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Antegrade and retrograde decremental conduction properties of an accessory pathway associated with the coronary sinus musculature.

Nakamura K, Naito S, Kaseno K, Oshima S - Indian Pacing Electrophysiol J (2015)

Bottom Line: A 32-year-old man underwent catheter ablation of an orthodromic atrioventricular reentrant tachycardia.The sinus rhythm electrocardiogram exhibited a normal PQ interval and no delta waves, but atrial pacing produced a prolonged PQ interval and wide QRS morphology with right bundle-branch block due to antegrade accessory pathway (AP) conduction.In this case, the CSM was associated with the bidirectional decremental conduction properties of the AP, and the antegrade slow conduction resulted in the absence of a shortening of the PQ interval and delta waves during sinus rhythm despite the continuous presence of antegrade AP conduction.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Gunma Prefectural Cardiovascular Center, 3-12 Kameizumi-machi, Maebashi City, Gunma 371-0004, Japan.

ABSTRACT
A 32-year-old man underwent catheter ablation of an orthodromic atrioventricular reentrant tachycardia. The sinus rhythm electrocardiogram exhibited a normal PQ interval and no delta waves, but atrial pacing produced a prolonged PQ interval and wide QRS morphology with right bundle-branch block due to antegrade accessory pathway (AP) conduction. During the tachycardia, atrial double potentials consisting of the coronary sinus musculature (CSM) and left atrial (LA) potentials were observed. Ventricular extrastimulation exhibited retrograde decremental conduction with an identical atrial activation sequence as during the tachycardia. A radiofrequency application within the posterolateral CS during ventricular pacing eliminated the CSM-LA conduction and concomitantly the ventriculoatrial conduction via the AP was abolished. In this case, the CSM was associated with the bidirectional decremental conduction properties of the AP, and the antegrade slow conduction resulted in the absence of a shortening of the PQ interval and delta waves during sinus rhythm despite the continuous presence of antegrade AP conduction.

No MeSH data available.


Related in: MedlinePlus

A: Twelve-lead electrograms during the clinical tachycardia induced by single atrial extrastimulation with an S1-S2 interval of 280 ms at a basic cycle length (S1-S1) of 500 ms. The arrows indicate the retrograde P waves during the tachycardia. B: Surface and intracardiac electrograms during the tachycardia. Atrial double potentials (DPs) were recorded along the CS and the earliest DP1 and DP2 sites were identified at the lateral (CS1-2) and posterolateral mitral annulus (CS4-5), respectively. The black and gray arrows indicate DP1 and DP2, respectively. C, D: Single ventricular extrastimulation (S2) at a basic cycle length (S1-S1) of 500 ms demonstrating decremental retrograde conduction. When the S1-S2 interval was shortened from 260 (C) to 220 ms (D), the S2-DP1 interval prolonged from 176 to 219 ms. The arrows represent DP1. DP1, the first component of the atrial double potentials; DP2, the second component of the atrial double potentials; LVP, left ventricular potential. The other abbreviations are as in Figure 1.
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Figure 2: A: Twelve-lead electrograms during the clinical tachycardia induced by single atrial extrastimulation with an S1-S2 interval of 280 ms at a basic cycle length (S1-S1) of 500 ms. The arrows indicate the retrograde P waves during the tachycardia. B: Surface and intracardiac electrograms during the tachycardia. Atrial double potentials (DPs) were recorded along the CS and the earliest DP1 and DP2 sites were identified at the lateral (CS1-2) and posterolateral mitral annulus (CS4-5), respectively. The black and gray arrows indicate DP1 and DP2, respectively. C, D: Single ventricular extrastimulation (S2) at a basic cycle length (S1-S1) of 500 ms demonstrating decremental retrograde conduction. When the S1-S2 interval was shortened from 260 (C) to 220 ms (D), the S2-DP1 interval prolonged from 176 to 219 ms. The arrows represent DP1. DP1, the first component of the atrial double potentials; DP2, the second component of the atrial double potentials; LVP, left ventricular potential. The other abbreviations are as in Figure 1.

