Telemedicine-guided, very low-dose international normalized ratio self-control in patients with mechanical heart valve implants.

AIM: To study in patients performing international normalized ratio (INR) self-control the efficacy and safety of an INR target range of 1.6-2.1 for aortic valve replacement (AVR) and 2.0-2.5 for mitral valve replacement (MVR) or double valve replacement (DVR). METHODS AND RESULTS: In total, 1304 patients undergoing AVR, 189 undergoing MVR and 78 undergoing DVR were randomly assigned to low-dose INR self-control (LOW group) (INR target range, AVR: 1.8-2.8; MVR/DVR: 2.5-3.5) or very low-dose INR self-control once a week (VLO group) and twice a week (VLT group) (INR target range, AVR: 1.6-2.1; MVR/DVR: 2.0-2.5), with electronically guided transfer of INR values. We compared grade III complications (major bleeding and thrombotic events; primary end-points) and overall mortality (secondary end-point) across the three treatment groups. FINDINGS: Two-year freedom from bleedings in the LOW, VLO, and VLT groups was 96.3, 98.6, and 99.1%, respectively (P = 0.008). The corresponding values for thrombotic events were 99.0, 99.8, and 98.9%, respectively (P = 0.258). The risk-adjusted composite of grade III complications was in the per-protocol population (reference: LOW-dose group) as follows: hazard ratio = 0.307 (95% CI: 0.102-0.926; P = 0.036) for the VLO group and = 0.241 (95% CI: 0.070-0.836; P = 0.025) for the VLT group. The corresponding values of 2-year mortality were = 1.685 (95% CI: 0.473-5.996; P = 0.421) for the VLO group and = 4.70 (95% CI: 1.62-13.60; P = 0.004) for the VLT group. CONCLUSION: Telemedicine-guided very low-dose INR self-control is comparable with low-dose INR in thrombotic risk, and is superior in bleeding risk. Weekly testing is sufficient. Given the small number of MVR and DVR patients, results are only valid for AVR patients.

Correction of aortic regurgitation after transcatheter aortic valve implantation of the Medtronic CoreValveTM prosthesis due to a too-low implantation, using transcatheter repositioning.

BACKGROUND AND AIM OF THE STUDY: Transcatheter aortic valve implantation (TAVI) has been introduced for the treatment of severe symptomatic aortic stenosis in patients not suitable for surgical valve replacement. However, a potential problem of TAVI is the development of severe aortic insufficiency after valve implantation due to a too-low implantation of the valve. METHODS: Since August 2008, a total of 33 TAVI procedures using the 18 Fr Medtronic CoreValve ReValving system has been performed at the authors' institution. RESULTS: Severe post-implantation aortic regurgitation occurred in three patients (9%), due to a too-low implantation. Two of these patients underwent a catheter-based repositioning of the valve using a standard snare; the third patient declined any further intervention. Both repositioning procedures were uneventful, with no significant residual regurgitation. CONCLUSION: Severe aortic regurgitation after TAVI with the Medtronic CoreValve system is not uncommon. If the valve is implanted too low, a catheter-based valve repositioning may be the method of choice to resolve the problem.

Efficacy and safety of very low-dose self-management of oral anticoagulation in patients with mechanical heart valve replacement.

BACKGROUND: Self-management improves oral anticoagulation control. Here we provide data of a preplanned interim analysis of very low-dose early self-controlled anticoagulation. METHODS: In a prospective, randomized, multicenter trial, 1,137 patients performed low-dose international normalized ratio (INR) self-management with a target INR range of 1.8. to 2.8 for aortic valve replacement recipients and 2.5 to 3.5 for mitral or double valve replacement recipients for the first six postoperative months. Thereafter, 379 patients continued to achieve the aforementioned INR target range (LOW group), whereas the INR target value was set at 2.0 (range, 1.6 to 2.1) for the remaining patients with aortic valve replacement and 2.3 (range, 2.0 to 2.5) for the remaining patients with mitral valve or double valve replacement. One half of this latter group had to check their INR values once a week (VL1 group) the other half twice a week (VL2 group). Patients were followed up for 24 months. RESULTS: Beyond study month six, the incidence of thromboembolic events that required hospital admission was 0.58%, 0.0%, and 0.58% in the LOW, VL1, and VL2 groups, respectively (p = 0.368). The incidence of bleeding events per patient-year was 1.16%, 1.07%, and 0.58% in the LOW, VL1, and VL2 groups, respectively (p = 0.665). Mortality rate did not differ among study groups. CONCLUSIONS: Data demonstrate the efficacy and safety of very low-dose INR self-management.

