Atrial Isthmus Research Articles

Morphometry of left atrial appendage isthmus and mitral isthmus: implications for atrial fibrillation catheter ablation.

Radiofrequency catheter ablation (RFA) targets the left atrial appendage isthmus (LAA isthmus) and mitral isthmus for treatment of atrial fibrillation. However, proximity of left circumflex artery (LCxA) and great cardiac vein (GCV) in the isthmuses poses fatal risks during ablation. This study investigated relationships of LCxA and GCV across three lines in the LAA and mitral isthmus, using 15 human cadaveric hearts. Distances between the vessels and the endocardium, myocardium, and perivascular fat thickness were measured. The results showed that LCxA was mostly consistently located in lower atrial segments and GCV was in lower/upper atrial segments, with change of course mainly observed in the middle of the LAA. The LCxA was found as close as 3-5 mm from the lower border of the LAA isthmus in 80% of specimens, at a depth of 2-3 mm within the LAA isthmus, where 1 mm consisted of myocardium and the remainder was fat, which may not provide adequate protection due to the possibility of liquefaction of fat with heat application. The effective myocardial thickness was consistently 1 mm across all cases in both isthmuses. LCxA was 2 mm in second and third sections of LAA isthmus ("careful segment"). LCxA distances from left inferior pulmonary vein opening was 5 to 12 mm, occasionally dangerously close as <1 mm in 16% of cases. This study measured LCxA and GCV in the LAA and mitral isthmus across three lines for the first time in the Indian population, aiding surgeons in RFA planning.

High efficacy and safety of endocardial pulsed electrical field ablation via contact force-controlled catheters for mitral isthmus ablation

Abstract Background A new technology of a pulsed field generator enables established contact force-controlled radiofrequency (RF) catheters to apply point by point monopolar pulsed electrical field (PEF) energy for linear lesions in atrial fibrillation (AF) ablation. Purpose We evaluated this novel monopolar PEF ablation technique for creating lateral mitral isthmus ablation lines in case of perimitral flutter or complex AF patients non responder to pulmonary vein isolation (PVI). Methods Patients (n=44, age 65±11 years) referred for ablation/re-ablation of AF with spontaneous or inducible perimitral atrial flutter (n=34, 77%) or persistent AF and severe enlarged atrium (n=7) or de novo longstanding persistent AF (n=3) without signs of atrial fibrosis were included in our patient cohort for lateral mitral isthmus ablation with PEF applications. After 3D high density voltage mapping of the left atrium with multipolar microelectrode catheters, and confirmation/completion of PVI, an endocardial lateral mitral isthmus line was performed. Using contact force sensing catheter, 25A PEF energy pulses were applied targeting a minimum of 10g contact force and an interlesion distance ≤5mm. Before PEF application 0.2 mg nitroglycerin was intravenously injected. If the inferolateral mitral isthmus line to the left inferior pulmonary vein could not be blocked, a more superior lateral line to the left superior pulmonary vein was performed. If the mitral isthmus could not be blocked by endocardial PEF application or conduction recurred after adenosine injection an additional epicardial ablation via RF application in the coronary sinus was performed. Results Exclusively endocardial PEF application blocked the lateral mitral line in 37 out of 42 cases (88%) with 23±14 PEF applications. After an unsuccessful inferior lateral mitral line, in 34% of cases a second superior lateral mitral line have to be performed. Only in five cases additional epicardial RF applications via coronary sinus were necessary to complete the mitral isthmus block. Block time between superior lateral mitral anulus and infero lateral coronary sinus was 196±48 ms. One pericardial tamponade which could be successfully drained, and no other serious complication occurred throughout all procedures (no ST segment elevation, no tamponade requiring surgery, no cerebrovascular event). Limited follow-up will be available at the time of presentation. Conclusion Blockade of left atrial mitral isthmus line with PEF application via contact force-sensing catheters for ablation of complex atrial fibrillation patients is very efficient and safe. Especially the high efficacy of exclusively endocardial PEF application for creation of a lateral mitral isthmus block in most patients is very promising. However, the long term permanence of the linear lines have to be awaited.

Acute oesophageal safety and long-term follow-up of AI-guided high-power short-duration with 50 W for atrial fibrillation ablation.

