Physical Activity Guided by Pulse Pressure in Patients With Continuous Flow Left Ventricular Assist Devices
Authors: Sven Haufe, Christoph Bara, Julian Eigendorf, Kristine Chobanyan-Jürgens, Sebastian V. Rojas, Jan Schmitto, Uwe Tegtbur, Jens Jordan, Jens Tank
Journal: Circulation (2017)

Continuous flow left ventricular assist devices (cfLVADs) are increasingly used as a bridge to cardiac transplantation or destination therapy in patients with end-stage heart failure. 1 Patients implanted with cfLVADs exhibit marked arterial pulse pressure (PP) reductions that could adversely affect cardiovascular health.Indeed, a pulsatile blood pressure provides stimuli for vascular smooth muscle cell growth and arterial baroreceptor functions. 2,3LVAD designs attempting to simulate PP have been developed recently with the hope to improve clinical outcomes. 4Perhaps physiological PP could be augmented through regular physical exercise in nonpulsatile patients implanted with cfLVADs.Yet specific recommendations guiding exercise intervention after cfLVAD implantation do not exist.We reasoned that a standardized exercise training regimen could be developed based on a reference of exercise-induced PP.In this pilot study, we tested the hypothesis that the in-laboratory evaluation of PP during exercise by photoplethysmography could serve as a guide for home-based walking and cycling exercise prescriptions.We included 3 patients with very low (<10 mm Hg) and 1 control patient with normal resting PP (69 mm Hg) without signs of decompensation (age: 57±11 years, body mass index: 27.9±8.0kg/m 2 , preimplant LV ejection fraction: <25%) who had been implanted with cfLVADs (HVAD, HeartWare Inc.).Repeated echocardiography and vascular-doppler ultrasound measurements revealed no aortic valve opening during sinus rhythm in the 3 nonpulsatile patients.The aortic valve opened with every heart beat in the pulsatile patient.Patients received standard heart failure medications.Patients with acute or chronic infections, severe atherosclerosis, or musculoskeletal comorbidities restricting exercise were excluded.Our ethics committee approved the study and written informed consent was obtained.During incremental exercise testing on bicycle and treadmill ergometers, we assessed beat-to-beat PP by finger photoplethysmography (Finometer-midi and ECG modul, Finapres Medical Systems, Netherlands).We also measured arterialized lactate concentrations and gas exchange.Daily activity was determined for 7 days with triaxial sensors (SenseWear, BodyMedia) and brachial arterial wall thickness by 2-dimensional Doppler ultrasound.The physical activity program over 2 months included both walking and cycling at home.Patients with low PP trained at PP levels sufficient to ensure aortic valve opening and closing during systole (pulsatility).Aortic valve closure was defined as the end systolic incision point in the finger blood pressure pulse wave (Figure ,A).The intensity of the home-based training had to be considered safe by the treating physician and tolerable for the patient.Therefore, ECG recordings, lactate and oxygen kinetics, and the current overall physical status were also considered to define the specific exercise training level.The exercise prescription in the control patient with normal resting PP was identical except for the PP criterion.