Impact of left ventricular lead position on the incidence of ventricular arrhythmia and clinical outcome in patients with cardiac resynchronization therapy.

PURPOSE: The aim of the study was to evaluate the incidence of ventricular arrhythmia and clinical outcome in patients receiving a cardiac resynchronization therapy (CRT) depending on the left ventricular (LV) lead position. METHODS: A total of 187 consecutive patients with advanced heart failure who received a CRT-implantable cardioverter defibrillator were analyzed. Forty patients (21%) had a LV lead in the anterior/apical (anterior) and 147 patients (79%) in the posterior/posterolateral (posterior) region. The total median follow-up time was 644 days. RESULTS: The incidence of ventricular arrhythmia was 35% in patients with an anterior LV lead versus 30% in patients with a posterior LV lead (p = 0.53). The 1- and 2-year mortality in the anterior LV lead group was 19% and 22%, as compared with 0.7% and 3.2%, respectively, in the posterior LV lead group (p < 0.001). In a multivariable analysis, an anterior LV lead was independently associated with an increased mortality (hazard ratio 5.88, 95% confidence interval 2.22-16.67). The major cause of death was end-stage heart failure whereas the incidence of sudden cardiac death was not different between both groups. CONCLUSIONS: Thus, biventricular pacing with an anterior LV lead seems to have no impact on the incidence of ventricular arrhythmia but may be associated with an increased mortality rate due to worsening heart failure.

Prevalence of bacterial colonization of generator pockets in implantable cardioverter defibrillator patients without signs of infection undergoing generator replacement or lead revision.

AIMS: This study was designed to evaluate the prevalence of bacterial colonization of generator pockets in implantable cardioverter defibrillator (ICD) patients without signs of infection and to analyse the impact of bacterial colonization on the incidence of device infection during follow-up. METHODS AND RESULTS: In 122 ICD patients undergoing generator replacement or surgical lead revision between January 2006 and July 2008, microbiological cultures of generator pockets and extracted leads were consecutively obtained. Patients with clinical evidence of a device infection were excluded. Positive cultures from the generator pocket and leads were found in 40 (33%) patients. The most common bacteria isolated were coagulase negative staphylococci (68%). During a median follow-up time of 203 days after the revision device infection occurred in three [7.5%, confidence interval (CI) 1.6-20.4%] patients with a positive culture vs. two (2.4%, CI 0.3-8.5%) patients with a negative culture (P = 0.33). Time from revision to infection was 108 +/- 73 days in patients with positive culture vs. 60 +/- 39 days in patients with negative culture (P = 0.50). CONCLUSION: A third of ICD patients undergoing generator replacement or lead revision have an asymptomatic bacterial colonization of generator pockets. After revision 7.5% of these patients develop a device infection with the same species of microorganism.

The impact of intravenous aspirin administration on platelet aspirin resistance after on-pump coronary artery bypass surgery.

Aspirin resistance continues to be a major challenge in patients after coronary artery bypass grafting (CABG). We investigated the impact of intravenous aspirin on platelet function in this clinical setting. Forty-two patients received 100 mg of oral aspirin once daily, beginning on day 1 after the operation. Between day 6 and 8 post operation one oral dose was replaced by an intravenous dose of 300 mg. Platelet function analyzer (PFA-100) closure times (CT), turbidimetric platelet aggregation (TPA) and impedance platelet aggregation (IPA) induced by arachidonic acid (AA), collagen and ADP were measured prior to and 1 h and 24 h after intravenous aspirin. Results obtained prior to the intravenous aspirin were compared with respective values from 120 healthy individuals. Despite the postoperative oral aspirin that was given once daily, ADP-induced TPA (ADPTPA) and IPA values induced by AA, ADP or collagen were significantly greater in patients than in controls, while PFA-100 CT were significantly shorter. Intravenous aspirin induced a significant reduction of platelet aggregability as measured by collagen/epinephrine (CEPI) CT, TPA and IPA induced by AA and collagen 1 h and 24 h after administration. Intravenous aspirin was not found to influence collagen/ADP (CADP) CT and IPA induced by ADP. Concomitantly, the number of patients with laboratory aspirin resistance as measured by CEPI-CT and TPA but not by IPA induced by AA or collagen dropped significantly. Agreement in the detection of aspirin responders and non-responders among platelet function tests was poor. Our findings indicate that the intravenous aspirin appears to be a promising approach for reducing laboratory aspirin resistance during the postoperative phase of CABG.