Pulmonary vein isolation using radiofrequency ablation is an effective treatment option for patients with symptomatic atrial fibrillation (AF). Application of high power over a short period of time (HPSD) is reported to create more efficient lesions and may prevent collateral thermal oesophageal injury. This study aims to compare efficacy and safety of two different HPSD ablation approaches using different ablation index settings. Consecutive patients undergoing AF ablation with HPSD (50 W; ablation index-guided) using the ThermoCool SmartTouch SF catheter were included. Patients were grouped by ablation protocol: ablation with target ablation index (AI) of 400 on the anterior left atrial wall vs. 300 at the posterior left atrial wall (AI 400/300) or AI 450/350 was performed upon the operator's preference and compared. Peri-procedural parameters and complications were recorded, and incidences of endoscopically detected thermal oesophageal lesions (EDEL) analysed. Recurrence rates after a mean follow-up of 25 ± 7 months and reconnection patterns in patients undergoing redo procedures were investigated. A total of 795 patients (67 ± 10 years; 58% male; 48% paroxysmal AF) underwent a first AF ablation with HPSD (211 in group AI 400/300 and 584 in group 450/350). Median procedure time was 82.9 ± 24.6 min with longer ablation times in patients with target AI 400/300 due to higher intraprocedural reconnection rates, increased box lesions, and additional right atrial isthmus ablations. EDEL rates among target AI 400/300 procedures were significantly lower (3% vs. 7%; P = 0.019). Correspondingly, AI 450/350 was the strongest independent predictor of post-ablation EDEL (OR 4.799, CI 1.427-16.138, P = 0.011). Twelve-month (76% vs. 76%; P = 0.892) and long-term ablation single procedure success (68% vs. 71%; log-rank P = 0.452) after a mean of 25 ± 7 months were comparable among both target AI groups; however, long-term success was significantly higher for paroxysmal AF compared to persistent AF (12 months: 80% vs. 72%; P = 0.010; end of follow-up: 76% vs. 65%; log-rank P = 0.001). One hundred three patients (16%) underwent a redo procedure during follow-up documented comparable pulmonary vein (PV) reconnection among groups. Multivariate predictors of AF recurrence were age, left atrium (LA) size, persistent AF, and extra-PV ablation targets. High-power short-duration AF ablation with target AI of 400 for non-posterior wall and 300 for posterior wall lesions resulted in comparable long-term results compared to higher AI (450/350) ablations with significantly lower risk for thermal oesophageal lesions. Older age, larger LA size, persistent AF, and extra-PV ablation targets were identified in a multivariate analysis as independent risk factors for recurrences of atrial arrhythmias.

The mitral inflow E/A ratio before the procedure may predict late recurrence after pulmonary vein isolation using second-generation cryoballoon

Abstract Funding Acknowledgements Type of funding sources: None. Background The left ventricular (LV) diastolic dysfunction (DD) increases the risk of atrial fibrillation (AF) development. Some studies investigated whether a relationship between DD and late recurrence after catheter ablation for AF, but they found conflictory results. Such studies had relatively short follow-up duration and they did not have a standard ablation protocol. Some patients were taken to PVI only, while additional linear lesions in localizations such as the left atrial (LA) roof, LA isthmus, and cavotricuspid isthmus were added in others. Purpose The mitral inflow E/A ratio is a simple and practical method commonly used to evaluate LV DD. We aimed to investigate whether the E/A ratio before the procedure was predictive for late recurrence in patients with AF undergoing pulmonary vein isolation (PVI) with cryoballoon (CB). Methods A total of 100 patients undergoing AF ablation for the first time using second-generation CB were included. Only patients with paroxysmal AF and sinus rhythm the day before the procedure, and with pre-procedural pro-B natriuretic peptide levels within normal limits were included. The patients with and without late recurrence were compared in terms of basal characteristics and procedural features. Any atrial tachyarrhythmia episode longer than 30 s after the blanking period was defined as late recurrence. Results The patients [age: 58.0 (50.2-62.0) years, 53 female] were followed up for a median of 44.5 (14.2-62.7) months and late recurrence developed in 25 patients. Female gender (72.0% vs 46.7%), hypertension (72.0% vs 48.0%), and the frequency of early recurrence (20.0% vs 4.0%) were found to be higher in patients with late recurrence than in those without it (p =0.028, 0.037 and 0.022, respectively). The CHA2DS2-Vasc score was higher [2.0 (1.0-3.0) vs 1.0 (0-2.0)], AF duration was longer (27.8 ± 9.4 vs 22.0 ± 8.4 months) and the E/A ratio was lower [0.5 (0.4-1.2) vs 1.4 (0.6-1.7)] in patients with late recurrence than in those without it (p=0.014, 0.006 and 0.001, respectively) (Figure 1). The groups were similar in terms of precedural features. A multivariate analysis showed that female gender (HR: 4.46, 95%CI: 1.24-15.97, p=0.021), early recurrence (HR: 10.22, 95% CI: 2.49-41.99, p=0.001), and E/A ratio (HR: 0.25, 95%CI: 0.11-0.57, p=0.001) were independent predictors for late recurrence (Figure 2). Receiver operating characteristic analysis showed that the optimal cut-off level of the E/A ratio was 0.84. Any ATa free survival rate was significantly lower in patients with E/A ratio &amp;lt;0.84 than in those with ≥0.84 (56.1% vs 88.1%, log-rank p&amp;lt;0.001). Conclusions Female gender, early recurrence, and E/A ratio are independent predictors of late recurrence in patients with AF undergoing PVI using second-generation CB. Measuring the E/A ratio in patients with sinus rhythm before AF ablation may help to predict future recurrences.

