Cardiorespiratory response to early exercise testing after orthotopic cardiac transplantation

Adaptation to exercise following cardiac transplantation

“…At the peripheral level, reduction of peripheral oxygen extraction occurs 17,21,22,[27][28][29] . An exaggerated neuroendocrine response 19 and reduced capacity of pulmonary diffusion 20,30 also seem to be involved in decreased tolerance to exercise.Heart Rate -Heart rate values at rest have been observed to be higher in transplanted compared with healthy individuals due to the absence of parasympathetic innervation and corresponding to the intrinsic frequency of the sinus node 17,23,[31][32][33][34][35] . The resting heart rate of transplanted subjects is 14 to 15 bpm above that of their controls paired by sex and age 36 , and 0 to 26 bpm above controls paired by sex, age, weight and height 6,7 .…”

“…Marzo et al 18 found a 35% reduction in the absolute values of the anaerobic threshold. Degré et al 23 reported an early and intense accumulation of lactate during exercise, attributed to increased production in active tissues and reduced clearance secondary to decreased blood flow in the liver and other inactive tissues. In our study 7 , VO 2 in light to moderate submaximal exercise (40 watt load) below the anaerobic threshold was 12.34 and 12.38ml/kg/ min, in transplanted and healthy subjects, respectively, without significant differences between these groups.…”

“…Heart Rate -Heart rate values at rest have been observed to be higher in transplanted compared with healthy individuals due to the absence of parasympathetic innervation and corresponding to the intrinsic frequency of the sinus node 17,23,[31][32][33][34][35] . The resting heart rate of transplanted subjects is 14 to 15 bpm above that of their controls paired by sex and age 36 , and 0 to 26 bpm above controls paired by sex, age, weight and height 6,7 .…”

“…Also, the reappearance of the circadian rhythm of heart rate in the late cardiac posttransplant follow-up seems to reinforce the hypothesis of partial reinnervation in some transplanted patients [46][47][48] . In the early phase of cardiac postransplantation, cardiac frequency keeps increasing during the first two minutes of the phase of recovery from exercise, despite the immediate decrease of circulating catecholamines 23,34 . This delayed deceleration is possibly due to an increased sensitivity of the denervated heart to catecholamines 49 ( fig.2).…”

“…This delayed deceleration is possibly due to an increased sensitivity of the denervated heart to catecholamines 49 ( fig.2). Individuals examined from one to ten years after transplantation had an immediately decreased heart rate in the first minute of recovery 23 . Kavanagh and Yacoub reported a reduction in resting heart rate and increased peak cardiac frequency after two years of physical training.…”