Left-Ventricular-Assist-Device Weaning Protocol Including Exercise and Invasive Hemodynamics - Multi-Institutional Experience

Background: The possibility of weaning from implantable left ventricular assist devices is excellent treatment alternative for end-stage heart failure patients. This is a feasible possibility especially for patients suffering from end-stage heart failure due to myocarditis.

Methods: Our new standardized weaning protocol included 6 LVAD patients at two centers (33 month period; Age: 21 - 55 years mean: 39 years) who matched the inclusion criteria (LV-EF > 40%, LVEDD < 55 mm, no signs of heart failure). Patients were on heparin drip aiming a PTT of 50 to 70 seconds, a PA catheter was placed and transthoracic echo was utilized, as well as serial blood gas analysis and pBNP measurements.

During the evaluation in-bed treadmill (100 Newton meter) exercise and pump stop alone and in combination was evaluated. The following steps were performed:

Baseline (8,600 rpm, resting)/exercise 5 minutes (8,600 rpm, 100 nM)/pump stop 5 minutes (6,000 rpm, resting)/exercise + pump stop 5 minutes (6,000 rpm, 100 W)/recovery (8,600 rpm, resting).

Results: In all 6 patients the evaluation procedure could be performed according to our standarized protocol. During all steps of the weaning evaluation LV-EF, LVEDD, TAPSE and RV short/long geometry was stable in all patients. The Cardiac index increased with exercise (2.67 ± 0.36 vs. 4.6 ± 1.62 L/min/m²; p = 0.007) but did not changed with pump stop and exercise plus pump stop (2.99 ± 0.71 vs. 4.66 ± 1.37 L/min/m²; p = 0.02). Blood lactate samples showed the same increase during exercise (0.85 ± 0.21 vs. 4.42 ± 0.98 mmol/L; p = 0.004), and a trend during pump stop and pump stop plus exercise (2.19 ± 1.12 vs. 4.05 mmol/L ± 0.77; p = 0.08).

Explantation of the LVAD could be performed after 132 to 737 days of LVAD support (mean: 451 days). Surgery was safe and successful in all patients. During the Follow-up period of 68 to 1024 days (mean: 552) all patients stayed stable without signs of heart-failure.

Conclusion: The new weaning protocol proved safe and reproducible. The evaluation data showed an excellent prediction and a 100% short to mid-term survival. Therefore the question of more liberal inclusion criteria might be discussed.