Cracking the code of complex atrial tachyarrhythmias after heart transplantation: Can ultra–high-density mapping provide the key?

Figures

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  Figure 1. A: Electrocardiogram of the atrial tachyarrhythmia with a ventricular rate of 133 beats/min. B: Intracardial recordings of the arrythmia with a cycle length of 445 ms. CS activation was from distal (CS 1,2) to proximal (CS 9,10). The IntellaMap Orion catheter was positioned at the anastomosis of the right native and donor atria. A significant conduction delay between the donor RA and the native RA is observed. CS = coronary sinus; RA = right atrium.

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  Figure 2. Atrial activation patterns during SR before and after ablation of the right-sided AAC. A: Before ablation. Transition of the atrial tachycardia to SR after a premature atrial complex. During SR, CS activation was from proximal (CS 9,10) to distal (CS 1,2). B: After ablation, a change in CS activation sequence and a prolonged interval from the onset of the P wave to CS activation were observed compared with preablation (86 ms vs 36 ms). After ablation, sinus node activation from the native heart reached the AV node from the donor heart via conduction through the remaining AAC at the LA anastomosis, suggesting conduction block over the right-sided AAC. AAC = atrio-atrial connection; AV = atrioventricular; CS = coronary sinus; LA = left atrium; SR = sinus rhythm.

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  Figure 3. Schematic representation (A) and Rhythmia map (B) of activation sequence of biatrial flutter. Atrial activation in the donor RA propagates through the first AAC located laterally, subsequently reaching the posterior region of the native RA. The wavefront then traverses the Bachmann bundle to enter the native LA. Within the lateral region of the native LA, conduction proceeds via a second AAC connecting the native LA and donor LA, resulting in activation of the CS in a distal-to-proximal direction. Activation of the interatrial septum occurs from inferior to superior, involving both the donor LA and the donor RA. The activation wave then ascends along the superior aspect of the donor RA and reenters the circuit via the initial lateral AAC, thereby completing a macroreentrant circuit. This constitutes a biatrial flutter circuit involving all 4 atrial “chambers”: the donor and native RAs and LAs. AAC = atrio-atrial connection; CS = coronary sinus; LA = left atrium; RA = right atrium.

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  Figure 4. Intracardiac signals recorded with the IntellaMap Orion catheter at the right-sided AAC (A) and left AAC (B). Particularly at the right-sided AAC, low-voltage fractionated electrograms were observed. Ablation at this site resulted in termination of the tachycardia. AAC = atrio-atrial connection; LA = left atrium; RA = right atrium.