Effect of verapamil on right ventricular pressure and atrial tachyarrhythmia after thoracotomy

We have studied the effect of verapamil on the incidence of ECG changes and right ventricular pressures (RVP) in 25 male patients (aged 62 (SD 9) yr) undergoing thoracotomy in a placebo-controlled double-blind trial. Verapamil 0.01 mg kg-1 h-1 (n = 12) or saline (n = 13) i.v. was started after surgery and continued on the first day after operation with oral verapamil 80 mg or placebo, 8-hourly. Haemodynamic data were collected before operation and on three days after operation with the patients breathing air and then 60% oxygen (FIO2 0.60) for 10 min. Atrial tachyarrhythmia (AT) (4/13) and new ischaemic ECG changes (3/13) occurred only in the control group (P less than 0.05). With an FI02 of 0.21, systolic RVP increased by 54% on the first two days after operation in the control group and by 13% in the verapamil group (P less than 0.02). With an FIO2 of 0.60 for 10 min, systolic RVP decreased more in the control than in the verapamil group (P less than 0.01). In the control group, an increase in end-diastolic RVP (P less than 0.001) and central venous pressure (P less than 0.05) on the first day after operation was predictive of AT occurring on the second day.