Conclusion
A HRVPB can only reset an ORT if it ‘pulls in’ the local V at the ventricular insertion of an accessory pathway. As showcased here, erudite analysis of the pattern of perturbation (or the lack of it) of the local ventricular electrograms is of paramount significance when interpreting responses to this maneuver. This concept when fortified with a heightened index of clinical suspicion for mitral annular block, anatomical knowledge of the pattern of LA-CS muscular connections, and pathway orientation allows the astute electrophysiologist to tactically predict its atrial insertion when encountering such complex scenarios.
References
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Figure Legends
Figure 1- 12 lead ECG showing short RP tachycardia
Figure 2A- Long VA Tachycardia induction without AH jump
Figure 2B- VOP results in long PPI-TCL and VAV response
Figure 2C- HRVPB from RV apex didn’t affect the next A
Figure 2D- HRVPB from LV apex pulled in subsequent A.
Figure 3- His refractory PVC from Left ventricular apex advanced the local V as shown by the markers (‘ ‘) in CS 12 and CS34 (but not in His and proximal CS electrodes); and advances next “A” and reset the tachycardia suggestive the presence of an accessory pathway near distal CS. However, the A in CS still is late compared to His and proximal CS, suggesting the presence of a mitral annular block.
Figure 4A- Left Anterior Oblique (LAO) fluoroscopic view showing mapping ablation catheter at lateral mitral annulus lateral to CS12
Figure 4B - Earliest retrograde ‘A’ during tachycardia at RF1/2
Figure 4C- pacing from Lateral MA– concentric conduction due to isthmus block
Figure 4D - 3D activation map during tachycardia showing earliest activation at lateral MA
Figure 4E- RF catheter to CS12 conduction time=150 ms demonstrated by activation map during RF pacing
Figure 4F- Schematic diagram showing retrograde atrial activation pattern during orthodromic AVRT using left lateral accessory pathway (AP) in absence and presence of ‘Mitral Isthmus block’ respectively. Indicates the AP insertion site at the atrial aspect and indicates the site of isthmus block
Figure 1