographic evaluation of their homografts, 47 patients were studied by heart catheterization. Excellent functional results of the homograft valves were found in 92 patients (88.5%). Early degeneration of the homograft conduit leading to reoperation was observed in 12 patients. Freedom from wall calcification was 18% in aortic and 78% in pulmonary homografts while freedom from valve dysfunction in aortic and pulmonary homografts at 60 months was 60% and 67%, respectively. Freedom from reoperation was 81% overall, 78% and 84% in patients with aortic and pulmonary homografts respectively (p < 0.05). In conclusion, pulmonary homograft has proved to be more durable than the aortic homograft in the pulmonary position, hence it is the preferential valve for RVOT reconstruction in children.

Age Factors↗

PubMed1995

Preservation of papillary muscles and chordae during mitral valve replacement: possibilities and limitations.

The various techniques of preserving the chordal apparatus in mitral valve replacement applied in 1,453 cases at a single institution between 1986 and 1994 are described. The techniques include preservation of chordal attachment to the posterior mitral leaflet only and to both leaflets with five different technical variations. The specific advantages and risks of these techniques are demonstrated and discussed. It is concluded, that preservation of the entire subvalvular structures is feasible in almost all cases. Different procedures should be employed according to the variety of mitral disease, in particular with respect to mitral leaflet mobility.

Chordae Tendineae↗

PubMed1994

The present state of heart transplantation.

After more than 25 years, including long periods of scepticism, heart transplantation, with the introduction of several fundamental innovations, has become a routine clinical procedure for treating life-threatening end-stage heart failure. Annually, 3000-4000 transplantations are performed worldwide. Heart transplantation has been performed successfully in patients of almost all ages, from newborn babies with untreatable heart defects to 70-year-olds. Transplant organs are explanted from deceased donors who have suffered brain death. The circulation is kept stable for several hours during which time a well-functioning heart can be excised. In Europe, as a rule, donor organs are matched to recipients by national or multinational organ-sharing organisations. 'Eurotransplant', for example, serves medical institutions in Germany, Austria, and the Benelux states. This enables 500-600 hearts to be transplanted in Germany each year. Since 1986, 650 heart transplantations have been performed at the German Heart Institute Berlin (GHIB) and more than 100 are performed per year. In recent years, heart-lung, single-, and double-lung transplantations have been added to the GHIB's surgical program, accounting for more than 40 operations since the institute's inception. Patients at the GHIB have ranged in age from 8 days to 68 years, including 48 patients under the age of 16 years. Approximately two-thirds of the patients suffered from dilated cardiomyopathy and one-third from coronary artery disease. Smaller groups of patients suffered from valvular or congenital heart disease. Patients were selected for heart transplantation when heart failure was untreatable by other means and when their life expectancy was estimated to be 6 months or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

[Primary cutaneous Nocardia farcinica infection following heart transplantation].

A 57-year-old man, treated with immunosuppressive drugs for 3 months after a heart transplantation, developed a painful swelling of the left upper leg and fever. Needle biopsy of the lesion obtained pus from which Nocardia farcinica was cultured. Azathioprine treatment was discontinued and the dosage of cyclosporine reduced. Following antibiotic sensitivity tests, imipenem (4 g/d intravenously) and amikacin (1 g/d intravenously) were administered and the abscess split open. Although the fever responded and dissemination of the infection was excluded the response to treatment was not satisfactory. The drug dosages were repeatedly reduced in response to a rise in serum creatinine concentration to 3.4 mg/dl, deafness, double vision and generalized seizures: the local lesion got worse, but further surgical intervention then brought improvement. After 7 weeks of administration of the above antibiotics, treatment was changed to doxycycline (100 mg/d by mouth). 3 months later computed tomography could no longer demonstrate the lesion.

Abscess↗

PubMed1994

Formaldehyde-free collagen glue in experimental lung gluing.

Because of the well-known limitations of the adhesive strength of fibrin glue, it is imperative to develop a stronger glue with acceptable biocompatibility. This was accomplished by removing the formaldehyde component from gelatin-resorcinol-formaldehyde glue and replacing it by two less toxic aldehydes--pentanedial and ethanedial. To evaluate the adhesive strength of this new glue, GR-DIAL, lung incisions in rabbit hybrids were glued together. Each group (n = 5) was examined histologically after 2 days and 1, 2, and 4 weeks. The glue disintegrated gradually with good bioresorption when the incision was closed with a thin layer of glue. The healing process was favorable, indicating good biocompatibility. Therefore, GR-DIAL glue is capable of enhancing the use of surgical glues in the field of thoracic surgery by enabling surgeons to close larger parenchymal lesions than with fibrin glue.

Animals↗

PubMed1994

Noninvasive diagnosis of cardiac rejection through echocardiographic tissue characterization.

