Heart transplantation is now currently performed in adult (A-HTR) as well as in pediatric
cardiac patients (P-HTR). In A-HTR, heart denervation results in a delayed, blunted
heart rate (HR) response to exercise onset, mainly sustained by the level of circulating
catecholamines. At the offset of exercise HR resumes the pre-exercise level in 5 -
25 min, depending on the absolute work intensity. Peak HR is ∼ 140 beats/min. Maximal
aerobic power is 19 O2/kg × min, i.e., ∼ 60 % than that of healthy age-matched sedentary subjects and exercise
tolerance is therefore reduced. A functional impairment at the muscle level may also
be present, as suggested by the slow kinetics of the V˙O2 readjustment (phase II) at the onset of submaximal aerobic exercise. P-HTR generally
behave as A-HTR. However, recently, in a few P-HTR a fast HR response to exercise
and greater peak HR values (172 ± 22 beats/min) were demonstrated. Maximal aerobic
power of P-HTR was 32 ± 7 ml O2/kg × min, greater than that of A-HTR, but yet ∼ 60 % of that of healthy age-matched
controls. It may be concluded that occasionally P-HTR may resume an almost normal
cardiovascular response to exercise; nevertheless, their exercise tolerance is limited,
likely by functional impairment at the muscle level, whose origin is still unknown.
Key words:
Heart transplantation, children, exercise, reinnervation.
References
- 1
Cerretelli P, Grassi B, Colombini A, Carù B, Marconi C.
Gas exchange and metabolic transients in heart transplant recipients.
Respir Physiol.
1988;
74
355-371
- 2
Cerretelli P, Marconi C, Meyer M, Ferretti G, Grassi B.
Gas exchange kinetics in heart transplant recipients.
Chest.
1992;
101
199 -205
- 3
Christos S C, Katch V, Crowley D C, Eakin B L, Lindauer A L, Beekman R H.
Hemodynamic responses to upright exercise of adolescent cardiac transplant recipients.
J Pediatr.
1992;
121
312-316
- 4
Grassi B, Marconi C, Meyer M , Rieu M, Cerretelli P.
Gas exchange and cardiovascular kinetics upon different exercise protocols in heart
transplant recipients.
J Appl Physiol.
1997;
82
1952-1962
- 5
Hsu D T, Garofano R P, Douglas J M, Mochler R E, Quagebeur J M, Gersony W M, Addonizio L.
Exercise performance after pediatric heart transplantation.
Circulation.
1993;
88 (part 2)
238-242
- 6 Marconi C, Marzorati M, Fiocchi R, Mamprin F, Ferrazzi P, Ferretti G, Cerretelli P.
Cardiovascular and metabolic responses to exercise in heart transplanted children. In: Steinacker J, Ward SA (eds) The Physiology and Pathophysiology of Exercise Tolerance. London;
Adv Exp Med Biol, Plenum Press 1996: 199-203
- 7
Meyer M, Marconi C, Ferretti G, Fiocchi R, Cerretelli P, Skinner J E.
Heart rate variability in the human transplanted heart: nonlinear dynamics and QT
vs RR-QT alterations during exercise suggest a return of neurocardiac regulation in
long-term recovery.
Integr Behav Sc.
1996;
31
289-305
- 8
Nixon P A, Fricker F J, Noyes B E, Webber S A, Orenstein D M, Armitage J M.
Exercise testing in pediatric heart, heart-lung, and lung transplant recipients.
Chest.
1995;
107
1328-1335
- 9
Rowell L B, O'Leary D S.
Reflex control of the circulation during exercise: chemoreflexes and mechanoreflexes.
J Appl Physiol.
1990;
69
407-418
- 10
Zales V R, Wright K L, Pahl E, Backer C L, Mavroudis C, Muster A J, Benson D W Jr.
Normal left ventricular muscle mass and mass/volume ratio after pediatric cardiac
transplantation.
Circulation.
1994;
90 (part 2)
II-61-II-65
Dr. C. Marconi,M.D.
I.T.B.A.-C.N.R. L.I.T.A.
v. F.lli.Cervi 93 20090 Segrate (MI) Italy
Telefon: Phone:+ 39-226422114
Fax: Fax:+ 39-226422770
eMail: E-mail:marconi@itba.mi.cnr.it