Risk of New-Onset Atrial Fibrillation Post-cavotricuspid Isthmus Ablation in Typical Atrial Flutter Without History of Atrial Fibrillation.

Aims: The aim was to describe the incidence of atrial fibrillation (AF) after cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL) without history of AF and to identify risk factors for new-onset AF after the procedure.Methods: A total of 191 patients with typical AFL undergoing successful CTI ablation were enrolled. Patients who had history of AF, structural heart disease, cardiac surgery, or ablation or who received antiarrhythmic drug after procedure were excluded. Clinical and electrophysiological data were collected.Results: There were 47 patients (24.6%) developing new AF during a follow-up of 3.3 ± 1.9 years after CTI ablation. Receiver operating characteristic (ROC) curves indicated that the cut-off values of left atrial diameter (LAD) and CHA2DS2-VASc score were 42 mm and 2, with area under the curve of 0.781 and 0.550, respectively. The multivariable Cox regression analysis revealed that obstructive sleep apnea (OSA) [hazard ratio (HR) 3.734, 95% confidence interval (CI) 1.470–9.484, P = 0.006], advanced interatrial block (aIAB) (HR 2.034, 95% CI 1.017–4.067, P = 0.045), LAD > 42 mm (HR 2.710, 95% CI 1.478–4.969, P = 0.001), and CHA2DS2-VASc score > 2 (HR 2.123, 95% CI 1.118–4.034, P = 0.021) were independent risk factors of new-onset AF.Conclusion: A combination of OSA, aIAB, LAD > 42 mm, and CHA2DS2-VASc > 2 was a strongly high risk for new-onset AF after ablation for typical AFL, and it had significance in postablation management in clinical practice.

Abstract 12854: Long Term Outcomes of Pulmonary Vein Isolation With Additional Linear Ablation: Insights From the UC San Diego Atrial Fibrillation Registry

Introduction: Pulmonary vein isolation (PVI) alone or in combination with empiric linear ablations (PVI + lines) at the left atrial roof or mitral isthmus (MI) is often performed in patients undergoing first-time atrial fibrillation (AF) ablation despite lack of evidence of benefit from clinical trials and pro-arrhythmic potential, however real-world long-term follow-up is limited. Hypothesis: Patients undergoing PVI + lines will be more likely to experience long-term adverse outcomes as compared to PVI alone. Methods: Patients undergoing AF ablation with either PVI or PVI + lines were included with follow-up data from a single institution between 2005 and 2009. Long-term outcomes included late recurrence of atrial tachyarrhythmias (LRAT), defined as AF, atrial flutter, or atrial tachycardia lasting &gt; 30 seconds after the 3-month blanking period, repeat ablation, and cardioversion. Multivariable adjusted Cox regression was used to evaluate long-term outcomes. Results: Among 516 patients (64 ± 10 years, 68% male, 31% persistent AF) included, 376 (73%) underwent PVI only and 140 (27%) underwent PVI + lines. Of those with lines, 74 (53%) had both roof and MI line, 61 (43%) had a roof line, and 5 (4%) had a MI line. Predictors of PVI + lines included persistent AF, coronary artery disease, and male sex. Over a median follow-up of 1016 (IQR: 385 - 1752) days, approximately 63% of those with PVI only and 53% of those with PVI + lines experienced LRAT. After multivariable adjustment, there was a trend toward higher risk of LRAT in those with PVI + lines as compared to PVI only (HR 1.35, 95% CI 0.99 - 1.85, p = 0.06). There was no difference in the risk of repeat ablation (HR 0.96, 95% CI 0.63 - 1.45), while those with PVI + lines had a significantly higher risk of cardioversion as compared to PVI only (HR 2.50, CI 1.67-3.73, p&lt;0.001). Conclusions: Those receiving linear ablations to complement PVI experienced a trend in higher risk of LRAT as compared with PVI only. While there was no significant difference in the risk of repeat ablations, there was a two-fold higher risk of cardioversion associated with PVI + lines. In line with clinical trial data, these findings suggest that empiric linear ablations are not beneficial, but may also be associated with adverse outcomes in long-term follow-up.

