The murmur of pulmonic regurgitation in tetralogy of Fallot with absent pulmonic valve.

Absent pulmonic valve (APV) in tetralogy of Fallot produces a pulmonic regurgitation murmur (PRM) which is usually late in onset after A2, low pitched, and of crescendo-decrescendo character. We have seen three adult patients with tetralogy of Fallot with APV and have done intracardiac sound and pressure studies in two. The PRM was loudest in the RV outflow tract (RVOT), where the onset was earlier than the murmur recorded on the chest wall. The crescendo portion of the PRM occurred during an abnormally slow decline in the RVOT pressure pulse after the crossover of PA and RVOT pressures. The RVOT pressure reached its minimum 30 msec after the RV body pressure, resulting in a pressure gradient between the two. The PRM peaked 30 msec later in the RV body than in the RVOT. The delayed precordial onset of the PRM after A2 is likely due to failure of transmission of early vibrations through the chest wall. The morphology of the PRM in tetralogy of Fallot with APV may be related to delayed relaxation with altered diastolic compliance of the RVOT which is subjected to a large regurgitant volume from the massively dilated pulmonary arteries.