Septal VA Time: How Short Is Too Short for Atrioventricular Re-Entrant Tachycardia?
Worawan B Limpitikul1, Pattara Rattanawong2, Gregory F Michaud3
1Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Background:
A septal ventriculoatrial interval (VAI) of <70 ms often excludes atrioventricular reentrant tachycardia (AVRT) as a mechanism of supraventricular tachycardia (SVT).
Case Summary:
A 49-year-old woman presented with symptomatic Wolff-Parkinson-White syndrome. Her electrophysiology study showed an AVRT with an unusually short VAI of 45 ms. The difference between the atrial signal interval during right ventricular pacing in sinus rhythm and the VAI during SVT was 30 ms. A functional left bundle branch block was induced, with a VAI of 85 ms (40 ms longer than the narrow complex SVT), suggesting conduction through an ipsilateral accessory pathway. Antegrade accessory pathway activation was mapped to the ostium of the middle cardiac vein and successfully ablated, resulting in the loss of antegrade pre-excitation.
Discussion:
This case report highlights the importance of considering AVRT when the VAI is <70 ms and establishes a new shortest VAI of 45 ms.
Related Concept Videos
01:30Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
01:25Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
01:13The Cardiac Cycle
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and...
01:28Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow...
01:29Cardiac Cycle
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
01:28Mechanism of Cardiac Arrhythmias