Low-dose oral anticoagulation in patients with mechanical heart valve prostheses: final report from the early self-management anticoagulation trial II.

AIMS: In mechanical heart valve recipients, low-dose international normalized ratio (INR) self-management of oral anticoagulants can reduce the risk of developing thrombo-embolic events and improve long-term survival compared with INR control by a general practitioner. Here, we present data on the safety of low-dose INR self-management. METHODS AND RESULTS: In a prospective, randomized multi-centre trial, 1346 patients with a target INR range of 2.5-4.5 and 1327 patients with a target INR range of 1.8-2.8 for aortic valve recipients and an INR range of 2.5-3.5 for mitral or double valve recipients were followed up for 24 months. The incidence of thrombo-embolic events that required hospital admission was 0.37 and 0.19% per patient year in the conventional and low-dose groups, respectively (P = 0.79). No thrombo-embolic events occurred in the subgroups of patients with mitral or double valve replacement. The incidence of bleeding events that required hospital admission was 1.52 and 1.42%, respectively (P = 0.69). In the majority of patients with bleeding events, INR values were < 3.0. Mortality rate did not differ between the study groups. CONCLUSION: Data demonstrate that low-dose INR self-management does not increase the risk of thrombo-embolic events compared with conventional dose INR self-management. Even in patients with low INR target range, the risk of bleeding events is still higher than the risk of thrombo-embolism.

Heparin monitoring during cardiopulmonary bypass surgery using the one-step point-of-care whole blood anti-factor-Xa clotting assay heptest-POC-Hi.

The activated clotting time (ACT) generally used for monitoring heparinization during cardiopulmonary bypass (CPB) surgery does not specifically measure heparin anticoagulant activities. This may result in heparin over- or under-dose and subsequent severe adverse events. A new point-of-care whole blood clotting assay (Heptest POC-Hi [HPOCH]) for quantifying heparin anticoagulant activity specifically was compared with ACT and anti-factor Xa (anti-Xa) heparin plasma levels (Coatest heparin) in 125 patients undergoing CPB surgery. The analytical reliability of the HPOCH and the influence of preanalytical variables on assay results were also examined. The ACT and HPOCH clotting times determined throughout the entire observation period correlated closely (n=683; r = 0.80; p < .0001). Similarly, there was a significant linear correlation between HPOCH and Coatest anti-Xa levels (n=352; r = 0.87; p < .0001). Pre- and post-CBP values of HPOCH, ACT, and anti-Xa plasma levels correlated closely with each other (correlation coefficients between r = 0.90 and r = 0.99; p < .0001). During CPB, there was no significant relationship between ACT and whole blood or plasma heparin levels determined by HPOCH (n=157; r = 0.19) and the chromogenic anti-Xa assay (n=157; r = 0.04), respectively. In contrast, HPOCH and anti-Xa plasma levels correlated strongly during CPB (n=157; r = 0.57; p < .0001). However, bias analysis showed that the HPOCH and Coatest heparin could not be used interchangeably. The HPOCH was well reproducible and not influenced by aprotinin, hemodilution, or other factors affecting ACT. The HPOCH seems to be a promising new tool for specific on-site measurement of heparin activities in whole blood during CPB.

Annual rate of transvenous defibrillation lead defects in implantable cardioverter-defibrillators over a period of >10 years.

BACKGROUND: The number of patients with longer follow-up after implantation of an implantable cardioverter-defibrillator is increasing continuously. Defibrillation lead failure is a typical long-term complication. Therefore, the long-term reliability of implantable cardioverter-defibrillator leads has become an increasing concern. The aim of the present study was to assess the annual rate of transvenous defibrillation lead defects related to follow-up time after lead implantation. METHODS AND RESULTS: A total of 990 consecutive patients who underwent first implantation of an implantable cardioverter-defibrillator between 1992 and May 2005 were analyzed. Median follow-up time was 934 days (interquartile range, 368 to 1870). Overall, 148 defibrillation leads (15%) failed during the follow-up. The estimated lead survival rates at 5 and 8 years after implantation were 85% and 60%, respectively. The annual failure rate increased progressively with time after implantation and reached 20% in 10-year-old leads (P<0.001). Lead defects affected newer as well as older models. Patients with lead defects were 3 years younger at implantation and more often female. Multiple lead implantation was associated with a trend to a higher rate of defibrillation lead defects (P=0.06). The major lead complications were insulation defects (56%), lead fractures (12%), loss of ventricular capture (11%), abnormal lead impedance (10%), and sensing failure (10%). CONCLUSIONS: An increasing annual lead failure rate is noted primarily during long-term follow-up and reached 20% in 10-year-old leads. Patients with lead defects are younger and more often female.

