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Biomedical subjects

A Haverich

Publications and source records attributed to A Haverich.

At least 343 records · Page 19Linked to original sources
PubMed1991

Distinct down-regulation of cardiac beta 1- and beta 2-adrenoceptors in different human heart diseases.

Cardiac beta-adrenoceptor density and beta 1- and beta 2-subtype distribution were examined in human left ventricular myocardium from transplant donors serving as controls and from patients with mitral valve stenosis, aortic valve stenosis, idiopathic dilated cardiomyopathy, and ischaemic cardiomyopathy respectively. The total beta-adrenoceptor density was similar in transplant donors and patients with moderate heart failure (NYHA II-III) due to mitral valve stenosis, but was markedly reduced in all forms of severe heart failure (NYHA III-IV) studied. A reduction of both beta 1- and beta 2-adrenoceptors was found in patients with severe heart failure due to mitral valve stenosis or ischaemic cardiomyopathy. In contrast, a selective down-regulation of beta 1-adrenoceptors with unchanged beta 2-adrenoceptors and hence a relative increase in the latter was observed in idiopathic dilated cardiomyopathy and aortic valve stenosis. It is concluded that the extent of total beta-adrenoceptor down-regulation is related to the degree of heart failure. Selective loss of beta 1-adrenoceptors is not specific for idiopathic dilated cardiomyopathy but also occurs in aortic valve stenosis. Changes in beta 1- and beta 2-subtype distribution are rather related to the aetiology than to the clinical degree of heart failure.

Adult↗
PubMed1991

Extracorporeal membrane oxygenation as a bridge to lung transplantation.

The occurrence of severe graft failure after lung transplantation which appears refractory to conventional treatment represents a difficult situation with regard to the therapeutic strategies available. Of 17 patients undergoing single lung transplantation at our center, 2 developed early graft failure. In both, temporary artificial cardiopulmonary support by means of extracorporeal membrane oxygenation became necessary as a bridge to retransplantation. Both patients were successfully retransplanted after 8 h and 232 h, respectively, of extra-corporeal support. Postoperatively, there was a variety of complications. The first patient completely recovered from temporary severe cerebral dysfunction diagnosed as "locked-in syndrome". She was discharged from hospital on the 93rd postoperative day and remains alive and well 10 months after her operation. The other patient recovered well early after retransplantation. Later, however, airway problems developed, requiring the implantation of endotracheal stents. Cachexia and several episodes of viral pneumonia contributed to the progressive deterioration of her clinical status. She finally died after being hospitalized for 5 months after the original operation. These two cases illustrate the feasibility of using extracorporeal membrane oxygenation as a bridge to pulmonary transplantation.

Adult↗
PubMed1991

Intraoperative echocardiography to detect and prevent tricuspid valve regurgitation after heart transplantation.

Tricuspid valve regurgitation (TVR) is frequently observed following orthotopic heart transplantation. The etiology of this phenomenon remains unclear. In a prospective study, we tried to identify pre-, intra- and postoperative factors possibly related to the occurrence of TVR in 15 patients (14 male, 1 female). Epicardial echocardiography was used during the transplant procedure and transthoracic echocardiography was performed at weekly intervals thereafter, TVR was graded semiquantitatively (grade 0-4). If TVR grade greater than 1 was detected after discontinuation of cardiopulmonary bypass, pericardial reduction plasty was performed (group R). If no or mild TVR (less than grade 1) was present, simple closure of the pericardium was carried out (control group). In group R the mean grade of TVR was 1.6 +/- 0.3 (SEM) before and 0.6 +/- 0.07 after pericardial closure (p less than 0.05). Following moderate elevation during the first 5 weeks, the degree of TVR reached levels slightly above the initial levels after 8 weeks. In the control group, a moderate increase of TVR developed during the first 8 weeks after surgery and remained at a significantly higher level than in group R (p less than 0.05). No preoperative risk factors for TVR, such as underlying disease or hemodynamic status of the recipients, was identified. Estimation of differences in heart volume between recipient and donor organs, by contrast, showed a significant discrepancy in group R but not in the controls. We therefore conclude that TVR in recipients of orthotopic heart transplants may be due to a size mismatch of donor heart and recipient pericardial cavity, resulting in distortion of the tricuspid valve ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Bronchial circulation after experimental lung transplantation: the effect of direct revascularization of a bronchial artery.