Mentions: The clinical tachycardia with a cycle length of 325 ms was induced by programmed atrial stimulation and a retrograde P wave was observed approximately at the middle of the R-R interval (Figure 2A). During the tachycardia, the earliest ventricular activation was identified at the His-bundle region and atrial double potentials (DPs) were recorded along the CS (Figure 2B). The earliest site of the first component of the DPs (DP1) was identified on the lateral mitral annulus (MA) and the activation sequence was distal-to-proximal. On the other hand, the second component (DP2) exhibited an eccentric activation sequence with the earliest activation site at the posterolateral MA. Programmed ventricular extrastimulation revealed a decremental ventriculoatrial (VA) conduction property with an identical atrial activation sequence as during the tachycardia, which was mainly due to a delay in the conduction between the left ventricular (LV) potentials and DP1 (Figure 2C and 2D). The VA conduction could not be blocked by an intravenous administration of 20mg of adenosine. According to these results, the clinical tachycardia was diagnosed as an orthodromic atrioventricular reentrant tachycardia (AVRT) via the left-sided AP with both antegrade and retrograde decremental conduction properties. Using transseptal and retrograde transaortic approaches, a total of 25 endocardial RF applications targeting the earliest DP1 or DP2 were performed both above and beneath the mitral valve along the lateral through posterolateral MA, but failed to eliminate both the AP conduction and AVRT. Each application of RF energy using a 4-mm-tip ablation catheter (Celsius, Biosense Webster, Diamond Bar, USA) was delivered for a maximum duration of 90 seconds (<30 seconds at most locations) with a power of up to 50W. Mapping was then performed in the CS using the earliest atrial activation during constant ventricular pacing. Within just 6 seconds after commencing the initial RF application within the CS along the posterolateral MA where continuous DP1 and DP2 potentials were recorded, the DP1-DP2 conduction blocked and concomitantly the VA conduction via the AP was abolished (Figure 3A, 3B, and 3C). This finding demonstrated that DP1 was a CS musculature (CSM) potential and DP2 was a left atrial (LA) potential. During sinus rhythm before DP1-DP2 blocked, the LA potentials were immediately followed by the CSM potentials, which were slowly conducted by the LV potentials (Figure 4A). After DP1-DP2 blocked, an isoelectric line was observed between the LA and LV potentials, and the CSM potentials distal to the successful ablation site followed the LV potentials (Figure 4B). In addition, conduction of the CSM also blocked simultaneously between the proximal and distal sides of the successful ablation site. Thus, the activation sequence of the CSM distal to the ablation site changed from proximal-to-distal to distal-to-proximal, but that proximal to the ablation site did not change. An additional RF application within the posterolateral CS, delivered to minimize the risk of any reconduction of the AP, eliminated the LV-CSM conduction. A 12-lead ECG during sinus rhythm exhibited slightly smaller R waves and deeper S waves in the precordial leads after elimination of the AP conduction than before (Figure 1A, 1D), suggesting that the antegrade conduction was not latent but was constantly fusing over both the atrioventricular node and AP before ablation. Thereafter, the clinical tachycardia could never be induced with atrial or ventricular rapid pacing or extra-stimuli.


Antegrade and retrograde decremental conduction properties of an accessory pathway associated with the coronary sinus musculature.

Nakamura K, Naito S, Kaseno K, Oshima S - Indian Pacing Electrophysiol J (2015)

A: Twelve-lead electrograms during the clinical tachycardia induced by single atrial extrastimulation with an S1-S2 interval of 280 ms at a basic cycle length (S1-S1) of 500 ms. The arrows indicate the retrograde P waves during the tachycardia. B: Surface and intracardiac electrograms during the tachycardia. Atrial double potentials (DPs) were recorded along the CS and the earliest DP1 and DP2 sites were identified at the lateral (CS1-2) and posterolateral mitral annulus (CS4-5), respectively. The black and gray arrows indicate DP1 and DP2, respectively. C, D: Single ventricular extrastimulation (S2) at a basic cycle length (S1-S1) of 500 ms demonstrating decremental retrograde conduction. When the S1-S2 interval was shortened from 260 (C) to 220 ms (D), the S2-DP1 interval prolonged from 176 to 219 ms. The arrows represent DP1. DP1, the first component of the atrial double potentials; DP2, the second component of the atrial double potentials; LVP, left ventricular potential. The other abbreviations are as in Figure 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380695&req=5

