Left Posterior Hemiblock Following Aortic Valve Replacement

Report:

Sinus rhythm 98/min

Right bundle branch block

Left posterior hemiblock

Axis +115o

Nonspecific ST/T changes

Comment:

One can only diagnose the LPHB with clinical exclusion of RVH. It is easy if the hemiblock suddenly appears or disappears, as in this case. Below is the patient’s ECG a day later, virtually identical to his preoperative tracings. Why this patient had a pre-existing RBBB is unknown; it occurs in normal hearts anyway. It may be related to the expected calcification of the bicuspid valve, even at his age.

Aortic valve surgery often injures the conduction system, sometimes permanently.

It can be seen here how the hemiblock (either LAHB or LPHB) affects the RBBB morphology in leads V1 and V2. There is a small q wave and the RSR’ pattern morphs into qR or R complex.

The ST/T changes are common postoperatively and are (usually) best ignored. Some of the ST depression in V5-6 may reflect the pre-existing LVH, while the V2 elevation may be a pericardial reaction to surgery.

Fig 3a. Normalised axis, persistent RBBB, now in typical rSR’ configuration.

Fig 4. 30 year old man ventilated for a tricyclic antidepressant overdose with coma, hypotension, and mixed acidosis.

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