Subsidiary atrial pacemakers can maintain a supraventricular rhythm and respond to autonomic regulation even after complete excision of the SA node.
Subsidiary atrial pacemakers may sustain supraventricular rhythm post-SA node excision in animals; leaves open human translation.
Surgical excision of the sinoatrial node, verified histologically, is followed by a supraventricular (atrial) rhythm in both resting and exercising dog whether anesthetized or conscious. The ECG is characterized by a definitive P wave and associated atrial electrograms. Waxing and waning in heart rate, generally referred to as sinus arrhythmia continues in the awake animal after complete excision of the SA node. This arrhythmia is responsive to both adrenergic and cholinergic interventions, thus indicating the presence of both sympathetic and parasympathetic regulation of subsidiary atrial pacemaking tissues.
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Randall et al. (1978) studied this question.
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