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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 145 records · Page 8Linked to original sources
PubMed2000

Cardiopulmonary bypass in a patient with heparin-induced thrombocytopenia II and impaired renal function using heparin and the platelet GP IIb/IIIa inhibitor tirofiban as anticoagulant.

In a patient with heparin-induced thrombocytopenia II and impaired renal function, anticoagulation during cardiopulmonary bypass was successfully performed by the use of unfractionated heparin and the platelet glycoprotein IIb/IIIa inhibitor tirofiban. Postoperative antithrombotic therapy with recombinant hirudin was immediately initiated. This regimen for anticoagulation for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia II appears to be particularly appropriate for patients with impaired renal function or for hospitals without special experience with other alternative anticoagulation strategies.

Cardiopulmonary Bypass↗
PubMed2000

The biocompound method in coronary artery bypass operations: surgical technique and 3-year patency.

BACKGROUND: Complete arterial revascularization may be unsafe in patients with a high operative risk. In patients with varicose ectatic veins, the biocompound technique, which uses unsuitable autologous veins, enables the surgeon to influence the bypass graft wall stress levels and diameter. This report summarizes the 3-year patency of 53 patients, the survival rate of 200 patients, and operative technical considerations. METHODS: Biocompound grafts were used for aortocoronary bypass in 200 patients who were considered inappropriate subjects for complete arterial revascularization and who had unsuitable saphenous veins. RESULTS: The mortality rate (30 days) of 200 patients was 3.5%. The 3-year survival rate was 88.5%. The patency rate of the left internal thoracic artery (LITA) after 3 years was 97.3%, of the native vein was 68.7%, and of the biocompound graft was 68.3%. The LITA showed a superior patency rate (p = < 0.05). CONCLUSIONS: The LITA is the first choice in coronary bypass operation. The biocompound technique is a reliable method to achieve complete revascularization in patients with a lack of suitable saphenous veins.

Aged↗
PubMed2000

Hirudin as anticoagulant for cardiopulmonary bypass: importance of preoperative renal function.

BACKGROUND: Recombinant hirudin is an alternative anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II. Although there is no neutralizing agent for recombinant hirudin, its fast renal elimination enables quick cessation of bleeding after cardiopulmonary bypass. The aim of the study was to compare anticoagulant effects of recombinant hirudin in regards to renal function in patients with heparin-induced thrombocytopenia type II. METHODS: Twenty-one patients (mean age, 65 years, and range, 35 to 82 years) underwent different complex cardiovascular procedures using recombinant hirudin as the anticoagulant for cardiopulmonary bypass. Postoperative blood loss, transfusion requirements, and hemostatic variables were compared between patients with a creatinine level lower than 1.5 mg/dL (group 1, normal renal function; n = 17 patients) and those with a creatinine level greater than 1.5 mg/dL (group 2, impaired renal function; n = 4 patients). RESULTS: The patients in group 1 showed no increased tendency toward postoperative bleeding. In contrast, all 4 patients in group 2 required reexploration for increased postoperative bleeding. They had higher activated partial thromboplastin times and transfusion requirements postoperatively. CONCLUSIONS: If recombinant hirudin is used as the anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and impaired renal function, the risk of postoperative bleeding is increased.

Adult↗
PubMed2000

In vitro cross-reactivity of danaparoid sodium in patients with heparin-induced thrombocytopenia type II undergoing cardiovascular surgery.

