Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 139

The accelerated junctional rhythm is an automatic rhythm originating from the AV node at a rate of 70–130 bpm, often ~80 bpm. The junctional rhythm is faster than the sinus rhythm, which leads to AV dissociation. Sometimes, the junctional and sinus rhythms compete at close rates, leading to isorhythmic AV dissociation, i.e., some beats may be sinus beats preceded by sinus P waves, while the other beats may be junctional beats dissociated from P waves and showing up at any deceleration of the sinus P rate (see Chapter 13, Figure 13.9). The QRS is narrow, except in patients with a baseline bundle branch block. This rhythm may occur with inferior MI, is benign and transient, and does not generally require any specific therapy unless the patient is in shock. In shock, atrial pacing at a rate faster than the junctional rhythm may be performed to promote AV synchrony and a more appropriate rate for shock.

Persistent sinus tachycardia is a strong negative prognostic marker; it often signifies pump failure from a large MI. Do not necessarily attempt to slow it down, and avoid β-blockers in the first 24 hours if the heart rate exceeds 110 bpm. One may attempt to slow it down in young patients with hyperdynamic circulation and limited-size MI. Sinus tachycardia may improve with anticongestive measures and afterload reduction.