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December 25, 2002

Pathophysiology of Physiologic Cardiac Pacing: Advantages of Leaving Well Enough Alone

Author Affiliations

Author Affiliation: Johns Hopkins Medical Institutions, Baltimore, Md.

JAMA. 2002;288(24):3159-3161. doi:10.1001/jama.288.24.3159

The implantable cardiac pacemaker was first introduced in 1960, with a primary goal of maintaining adequate heart rates in individuals with symptomatic bradycardia. In such patients, single-ventricle stimulation was effective even though it was suboptimal from a physiologic standpoint. However, with sustained bradyarrhythmia requiring frequent ventricular activation, problems with this approach became apparent. Ventricular pacing disrupted the normal temporal sequence of atrial-ventricular systole, resulting in AV-dissociation, mitral and tricuspid valvular regurgitation, and cardiac cycles with variable filling and thus systolic dysfunction. For patients in whom cardiac performance was compromised, loss of effective atrial contraction and elevated filling pressures worsened symptoms.