STUDY OBJECTIVES: To assess the cross-reactivity of danaparoid sodium in patients undergoing cardiovascular surgery. DESIGN: Prospective investigation. SETTING: A major European heart center and university hospital. PATIENTS: 81 patients who underwent cardiovascular surgery during the period between January 1998 and April 1999 and were diagnosed with heparin-induced thrombocytopenia (HIT) II. INTERVENTIONS: Testing was performed in patients who revealed a decrease in the platelet count >30% or a platelet count <100,000/microL during heparin therapy. Testing for HIT was performed by the use of the heparin-induced platelet-aggregation assay. Patients were evaluated as positive if an agglutination occurred in two of four of the 0.2 IU/mL heparin chambers. Patients were judged to be cross-reactive with danaparoid sodium when an agglutination occurred in two of four chambers that contained 0.2 IU/mL Orgaran. MEASUREMENTS AND MAIN RESULTS: 281 patients (5.4% of the patients who underwent surgery during the period of the investigation) were tested for HIT II. Of these, 81 (1.5% of the total) gave a positive heparin-induced platelet-aggregation assay and 23 (28%) revealed a cross-reactivity with danaparoid sodium. CONCLUSION: Cross-reactivity with heparin-induced platelet antibodies occurred in 28% of the patients who tested positive for heparin-platelet antibodies. In these patients, Orgaran would not have been a safe option. In patients with HIT II undergoing cardiac surgery, cross-reactivity with danaparoid sodium must be excluded before initiation of therapy with Orgaran, otherwise, or in cases of cross-reactivity, other options such as r-hirudin are preferred.

Anticoagulants↗
PubMed2000

Tricuspid valve dysfunction and surgery after orthotopic cardiac transplantation.

OBJECTIVE: The study examines the prevalence of tricuspid regurgitation and biopsy-induced flail tricuspid leaflets after orthotopic heart transplantation and evaluates the results of the tricuspid valve surgery. METHODS: By a computerized search of the databases 647 of 889 patients who survived heart transplantation for more than 30 days were identified for this study. The primary tool for rejection monitoring in our institution is the daily observation of intramyocardial ECG (IMEG) based on day-by-day changes of the maximal QRS complex amplitude. Endomyocardial biopsy with 45-cm-long sheath bioptome was performed only in doubtful IMEG and echocardiographic data and at times of annual routine heart catheterization. Tricuspid regurgitation was diagnosed clinically and by echocardiography as mild, moderate and severe. Eleven patients received prosthetic valve replacements (four bioprostheses and seven mechanical valves) and six patients underwent valve reconstruction. The choice of xenograft valve was dictated by the condition of renal function. Patient survival and incidence of tricuspid regurgitation and freedom from operation for severe tricuspid regurgitation were analyzed with Kaplan-Meier method. RESULTS: The prevalence of tricuspid regurgitation was 20.1%. Mild and moderate tricuspid regurgitation was seen in 14.5 and 3.1% of the patients, respectively, who were responsive to medical therapy and remained clinically stable in NYHA class I-II. Severe tricuspid regurgitation was seen in 16 (2.5%) patients who presented signs of an acute right heart dysfunction. Tricuspid valve pathology at operation revealed biopsy-induced rupture of the Chordae tendineae at various valve segments mostly the anterior and posterior leaflets. There was one hospital death (<30 day) and five late deaths due to infection, arrhythmia and trauma and no procedural-related or directly cardiac related death. Ten patients (62.5%) are alive at a mean follow-up time of 29.9 months (range 4-81 months) and nine survivors are in NYHA class I-II and one in class III. CONCLUSIONS: Severe tricuspid regurgitation in transplanted hearts is associated mainly with biopsy-induced injury or endocarditis. Other regimes of rejection monitoring may help to eliminate this complication. Apart from our preference of valve repair, the choice of valve substitute may be influenced by the presence or the prospect of chronic renal failure. Heart transplant patients can safely undergo valve surgery with acceptable mortality, low morbidity and excellent intermediate-term clinical results. Mild to moderate functional tricuspid regurgitation is responsive to medical therapy and non-progressive and occur in 17.6% of orthotopic transplanted hearts without having a detrimental effect on the right ventricular performance.

Aged↗
PubMed2000

Optimal conduit size for extracardiac Fontan operation.

