Failed Biventricular Pacemaker

Report:

Sinus rhythm 63/min 1

Left atrial abnormality (LAA) 1

P wave 0.16”

First degree AV block 3

PR 0.28”

Right axis deviation +250o

Left bundle branch block 3

Dual pacemaker, failed, 70/min 2

Comment:

The combination of LBBB and RAD is virtually diagnostic of congestive cardiomyopathy (COCM)64. This patient’s ejection fraction was 25%. The marked LAA, with impressive notching in lead 1, is also consistent with COCM. It is better seen in the tracing below (Fig 124a). It is bizarre enough to preclude certain diagnosis of sinus rhythm at faster rates (Fig 124b)

The pacemaker is obviously dual, but what is not obvious is its biventricular pacing purpose. It is indeed unusual to see failure to pace in both leads, as well as the failure to sense ether the atrial activity or the native QRS complexes.

Pacemaker “synchronization” treatment of heart failure is a recognised therapeutic modality65. Like many new technologies, it seeks to expand its indications66. There may be money in it even if (or especially when) it fails!

The LBBB QRS complex here has an extreme, “Northwest” axis, either a marked right or left axis deviation. Patients with this can be as safely predicted to have congestive cardiomyopathy as those with conventional RAD. An interesting feature is the tall narrow R wave in the right precordial leads, said to represent previous anterior infarction. This may well be true in this case, since the patient had a known infarct, cardiac arrest and quadruple CABG 11 years previously. I have seen this, however, equally often in LBBB patients with “pure” cardiomyopathies.