Similarity of spontaneous and induced heart rate and blood pressure turbulence.

Background: Heart rate turbulence (HRT) is a transient tachycardia-bradycardia that follows premature ventricular complexes (PVCs). The physiology of turbulence is studied in the electrophysiology lab using induced premature ventricular stimuli but the reliability of this model for HRT is unknown.

Objectives: To compare heart rate and blood pressure signatures of induced and spontaneous HRT.

Methods: Each patient received 10 ventricular extrastimuli at 1-min intervals. Electrocardiogram and continuous blood pressure results were digitized for 34 electrophysiology patients.

Results: Fifteen patients yielded at least one induced and one spontaneous analyzable PVC. Per subject, 3.6+/-2.2 spontaneous and 6.1+/-3.3 induced HRT sequences were detected. Spontaneous and inducible HRT were indistinguishable according to turbulence onset (median -1.7% versus -2.3%, P=0.09), turbulence slope (median 7.1 ms/beat versus 10.0 ms/beat, P=0.73), turbulence tachycardia (median 29 ms versus 22 ms, P=0.97) and turbulence bradycardia (45 ms versus 72 ms, P=0.60). Accompanying blood pressure signatures were indistinguishable according to initial hypotension (-0.5+/-5.9 mmHg versus 12.1+/-5.5 mmHg, P=0.19), hypertension time (7.7+/-3.6 s versus 7.8+/-1.9 s, P=0.93) and turbulence hypertension (13.5+/-5.7 mmHg versus 16.1+/-9.2 mmHg, P=0.19). Baroreflex sensitivities estimated by the spontaneous sequence method were similar for spontaneous and induced turbulence (median 7.5 ms/mmHg versus 7.2 ms/mmHg, P=0.89) and correlated with each other (r2=0.81). Heart rate and blood pressure turbulence induced in the electrophysiology laboratory were similar to those following spontaneous PVCs and induced turbulence was a valid model for study under controlled conditions.