Direct revascularization of a bronchial artery has been proposed as a measure to alleviate the problem of bronchial ischemia after lung transplantation. To assess the effect of restoration of arterial blood flow to the transplanted bronchus, bronchial mucosal blood flow was measured in a model of modified unilateral lung transplantation in pigs. Laser Doppler velocimetry (LDV) and radioisotope studies using radio-labeled erythrocytes (RI) were used to measure blood flow at the donor main carina (DC) and upper lobe carina (DUC) after 3 h of reperfusion. The recipient carina was used as a reference point; values obtained by LDV and RI were expressed as percentage of blood flow at the recipient carina. Two groups of animals were studied. In group 1 (n = 6) standard unilateral transplantation was performed; in group 2 (n = 6) a left bronchial artery was reimplanted into the descending thoracic aorta of the recipient. No differences were observed between the two groups with respect to preoperative or postoperative gas exchange or hemodynamics. In group 1, bronchial blood flow at the DC was 37.6 +/- 2.2% (LDV) and 44.1 +/- 14.8% (RI) of reference blood flow. At the DUC, blood flow was 54.9 +/- 7.7% (LDV) and 61.6 +/- 25.7% (RI) of normal flow. In group 2, blood flow was increased at the DC as measured by LDV (55.3 +/- 17.1%; p less than 0.05) and by RI (60.8 +/- 25.3%; p less than 0.2). A similar increase was found at the DUC (LDV: 81.8 +/- 19.3%; p less than 0.05; RI: 88.6 +/- 31.0%; p less than 0.2). It is concluded that there is a significant gradient of blood flow from intra- to extrapulmonary airways after lung transplantation. Reimplantation of a bronchial artery results in significant improvement of graft bronchial blood flow. Restoration of bronchial perfusion to normal levels, however, cannot be achieved, suggesting a possible defect in the microcirculation of the donor airways.

Animals↗
PubMed1991

Hyperacute rejection in heart allografts. Case studies.

Hyperacute rejection in orthotopic heart allografts is a rare event. In our material from a total collective of 524 heart-transplanted patients, we have observed two cases of hyperacute rejection, which are presented in this case report. Histopathologically, this entity is characterized above all by the following triad: pronounced edema, hemorrhages, and regressive changes up to necroses of myocytes. Besides the well-known risk factors, our report draws attention to two further factors possibly associated with an increased risk of hyperacute rejection: 1) repeated cardiac surgery prior to the transplantation, and 2) presence of identical viral genomes in recipient's and donor's heart.

Adult↗
PubMed1991

Growth of lung allografts after experimental transplantation.

Heart and lung transplantation has been performed in cases of end-stage cardiopulmonary disease in infants. Nevertheless, it still remains unclear whether lung allografts adjust to a growing organism. In 6 young domestic pigs unilateral left lung allotransplantation was performed. Immunosuppression consisted of a triple drug therapy including cyclosporine, azathioprine, and corticosteroids. Lung growth was studied by using bronchography, pulmonary angiography, and lung histology. After 11 weeks the transplanted animals had doubled their body weight from 24 kg to 48 kg. Non-transplanted animals in contrast doubled their weight within only 6 weeks. The growth retardation was attributed to the immunosuppressive therapy. The bronchial tree and pulmonary vasculature of lung allografts showed a similar growth potential to non-transplanted lungs in animals of equivalent body weight. In one case of recurrent severe rejection of the lung no growth was observed. Therefore it was concluded that lung allografts grow adequately according to the development of the recipient organism. Lung transplantation in children does not seem to be restricted by a limited growth potential of the graft.

Animals↗
PubMed1991

Organ preservation for heart-lung and lung transplantation.

One of the most important restrictions in the field of heart-lung- and lung-transplantation remains the limited ischemic tolerance of the lung. From December 1987 through February 1991, 44 patients underwent either single-, double-, or heart-lung-transplantation. All organs were harvested in multiorgan procedures. For the first 4 patients core cooling of the donor was used. For the rest pulmonary artery flush with modified Euro-Collins solution and prostacyclin was employed. Ischemia time varied from 3-6.5 hours (mean 241; 176-390 minutes). Hearts were arrested with St. Thomas cardioplegia. Oxygenation was satisfactory at 24 hours: p O2 greater than 100 mmHg, FI O2 less than 30% oxygen. It is concluded that for lung preservation modified Euro-Collins solution and prostacyclin for flush perfusion of the pulmonary artery will result in excellent lung function early postoperatively with ischemic times up to 6.5 hours. This method seems advantageous compared to others due to the limited surgical and instrumental needs.

Adult↗
PubMed1991

Collagen-presealed or uncoated aortic bifurcation Dacron prostheses: a 5-year clinical follow-up study.