Evaluating a new method for maintaining body temperature during OPCAB and robotic procedures.

BACKGROUND: We evaluated the performance of a new temperature management system (Allon Thermowrap, MTRE, Israel) in maintaining normothermia during OPCAB (Off-Pump Coronary Artery Bypass) procedures and Zeus-robotic IMA (internal mammary artery) takedowns. MATERIAL/METHODS: One hundred patients were prospectively randomized to either a conventional temperature management method (thick blanket, warm intravenous fluids, operating room temperature 25 degrees C), or the new Allon Thermowrap system (pads with temperature-controlled water circulation placed on the patient's back, legs, and arms). The mean age, body surface area, total operating time, and OR air temperature were similar in both groups. RESULTS: The Allon Thermowrap system maintained a higher bladder and nasopharyngeal temperature (p<0.05). The SVR decreased (p<0.05) and the cardiac index increased (p<0.05) in patients with a body temperature>35.80 degrees C. Without reaching a significant level, the postoperative blood loss was lower in the Allon Thermowrap group. CONCLUSIONS: The Allon Thermowrap system significantly out-performed conventional techniques in achieving and maintaining normothermia during off-pump and robotic procedures.

Advanced sternal closure to prevent dehiscence in obese patients.

Sternal dehiscence is a frequent complication after cardiac surgical procedures. The objective was to evaluate a novel method for advanced sternal closure compared with standard techniques for preventing sternal dehiscence. Our investigation comprised 100 patients with a body mass index above 32. Patients were randomly assigned to receive either advanced sternal closure with three stainless steel double wires or standard techniques with stainless steel single wires. The incidence of sternal refixation was 6 of 50 patients in the standard techniques group and 1 of 50 in the advanced sternal closure group during a follow-up period of 6 months.

Relationship between factor XIII activity, fibrinogen, haemostasis screening tests and postoperative bleeding in cardiopulmonary bypass surgery.

We investigated the relationship between factor XIII, fibrinogen, blood coagulation screening tests and postoperative bleeding in 98 patients undergoing cardiopulmonary bypass (CPB) surgery. All patients received aprotinin. Blood samples were collected preoperatively (T1),after termination of CPB (T2),12 h (T3) and 24 h (T4) after surgery to determine FXIII activity, fibrinogen, platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT) and D-dimers (DD). Laboratory results were correlated with the chest tube drainage 24 h after surgery and compared between patients with 24-hour chest tube drain volumes in the lower (Group 1) with those in the upper tertile (Group 3). Median FXIII and fibrinogen levels dropped by 33.9% and 34.2%, respectively, during CPB. No association between FXIII activity and the extent of postoperative bleeding was found. However, chest tube bleeding was significantly correlated with preoperative and postoperative fibrinogen. This was confirmed by comparing Groups 1 and 3. Group 3 patients had significantly lower fibrinogen levels than Group 1 at T1 - T4, although most fibrinogen values were within or above the reference range (medians, g/l: 3.5 vs. 4.0, p = 0.043 at T1; 2.3 vs. 2.7, p = 0.015 at T2; 2.9 vs. 3.3, p = 0.008 at T3; 4.2 vs. 5.2, p = 0.002 at T4). There was also a significant relationship of platelet count, PT and APTT, as measured after CPB (T2), with postoperative chest tube drainage. In conclusion, plasma FXIII activity does not influence postoperative bleeding in patients undergoing CPB surgery. There is however an inverse association between preoperative or postoperative plasma fibrinogen levels and postoperative bleeding. These findings indicate a modulation of postoperative bleeding by fibrinogen levels.

Low-dose international normalized ratio self-management: a promising tool to achieve low complication rates after mechanical heart valve replacement.

