The Cath Lab Chronicles

Unusual & Remarkable

Rare anatomical variants, unexpected procedural findings, unusual imaging discoveries, and remarkable cases from structural and interventional cardiology practice. Updated regularly.

Rare Anatomy

Coronary Artery Fistula to Pulmonary Artery — Incidental TAVR Finding

During pre-TAVR coronary angiography, an incidental coronary-to-pulmonary artery fistula was identified — a rare finding with significant implications for TAVR planning and potential hemodynamic impact.

Pearl: Always complete diagnostic coronary angiography before TAVR — incidental findings alter the procedural plan more often than expected.

Fistula TAVR Prep Rare

Structural Surprise

Quadricuspid Aortic Valve Discovered During Structural Echo Workup

A quadricuspid aortic valve — one of the rarest congenital cardiac anomalies (fewer than 300 cases reported) — identified during echocardiographic workup for aortic regurgitation in a patient referred for valve assessment.

Pearl: Quadricuspid AV is almost always associated with AR rather than AS. TEE is essential for delineating cusp morphology and informing repair vs. replacement decisions.

Congenital Quadricuspid Echo

Imaging Finding

IVUS Reveals "Napkin Ring" Sign — Near-Fatal Left Main Stenosis Missed by Angiography

A patient with "non-obstructive" left main disease by angiography underwent IVUS revealing a calcified napkin ring pattern with 85% area stenosis — a pattern angiography severely underestimates due to diffuse disease and positive remodeling.

Pearl: The napkin ring sign on IVUS (circumferential calcium with abluminal necrotic core) predicts adverse events independent of stenosis severity. Treat the IVUS, not the angiogram.

IVUS Left Main Calcium

MCS Finding

Microbubble Formation During Impella Support — Without a Cardiac Shunt

A patient on Impella support developed visible microbubbles on echocardiography in the absence of a patent foramen ovale or other intracardiac shunt — an unusual Impella-related phenomenon raising questions about gas handling during mechanical support.

Pearl: Microbubbles during Impella support have been observed without shunts — likely related to cavitation at the device inlet. Monitor echo carefully for air during MCS troubleshooting.

Impella MCS Echo Finding

Arrhythmia

Bidirectional Ventricular Tachycardia — The Digitalis Signature

A 74-year-old with HFrEF presented with syncope. ECG revealed bidirectional VT — the alternating QRS axis morphology classic for digitalis toxicity or catecholaminergic polymorphic VT (CPVT). The finding prompted immediate digoxin level and toxicology workup.

Pearl: Bidirectional VT has only two causes worth remembering: digitalis toxicity and CPVT. The alternating axis on ECG is pathognomonic — treat the underlying cause, not the arrhythmia in isolation.

VT ECG Digitalis

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