Abstract
PurposeHeart transplantation causes denervation of the donor heart, but the consequences for cardiovascular homeostasis remain to be fully understood. The present study investigated cardiovascular autonomic control at supine rest, during orthostatic challenge and during isometric exercise in heart transplant recipients (HTxR).MethodsA total of 50 HTxRs were investigated 7–12 weeks after transplant surgery and compared with 50 healthy control subjects. Continuous, noninvasive recordings of cardiovascular variables were carried out at supine rest, during 15 min of 60° head-up tilt and during 1 min of 30% of maximal voluntary handgrip. Plasma and urine catecholamines were assayed, and symptoms were charted.ResultsAt supine rest, heart rate, blood pressures and total peripheral resistance were higher, and stroke volume and end diastolic volume were lower in the HTxR group. During tilt, heart rate, blood pressures and total peripheral resistance increased less, and stroke volume and end diastolic volume decreased less. During handgrip, heart rate and cardiac output increased less, and stroke volume and end diastolic volume decreased less. Orthostatic symptoms were similar across the groups, but the HTxRs complained more of pale and cold hands.ConclusionHTxRs are characterized by elevated blood pressures and total peripheral resistance at supine rest as well as attenuated blood pressures and total peripheral resistance responses during orthostatic challenge, possibly caused by low-pressure cardiopulmonary baroreceptor denervation. In addition, HTxRs show attenuated cardiac output response during isometric exercise due to efferent sympathetic denervation. These physiological limitations might have negative functional consequences.
Highlights
Heart transplantation (HTx) remains the treatment of choice for end-stage heart failure, offering improved survival and quality of life for the recipients (Lund et al 2017; Alraies and Eckman 2014)
Symptoms of orthostatic intolerance do not appear to be more common among HTx recipients (HTxRs) than healthy controls; whether this is due to enhanced peripheral vessel responses has not been well addressed (Banner et al 1990; Doering et al 1991, 1996; Fitzpatrick et al 1993)
HTxRs show reduced exercise capacity (Nytrøen and Gullestad 2013), but it is not known to what extent factors other than attenuated heart rate acceleration and myocardial contractility might contribute to this phenomenon; in particular, the potential role of altered peripheral vessel responses during exercise has not been focused on in previous reports
Summary
Heart transplantation (HTx) remains the treatment of choice for end-stage heart failure, offering improved survival and quality of life for the recipients (Lund et al 2017; Alraies and Eckman 2014). Denervation results in altered cardiovascular control and performance, including impaired cardiovascular reflex responses (Banner et al 1990; Idema et al 1994; Doering et al 1996; Raczak et al 1999; Awad et al 2016). Symptoms of orthostatic intolerance do not appear to be more common among HTxRs than healthy controls; whether this is due to enhanced peripheral vessel responses has not been well addressed (Banner et al 1990; Doering et al 1991, 1996; Fitzpatrick et al 1993). HTxRs show reduced exercise capacity (Nytrøen and Gullestad 2013), but it is not known to what extent factors other than attenuated heart rate acceleration and myocardial contractility might contribute to this phenomenon; in particular, the potential role of altered peripheral vessel responses during exercise has not been focused on in previous reports. As several variables are strongly intercorrelated, p values were not adjusted for test multiplicity
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