BACKGROUND: International normalized ratio (INR) self-management can significantly reduce INR fluctuations, bleeding, and thromboembolic events compared with INR control managed by general practitioners. However, even patients with INR self-management may have an increased risk of bleeding if their INR value is above 3.5. This study evaluated the compliance, clinical complications, and survival of patients after mechanical heart valve replacement with low-dose INR self-management compared with conventional-dose anticoagulation. METHODS: Group 1 (n = 908) received low-dose anticoagulation with a target INR range of 1.8 to 2.8 for aortic valve replacement and 2.5 to 3.5 for mitral or double valve replacement. Group 2 (n = 910) received conventional-dose anticoagulation with a target INR range of 2.5 to 4.5 for all heart valve prostheses. RESULTS: In groups 1 and 2, 76% and 75% of INR values, respectively, were in the target range. Results did not differ according to schooling and age. The rate of thromboembolic events per patient year was 0.18% in group 1 and 0.40% in group 2 (p = 0.210). The rate of bleeding complications was 0.74% for group 1 and 1.20% for group 2 (p = 0.502). In most patients with clinically relevant bleeding, these complications occurred although their measured INR values were below 3.5. The survival rate did not differ between the study groups (p = 0.495). CONCLUSIONS: Low-dose INR self-management is a promising tool to achieve low hemorrhagic complications without increasing the risk of thromboembolic complications. INR self-management is applicable for all patients in whom permanent anticoagulation therapy is indicated. Even INR values below 3.5 can bear the risk of bleeding complications.

Blood-air interface during cardiopulmonary bypass.

The aim of this study was to compare the systemic blood activation with open and closed perfusion management during cardiopulmonary bypass. In 30 patients undergoing coronary artery bypass grafting, we prospectively studied systemic blood activation, blood loss and the need for donor blood. In 15 patients we used an open venous reservoir consisting of a hard shell venous reservoir with an integrated cardiotomy filter. In another 15 patients we used a totally closed venous reservoir consisting of a collapsible venous reservoir, no coronary suction, modified vent and cell saver. Venous blood samples were collected pre, post and 24 hours postoperatively. Sex, age and perfusion times were identical in both groups. There were no statistically significant differences in concentrations of FXIIa and C3a, amount of blood loss and need for donor blood. Interleukin-6 and Elastase levels showed trends toward a lesser inflammatory reaction in closed venous reservoir patients. Modification of perfusion management with optimized air management does not seem to be an effective strategy in reducing the inflammatory response and influencing the coagulation system in this small cohort.

Intracardiac left ventricular support in beating heart, multi-vessel revascularization.

BACKGROUND: Less invasive operation procedures without support of extracorporeal circulation are becoming increasingly important. A basic requirement for good long-term results in such cases is, however, the complete revascularization of the affected coronary vessels. The unsatisfactorily high conversion rate from bypass operations originally planned as off-pump to conventional operations with heart-lung machines, because of the failure to reach the target vessels on the rear wall of the heart through hemodynamic instability led to investigation of the efficiency of a microaxial pump (Impella elect) placed in the left ventricle. METHODS: In a prospective project 15 of 38 consecutive patients selected for coronary revascularization with beating heart had a micro pump transaortically implanted in the left ventricle to support the heart during the operation with a flow rate of 2.5 to 3.9 l/min. RESULTS: With 8 of 23 patients operated on without pump support, the operation had to be converted to conventional methods with a heart-lung machine. Only one patient out of the left-ventricle-supported group had to be further operated on conventionally because of a deep intramyocardial positioned left anterior descending coronary artery (LAD) (p < 0.05). The investigated laboratory parameters, especially creatine kinase (CK), CK-MB isoenzyme, and clotting showed no significant difference. There tended to be a higher blood loss recorded with the pump-supported patients. CONCLUSION: In summary, it appeared that the application of a left ventricular coaxial pump with comparable results seemed to make possible complete revascularization in nearly all patients.

Robotic surgery using Zeus MicroWrist technology: the next generation.

BACKGROUND: The use of computer-animated surgical instruments for various cardiac operations has been shown to be feasible, but to date, the available information regarding the operative and technical details of these procedures is still inadequate. METHODS: We used the Zeus (Computer Motion Inc., Goleta, Calif, USA) telemanipulation system to perform the internal mammary artery (IMA) takedown in 56 patients, in 12 of whom we used the newest model with MicroWristTM (Computer Motion Inc., Goleta, Calif, USA) technology. Port orientation was based on thoracic anatomy, the decisive landmarks being the mammillary line and the axillary line. The distance between ports was at least 9 cm, and the patient's arm was positioned with the left shoulder raised and angulated by not more than 90 degrees. RESULTS: Mean setup time was 44 +/- 18 minutes for the first five patients and 16 +/- 7 minutes for the last five patients, with an overall average of 24 +/- 12 minutes. IMA harvest time at the beginning reached a mean of 95 +/- 23 minutes and decreased to 44 +/- 18 minutes in the last five cases. Average IMA takedown time was 58 +/- 17 minutes. The IMA was patent with a good flow in all 56 patients. CONCLUSIONS: The introduction of robotic technology into clinical routine has resulted in safe procedures with a short learning curve. However, basic training in the modality is a must in order to achieve technical excellence.

