The IMPULSE Study: Pilot (IMPULSE)

The IMPULSE Pilot Study-- Investigating a Novel Synergy: Applying Ischemic Conditioning to Modulate the Altered Physiology From Contemporary continUous Flow Left Ventricular Assist Devices, to Reduce Stroke and Other Adverse Effects

Continuous-flow (CF) left ventricular assist devices (LVADs) are an important tool in the treatment of end-stage heart failure, affording patients significantly improved quantity and quality of life. In recent years, tens of thousands of LVADs have been implanted worldwide, with nearly 1,000 at the Texas Heart Institute (THI). Despite the benefits from LVAD therapy, one major weakness is the high frequency of late strokes, reported up to 19%. CF LVADs minimize or remove the pulsatility within the blood system, introducing a new and incompletely understood physiology. Increased sympathetic ("fight or flight" nervous system) tone secondary to lack of pulse in the blood system can cause high blood pressure, with subsequent hemorrhaging strokes (bleeding into the brain) are one possible explanation for this high adverse event rate in CF LVAD patients. A simple intervention to decrease the increased sympathetic tone is called "ischemic conditioning"; a sphygmomanometer (blood pressure cuff) is placed on the patient's arm to compress a major artery (ischemia) with subsequent release of the cuff (reperfusion) for set periods of time. This has been shown to reduce blood pressure and major adverse cardiovascular events in other patient populations. We plan to conduct a trial to evaluate this intervention, ischemic conditioning, in patients with CF LVADs. We hypothesize that IC will cause a reduction in blood pressure and strokes in this patient population.

left ventricular assist device, continuous flow, remote ischemic conditioning, hypertension, sympathetic tone, endothelial dysfunction

Our intervention will be ischemic conditioning (IC) remotely applied using a sphygmomanometer. We will use the standard, validated protocol, which is inflation of the sphygmomanometer to 200 mmHg for 5 minutes, then deflation with 5 minutes of reperfusion, repeated for 3 cycles (total 30 minutes). This will be done in the dominant arm, twice daily. Once patients are discharged home on a stable pharmacotherapy regimen, they will be expected to follow the above intervention for 6 weeks, followed by another 6 weeks in the control (no intervention) phase. Patients will be randomized as to which phase they begin the study.

Patients in experimental arm will have validated protocol of Remote Ischemic Conditioning (using Sphygmomanometer): 5 minutes with blood pressure cuff inflated at 200 mmHg, then deflated for 5 minutes; repeated for 3 cycles. Patient in control group will not perform this.

Patients will follow a standard, validated protocol for this non-invasive technique for 6 weeks, followed by 6 weeks in the control phase (or vice versa based on randomization of order). Each week, they will have Doppler blood pressure measurements and blood samples drawn for analysis.

change in mean levels of inflammatory markers (TNFa, IL6, IL8, IL10) and endothelial function (adenosine, acetylcholine, bradykinin, nitric oxide, angiotensin, aldosternone)

Inclusion Criteria: continuous flow LVAD and able to provide informed consent and comply with follow-up Exclusion Criteria: < 18 years of age