A total of 70 patients undergoing replacement of the aortic bifurcation between October 1983 and June 1985, were studied 5 years postoperatively for graft patency. In 35 cases a collagen-coated knitted Dacron prosthesis (group I) was implanted, while an identical, but uncoated, Dacron graft was used in a second group of 35 patients (group II). Distribution of vascular risk factors were similar in both patient groups. The underlying disease was aortoiliac occlusive disease in 24 patients of group I and in 33 of group II. Aortoiliac aneurysmal disease was present in 10 patients of group I and in 2 patients of group II. One patient of group I was suffering from Takayasu's disease of the descending type. At follow-up, all grafts were patent in group I, while in group II 8 distal limb occlusions occurred between 6 and 46 months postoperatively. This represents a 5-year limb patency rate of 100% for collagen-presealed grafts versus 88.6% for uncoated prostheses (p less than 0.01). A higher incidence of distal anastomotic aneurysms was found in group I (7/70 limbs) compared to group II (1/70 limbs) (p less than 0.05). It is concluded that long-term patency of knitted Dacron prostheses in aortic bifurcation replacement is not reduced by presealing with collagen. It appears that this type of coating may actually enhance long-term patency after reconstruction of the aortoiliac axis. The higher rate of distal anastomotic aneurysm formation in patients with presealed grafts, however, could not be correlated with a failure of the sealant material or with the underlying disease of the patients involved.

Aorta, Abdominal↗
PubMed1991

Signs of endothelial inflammation in human heart allografts.

The expression of leucocyte adhesion facilitating molecules on endothelia is a major stimulus for tissue inflammation and cell infiltration. Recently, specific receptor ligands have been identified that mediate cellular adhesion of lymphocytes or monocytes. In the present study, sequential changes in the expression of immune adhesion receptors (LFA-1, CD2) and their ligand molecules (ICAM-1, LFA-3) were studied in heart allografts during rejection. Consecutive endomyocardial biopsies (n = 157; d.3-1013) of 16 heart transplanted patients were studied using monoclonal antibodies and standard immunohistology. In biopsies that showed no rejection, immune adhesion molecules (ICAM-1) were weakly expressed on a few endothelial cells. ICAM-1 was induced on blood vessel and capillary endothelia during rejection. After treatment, expression declined, as did the clearance of infiltrates. Occasionally, ICAM-1 persisted on capillaries compared with class II MHC expression. Weak LFA-3 induction on endothelia was observed in acute rejection, similar to ICAM-1, however LFA-3 expression was more restricted. Infiltrating lymphocytes expressed the adhesion receptor molecules LFA-1 and/or CD2. The variability of expression of ICAM-1 and FA-3 ligand molecules was related to the inflammatory changes in the graft during acute rejection. It is likely that the induction of adhesion ligand molecules in tissue is regulated by systemic and local release of cytokines, and is an initiating step in graft infiltration. The demonstration of immune adhesion-molecule induction in heart graft rejection may also be applicable to inflammatory heart disease in viral myocarditis.

Antigens, CD↗
PubMed1991

Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography. Comparison of the transthoracic and transesophageal approaches.

This study was conducted in 46 patients with cardiac thrombi, 15 patients with atrial myxomas, and 32 patients with other cardiac or paracardiac tumors. Diagnoses were subsequently proven by surgery, autopsy, computed tomography, magnetic resonance imaging, or angiography in all patients. All patients underwent precordial and transesophageal two-dimensional echocardiography to assess the various mass detection rates. Atrial myxomas and predominantly left-sided cardiac tumors were identified by both echocardiographic techniques with comparable detection rates. Left ventricular apical thrombi were detected more frequently by precordial echocardiography. In contrast, transesophageal echocardiography was superior in visualizing left atrial appendage thrombi, small and flat thrombi in the left atrial cavity, thrombi and tumors in the superior vena cava, and masses attached to the right heart and the descending thoracic aorta. These data indicate that transesophageal echocardiography leads to a clinically relevant improvement of the diagnostic potential in patients in whom cardiac masses are suspected or have to be excluded in order to ensure the safety of clinical procedures.

Adult↗
PubMed1991

Extracorporeal membrane oxygenation (ECMO): extended indications for artificial support of both heart and lungs.

Extracorporeal membrane oxygenation (ECMO) was used to achieve temporary artificial support in cardiac and pulmonary function in 22 patients from 1987 to September 1990. Standard indications were postcardiotomy cardiogenic shock (n = 4), neonatal (n = 1) and adult respiratory distress syndrome (n = 4). ECMO was also used for extended indications, such as graft failure following heart (n = 11) or lung transplantation (n = 2). In six of these cases ECMO was instituted as a bridge device to subsequent retransplantation of either the heart (n = 4) or one lung (n = 2). One out of nine patients supported by ECMO for standard indications, and two out of 13 patients supported for extended indications are long-term survivors. This series illustrates the results with ECMO in emergency situations, in patients under immunosuppressive protocols, or in patients with advanced lung failure requiring almost complete artificial gas exchange. In such complex situations, ECMO does provide stabilization until additional therapeutic measures are in effect. ECMO cannot be recommended for postoperative cardiogenic shock but short-term ECMO support is an accepted method in most cases with graft failure or pulmonary failure or other origin.