BACKGROUND: Lack of conduit growth potential and thrombogenicity are the main drawbacks of the extracardiac Fontan operation (ECFO). Optimal size of the conduit according to the patients age and inferior vena cava diameter has not been established. OBJECTIVES: We set out to ascertain whether the optimal dimensions of the conduit could be determined before an ECFO. METHODS: Actual and expected age-related inferior vena cava diameters were compared with the extracardiac conduit diameter in 20 patients after ECFO. In 50 other pediatric and adult patients, the distance between intrapericardial part of the inferior vena cava and the undersurface of the right pulmonary artery (IVC-RPA) was measured. Cases of conduit thrombosis were analyzed. RESULTS: The actual diameter of the inferior vena cava was variable and has a weak correlation with anthropometric data and expected diameter (R=0.07-0.23, P=0.32-0.76). The IVC-RPA distance correlated with height (R=0.87, P=0.0001), but was also variable. At the age of 2-4 years and body weight 12-15 kg IVC diameter and IVC-RPA distance are equal to 60-80% of adult values. Conduit thrombosis developed in two patients with unfavorable Fontan hemodynamics and oversized conduits. CONCLUSIONS: Considering the inferior vena cava size, ECFO may be performed at the age of 2-3 years and at a body weight 12-15 kg, when a hemodynamically optimal almost adult sized conduit can be implanted. Optimization of the conduit is necessary on the basis of the actual inferior vena cava diameter and IVC-RPA distance. Anticoagulation postoperatively should be considered to prevent conduit thrombosis in patients with suboptimal Fontan circulation

Adolescent↗
PubMed2000

Medium-term results of heart transplantation using older donor organs.

BACKGROUND: Donor heart shortage has necessitated the expansion of the donor pool by the use of older hearts. PATIENTS AND METHODS: In a 13-year period, 1,070 heart transplants were performed in 1,035 adults at the German Heart Institute Berlin. We divided the patients into 3 groups: Group I, donor age <35 years (n = 524); Group II, donor age 35 to 50 years (n = 379); Group III, donor age >50 years (n = 167). We analyzed post-operative mortality (up to 30 days), cumulative survival rates, cardiac dependent morbidity, and changes in the left/right ventricular ejection fraction as well as freedom from cytomegalovirus infection and freedom from acute rejection episodes grade >/= 2 (International Society for Heart and Lung Transplantation). We also calculated the rate of cardiac interventions per patient in the groups. RESULTS: Recipients in Group III were significantly older, compared with Groups I and II. The post-operative mortality was 16.8% in Group I, 29.8% in Group II, and 23.4% in Group III. The differences were significant (p = 0. 00001) between Group I and Group II. The long-term cumulative survival rates were significantly better in Group I when compared with Groups II and III (p < 0.00001, p = 0.014), but it did not differ between Groups II and III (p = 0.18). However, cardiac morbidity in Groups I and II was significantly lower when compared with Group III (p = 0.0009, p = 0.037). Mean left and right ventricular ejection fraction was >55% and did not significantly change in groups for up to 10 years. Freedom from cytomegalovirus infection was not significantly different between Groups II and III (p = 0.09). Significantly fewer percutaneous transluminal coronary angioplasties were performed in Group I, but comparable numbers were carried out in Groups II and III (p = 0.53). For retransplantation a similar situation occurred. CONCLUSION: We did not find significant differences in the mid-term follow-up between patients who received hearts from 35- to 50-year-old donors and from those who had received hearts from donors >50 years, despite increased cardiac morbidity in Group III. Close monitoring of the coronary situation after heart transplantation and expanded indications for revascularization in Group III makes heart transplantation with older hearts a suitable option to save the lives of patients in end-stage heart failure.

Adult↗
PubMed2000

Surgical treatment of active infective aortic valve endocarditis with associated periannular abscess--11 year results.

