Carotid Sinus Massage: 2o AV Block

Report:

Sinus rhythm

?Accelerated conduction (PR interval 0.11”)

Second degree AV block

Comment:

The massage was performed in the hope of unmasking WPW conduction, of which there is a soupçon in the initial slurring of the QRS. Instead of broadening the QRS, the massage slowed down the sinus rate and caused a vagally-mediated AV block. This has no diagnostic significance for any intrinsic heart disease.

The term accelerated conduction is a misnomer in that the conduction speed is normal; it more a matter of bypass than acceleration. Lown-Ganong-Levine (LGL) or WPW conduction would be better, but the term is retained here because our hospital ECG computer likes it. In this case, with only a single lead available, this diagnosis is (was) only a possibility.

The patient had, however, quite striking LVH with T wave inversion on her ECG (Fig 27a). The reason remained unknown; in the absence of hypertension, hypertrophic cardiomyopathy, perhaps of the apical variety, is another electrocardiographically suggested possibility. Yet another is angiokeratoma corporis diffusum (Fabry’s disease)22, which features both LVH and short PR interval. She was discharged from the hospital before I could organise an echocardiogram; her surgeon did not want it!

Fig 27a. There is LVH with striking T wave inversion and RAA.

Fig 28. Asymptomatic 80 year old man 8 hours following a syncopal episode. He had been on chronic digoxin therapy. What is the treatment of choice?