Clinical InvestigationSkeletal Muscle Perfusion During Mechanical Circulatory SupportContrast Ultrasound Assessment of Skeletal Muscle Recruitable Perfusion after Permanent Left Ventricular Assist Device Implantation: Implications for Functional Recovery
Section snippets
Study Subjects
The study was approved by the investigational review board at Oregon Health & Sciences University and registered with ClinicalTrials.gov (NCT02105831). Subjects between 18 and 75 years of age with chronic stage D HFrEF and LV ejection fraction ≤ 35% who were referred for LVAD implantation for refractory symptoms between January 2014 and September 2015 were recruited. Exclusion criteria were moderate or greater peripheral arterial disease (claudication, ankle-brachial index < 0.6, history of
Baseline Clinical and Echocardiographic Data
A total of 22 subjects qualified for the study, consented, and underwent LVAD placement with either a HeartMate II (n = 16; Abbott Laboratories, Abbott Park, IL) or a HeartWare (n = 6; Medtronic, Minneapolis, MN) device. The baseline demographic and clinical characteristics of the study population are provided in Table 1. The study population was nearly evenly balanced between nonischemic and ischemic etiologies of HFrEF. The vast majority of subjects had NYHA functional class IV heart failure
Discussion
The inability to meet the oxygen requirements of working muscle during exertion is one of many contributors to exertional fatigue and dyspnea in patients with HFrEF. This deficit is not caused by impaired cardiac output alone. Peripheral vascular structural and functional abnormalities in HFrEF often impair the normal metabolic and shear-mediated increases in vascular conductance during muscle work.1,2 Although reversal of low-output states with LVAD would be predicted to improve peripheral
Conclusion
In summary, our findings provide evidence that exercise-mediated skeletal muscle blood flow is reduced in patients with severe HFrEF and is improved soon after placement of a permanent LVAD in the subgroup of patients who have substantial improvement in function class. Impairment in muscle perfusion during exercise in those with HFrEF occurs from both impaired microvascular flux rate and a near inability to recruit microvascular units. Post-LVAD improvements in perfusion are attributable almost
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Cited by (0)
Drs. Soman and Hodovan contributed equally to this work.
Dr. Soman was supported by a Fellowship Grant from the Oregon Health & Science University Tartar Trust. Dr. Lindner is supported by grants R01-HL078610, R01-HL130046, and P51-OD011092 from the National Institutes of Health, and grant 18-18HCFBP_2-0009 from NASA.
Conflicts of interest: None.