Adrenaline Bradycardia

Report:

Sinus tachycardia 115/min (top)

Sinus rhythm 90/min (bottom)

VEBs

Fusion beats

Comment:

The rate response is paradoxical, but well documented in normal volunteers. The pressor effect of adrenaline can evoke reflex slowing of the heart rate, overcoming the β1 chronotropic effect. It is of course the regular response to pure α-blockers.

In this patient, the prolonged catecholamine exposure caused a down-regulation of β1 receptors to an extreme degree, with adrenaline behaving like a pure α agonist204. An even more striking response earlier in his illness is shown on the following pages (Figs 273a, 273b, 273c).

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