Key Clinical Messages
Very thick left ventricular papillary muscles (PAMs) may kiss each other
and premature ventricular contractions (PVCs) can originate from the
facing side of the PAMs. In such a setting, mapping of those PVCs is
confusing, rendering catheter ablation challenging.
KEY WORDS: catheter ablation; papillary muscle; premature
ventricular contraction.
A 73-year-old woman with symptomatic idiopathic premature ventricular
contractions (PVCs) exhibiting a right bundle branch block and right
inferior axis QRS morphology underwent electrophysiological testing.
Pre-procedural cardiac magnetic resonance imaging and intracardiac
echocardiography revealed very thick posteromedial and anterolateral
papillary muscles (PPM and APM, respectively) in the left ventricle that
were kissing each other during systole. Activation mapping during the
PVCs was confusing because the earliest ventricular activation was
recorded in the middle between the PPM and APM. Pace mapping was helpful
for recognizing the location of the mapping catheter on the PPM or APM
because the QRS axis dramatically changed between them. Radiofrequency
catheter ablation was successful on the septal side of the APM where an
excellent pace map was recorded.
Catheter ablation of ventricular arrhythmias originating from the
papillary muscles (PAMs) is often challenging because their origins are
located deep inside thick PAMs. However, in this case, mapping of the
PAM PVCs was challenging because a very thick PPM and APM were kissing
each other and the PVC origin was located on the septal side of the APM
that faced the PPM. This case illustrated an unusual type of challenge
in catheter ablation of PAM PVCs.