AIMS: The aim of the study was to evaluate the long-term results of allograft and prosthetic valve replacement in the treatment of infective aortic valve endocarditis with periannular abscess. METHODS: Between March 1988 and March 1996, 65 patients underwent surgery for active aortic valve endocarditis and paravalvular abscess. The indications for surgery were congestive heart failure, systemic emboli and atrioventricular block III. The pre-operative evaluation was performed with transoesophageal echocardiography. Aortic valve replacement was performed with allografts in 47 cases, with mechanical valves in 15, and bioprosthetic valves in three cases. All patients with total ventricular-aortic dehiscence and prosthetic valve endocarditis were treated with allografts. RESULTS: The 30-day mortality rate was 23.5% in the prosthetic group, when compared with 8.5% in the patients treated with allografts. The rate of recurrent valve infections during the 11-year follow-up period was 27.1% in the prosthetic group and 3.2% in the allograft group. The actuarial 11-year survival rate was 82.1% in the allograft group and 64.7% in the prosthetic group. CONCLUSION: Aortic allografts are an effective treatment for infective aortic valve endocarditis with associated periannular abscess. The operative mortality and recurrent infection rates are lower than in the prosthetic group, resulting in a significantly higher survival rate. Diagnosis and surgical management of these cases should be based on pre-operative transoesophageal echocardiography.

Abscess↗
PubMed2000

[Pre- and postoperative evaluation of ventricular function, muscle mass and valve morphology by magnetic resonance tomography in Ebstein's anomaly].

PURPOSE: To evaluate the value of MRT with spin echo (SE) and CINE gradient echo (GE) sequences for the pre- and postoperative assessment of patients with Ebstein's anomaly. METHODS: Twelve patients within the ages of four to 49 years (mean 22 +/- 12 years) were examined pre- (n = 5) or postoperatively (n = 7) after tricuspid valve reconstruction with a 1.5 T scanner. For the anatomical assessment, an ECG-gated transverse SE-sequence, for the assessment of valve morphology and function as well as for volumetry a CINE GE-sequence with retrospective gating was used. With the use of the multislice-multiphase technique, after summing up the manually outlined epi- and endocardial areas, endsystolic (ESV) and enddiastolic volumes (EDV), ejection fraction (EF), stroke volume (SV), and muscle mass (MM) were calculated for both ventricles. RESULTS: The differentiation of the displaced parts of the tricuspid valve (TV) was insufficient with static SE, but was possible in all patients with CINE-MRT. Like in Doppler echocardiography, a qualitative assessment of tricuspid insufficiency was possible in CINE-MRT, the mean incompetence grade preoperative was 1.8 (+/- 0.8), postoperative 0.7 (+/- 0.5). The mean RV-EF in the preoperative group was 41.8% (+/- 6.4), in the postoperative group 47.9% (+/- 10.6), the mean LV-EF preoperative 47.4% (+/- 8.5%), postoperative 63.0% (+/- 9.4). CONCLUSION: CINE-MRT should rather be used than SE for the assessment of valve morphology. EF, muscle mass and tricuspid incompetence can also be calculated pre- and postoperative with CINE-MRT.

Adolescent↗
PubMed2000

The correction of congenital heart defects with less invasive approaches.

BACKGROUND: The minimally and less invasive approaches for the surgical treatment of different heart diseases are rapidly increasing because of their cosmetic and recovery-related advantages. Presented here are the results of less invasive surgery in 51 patients with congenital heart defects. METHODS: From June 1996 to January 1999, we used less invasive techniques for the correction of congenital heart defects in 51 patients. In 32 patients, we performed right anterolateral thoracotomy (6-13 cm), and on the other 19 patients, we used the partial inferior sternotomy (4-7 cm). The ascending aorta and the caval veins were cannulated in all patients. RESULTS: The following congenital heart defects were corrected: ostium secundum atrial septal defect (n = 35), sinus venosus atrial septal defect with partial anomalous pulmonary venous connection (n = 7), ventricular septal defect (n = 7), tetralogy of Fallot (n = 1), and cor triatriatum sinistrum (n = 1). The average age of the patients was 15 years old ranging from 2 months to 48 years and the average weight 39.6 kg (range 3.8-86 kg). The patients were removed from artificial respiratory support on average 8 hours (range 1-48 hours) after surgery and left the hospital after 7 days (range 2-10 days). In 16 patients, blood transfusions were required, an average 5.7 ml/kg BW (range 1.45-19.75 ml/kg BW). The postoperative course was uneventful in all patients. Follow-up (range 3-33 months, mean 17.5 months) was complete with no late deaths or residual defects. CONCLUSION: The right anterolateral thoracotomy and the partial inferior sternotomy provide a safe approach for the correction of certain congenital heart defects. These techniques enable operative correction without any additional risks being incurred and can be performed with standard instruments and cannulation. Additional approaches for extracorporeal circulation are unnecessary.