Rates of atrial flutter occurrence and cavotricuspid isthmus reconduction after prophylactic isthmus ablation performed during atrial fibrillation ablation: a clinical study, review, and comparison with previous findings.

Based on the high rate of coexisting atrial fibrillation (AF) and atrial flutter (AFL), prophylactic cavotricuspid isthmus ablation (CTIA) adjunctive to AF ablation has recently been attempted in patients with AF and without AFL. The present study aimed to determine the rates of AFL occurrence and CTI reconduction after performing CTI ablation adjunctive to AF ablation. We analyzed the data of 3833 consecutive patients with AF, who underwent prophylactic CTIA with AF ablation between 2009 and 2020. In all patients, CTIA and AF ablations were successful. Clinical AFL occurred in seven patients (0.18%, 7/3,833), and the observed rate was lower than those reported for cases of AF ablation without CTIA and for those of CTIA for pure AFL. A second ablation was needed in 745 patients at a median of 253days (25 and 75 percentiles, 116 and 775days) after the first ablation. In 12.1% (90/745) of the patients, CTI reconduction was observed. The reconduction rate was lower than that previously reported for CTIA for pure AFL. The present retrospective study found acceptably low rates of clinical AFL occurrence and CTI reconduction following prophylactic CTIA performed with AF ablation, which was supported by the findings obtained after performing a comparison of the rates with those of other ablations (AF ablation only and CTIA for pure AFL). Considering the high correlation between AF and AFL, the present study provided information regarding the efficacy of adjunctive CTIA.

A new electrophysiological triad for atrial flutter critical isthmus identification and localization

Abstract Introduction In a previous retrospective study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. This study aimed to prospectively assess the ability of an electrophysiological triad to identify and localize the AFL's critical isthmus. Methods Prospective analysis of a unicentric registry of individuals who underwent left AFL ablation with Carto® EAM. All patients with non-left AFL, lack of high-density EAM, less than 2000 collected points or lack of mapping in any of the left atrium walls or structures were excluded. Ablation sites of arrhythmia termination were compared to an electrophysiological triad constituted by: areas of low-voltage (0.05 to 0.3mV), sites of deep histogram valleys (LAT-Valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the TCL. The longest LAT-Valley was designated as the primary valley, while additional valleys were named as secondary. Results A total of 12 patients (9 men, median age 72 IQR 67–75 years) were included. All patients presented with left AFL and 67% had a previous atrial fibrillation and/or flutter ablation. The median TCL and number collected points were 250 (230–290) milliseconds and 3150 (IQR 2340–3870) points, respectively. All AFL presented with at least 1 LAT-Valley in the analysed histograms, which corresponded to heterogeneous low-voltage areas (0.05 to 0.3mV) and encompassed more than 10% of TCL. Eleven of the 12 patients presented with at least 1 secondary LAT-Valley. All arrhythmias were effectively terminated after undergoing radiofrequency ablation in the primary or the secondary LAT-Valley location. Conclusion In a prospective analysis, an electrophysiological triad was able to identify the AFL critical isthmus in all patients. Further studies are needed to assess the usefulness of this algorithm to improve catheter ablation outcomes. Funding Acknowledgement Type of funding sources: None.

Comparison of clockwise and counterclockwise right atrial flutter using high-resolution mapping