Ultrasonic tissue characterization is based on the assumption that microscopic tissue structures are identifiable by their acoustic properties. Our study group consisted of 23 cardiac recipients. Two-dimensional images were obtained within 2 hours of endomyocardial biopsy. The end-diastolic echo frames were digitized into the matrix of an image-processing system. A region of interest was placed into the anteroseptal segment of the left ventricle. The texture within the region of interest was analyzed using four major groups of texture analysis (first-order histogram, co-occurrence matrix, run-length statistic, and power spectrum). A total of 408 echocardiographic examinations were compared with histologic findings. The 117 initially calculated texture parameters were reduced incrementally using a series of discriminant analyses. A set of three texture parameters (inverse difference moment undirected, run-length nonuniformity vertical, and sector sum) was able to describe changed echocardiographic texture when rejection occurred. Using these three parameters, echocardiographic sensitivity was 89.0% and specificity was 83.6% for moderate rejection. We conclude that cardiac rejection is associated with echocardiographic texture alterations and that serial echocardiographic texture analysis can reliably identify rejection.

Adult↗

PubMed1994

The impact of gelatin-resorcinol glue on aortic tissue: a histomorphologic evaluation.

PURPOSE: Although gelatin-resorcinol-formaldehyde glue has been used to treat acute aortic dissections for some time, concerns about formaldehyde's mutagenicity and carcinogenicity made it imperative to develop a new glue compound. Gelatin-dialdehyde glue was produced by omitting the formaldehyde component and replacing it with two less toxic aldehydes, glutaraldehyde and glyoxal. This study evaluated the histomorphologic effects of the new glue through in vivo use on the aortic tissue of domestic pigs. METHODS: Each animal's infrarenal aorta was glued around an implanted prosthesis. Histomorphologic evaluation was performed after operation after 1 and 4 weeks. RESULTS: The results demonstrated that the clinically observed tanning effect can be attributed primarily to the disintegration of the fiber texture, specifically collagenous, as well as smooth muscle fibers, and to the reciprocal alterations of the proteoglycan interstitial substance in the aortic wall. Macroscopic, microscopic, and electron microscopic analysis of the gluing process revealed an adequate healing process without any morphologically significant difference between formaldehyde and formaldehyde-free gelatin-resorcinol glue. CONCLUSIONS: Gelatin-dialdehyde glue is able to produce the same effects in the area of the aortic wall as the substantially more toxic gelatin-resorcinol-formaldehyde glue and thus could be recommended for clinical trials for treating acute aortic dissections thus far yielding excellent initial results.

Animals↗

PubMed1994

Successful extracorporeal circulatory support after aortic reimplantation of anomalous left coronary artery.

The development of severe heart failure is the main cause of postoperative mortality after the surgical treatment of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA). Two patients with ALCAPA who developed low cardiac output and could not be weaned from cardiopulmonary bypass (CPB) after aortic reimplantation of the anomalous left coronary artery were successfully treated with a centrifugal left ventricular assist device (LVAD) and extracorporeal membrane oxygenation (ECMO). The circulation of a 10-month-old infant with severe left ventricular dysfunction was supported 192 h postoperatively with a LVAD and a 9-year-old boy with severe right ventricular failure received ECMO support for 99 h following surgery. Both patients survived and, 4 and 9 months after surgery, are asymptomatic and have normal ventricular function. If CPB (up to 3 h) is not effective in improving ventricular function after surgery for ALCAPA, ECMO or LVAD must be used since myocardial recovery in these patients can occur only after prolonged extracorporeal circulatory support.

Cardiopulmonary Bypass↗

PubMed1994

Improvement in left ventricular dysfunction after aortic reimplantation in 11 consecutive paediatric patients with anomalous origin of the left coronary artery from the pulmonary artery. Early results of a serial echocardiographic follow-up.

To study the potential for recovery of left ventricular function in patients with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) after aortic reimplantation, serial two-dimensional echocardiographic examinations were performed before and up to 9 months after operation in 11 consecutive paediatric patients (group 1: six infants; group 2: five children above the age of 1 year). End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial volume (MV), ratio of myocardial volume/end-diastolic volume (MVI), and regional wall motion of the left ventricle (LV) were studied. Pre-operatively, mean LVEDV was 339% of normal in group 1 and 289% in group 2 (P < 0.001); mean LVMV was about twice the normal value in both groups (P < 0.001); LVMVI was 0.79 +/- 0.23 in group 1 and 0.83 +/- 0.3 in group 2; LVEF was 28 +/- 10% in group 1 and 46 +/- 18% in group 2; regional wall motion was normal in two group 2 patients, the other showed uniform reduction in segmental shortening fraction. Postoperatively, mean LVEDV tended to become normal after 2 weeks in group 1 and after 3 months in group 2. In both groups mean LVEF reached the normal range after 3 months; LVMV as well as LVMVI normalized after 9 months. Three months after the operation, all infants had a nearly normal pattern of regional wall motion, while in three group 2 children a residual reduced shortening fraction could be observed in anterior or lateral segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Thoracic↗

PubMed1994

Interleukin-6 and interleukin-8 concentrations as predictors of outcome in ventricular assist device patients before heart transplantation.