Adolescent↗
PubMed2000

A quick assay for monitoring recombinant hirudin during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II : adaptation of the ecarin clotting time to the act II device.

BACKGROUND: Recombinant hirudin is increasingly advocated as a promising alternative anticoagulation for patients with heparin-induced thrombocytopenia type II during cardiopulmonary bypass. This requires monitoring of the ecarin clotting time. No commercial ecarin clotting time assay is available for clinical use. We adapted the ecarin clotting time to the easy-to-handle ACT II device. METHODS: Three different concentrations of the ecarin reagent (20, 10, 5 U/mL) were investigated as preliminary studies. Standard calibration curves were constructed for concentrations of recombinant hirudin ranging from 0 to 5 microgram/mL. In vivo samples were collected from patients with heparin-induced thrombocytopenia type II who underwent cardiopulmonary bypass, and the values were compared with the values obtained by the chromogenic method. The final concentration for the assay of 5 IU/mL ecarin was further assessed in vitro for reproducibility and the influence of variations in hematocrit, platelet count, and procoagulants. RESULTS: All three concentrations of ecarin revealed linearity to 5 microgram/mL concentrations of recombinant hirudin. The ecarin concentration of 5 U/mL revealed the best correlation (0.87) to the laboratory method, was reproducible over the whole recombinant hirudin range, and was not influenced by the variations in the in vitro setup. CONCLUSIONS: The ACT II/ecarin clotting time with an ecarin concentration of 5 U/mL is a simple and reliable assay for monitoring recombinant hirudin during cardiopulmonary bypass. Use of this assay allows a wider use of recombinant hirudin in patients with heparin-induced thrombocytopenia type II during bypass and thereby may contribute to the safer management of these patients.

Anticoagulants↗
PubMed2000

Midterm follow-up of patients who underwent removal of a left ventricular assist device after cardiac recovery from end-stage dilated cardiomyopathy.

OBJECTIVE: Cardiac recovery in end-stage idiopathic dilated cardiomyopathy recently occurred after temporary support with a left ventricular assist device. We report the case histories of patients who underwent removal of the device more than 4 years ago. METHODS: Since June 1994, 23 patients with end-stage idiopathic dilated cardiomyopathy who were supported by a left ventricular assist device or biventricular assist device for 1 to 26 months (mean, 6 months) underwent removal of the device after complete or extensive cardiac recovery, as revealed by echocardiography. RESULTS: Seven patients (group A) had recurrent cardiac failure after 4 to 24 months. Transplantation was performed in 6 patients, and one died while on the waiting list. Three patients died of noncardiac causes within a period of 4 months and 3 days after removal of the assist device. Stable cardiac recovery occurred in 13 patients (group B) for 3 to 49 months (mean, 23 months). At the time of implantation, there were no significant differences between the groups with regard to age, hemodynamics, left ventricular ejection fraction, left ventricular internal diameter in diastole, and autoantibody levels. The increase of ejection fraction and the decrease of left ventricular internal diameter in diastole after 2 months were highly significant. The patients in group A had longer histories of heart failure and first cardiac symptoms and duration of assist when compared with group B. Group B demonstrated a quicker cardiac recovery on the assist device, and thus support was shorter. Also, the degree of recovery at assist device explantation was more complete in group B. The age at the time of device placement was the only influencing factor for duration on the assist device. The probability of recurrence of heart failure was influenced by the duration of heart failure. CONCLUSIONS: In selected patients with idiopathic dilated cardiomyopathy, lasting recovery can be achieved after unloading with a left ventricular assist device. Lasting cardiac recovery seems to be related to functional normalization and a more rapid recovery during the unloading period.

Adolescent↗