Abstract Background To the best of our knowledge, few studies have been performed that explore the electrophysiological differences between clockwise (CW) and counterclockwise (CCW) right atrial (RA) cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) using the high-resolution Rhythmia mapping system. Objectives. Accordingly, our prospective cohort study, sought to compare CW and CCW CTI-dependent AFL in preselected pure right AFL patients (pts) using the ultra-high-definition (ultra-HD) Rhythmia mapping system. The study also aimed to mathematically develop a cartography model based on automatic velocity RA measurements to identify electrophysiological AFL specificities. Methods and results Between October 2019 and July 2020, 33 patients were recruited. The mean age was 71±13 years old. No difference was found concerning clinical variables between CCW AFL and CW AFL or regarding left ventricular ejection fraction (LVEF) (55.5±10 vs. 56.6±12; p=0.76). The AFL cycle length was very similar (248±20 vs. 252±28 ms; p=0.6). The sinus venosus (SV) block line was present in 32/33 of cases (97%) and no significant difference was found between CCW and CW CTI AFL (100% vs. 91%; p=0.7). No line was localized in the region of the crista terminalis (CT). A superior gap was present in the posterior line in 14/31 (45.2%) but this was similarly present in CCW AFL, when compared to CW AFL (10/22 [45.5%] vs. (4/10 [40%]); p=0.9). When present, the extension of the posterior line of block was observed in 18/31 pts (58%) without significant differences between CCW and CW CI AFL (12/22 [54.5%] vs. (6/10 [60%]) (p=.9) The Eustachian ridge line of block was similarly present in both groups (82% [18/22] vs. 45.5% [5/11]; p=0.2). The absence of the Eustachian ridge line of block led to significantly slowed velocity in this area (28±10cm/s; n=8),and the velocities were similarly altered between both groups (26±10 [4/22] vs. 29.8±11cm/s [4/11]; p=0.6). We created mathematical, three-dimensional RA reconstruction-velocity model measurements. In each block localization, when the block line was absent, velocity was significantly slowed (≤20cm/s). A systematic slowdown in conduction velocity was observed at the entrance and exit of the CTI in 100% of cases. This alteration to the conduction entrance was localized at the lateral side of the CTI for the CCW AFL and at the septal side of the CTI for CW AFL. The exit-conduction alteration was localized at the CTI septal side for the CCW AFL and at the CTI lateral side for the CW AFL. The only differences between CW and CCW AFL concerned activation patterns. Conclusions The ultra-HD Rhythmia mapping system confirmed the absence of significant electrophysiological differences between CCW and CW AFL. The mechanistic posterior SV and Eustachian ridge block lines were confirmed in each arrhythmia. A systematic slowing down at the entrance and exit of the CTI was demonstrated in both CCW and CW AFL, but in reverse positions. Funding Acknowledgement Type of funding sources: None.

Comparison of clockwise and counterclockwise right atrial flutter using high-resolution mapping and automated velocity measurements.

Only few studies have been performed that explore the electrophysiological differences between clockwise (CW) and counterclockwise (CCW) right atrial (RA) cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) using the high-resolution Rhythmia mapping system. We sought to compare CW and CCW CTI-dependent AFL in pure right AFL patients (pts) using the ultra-high-definition (ultra-HD) Rhythmia mapping system and we mathematically developed a cartography model based on automatic velocity RA measurements to identify electrophysiological AFL specificities. Thirty-three pts were recruited. The mean age was 71 ± 13 years old. The sinus venosus (SV) block line was present in 32/33 of cases (97%) and no significant difference was found between CCW and CW CTI AFL (100% vs. 91%; p = .7). No line was localized in the region of the crista terminalis (CT). A superior gap was present in the posterior line in 14/31 (45.2%) but this was similarly present in CCW AFL, when compared to CW AFL (10/22 [45.5%] vs. 4/10 [40%]; p = .9). When present, the extension of the posterior line of block was observed in 18/31 pts (58%) without significant differences between CCW and CW CI AFL (12/22 [54.5%] vs. 6/10 [60%]; p = .9) The Eustachian ridge line of block was similarly present in both groups (82% [18/22] vs. 45.5% [5/11]; p = .2). The absence of the Eustachian ridge line of block led to significantly slowed velocity in this area (28 ± 10 cm/s; n = 8), and the velocities were similarly altered between both groups (26 ± 10 [4/22] vs. 29.8 ± 11 cm/s [4/11]; p = .6). We created mathematical, three-dimensional RA reconstruction-velocity model measurements. In each block localization, when the block line was absent, velocity was significantly slowed (≤20 cm/s). A systematic slowdown in conduction velocity was observed at the entrance and exit of the CTI in 100% of cases. This alteration to the conduction entrance was localized at the lateral side of the CTI for the CCW AFL and at the septal side of the CTI for CW AFL. The exit-conduction alteration was localized at the CTI septal side for the CCW AFL and at the CTI lateral side for the CW AFL. The ultra-HD Rhythmia mapping system confirmed the absence of significant electrophysiological differences between CCW and CW AFL. The mechanistic posterior SV and Eustachian ridge block lines were confirmed in each arrhythmia. A systematic slowing down at the entrance and exit of the CTI was demonstrated in both CCW and CW AFL, but in reverse positions.

A new electrophysiological triad for atrial flutter critical isthmus identification and localization