Topical application of aprotinin in cardiac surgery.

The aim of our study was to compare a systemic and a local aprotinin application in patients during coronary artery bypass graft (CABG) surgery. The advantage of a topical aprotinin application is seen in the fact that this may not lead to systemic side effects. A prospective, randomized study comprising 97 patients was conducted. A dose of 5 x 10(6) KIU aprotinin was given systemically to 49 patients and four doses of 1.25 x 10(6) KIU aprotinin were applied topically to 48 patients by spraying the substance on the target area (A. mammaria interna region and pericardium). We determined markers for the inflammatory response, coagulation system, standard haematological markers and postoperative complications. Exclusion criteria were defined as surgical bleeding, redo operations, neurological, haematological, liver and kidney disorders. Sex, age, perfusion times, mortality, renal failure and strokes were identical in both groups. Biochemical markers and clinical outcome demonstrated no significant differences between the systemic and local applications. Interleukin 6 and elastase were tendentially higher (p = 0.1) in the local group, but with a high standard deviation in each patient. Our results suggest that there is no difference between the perioperative application of 5 x 10(6) KIU systemically given aprotinin and 1.25 x 10(6) KIU locally applied aprotinin.

Atrial cardiomyoplasty in a Fontan circulation.

INTRODUCTION: The Fontan circulation is a direct connection between the systemic veins and the pulmonary artery (PA). Consequently, the pulmonary flow is passive due to the gradient between the right and left atrial pressure. In patients with increased pulmonary vascular resistance, the surgical procedure of atrio-pulmonary connection is therefore prone to failure. The goal of this experiment was to increase the pulmonary flow in an experimental model of a Fontan circulation by performing a right atrial cardiomyoplasty (ACMP). METHODS: In 19 Foxhounds the left m. latissimus dorsi (LD) was mobilised and transferred as a pedicle into the chest. After sternotomy a 'Fontan circulation' was created under cardiopulmonary bypass (CPB) by connecting the right atrium (RA) with the PA by a valveless conduit. The tricuspid valve was closed with a patch. In 11 dogs (group 1) a valve was implanted in the inferior vena cava (IVC) and pulmonary inflow impedance was increased by partial occlusion of the conduit to a gradient of 10 mmHg between RA and PA. In the other eight dogs (group 2) no valve was implanted, but flowmeters were placed in the IVC and the superior vena cava (SVC). In all dogs the RA was enlarged by a fascia lata patch before the LD was wrapped over the RA and stimulated synchronously to the R-wave with burst impulses. RESULTS: After coming off CPB, relatively high central venous pressures (22.5+/-5.8 mmHg) were necessary to maintain haemodynamic stability. With LD-stimulation in a 1:3 mode in group 1, RA pressure (P) increased from 23.1+/-7.7 to 45+/-10.5 mmHg (P<0.001), pulmonary atrial pressure (PAP) from 15.5+/-4.3 to 25.5+/-7.6 mmHg (P<0.001) and central venous pressure increased to 33.1+/-11.3 mmHg (P<0.05). Stroke volume increase from 11.4+/-4.7 to 17.2+/-4.3 ml and peak conduit-flow from 1286.3+/-880.3 to 2329+/-1173 ml/min (all P<0.001). In a 1:1 stimulation mode a pulsatile pressure/flow profile was obtained in the PA-conduit. Furthermore, at higher frequencies of about 120 beats/min muscle relaxation was still fast enough as not to interfere with the RA filling. In group 2 caval flow without stimulation occurred mainly during diastole. However, with LD-stimulation, a strong backflow into IVC and SVC was observed resulting in a less pronounced pressure/flow increase in the PA. CONCLUSIONS: Our experimental model demonstrates the possibility of a 'ventricularisation' of the RA by using the force of the LD. However, the haemodynamic benefit of ACMP was achieved only, when a valve was implanted in the ICV.