A safe and simple method of preserving right ventricular function during implantation of a left ventricular assist device.
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Aorta↗
Biomedical subjects
M Loebe
Publications and source records attributed to M Loebe.
Anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and renal impairment using heparin and the platelet glycoprotein IIb-IIIa antagonist tirofiban.
BACKGROUND: Patients with heparin-induced thrombocytopenia type II require an alternative to standard heparin anticoagulation. However, in patients with renal impairment, anticoagulation during cardiopulmonary bypass with agents such as danaparoid sodium or r-hirudin are associated with hemorrhage. Anticoagulation with unfractionated heparins combined with prostacyclin, a potent platelet aggregation inhibitor, is associated with severe hypotension. The authors investigated a new concept using unfractionated heparins after platelet inhibition with the short-acting platelet glycoprotein IIb-IIIa antagonist tirofiban. METHODS: Ten patients with heparin-induced thrombocytopenia type II and renal impairment were enrolled in the investigation. All had heparin-induced thrombocytopenia type II antibodies present as proved by the heparin-induced platelet aggregation assay, the heparin-platelet factor 4 enzyme-linked immunosorbent assay, or both. In all patients, preoperative anticoagulation to an activated partial thromboplastin time of 40-60 s was performed with r-hirudin. Anticoagulation during cardiopulmonary bypass was achieved with a bolus of 400 IU/kg unfractionated heparins after a bolus of tirofiban 10 microg/kg followed by an infusion of tirofiban at a rate of 0.15 microg x kg(-1) x min(-1) until 1 h before conclusion of cardiopulmonary bypass. Additional unfractionated heparins were only administered if activated clotting time decreased below 480 s. Coagulation was monitored by a abciximab-modified TEG and the adenosine diphosphate-stimulated (20 microm) platelet aggregometry. D-dimer concentrations, as a marker of venous thromboembolism, were measured before and 12, 24, and 48 h after surgery. Postoperative antithrombotic therapy was started immediately with r-hirudin to anticoagulation to an activated partial thromboplastin time of 40-60 s. RESULTS: The postoperative blood loss ranged from 110 to 520 ml. No patient needed reexploration. In no patient was there clinical evidence of thrombosis or embolism in the postoperative period or of a critical increase of the D-dimer concentrations, suggesting venous thromboembolism. Transfusion of platelets was necessary in only two patients. CONCLUSIONS: The protocol is easy to perform and no increased postoperative bleeding and no thromboembolic complications occurred. The combination of unfractionated heparins and tirofiban may be an alternative to other anticoagulation strategies in patients with heparin-induced thrombocytopenia.
Adult↗
New strategies for the management of acute decompensated heart failure.
Acute heart failure in adults is the unfolding of heart failure in minutes, hours or a few days. Low output heart failure describes a form of heart failure in which the heart pumps blood at a rate at rest or with exertion that is below the physiological range and the metabolizing tissues extract their required oxygen from blood at a lower rate, causing a proportionately smaller oxygen amount remaining in the blood. Therefore, a widened arterial-venous oxygen difference occurs. High output heart failure is characterized by pumping blood with a rate above the physiological range at rest or during exertion, resulting in an arterial-venous oxygen difference, which is normal or low. This may be caused by peripheral vasodilatation during sepsis or thyrotoxicosis, blood shunting, or reduced blood oxygen content/viscosity (Fig. 1). The differentiation between low output heart failure versus high output heart failure is of highest importance for the choice of therapy and therefore the information and the monitoring of the systemic vascular resistance. Patients who present with acute heart failure suffer from a severe complication of different cardiac disorders. Most often they have an acute injury that affects their myocardial performance (eg, myocardial infarction) or valvular/chamber integrity (mitral regurgitation, ventricular septal rupture), which leads to an acute rise in left-ventricular filling pressures resulting in pulmonary edema.
Acute Disease↗
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↗
[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↗
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↗
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↗
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↗
Heart transplantation after mechanical circulatory support.
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Adolescent↗
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↗
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↗
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↗
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↗
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↗
Elimination of recombinant hirudin by modified ultrafiltration during simulated cardiopulmonary bypass: assessment of different filter systems.
UNLABELLED: Recombinant hirudin (r-hirudin) is being used increasingly in patients with heparin-induced thrombocytopenia type II. Renal failure has been demonstrated to prolong the half-life of r-hirudin and to cause bleeding in patients who have undergone cardiopulmonary bypass (CPB). We assessed the ability of different filter systems for modified ultrafiltration to eliminate r-hirudin in vitro using simulated CPB. r-Hirudin concentration was measured (chromogenic laboratory standard plus ecarin clotting time) before and after filtration, and its elimination was calculated using both controlled system flow and arterial inflow (separate pump). Four hemofilters (Renoflow II, Baxter; Arylane H4, Cobe; Ultraflux AV 600, Fresenius; and BCS 110 Plus, Iostra) and two plasmapheresis filter systems (ASAHI Plasmaflow OP, Diamed; and PF 2000 N, Gambro) were assessed (5 filters of each brand = 30 filters) in a closed in vitro CPB system applying conditions usually occurring during CPB. Ten plasmapheresis filters showed a greater ability than 20 hemofilters to eliminate r-hirudin (60%-70% vs 15%-42%) within the shortest time (80 vs 180 s). Among the four hemofilter systems, the Arylane H4 filter provided the most effective (42%) r-hirudin elimination. Elimination of r-hirudin was markedly improved using plasmapheresis systems, compared with hemofilter systems. Our findings may be relevant to patients with impaired renal function, who have been administered r-hirudin during CPB. IMPLICATIONS: Modified ultrafiltration may enhance the elimination of recombinant-hirudin, although plasmapheresis systems provide the most rapid and complete elimination of recombinant-hirudin during simulated cardiopulmonary bypass. The decision to use a specific system will ultimately depend on the prevailing clinical situation and overall health of the patient.
Adult↗
Device selection in mechanical circulatory support.
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Animals↗
The 'Berlin Heart' assist device.
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Heart-Assist Devices↗
[Advances and perspectives in mechanical heart assist].
Mechanical circulatory support devices were first developed to permanently replace the failing heart. Today, however, the majority of these devices are used as a mechanical bridge in patients awaiting heart transplantation. With this indication, important information on using mechanical assist devices has been assembled. We present our experience, which has been gained since 1987 in the area of patient selection, post-implant patient care and device maintenance. More than 450 patients have since been implanted with assist devices at our institution. Mechanical circulatory support may not only lead to recovery from secondary organ failure, but also to myocardial remodeling and recovery of the heart function in some patients. Additionally we report our experience with a newly developed implantable axial flow pump and discuss the possibility and costs of permanent support in some patients.
Adult↗