Key result
Impaired postoperative sinus node function in cardiac transplant recipients resulted in a lower peak exercise heart rate compared to normal function (108.3 vs 124.2 beats/min, P<0.02).
Why the study?
Does impaired postoperative sinus node function reduce exercise chronotropy in cardiac transplant recipients?
Observational (n=32)
Does impaired postoperative sinus node function reduce exercise chronotropy in cardiac transplant recipients?
Cardiac transplant recipients with postoperative sinus node deficiency exhibit lower chronotropy during rest and peak exercise despite apparent normalization of sinus rhythm.
Associated with reduced exercise chronotropy in transplant recipients; hypothesis-generating and requires prospective validation before guiding practice.
The chronotropic response during graded, symptom limited exercise was investigated in 32 cardiac transplant recipients a mean of 49 +/- 18 days after transplantation. All patients had systematic evaluation of postoperative donor sinus node (SN) function and the cardioacceleratory response was compared according to the SN function. Twenty-one patients had normal postoperative SN studies (corrected SN recovery time < 520 msec, group I) while the SN function was impaired postoperatively in the remainder (n = 11, group II; corrected SN recovery time 4,149 +/- 6,283 msec in 5 patients, junctional escape rhythm in 6 patients). All patients had regained sinus rhythm at time of the exercise test. Patients in group II had lower basal sinus rates at the beginning of exercise (91.5 +/- 11 vs 101.4 +/- 7 beats/min, P < 0.02). This lower chronotropy was maintained over every incremental step (F rate between groups = 30, P = 0.0001, F rate vs workload = 15, P = 0.0001 by two-way ANOVA) and resulted in a significantly lower heart rate at individual peak exercise (108.3 +/- 20 vs 124.2 +/- 13 beats/min, P < 0.02). A total of 14/16 patients in group I but only 2/16 patients in group II accomplished a peak heart rate > or = 120 beats/min (P = 0.009). The workload achieved did not differ between the groups (107 +/- 29 vs 102 +/- 32 watts, P > 0.5). These data show a lower SN chronotropy during rest and at peak exercise in cardiac transplant recipients with postoperative SN deficiency and apparent normalization of SN function.
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Heinz et al. (1993) conducted an observational in Cardiac transplant recipients (n=32). Impaired postoperative sinus node function vs. Normal postoperative sinus node function was evaluated on Heart rate at individual peak exercise (p=<0.02). Impaired postoperative sinus node function in cardiac transplant recipients resulted in a lower peak exercise heart rate compared to normal function (108.3 vs 124.2 beats/min, P<0.02).
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