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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 307 records · Page 17Linked to original sources
PubMed1994

Diurnal variation in blood pressure in patients with biventricular assist devices and retained, nonpumping native hearts.

BACKGROUND: Studies indicate that centrally mediated rhythms in sympathetic tone play a prominent role in diurnal cardiovascular variability. Recent evidence from heart transplant recipients, in whom blood pressure does not decline during sleep despite normal variability in plasma norepinephrine, however, suggests that afferent cardiac nervous traffic is necessary for the generation of diurnal variability. This implies that in the presence of an innervated heart excluded from the systemic circulation, blood pressure would still decrease during sleep. To assess this hypothesis, we studied 24-hour blood pressure, heart rate, and neuroendocrine variability in patients with biventricular assist devices in whom the retained native hearts had ceased to pump. METHODS AND RESULTS: Eight patients were free of medication and were studied every 3 hours. Pump rates and output were kept constant throughout the study. Blood pressure showed a significant decline during sleep, as did norepinephrine and epinephrine (all P < .05). Atrial natriuretic factor showed a significant increase around midnight (P < .01). Significantly elevated levels were found for all hormones studied except for aldosterone and endothelin. CONCLUSIONS: Our results suggest that diurnal variations in cardiac function or in catecholamine levels (indicative of sympathetic activity) as found in cardiac transplant recipients alone are not responsible or sufficient for producing a nocturnal drop in blood pressure. The presence of an innervated heart appears crucial in this respect. This could be of importance for the understanding of circadian cardiovascular pathophysiology.

Adult↗
PubMed1994

Diagnostic evaluation and surgical management of the aberrant right subclavian artery.

A case of dysphagia and dyspnea secondary to compression of the esophagus and the trachea by an aberrant right subclavian artery is presented. As the pathology of the aberrant right subclavian artery is extremely diverse, the diagnosis without radiologic investigation is hardly feasible. Conventional angiography of the aortic arch may be avoided by 3-dimensional magnetic resonance angiography, that is a suitable noninvasive method to diagnose and visualize the vascular pathology and the postoperative results after corrective vascular surgery. With the use of a Gore-Tex prosthesis the right aberrant subclavian artery was successfully translocated to the ascending aorta through a mid-sternal, transmediastinal approach. In contrast to previous reports the retro-esophageal vascular segment was kept in situ. The literature is reviewed with the reference to the diagnostic procedure and the treatment of dysphagia lusoria.

Adult↗
PubMed1994

Mitral annular function assessed by 3D imaging for mitral valve surgery.

We developed a surgical technique for mitral valve reconstruction without a prosthetic ring. This procedure may have two advantages. One is avoidance of the potential thrombogenicity of the prosthetic ring, and the other is that this procedure may maintain the normal function of mitral annulus. To clarify the latter advantage, we defined a method for 3D assessment of the heart, especially for the dynamic changes of the mitral annulus. 3D images of the heart, including both mitral and tricuspid annuli in eight phases during the cardiac cycle, were reconstructed from magnetic resonance images of seven normal subjects, and used for this study. To depict the changes in the annular shape, we determined the following parameters of the annular function: (a) annular excursion, (b) direction of motion (direction cosine) and (c) orientation of the annulus (direction cosine) for the annular motion, (d) annular area and (e) displacement of the anterior portion from the approximated plane of the annulus. The data for the systolic annular motion indicate that the mitral annulus moves towards the apex with slight caudal deviation, with the excursion of 12.1 mm. The change in annular orientation indicates that the mitral annulus shows translational motion during systole. The mitral area was reduced by 25.6% (n = 5) from mid-diastole to mid-or late systole. Displacement at the anterior portion of the annulus did not change markedly during systole. The results demonstrate the physiologic function of the mitral annulus in normal subjects. This method will be applied to the clinical study of mitral valve reconstruction surgery. Based on the differences in annular length in intact and excised states, we describe the intact state of the posterior leaflet as "natural redundancy." Restoration of this natural redundancy has been a hallmark of successful mitral repair for over 20 years.

Adult↗
PubMed1994

Anomalous origin of the left coronary artery from the pulmonary artery. Early results with direct aortic reimplantation.

