Load Dependency of Right Ventricular Performance Is a Major Factor to be Considered in Decision Making Before Ventricular Assist Device Implantation

Background—

Left ventricular assist devices (LVADs) provide better outcome than biventricular devices, but it is a challenge to predict the impact of LV mechanical unloading on postoperative right ventricular (RV) function preoperatively. We assessed the load dependency in RV performance before and after LVAD implantation aiming to improve preoperative decision making.

Methods and Results—

Laboratory, echocardiography, and right heart catheterization data collected from 205 patients before LVAD implantation were tested for relationship with postoperative RV function. Comparing patients with different time-course of RV function after LVAD implantation, we found significant differences ( P <0.01) in preoperative RV end-diastolic short-/long-axis and long-axis/length-area ratios, tricuspid annulus peak systolic velocity, RV peak longitudinal global systolic strain rate, systolic pressure gradient between RV and right atrium (Δ P RV−RA ), tricuspid regurgitation velocity-time integral, and pulmonary arterial pressure between patients with and without postoperative RV failure. High predictive values for postoperative RV failure were found for end-diastolic short-/long-axis ratio ≥0.6, tricuspid annulus peak systolic velocity <8 cm/s, and peak systolic longitudinal strain rate <0.6/s in patients with maximum Δ P RV−RA <35 mm Hg. These parameters also seemed predictive for RV failure in patients with tricuspid regurgitation grade >2 and pulmonary arterial pressure <50 mm Hg. End-diastolic short-/long-axis ratio <0.6, tricuspid annulus peak systolic velocity ≥8 cm/s, and peak systolic longitudinal strain rate ≥0.6 in patients with maximum Δ P RV−RA ≥35 mm Hg showed high predictive values for postoperative freedom from RV failure. The RV load adaptation index seemed particularly predictive for RV function after LVAD implantation.

Conclusions—

RV geometry and velocity of contraction before LVAD implantation become more predictive for postoperative RV function and can improve decision making before VAD implantation if preoperative RV pressure load and tricuspid regurgitation are also considered.

Expeditious and less traumatic explantation of a heartware LVAD after myocardial recovery

After 169 days on left ventricular assist device (LVAD) support, a 62-year-old male patient suffering from idiopathic dilatative cardiomyopathy showed signs of left ventricular recovery. Off-pump trials were done, and our explantation criteria were met. The LVAD removal procedure was performed after 338 days on the device, using a left lateral thoracotomy in the sixth intercostal space. First, the outflow graft was transected and the distal end was sewed. Then, the pump was replaced by an individually manufactured titanium plug. Finally, the driveline was cut so that the device could be completely withdrawn. The rest of the driveline was accessed through a small abdominal incision and explanted through the percutaneous exit site.

[Improvements in implantable mechanical circulatory support systems : literature overview and update]

In recent years, ventricular assist devices (VAD) supporting the left (LVAD), the right (RVAD) or both ventricles (BVAD) have rapidly emerged as the standard of care for advanced heart failure patients. Both the numbers and ages of patients in which they are used are rising worldwide, especially when used as a permanent support (bridge to destination, BTD). Due to the continuing lack of donor organs, these devices now represent a viable alternative to bridge patients to transplantation (BTT), with a 1-year survival rate of 86%. BTD, especially in long-term support, might be a valid, and the sole, option for those patients in whom heart transplantation is contraindicated. Patient selection, pre- and intra-operative preparation, as well as the timing of VAD implantation are important factors critical to successful circulatory support. While BTT remains the goal in the majority of patients, the number of permanent VADs (i. e. BTD) is rising significantly. Although explantation of a VAD system as a bridge to recovery (BTR) can be considered in only a small number of patients, it represents a very special part of this therapy modality.

Argatroban anticoagulation for heparin induced thrombocytopenia in patients with ventricular assist devices

BACKGROUND

Patients receiving implantation of ventricular assist devices (VAD) suffer a high incidence of heparin induced thrombocytopenia (HIT); the occurrence of this condition is associated with increased complications and worse outcomes. We report our experience in the management of patients who were diagnosed with HIT either before (HITpre) or after (HITpost) implantation of VAD with argatroban, a direct thrombin inhibitor.

METHODS

This retrospective analysis assessed data of VAD patients diagnosed with HIT at Deutsches Herzzentrum Berlin between November 2005 and April 2009. Argatroban dose requirements, anticoagulation efficacy and adverse events (death, thromboembolism, bleeding) were recorded. Procedural success (discharge from the hospital, heart transplantation, or recovery of the failing heart) was also assessed.

RESULTS

Twenty-seven patients were identified (11 HITpre, 16 HITpost). Argatroban was effective in obtaining adequate anticoagulation with a reduced dose regimen (0.02-0.42 mcg/Kg/min starting dose; 0.02-1.5 mcg/Kg/min maintenance dose). We noted 5 thromboembolic complications (18%), 6 cases of major bleeding (22%) and 5 deaths (18%), all cause composite adverse end point occurring in 40% of patients. Procedural success was obtained in 81% of patients (92% HITpre, 69% HITpost). As compared to historical controls of patients treated with lepirudin in the period 2000-2005, results were significantly improved.

CONCLUSION

Argatroban anticoagulation is feasible in patients with HIT after VAD implantation, without increasing bleeding risk. Its impact in terms of survival should be reviewed also in the light of the technological improvements of assist devices.

Biventricular Circulatory Support With Two Miniaturized Implantable Assist Devices

Background—

Up to 30% of patients with end-stage heart failure experience biventricular failure that requires biventricular mechanical support. For these patients, only bulky extracorporeal or implantable displacement pumps or the total artificial heart have been available to date, which enables only limited quality of life for the patients. It was our goal to evaluate a method that would allow the use of 2 implantable centrifugal left ventricular assist devices as a biventricular assist system.

Methods and Results—

Seventeen patients have been implanted with 2 HeartWare HVAD pumps, 1 as a left ventricular assist device and 1 as a right ventricular assist device. Seventy-seven percent of the patients had idiopathic dilated or ischemic cardiomyopathy. Their age ranged from 29 to 73 years (mean 51.8±14.5 years), and 11 (64.7%) received intravenous catecholamine support preoperatively. The right ventricular assist device pump was implanted into the right ventricular free wall. The afterload of this pump was artificially increased by local reduction of the outflow graft diameter, and the effective length of its inflow cannula was reduced by the addition of two 5-mm silicon suture rings to the original HVAD implantation ring. All right ventricular assist device devices could be operated in appropriate speed ranges and delivered a flow of between 3.0 and 5.5 L/min. Thirty-day survival was 82%, and 59% of the patients could be discharged home after recovering from the operation. There was no clinically relevant hemolysis in any of the patients.

Conclusions—

Two HeartWare HVAD pumps can be used as a biventricular assist system. This implantable biventricular support gives the patients more comfort and mobility than usual biventricular ventricular assist devices with large and noisy displacement pumps.