Exercise Chronotropy in Patients with Normal and Impaired Sinus Node Function After Cardiac Transplantation

The chronotropic response during graded, symptom limited exercise was investigoted 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, junctionai 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_{rato between groups}= 30, P = 0.0001, F_{rate vs workload}= 15, P = 0.0001 by two-way ANOVAJ 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 patiejils in group 11 accomplished a peak heart rate ± 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 fundion.     

EFFECT OF INTERPLEURAL MORPHINE ON POSTOPERATIVE PAIN AND PULMONARY FUNCTION AFTER THORACOTOMY

We have investigated the effect of interpleural morphine onpostoperative pain and pulmonary function after thoracotomy.At the end of surgery, an interpleural catheter was insertedin 17 patients and, in a double-blind and randomized manner,either a bolus of morphine 2.5 mg interpleurally (i.p.) andnormal saline i.v. (group I) or, as a control for systemic absorption,morphine 2.5mg i.v. and i.p. saline (group II) was injected.After the initial bolus, a continuous infusion of morphine 0.5mg h^–1 i.p. and saline i.v. (group I) or morphine 0.5mg i.v. and saline i.p. (group II) was maintained for 24 h.Postoperative pain was assessed by a visual analogue scale,a numerical rating scale and the McGill Pain Questionnaire.Pulmonary function was assessed by spirometry. Supplementaryanalgesics, side effects, degree of sedation, vital signs andchest tube drainage were recorded. All variables were assessedon the day before surgery and 1, 2, 3, 4, 5, 6 and 24 h and7 days after surgery. Supplementary morphine was given uponrequest. There was no significant difference in any pain measureor postoperative pulmonary function variable between the groups.We conclude that, after thoracotomy. interpleural morphine doesnot provide superior analgesia or improve pulmonary functioncompared with systemic morphine.