Between January 1991 and June 1993, eleven children with anomalous origin of the left coronary artery from the pulmonary artery underwent direct aortic reimplantation of the left coronary artery at the German Heart Institute Berlin. The patients' ages ranged from 2.5 months to 10.5 years; six were infants. Three infants were intubated and their lungs ventilated before the operation, and one was resuscitated 2 days before the operation. The electrocardiograms of eight patients indicated deep Q waves. All but three of these patients had insufficient collaterals between the right and left coronary arteries. The entire group exhibited reduced left ventricular ejection fraction (minimum 15%) including mitral valve incompetence, which was moderate in six patients and severe in three. All six infants underwent emergency operations, and the remaining children, who were older, underwent elective operations involving moderate hypothermic perfusion and cold crystalloid cardioplegia. Aortic cross-clamping time ranged from 22 to 79 minutes (mean 54 minutes). A two-coronary artery system was established in all patients by direct reimplantation of the anomalous left coronary artery into the ascending aorta. Three patients who also exhibited severe mitral valve incompetence underwent modified Kay mitral valve annuloplasty. A delayed sternal closure procedure (closure performed 1 to 10 days after the operation) was used on eight patients. A 10-month-old patient was successfully treated after the operation with a centrifugal left heart assist device and a 9-year-old patient received extracorporeal membrane oxygenation because of severe heart failure. No postoperative deaths occurred. Left ventricular end-diastolic volume decreased dramatically after the operation and returned to near normal values 1 to 9 months postoperatively. At the same time, the preoperatively depressed left ventricular ejection fraction returned to normal and mitral valve incompetence decreased or vanished in eight patients. Color Doppler echocardiograms (eleven patients) and coronary angiograms (three patients) indicated that the reimplanted left coronary artery was patent in all eleven patients during the follow-up period. Reimplantation of the left coronary artery into the ascending aorta is an effective method of establishing a two-coronary artery system in children with anomalous origin of the left coronary artery from the pulmonary artery. Mitral valve annuloplasty is recommended for patients who also have severe mitral valve incompetence. Prolonged assisted circulation must be used in cases of severe postoperative heart failure.

Aorta↗
PubMed1994

[MR-angiography in diagnosis and follow-up of therapy: arteria lusoria].

Diagnostic and therapeutic procedures are presented in a 29-year-old female patient who suffered from severe dysphagia and rapid loss in weight. In the conventional X-ray examination and barium swallow an aberrant right subclavian artery was suspected. MR imaging (MRI) and MR angiography (MRA) were done to plan the surgical correction. Postoperative MRA documented exactly the complex topography after surgical correction and the flow pattern in the implanted Gore-Tex stretch graft prosthesis. Non-invasive MR angiography renders possible the concrete planning of complex corrections of thoracic vessels replacing invasive catheter angiography.

Adult↗
PubMed1994

Low-dose enoximone therapy in pre-transplant patients: hemodynamic, echocardiographic, and neurohumoral findings.

Keeping pre-transplant patients alive while waiting for a suitable donor to be found is still a major challenge. New pharmacological agents which can provide improved hemodynamics are urgently needed in patients with severe heart failure who are on the waiting list for cardiac transplantation. Intravenous enoximone therapy (an initial 0.5 mg/kg bolus, then 1.25-5.0 mcg/kg/min infusion) was administered to 18 transplant candidates with heart failure progression despite optimal drug regimen including digoxin, diuretics, and ACE-inhibitors. Complete hemodynamic, echocardiographic, and neurohumoral studies were performed before and 24 h after intravenous enoximone infusion. Enoximone infusion increased cardiac index (1.78 +/- 0.45 l/min/qm vs. 3.04 +/- 0.83 l/min/qm; p < 0.001) and stroke volume index (22.33 +/- 9.45 ml/qm vs. 32.28 +/- 7.29 ml/qm; p < 0.05) and decreased wedge pressure (24.1 +/- 11.98 mmHg vs. 17.78 +/- 8.76 mmHg; p < 0.05) and systemic vascular resistance (1700.8 +/- 555.8 dyn x s x cm-5 vs. 952.8 +/- 384.0 dyn x s x cm-5; p < 0.001). Heart rate and mean arterial pressure were unchanged. Left ventricular ejection time (225.1 +/- 26.9 ms vs. 242.2 +/- 25.8 ms; p < 0.05) was increased, whereas other echocardiographic parameters were unchanged (left ventricular end-diastolic dimension, left ventricular end-systolic dimension, fractional shortening, early diastolic relaxation parameter Te). Plasma neurohumoral parameters did not change (aldosterone, epinephrine, renin, atrial natriuretic factor) except for a significant drop of norepinephrine (936.7 +/- 443.2 pg/ml vs. 522.4 +/- 287.6 pg/ml; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Monitoring of the cellular immune system in patients with biventricular assist devices awaiting cardiac transplantation.

