Hemodynamic changes in 8 patients after long-term cardiac pacing were discussed.
The rate-output curve of these patients showed a tendency toward a flat tracing after long-term pacing.
The pulse rate at maximal cardiac output decreased from 70 to 65 in two patients, and from 70 to 60 in one after long-term pacing.
The stroke index of these patients decreased to an average of 42.7% after long-term pacing.
These facts may indicate an increase of reserve cardiac performance. At the maximal output pulse rate, right atrial mean pressure never reached a higher value, and left ventricular work had a higher value both before and after long-term pacing.
