| Abstract: |
Background: Occasionally, emergency perioperative pacing is necessary. Transcutaneous cardiac pacing is noninvasive, safe, and readily available. Its feasibility and hemodynamic effects during thoracic surgery and one-lung ventilation have not been established. Methods: Twenty anesthetized patients (aged 25-70 yr) without cardiac disease undergoing elective pulmonary resection (right n = 10, left n = 10) were studied in normal sinus rhythm and during transcutaneous cardiac pacing. Patients were paced in supine and lateral decubitus positions (with closed and opened chest) at the minimal current necessary to produce ventricular capture. Invasive arterial monitoring permitted calculation of mean arterial pressure, and transesophageal echocardiography was used to assess atrial and ventricular wall motion and the evaluation of transmitral flow. Twelve patients underwent Doppler analysis of pulmonary venous flow. Results: Pacing was achieved in all patients, with a mean threshold of 86.9 ± 20.6 mA for the right thoracotomy group, and 106.7 ± 16.2 mA for the left thoracotomy group. The mean paced heart rates for the right and left thoracotomy groups were 101.6 ± 18.2 and 105.4 ± 11.5 beats/min, respectively. During pacing, all patients sustained reversible transient decrements in mean arterial pressure (9-19%) from baseline, the loss of AV synchrony, and the development of paradoxical ventricular septal wall motion. No patient had significant mitral regurgitation during sinus or paced rhythms. Decreased systolic pulmonary venous flow velocity and abnormal systolic flow reversal were seen during pacing in 11 of the 12 patients studied. Conclusions: Transcutaneous cardiac pacing is effective in patients undergoing thoracotomy and one-lung ventilation. Its use in patients in normal sinus rhythm induces reversible decrements in mean arterial pressure because of the effects of altered atrioventricular association, ventricular wall motion, and pulmonary venous return. |
