Effects of physical training on cardiovascular control after heart transplantation.
BACKGROUND
Exercise performance in heart-transplanted patients increases with respect to pre-transplantation but remains subnormal, and it does not improve with time after surgery. Possible causes include persisting denervation, and sympathetic vasoconstriction inducing functional vascular abnormalities that prevent adequate increase in blood flow to the exercising limbs. We tested the effects of physical training on baroreceptors-mediated control of heart rate and blood pressure in recently heart-transplanted subjects.


METHODS
Patients were randomly allocated to physical training (n=13, 30 min cycling at 60-70% of peak oxygen consumption for 5 days/week for 6 months) or to control (n=11). Upright exercise test to exhaustion was performed at the beginning of the study after 3 and 6 months. Reflex changes in RR interval and blood pressure in response to sinusoidal neck suction (6 and 12 cycles/min 0 to -30 mm Hg swing) were considered as evidence of reinnervation and baroreflex control of blood pressure, respectively.


RESULTS
After 6 months peak oxygen consumption (p<0.001), exercise time (p<0.01) and workload (p<0.01) increased in trained patients. Before training RR interval and blood pressure were not modified by neck suction. After physical training systolic (p<0.01) and diastolic blood pressure decreased, RR interval and blood pressure could be modulated (p<0.05) by slow (6 cycles/min) neck suction, indicating initial cardiac sympathetic reinnervation and restored sensitivity to autonomic modulation on the arteries. No changes were observed in controls.


CONCLUSIONS
Physical training improved exercise performance and the control exerted by the autonomic nervous system through the sympathetic nerves at both cardiac and vascular level.
Bernardi
Luciano
L
Department of Internal Medicine, IRCCS Policlinico S Matteo, University of Pavia, Italy. lbern1ps@unipv.it <lbern1ps@unipv.it>
Radaelli
Alberto
A
Passino
Claudio
C
Falcone
Colomba
C
Auguadro
Carla
C
Martinelli
Luigi
L
Rinaldi
Mauro
M
Viganò
Mario
M
Finardi
Giorgio
G
D000328:Adult; D001795:Blood Pressure Determination; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D016027:Heart Transplantation / Q000379:methods* / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D011182:Postoperative Care; D011311:Pressoreceptors / Q000502:physiology; D011659:Pulmonary Gas Exchange; D012016:Reference Values; D012307:Risk Factors; D016896:Treatment Outcome