Lack of objective parameters to predict the clinical course and outcome are a major problem in managing the patients selected for BVAD-support as a bridge to heart transplantation. This study was intended to assess whether cellular immune parameters have a predictive value for the clinical result of VAD-support. Various cellular immune markers were monitored by multiparameter cytofluorometry in 30 patients who received a VAD system (Berlin Heart). We did not find significant differences in preoperative values of immune parameters between groups of survivors (n = 14) and non-survivors (n = 16). All 9 patients who died of septic multiple organ failure (MOF) had shown increased levels of T-cell activation (CD 71, CD 25, HLA-DR) as well as leukocytosis and 7 patients who died of noninfectious complications (mostly hemorrhage or cerebral complications) had exhibited T-lymphopenia. Seven of 9 patients who died of septic MOF had extremely decreased levels of HLA-DR+ monocytes (< 30%) while all 14 survivors and all 7 patients who died of noninfectious complications showed almost normal monocytic HLA-DR antigen expression, antigen-presenting capacity and cytokine secretion. These observations point to the reduced antimicrobial immunity ("immunoparalysis") in the non-survivors and may explain the fatal course of infection in these individuals. The in vitro results of restitution experiments call for new therapeutic strategies to improve the survival of VAD-patients.

Adolescent↗
PubMed1993

Myocardial preservation using HTK solution for heart transplantation. A multicenter study.

Bretschneider HTK solution is commonly used for myocardial preservation. In order to evaluate its protective effect for heart transplantation, a retrospective study was initiated in cooperation with Eurotransplant and five heart transplant centers. Seventy-six female and 524 male patients who underwent cardiac transplantations between 1981 and 1991 were included in this study. Using standardized questionnaires, donor and recipient laboratory data, immunosuppressive therapy and the preoperative, intraoperative and postoperative organ function were documented. The average ischemic time of the donor hearts was 160 min, ranging from 75 min-304 min. Immediate postoperative graft failure was observed in 25 transplantations (4.2%). Within the first 30 days 71 organs (11.8%) failed. Using the chi2-test, a statistically significant increase of acute graft failure and early mortality was evident when they were correlated with the length of ischemic time (P = 0.01). In addition, a higher incidence of early graft failure was observed when the perfusion volume was less than 1500 ml. The 1- and 5-year survival rates were 72% and 63%, respectively. Organ preservation with HTK shows good results as long as the ischemic time does not exceed 4 h. The possibility that an increased perfusion volume allows longer ischemic times cannot be excluded with this study.

Cardioplegic Solutions↗
PubMed1993

Intramyocardial electrogram recordings for diagnosis and therapy monitoring of cardiac allograft rejection.

The registration of intramyocardial ECG amplitudes (IMEG) is a non-invasive diagnostic method of monitoring cardiac allograft rejection. In order to detect possible sources of error IMEG signals were recorded in heterotopic neck hearts in ten beagle dogs. Immunosuppression was based on cyclosporin A. The rejection process was followed by IMEG registrations as well as by serial myocardial biopsies. Intramyocardial electrogram recordings were made via three unipolar and three bipolar leads obtained from screw-in electrodes in both ventricles and the apex of the allograft. A 10% voltage drop was used as an indicator of rejection. In four dogs, the first rejection episode was treated with methyl-prednisolone and the therapy's success was monitored by IMEG and repeat biopsy. At autopsy the histology of each electrode circumference was correlated with the corresponding IMEG. The average sensitivity of a single lead was not acceptable (unipolar: 28%, bipolar: 47%). When the voltages of different leads were summed up the sensitivity rose to 43% (3 x unipolar), 85% (3 x bipolar) and 100% (all leads). During rejection therapy the IMEG recovered within 24-48 h. We conclude that in moderate allograft rejection (grade 2/3a ISHT classification), the rejection-related changes of intramyocardial ECG voltage amplitude (IMEG) seem to follow a "focal pattern" similar to the histology. Therefore the recording of several, preferably bipolar, electrode configurations appears to enhance adequate diagnostic reliability.

Animals↗
PubMed1993

Enoximone therapy as pharmacological bridging to cardiac transplantation.

Keeping pre-transplant patients alive while waiting for a suitable donor is still a major challenge. New pharmacological agents which can provide improved hemodynamics are urgently needed in patients with severe heart failure who are on the waiting list for cardiac transplantation. Intravenous enoximone therapy (an initial 0.5 mg/kg bolus, then 1.25-5.0 mcg/kg/min infusion) was administered to 35 transplant candidates with progressive heart failure despite optimal drug regimen including digoxin, diuretics, and ACE-inhibitors. In 18 out of 35 patients complete hemodynamic, echocardiographic, neurohumoral, and Holter-ECG studies were performed before and 24 hours after intravenous enoximone infusion. Patients were then continued on chronic oral therapy of 100 mg twice a day. Enoximone infusion increased the cardiac index (CI) (1.78 +/- 0.45 l/min/m2 vs 3.04 +/- 0.83 l/min/m2; p < 0.001) and stroke volume index (SVI)(22.33 +/- 9.45 ml/m2 vs 32.28 +/- 7.29 ml/m2; p < 0.05) and decreased wedge pressure (PCP)(24.1 +/- 11.98 mmHg vs 17.78 +/- 8.76 mmHg; p < 0.05) while mean arterial pressure (MAP) was unchanged. Left ventricular ejection time (LVET)(225.1 +/- 26.9 ms vs 242.2 +/- 25.8 ms; p < 0.05) was increased whereas other echocardiographic parameters were unchanged (Left ventricular end-diastolic dimension LVEDD, left ventricular end-systolic dimension LVESD, fractional shortening FS, early diastolic relaxation parameter Te). Plasma neurohumoral parameters did not change (Aldosterone, epinephrine, renin, atrial natriuretic factor) except for a significant drop in norepinephrine (936.7 +/- 443.2 pg/ml vs 522.4 +/- 287.6 pg/ml; p < 0.05). Holter-ECG parameters (ventricular premature beats VPB, couplets, ventricular tachycardia VT) were not influenced by enoximone infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Heart transplantation in Berlin--1993 update.