Adult↗
PubMed1991

[Hemodynamic characteristics of heart transplant patients in the early postoperative period].

In spite of good long-term results, heart transplantation continues to carry a significant risk of hospital mortality (about 10%). Among cardiac deaths, right-heart failure due to an elevated pulmonary vascular resistance represents a main contributing factor. Since no quantitative data on the hemodynamic situation early after transplantation are available, we monitored 27 heart transplant patients during the first four postoperative days. Data derived from right-heart catheterization, dosages of catecholamines and vasodilative substances were measured at 2, 4, 16, 24, 48, 72, and 96 h after the operation. Oxygen consumption and serum lactate levels were determined until 48 h postoperatively. During that time cardiac output remained constant (2 h: 6.6 +/- 1.4 l/min). The dosage of catecholamines was highest immediately after transplantation (2 h: 0.229 +/- 0.136 micrograms adrenaline/kg/min) and could be reduced thereafter. Highest values of pulmonary vascular resistance were obtained 2 h postoperatively (160 +/- 48 dyn.s.cm-5). This early postoperative situation may result in the development of right-heart failure as observed in two patients who died despite the use of prostacycline on the third and eighth postoperative days. To counteract the systemic vasodilative side-effects of prostaglandins, temporary atrial pacing seems to be useful. In our study atrial stimulation led to an increase of cardiac output and a moderate elevation of mean arterial blood pressure. Only a poor correlation between pre- and postoperative (2-h) pulmonary vascular resistance data could be observed. In most patients the pulmonary vascular resistance decreased during the postoperative course. This was not the case in patients with fixed pulmonary hypertension. We, therefore, conclude that preoperative diagnostics should be refined to recognize patients at risk in order to reduce postoperative mortality.

Adult↗
PubMed1991

[Unilateral lung transplantation in terminal pulmonary emphysema].

Early attempts of single lung transplantation for end-stage chronic obstructive pulmonary disease mostly failed due to a ventilation-perfusion mismatch between the allograft and the contralateral native lung. We performed unilateral lung transplantation in a 39-year-old female with severe pulmonary emphysema and could demonstrate in a one year follow-up that the transplanted lung will be given preference for both--ventilation and perfusion in approximately the same ratio (80%/90%). With improvement of pulmonary preservation, individual adjustment of immunosuppression and detailed monitoring of the transplanted lung unilateral lung transplantation becomes a therapeutical option in patients with severe emphysema.

Adult↗
PubMed1991

[Propofol for induction and maintenance of anesthesia during heart surgery. Results of pharmacological studies in man].

Numerous reports have concluded that propofol is suitable for maintenance of anesthesia by continuous infusion. The aim of this study was to evaluate the use of propofol and fentanyl for coronary bypass surgery in patients with good left ventricular function. The effects of this anesthetic combination on quality of anesthesia, hemodynamic status, and endocrine and metabolic responses were assessed. Postoperative recovery and side effects were also noted. The effects were compared with those of a standard method using etomidate, midazolam, and fentanyl. METHODS. Twenty patients who presented for aortocoronary bypass surgery (NYHA class II-III) were randomly allocated to one of two groups: propofol-fentanyl (group A) or etomidate-midazolam-fentanyl (group B). In each patient the dosage of the drugs was adjusted to obtain the optimum responses during induction and maintenance. RESULTS. Propofol in combination with fentanyl diminished mean arterial pressure (-28.7%) and heart rate (-17.3%) when used for induction in patients with ischemic heart disease, even in low doses and with slow administration. In 5 of the 10 patients it was impossible to prevent a critical fall in coronary perfusion without active intervention. However, during maintenance anesthesia, stable circulatory parameters were obtained with both drug regimens. Clinical signs thought to reflect myocardial ischemia were not observed. In both groups reductions in basal and stimulated catecholamine secretion were demonstrated. Similarly, perioperative cortisol secretion was reduced with both techniques. Despite all the complicated metabolic inhibitory effects seen, preoperative hormonal levels were restored within 1 h of the end of anesthesia. The magnitude and duration of the metabolic changes were found to be related to the duration of surgery. There was no evidence of non-homogeneous tissue perfusion as assessed by increases in lactate concentration, cardiac ischemia, or liver dysfunction in any of the patients. There were no postoperative complications in either group, but the return of consciousness, adequate spontaneous ventilation, and psychomotor activity was more rapid in the propofol patients. CONCLUSION. In summary, it can be concluded that a propofol infusion technique positively enhances the recovery period after cardiac surgery and provides good control during anesthesia. However, the use of propofolfentanyl for induction of anesthesia in patients with limited coronary perfusion is not recommended because of its hypotensive effect.

Anesthesia, Intravenous↗