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In a previous retrospective study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. This study aimed to prospectively assess the ability of an electrophysiological triad to identify and localize the AFL’s critical isthmus. Methods Prospective analysis of a unicentric registry of individuals who underwent left AFL ablation with Carto® EAM. All patients with non-left AFL, lack of high-density EAM, less than 2000 collected points or lack of mapping in any of the left atrium walls or structures were excluded. Ablation sites of arrhythmia termination were compared to an electrophysiological triad constituted by: areas of low-voltage (0.05 to 0.3mV), sites of deep histogram valleys (LAT-Valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the TCL. The longest LAT-Valley was designated as the primary valley, while additional valleys were named as secondary. Results A total of 12 patients (9 men, median age 72 IQR 67-75 years) were included. All patients presented with left AFL and 67% had a previous atrial fibrillation and/or flutter ablation. The median TCL and number collected points were 250 (230─290) milliseconds and 3150 (IQR 2340─3870) points, respectively. All AFL presented with at least 1 LAT-Valley in the analysed histograms, which corresponded to heterogeneous low-voltage areas (0.05 to 0.3mV) and encompassed more than 10% of TCL. Eleven of the 12 patients presented with at least 1 secondary LAT-Valley. All arrhythmias were effectively terminated after undergoing radiofrequency ablation in the primary or the secondary LAT-Valley location. Conclusion In a prospective analysis, an electrophysiological triad was able to identify the AFL critical isthmus in all patients. Further studies are needed to assess the usefulness of this algorithm to improve catheter ablation outcomes.

ST-segment elevation during arrhythmia ablations-A review.

Coronary injury presenting as ST segment elevation (STE) during ablation procedures for different arrhythmias is a rare and most feared complication. There have been multiple reports on STE during various ablation procedures in the recent past. Herein, we review various mechanisms, presentations, and management of STE observed during various ablations, including atrial fibrillation ablation cavotricuspid isthmus and ablation, supraventricular tachycardia ablations, coronary sinus ablation, and ventricular arrhythmia ablations.

Semi-urgent pulmonary vein isolation using cryoballoon for haemodynamically unstable atrial fibrillation storm in a patient with low cardiac output syndrome: a case report

BackgroundAtrial fibrillation and heart failure are common coexisting conditions requiring hospitalisation for heart failure and death. Pulmonary vein isolation is a well-established option for symptomatic atrial fibrillation and for atrial fibrillation concomitant with heart failure with reduced left ventricular ejection fraction. Recently, pulmonary vein isolation using cryoballoon showed non-inferiority to radiofrequency ablation with respect to the treatment of patients with drug-refractory paroxysmal atrial fibrillation. However, the effectiveness of acute-phase rhythm control by semi-urgent pulmonary vein isolation using cryoballoon in patients with haemodynamically unstable atrial fibrillation storm accompanied with low cardiac output syndrome is unclear. Herein, we present a case in which semi-urgent pulmonary vein isolation using cryoballoon was effective for acute-phase rhythm control against drug-resistant and haemodynamically unstable repetitive atrial fibrillation tachycardia accompanied with low cardiac output syndrome.Case presentationA 57-year-old man was hospitalised for New York Heart Association functional class 4 heart failure with atrial fibrillation tachycardia and reduced left ventricular ejection fraction of 20% accompanied with low cardiac output syndrome-induced liver damage. The haemodynamics collapsed during atrial fibrillation tachycardia, which had become resistant to intravenous amiodarone and repeated electrical cardioversions. In addition to atrial fibrillation, atrial tachycardia and common-type atrial flutter appeared on day 3. Multiple organ failure progressed gradually due to haemodynamically unstable atrial fibrillation tachycardia storm accompanied with low cardiac output syndrome. On day 4, to focus on treatment of heart failure and multiple organ failure, semi-urgent rescue pulmonary vein isolation using cryoballoon to atrial fibrillation and cavotricuspid isthmus ablation to common-type atrial flutter were performed for acute-phase rhythm control. Soon after the ablation procedure, atrial fibrillation and common-type atrial flutter were lessened, and sinus rhythm was restored. A stable haemodynamics was successfully achieved with the improvement of hepatorenal function. The patient was discharged on day 77 without complications.ConclusionsThis case demonstrates that acute-phase rhythm control by semi-urgent pulmonary vein isolation using cryoballoon could be a treatment option in patients with haemodynamically unstable atrial fibrillation tachycardia storm accompanied with low cardiac output syndrome, which is refractory to cardioversion and drug therapy.

Benefit of ultra-high-density mapping-guided radiofrequency reablation in pulmonary vein isolation non-responders after initial cryoballoon procedure.