Heart transplantation has become a routine procedure. Surgical techniques have been standardized and triple-drug immunosuppression has proven to be the most effective posttransplantation medical treatment. A shortage of donor organs has remained the major factor inhibiting extensive application of heart transplantation. Improved techniques of organ protection may eventually contribute to an extension of the donor pool. However, it seems to be more important to develop alternative procedures further (artificial heart, xenotransplantation, extended use of conservative surgical or medical treatment). The patient population undergoing heart transplantation will undoubtedly include more older, severely ill, polymorbid patients who are not suitable for alternative procedures. Pediatric heart transplantation may increase in the coming years and mechanical circulatory support will surely gain in importance for both adult and pediatric patients awaiting heart transplantation.

Adolescent↗
PubMed1993

Survival predictors in patients with a left ventricular ejection fraction of 10-30% receiving a coronary bypass: analysis of preoperative variables.

A total of 224 patients with angina pectoris and a left ventricular ejection fraction in the range of 10-30% (mean 24.2%) underwent coronary artery bypass grafting between April 1986 and August 1991. These patients received a mean (s.d.) of 2.9 (0.3) aortocoronary vein grafts. The overall operative mortality rate was 8.9%. The 1-, 2- and 3-year survival rates were 87.7%, 86.7% and 85.2%, respectively. Analysis of operative risk factors showed that patients with an end-diastolic left ventricular pressure > 24 mmHg were significantly more at risk (mortality rate 20.0%, P < 0.05) than those with an end-diastolic left ventricular pressure < or = 24 mmHg (mortality rate 6.2%). Patients with a perioperative cardiac index < 2.5 l min-1m-2 had higher mortality (25.4%) than those with a cardiac index > or = 2.5 l min-1m-2 (mortality 1.9%, P < 0.001). The operative mortality rate of patients with a cardiac index < 2.5 l min-1m-2 and an end-diastolic left ventricular pressure > 24 mmHg was 40.5%. Patients with a left ventricular ejection fraction of 10-20% were not significantly more at risk (P > 0.05) than those with a left ventricular ejection fraction of 21-30%.

Adult↗
PubMed1993

Use of polytetrafluoroethylene surgical membrane as a pericardial substitute in the correction of congenital heart defects.

Patients who undergo repair of congenital heart defects have a high probability of eventually needing a repeat operation. In such cases, use of a pericardial substitute can preclude adhesion formation, thereby helping to avert the complications of a repeat sternotomy. This report describes our use of the GORE-TEX polytetrafluoroethylene surgical membrane in 321 patients who underwent repair of congenital heart disease at our hospital between May of 1989 and December of 1992 (these cases account for 37.1% of all such repairs performed during this period). The patients' ages ranged from 2 days to 31 years (mean, 5.9 years). Eighty-eight patients (27.4%) had at least 1 previous median sternotomy, and 234 (73.0%) had a moderate to high probability of reoperation. Seventy-eight patients (24.3%) received a homograft, which was positioned extracardially in 63 cases. During a maximum follow-up period of 43 months (mean, 26 +/- 5.6 months), 11 patients died, for an overall mortality of 3.4%. In no case was death attributable to membrane-related complications. Postoperative complications were encountered in 12 patients (3.7%), 10 of whom required an early repeat thoracotomy. One patient had mediastinitis, for an incidence of 0.3% (in contrast to 0.2% in 864 patients who underwent similar repair without the use of a surgical membrane). No complications were encountered in the 27 patients in whom the membrane was implanted during delayed sternal closure. Seventeen patients (5.5% of the survivors) underwent a repeat sternotomy, for further correction of congenital heart defects, a mean of 20 months after the original repair. At reoperation, major complications were encountered. Although the number of reoperations was low, we conclude that use of the polytetrafluoroethylene surgical membrane for pericardial closure in children is a safe procedure that helps prevent complications at reoperation.

Adolescent↗