P congenitale: Tetralogy of Fallot

Report:

Sinus rhythm

First degree AV block

PR 0.24”

Right atrial abnormality

P congenitale (P axis +60o)

Right axis deviation +125o

Right bundle branch block

Right ventricular hypertrophy

Comment:

In P congenitale the atrial wave is quite large in standard lead 1. This contrasts with acquired RAA where it is, characteristically, flat – conferring a P wave axis of +70o or more. In this example, there is also a striking increase in the right atrial component of P wave in V1 and V2.

As Marriott points out, the precordial T wave inversion is usually confined to V1-2 in Fallot’s tetralogy RVH64; in the case of pulmonic stenosis, the inverted T’s can be found as far as V5. This holds true here despite RBBB and large right precordial R waves. RBBB is the rule in adults with repaired tetralogy, regardless of whether right ventriculostomy was done in the course of the procedure. A really broad RBBB (over 0.18”) is a marker of future VT and other unpleasant events65.

Below (Fig 94a) is another tetralogy, repaired, in a 10 year old boy with palpitations as his only remaining symptom. This patient had undoubted RVH, but its sole manifestations appear to be a large secondary (in RBBB) R wave in V1 and borderline RAA. Voltage is never a very reliable criterion in the presence of conduction defects.

There is a diminution and again an increase in the rsR’ size in V2 and V3, suggesting a lead reversal, but a trace taken 6 months later (not shown) confirms the correct lead sequence. Interestingly, the trace below also shows more of a right axis deviation in the frontal plane than its predecessor. Even in the presence of true RVH, conduction delays may dominate the ECG picture.