Figure 2: A: Twelve-lead electrograms during the clinical tachycardia induced by single atrial extrastimulation with an S1-S2 interval of 280 ms at a basic cycle length (S1-S1) of 500 ms. The arrows indicate the retrograde P waves during the tachycardia. B: Surface and intracardiac electrograms during the tachycardia. Atrial double potentials (DPs) were recorded along the CS and the earliest DP1 and DP2 sites were identified at the lateral (CS1-2) and posterolateral mitral annulus (CS4-5), respectively. The black and gray arrows indicate DP1 and DP2, respectively. C, D: Single ventricular extrastimulation (S2) at a basic cycle length (S1-S1) of 500 ms demonstrating decremental retrograde conduction. When the S1-S2 interval was shortened from 260 (C) to 220 ms (D), the S2-DP1 interval prolonged from 176 to 219 ms. The arrows represent DP1. DP1, the first component of the atrial double potentials; DP2, the second component of the atrial double potentials; LVP, left ventricular potential. The other abbreviations are as in Figure 1.
Mentions: The clinical tachycardia with a cycle length of 325 ms was induced by programmed atrial stimulation and a retrograde P wave was observed approximately at the middle of the R-R interval (Figure 2A). During the tachycardia, the earliest ventricular activation was identified at the His-bundle region and atrial double potentials (DPs) were recorded along the CS (Figure 2B). The earliest site of the first component of the DPs (DP1) was identified on the lateral mitral annulus (MA) and the activation sequence was distal-to-proximal. On the other hand, the second component (DP2) exhibited an eccentric activation sequence with the earliest activation site at the posterolateral MA. Programmed ventricular extrastimulation revealed a decremental ventriculoatrial (VA) conduction property with an identical atrial activation sequence as during the tachycardia, which was mainly due to a delay in the conduction between the left ventricular (LV) potentials and DP1 (Figure 2C and 2D). The VA conduction could not be blocked by an intravenous administration of 20mg of adenosine. According to these results, the clinical tachycardia was diagnosed as an orthodromic atrioventricular reentrant tachycardia (AVRT) via the left-sided AP with both antegrade and retrograde decremental conduction properties. Using transseptal and retrograde transaortic approaches, a total of 25 endocardial RF applications targeting the earliest DP1 or DP2 were performed both above and beneath the mitral valve along the lateral through posterolateral MA, but failed to eliminate both the AP conduction and AVRT. Each application of RF energy using a 4-mm-tip ablation catheter (Celsius, Biosense Webster, Diamond Bar, USA) was delivered for a maximum duration of 90 seconds (<30 seconds at most locations) with a power of up to 50W. Mapping was then performed in the CS using the earliest atrial activation during constant ventricular pacing. Within just 6 seconds after commencing the initial RF application within the CS along the posterolateral MA where continuous DP1 and DP2 potentials were recorded, the DP1-DP2 conduction blocked and concomitantly the VA conduction via the AP was abolished (Figure 3A, 3B, and 3C). This finding demonstrated that DP1 was a CS musculature (CSM) potential and DP2 was a left atrial (LA) potential. During sinus rhythm before DP1-DP2 blocked, the LA potentials were immediately followed by the CSM potentials, which were slowly conducted by the LV potentials (Figure 4A). After DP1-DP2 blocked, an isoelectric line was observed between the LA and LV potentials, and the CSM potentials distal to the successful ablation site followed the LV potentials (Figure 4B). In addition, conduction of the CSM also blocked simultaneously between the proximal and distal sides of the successful ablation site. Thus, the activation sequence of the CSM distal to the ablation site changed from proximal-to-distal to distal-to-proximal, but that proximal to the ablation site did not change. An additional RF application within the posterolateral CS, delivered to minimize the risk of any reconduction of the AP, eliminated the LV-CSM conduction. A 12-lead ECG during sinus rhythm exhibited slightly smaller R waves and deeper S waves in the precordial leads after elimination of the AP conduction than before (Figure 1A, 1D), suggesting that the antegrade conduction was not latent but was constantly fusing over both the atrioventricular node and AP before ablation. Thereafter, the clinical tachycardia could never be induced with atrial or ventricular rapid pacing or extra-stimuli.

Bottom Line: A 32-year-old man underwent catheter ablation of an orthodromic atrioventricular reentrant tachycardia.The sinus rhythm electrocardiogram exhibited a normal PQ interval and no delta waves, but atrial pacing produced a prolonged PQ interval and wide QRS morphology with right bundle-branch block due to antegrade accessory pathway (AP) conduction.In this case, the CSM was associated with the bidirectional decremental conduction properties of the AP, and the antegrade slow conduction resulted in the absence of a shortening of the PQ interval and delta waves during sinus rhythm despite the continuous presence of antegrade AP conduction.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Gunma Prefectural Cardiovascular Center, 3-12 Kameizumi-machi, Maebashi City, Gunma 371-0004, Japan.

ABSTRACT
A 32-year-old man underwent catheter ablation of an orthodromic atrioventricular reentrant tachycardia. The sinus rhythm electrocardiogram exhibited a normal PQ interval and no delta waves, but atrial pacing produced a prolonged PQ interval and wide QRS morphology with right bundle-branch block due to antegrade accessory pathway (AP) conduction. During the tachycardia, atrial double potentials consisting of the coronary sinus musculature (CSM) and left atrial (LA) potentials were observed. Ventricular extrastimulation exhibited retrograde decremental conduction with an identical atrial activation sequence as during the tachycardia. A radiofrequency application within the posterolateral CS during ventricular pacing eliminated the CSM-LA conduction and concomitantly the ventriculoatrial conduction via the AP was abolished. In this case, the CSM was associated with the bidirectional decremental conduction properties of the AP, and the antegrade slow conduction resulted in the absence of a shortening of the PQ interval and delta waves during sinus rhythm despite the continuous presence of antegrade AP conduction.

No MeSH data available.


Related in: MedlinePlus