OBJECTIVE: To determine whether the serum concentrations of some circulating cytokines (as highly sensitive markers of inflammation) are of value in predicting the outcome of patients with cardiogenic shock and end-stage heart disease, who undergo ventricular assist device implantation until heart transplantation. DESIGN: Cohort study. SETTING: University teaching hospitals. PATIENTS: Twenty patients with cardiogenic shock or end-stage heart disease were consecutively selected for this study, if assist device implantation was performed as a bridge to heart transplantation. MEASUREMENTS AND MAIN RESULTS: The circulating concentrations of the cytokines interleukin (IL)-1 beta, IL-6, IL-8 and tumor necrosis factor (TNF)-alpha were monitored from the beginning to the end of assist device support two to three times a week, using commercial enzyme-linked immunosorbent assays (ELISA). In all patients, circulating IL-6 and IL-8 values were increased shortly after assist device implantation. In patients with uncomplicated courses, IL-6 and IL-8 concentrations decreased after an initial increase and were low at the time of transplantation, whereas serum cytokine concentrations increased and remained increased in the nonsurvivors (survivors vs. nonsurvivors, p < .001). Circulating IL-1 beta and TNF-alpha concentrations were rarely detectable. CONCLUSIONS: Monitoring of IL-6 and IL-8 values during ventricular assist device support provides a means of early identification of high-risk patients that may allow optimization of antimicrobial therapy and selection of the appropriate time for transplantation.

Adolescent↗

PubMed1994

Measuring left ventricular function after heart transplantation via digitization of M-mode echocardiograms.

The aim of the study was to assess the usefulness of M-mode echocardiography for noninvasive diagnosis of cardiac rejection. For this purpose, 292 M-mode images of 26 heart transplant recipients were analyzed. The echocardiographic images were digitized into an image analysis system. The curves of left ventricular diameter changes were obtained and its first differential calculated. A total of 23 parameters were measured. The most important parameters were: peak velocity of systolic diameter change, peak velocity of diastolic diameter change, time to peak velocity of systolic diameter change, time to peak velocity of diastolic diameter change (TPEAK-D), isovolumetric relaxation time (IVRT), rapid filling time (RFT), shortening fraction (SF), and mean velocity of circumferential fiber shortening (MVCF). The echocardiographic parameters were compared to biopsy results. In 18 patients, 23 biopsy-proven moderate rejections occurred. When rejection occurred, IVRT decreased 23% +/- 6% (P < 0.05), SF decreased 13% +/- 14% (P<0.05), MVCF decreased 18% +/- 18% (P<0.05), and TPEAK-D increased 27% +/- 27% (P<0.05). We concluded that the analysis of digitized M-mode images can identify heart transplant rejection.

Biopsy↗

PubMed1994

A new electrohydraulic energy converter for a left ventricular assist device.

An energy converting system that can function for years without maintenance is required for the drive of a left ventricular assist device (LVAD). To meet the requirements of safety, the energy converter should have a simple design with few moving elements. The design applied herein has only one moving part and thus has greater inherent safety than competing systems. The only moving part is the rotor unit, comprised of the impeller of a centrifugal pump, the rotor of an electric motor, and the rotor of an electric axial actuator. A reversal of flow of the transmitter fluid can be achieved with an axial shift of this rotor unit. This fluid acts on the outer surface of a blood chamber and enables it to draw in blood and to expel it. Valves direct the flow of blood. The energy converter performs a flow of 12 L/min at a motor speed of 6,000 rpm against a pressure head of 115 mm Hg according to an output of the pulsatile blood pump of 5 L/min.

Electric Power Supplies↗

PubMed1994

Coronary artery bypass grafting and heart transplantation in end-stage coronary artery disease: a comparison of hemodynamic improvement and ventricular function.

Heart transplantation has now become an accepted treatment for end-stage coronary heart disease (CAD). However, the limited supply of suitable donor organs imposes constraints upon the decision of whether patients are selected for transplantation or for coronary artery bypass grafting (CABG). From April 1986 until the end of March 1992, 265 patients with end-stage CAD involving left ventricular ejection fraction (LVEF) 10% to 30% and predominant angina pectoris underwent CABG. All patients received an average of 2.9 +/- 0.3 venous grafts. Intraaortic balloon pumps were implanted in 30 patients (11.3%) who began to develop low cardiac output syndrome intraoperatively. The actuarial survival rate was 87.8% after 2 years and 86.9% after 3 years. LVEF was measured in 35 patients via left heart catheterization 12 months after their operations and was found to have increased from a mean of 23.8% to 38.1%. Left ventricular end-diastolic pressure had decreased from 16.2 mmHg to an average of 12.1 mmHg. Swan-Ganz catheterization was performed on 120 patients 6 months postoperatively. The pulmonary wedge pressure had reduced significantly from 18.1 mmHg to a mean of 12.7 mmHg (p < 0.01). From 1990 until the end of March 1992, 55 patients with CAD and predominant heart failure received transplants. Their 2-year survival rate was 66.3%. Mean LVEF was 55.6% postoperatively. We conclude that CABG is adequate for patients who have end-stage CAD and angina pectoris symptoms, and that it significantly improves hemodynamic functions. Patients suffering predominantly from heart failure (NYHA Class IV) can be transplanted and subsequently regain normal heart function.

Actuarial Analysis↗