Symptomatic atrial arrhythmias despite complete pulmonary vein isolation (PVI) are common. The purpose was to evaluate ultra-high-density multi-electrode electroanatomical mapping-guided radiofrequency ablation (RFA) in PVI non-responders. Ultra-high-density multi-electrode electroanatomical mapping-guided RFA in consecutive symptomatic atrial fibrillation (AF) patients after initial cryoballoon PVI was performed. Patients were included if all pulmonary veins (PVs) were still isolated. Radiofrequency targets were atrial tachycardia (AT), extra-PV trigger, and/or substrate. Procedural results and outcome were evaluated. Of 95 patients, 67 (70.5%) with complete PVI were included (70 years, CHA2DS2Vasc 2.9, left atrium 45 mm, persistent AF 45%, AT 45%). The median time to reablation was 26 months. One hundred and seven maps (1.6/patient) and 11.890 ± 9.018 electrograms were acquired in 33 ± 12 min. Twenty-eight percent of the left atrial (LA) wall showed pathological voltage signals, predominantly at the anterior (37%) and septal wall (26%). Atrial tachycardia (49 left, 4 right) were ablated in 35 patients (52%), extra-PV trigger in two patients (3%). One atrioventricular nodal re-entry tachycardia and seven right atrial isthmus ablation (10%) were performed. In 32 patients (48%), no AT was present and substrate-based ablation was performed. Mean LA area ablated was 7 ± 6 cm2 (7%). No major complication occurred. The mean follow-up time was 772 ± 317 days. Freedom from atrial arrhythmia recurrence off antiarrhythmic drugs was 49% at 12 months. Pulmonary vein isolation non-responders are older, mainly suffering from complex atrial arrhythmias. Left atrial substrate is predominantly located at the anterior and septal wall. Ultra-high-density multi-electrode electroanatomical mapping-guided RFA is safe and effective. At 1 year, 5 out of 10 patients were in stable sinus rhythm off antiarrhythmic drugs.

Feasibility, safety, and durability of porcine atrial ablation using a lattice‐tip temperature‐controlled radiofrequency ablation catheter

Pulmonary vein isolation (PVI) using standard radiofrequency (RF) catheters is limited by incomplete contiguity and prolonged procedural times. A novel, 9-mm lattice-tip irrigated RF catheter can create wide lesions rapidly in swine atria. In five swine, temperature limited (75°C) irrigated RF for 5 seconds/ablation was selected, to isolate seven pulmonary veins (PVs; five right superior and two inferior commons) and create five right atrial lines. After 4 weeks, repeat mapping and additional ablation to create atrial isthmus lesions were performed. The chronic lesions were submitted for histology. This was compared with right superior PVI data using standard 3.5-mm irrigated tip ablation in six swine. All targeted PVs (seven of seven, 100%) were acutely isolated. Durable isolation was observed in all six of six PVs treated with 5-secondapplications, but not in one PV inadvertently treated with 4-second applications. For the durably isolated PVs, the mean lesion count/PV and total RF time/PV was 16.3 ± 5.2 applications and 81.3 ± 25.9 seconds for the right superior and 14.5 ± 0.7 applications and 71.1 ± 5.5 seconds for the inferior common PV. Right atrial linear ablation was performed with a lesion count of 12 ± 2.3 applications and RF times of 59.5 ± 12.5 seconds. Cavotricuspid and mitral isthmus linear ablations were transmural along their entire length. All 53 of 53 (100%) sections were transmural on histology. Rapid and durable PVI and linear atrial ablation is feasible with this novel 9-mm lattice-tip catheter.

Topographic characteristics of the left atrial medial isthmus.

The purpose of this study was to provide detailed topography of the left atrial medial isthmus (situated between the right inferior pulmonary vein ostium and the medial part of the mitral annulus). Two hundred human hearts (Caucasian, 22.5% females, 48.7 ± 4.9 years old) were investigated. The mean length of the medial isthmus was 42.4±8.6mm. Additionally, the medial isthmus line was divided by the oval fossa into three sections with equal mean lengths (upper: 14.2±7.2vs middle: 14.1±6.1vs lower: 14.9±4.6mm; P>.05). The left upper section of the atrial wall was thinner than the lower section (2.5±1.1vs 3.4±1.6mm; P<.0001). This study noted three separate spatial arrangements of the isthmus line. Type I (54.5%) had an oval fossa located outside the isthmus line; type II (32.5%) had an oval fossa crossed by the isthmus line, and type III (13.0%) had an oval fossa rim located tangentially to the isthmus line. In 68.5% of the examined specimens, the isthmus area had a smooth surface. Conversely, the remaining 31.5% had additional structures within its borders such as diverticula, recesses, and tissue bridges. This study is the first to describe the morphometric and topographical features of the left atrial medial isthmus. Interventions within the medial isthmus line should be performed cautiously, especially when they are transected by the oval fossa (32.5%). Careful navigation of the area is also recommended due to the possibility of existent additional structures. The latter could lead to catheter entrapment during ablation procedures.

MORPHOLOGY OF THE LEFT ATRIAL MEDIAL ISTHMUS

The left atrial medial isthmus (or alternative isthmus) is an anatomical space located between the right inferior pulmonary vein and the medial part of the mitral annulus. This area may be used clinically for transcatheter ablation of arrhythmogenic substrate and accessory pathways. The purpose of

Blood Vessels and Myocardial Thickness within the Left Atrial Appendage Isthmus Line.

Electric isolation of the left atrial appendage (LAA) and linear ablations in the area of the LAA base are gaining popularity. However, very little is known about the myocardial architecture and the presence of epicardial blood vessels within this region, which could significantly influence the course of such procedures. We examined 200 autopsied hearts (22.5% females, 46.7 ± 16.8 years old). The LAA isthmus (i.e., the line between the LAA ostium and the mitral annulus) was cut longitudinally. The myocardium was thickest at the LAA end of the isthmus (2.4 ± 0.7 mm) followed by its middle sector (2.1 ± 0.7 mm) inside the LAA, 5 mm from its ostium (1.9 ± 0.7 mm), and the mitral annulus end of the isthmus (1.8 ± 0.6 mm) (P < 0.0001). At least one artery was found in 96.5% of all samples (89.5% were single branched, 7% had two branches). The great cardiac vein was found in 77.0% and the left marginal vein in 2.5%. The artery was interposed between the endocardium and the great cardiac vein in 31.5% of cases. The smallest distance between the endocardium and the artery was 0.5 mm and between the endocardium and the vein was 0.7 mm. In total, we were able to distinguish fifteen different types of vascular arrangements within the LAA isthmus line in this study. The myocardium within the LAA isthmus is thickest at its LAA end. The left circumflex coronary artery branches are the most frequently-occurring vessels within the isthmus and are present in almost all cases, while the great cardiac vein is present in three quarters of hearts. Clin. Anat. 31:1024-1030, 2018. © 2018 Wiley Periodicals, Inc.

Anatomic characteristics of the mitral isthmus region: The left atrial appendage isthmus as a possible ablation target

The mitral isthmus is a part of the postero-inferior area of the lateral left atrial wall located between the mitral annulus and the left inferior pulmonary vein ostium. Linear ablation lesions are created within the mitral isthmus for the invasive treatment of left atrial arrhythmias. However, the anatomy of this region is not fully understood. The aim of this study has been to provide a detailed morphometric description of the mitral isthmus region and to propose another possible isthmus within the investigated heart area that may serve as a potential new ablation target. Two hundred autopsied, non-atrial fibrillation hearts (23.5% deriving from females) whose donors were a mean of 47.6±17.6years old were investigated. We macroscopically assessed the anatomy of the postero-inferior area of the lateral left atrial wall. The mean mitral isthmus length was 28.8±7.0mm and was significantly longer than the left atrial appendage (LAA) isthmus (14.2±4.8mm) (p=.00). The distance between the LAA orifice and the left inferior pulmonary vein ostium (18.4±4.8mm) was longer than the LAA isthmus (p=.00) and shorter than the mitral isthmus (p=.00). The LAA isthmus was longer in hearts with a common left pulmonary vein (p=.037). In 65.5% of all cases the area between the right and left mitral isthmus lines was completely smooth. In the remaining hearts, crevices and diverticula (18.0%), intertrabecular recesses (7.0%), trabecular bridges (3.5%), or co-existence of these structures (6%) could be observed. The LAA isthmus line was smooth in 95.5% of all cases, with only small crevices in the remaining 4.5%. In conclusion, regardless of the anatomical variants of the left-sided pulmonary veins, the mitral isthmus area is quite uniform in size. The LAA isthmus is considerably shorter than the mitral isthmus. The mitral isthmus line has many unwanted structures that may entrap the catheter, which is not the case for the LAA isthmus. We proposed the LAA isthmus line for potential clinical use.

A Story of Migrating Azygous Vein

SESSION TITLE: Student/Resident Case Report Poster - Cardiovascular Disease II SESSION TYPE: Student/Resident Case Report Poster PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM INTRODUCTION: Azygous continuation of IVC is a rare anomaly and reported incidence is < 0.3 % in general population1. This anomaly is associated with atrial flutter1, increased incidence of lower extremity deep vein thrombosis1 and asplenia/polysplenia syndromes2. CASE PRESENTATION: A 50-year-old Caucasian male presented with worsening dyspnea and fatigue and was found to be in typical atrial flutter with 2:1 block. Flutter ablation was attempted by a femoral venous access but later the procedure was abandoned due to difficulty in advancing catheter into the right atrium. CT scan of the chest with 3-D reconstruction showed retrocrural continuation of inferior vena cava (IVC) as azygous vein (AZV); passing behind the aorta and draining into the coronary sinus (CS) [Figures 1, 2 and 3]. We used CT angiography with 3-D rendition to plan access. The patient subsequently underwent successful atrial flutter ablation with placement of a diagnostic catheter into the CS and right atrial cavotricuspid isthmus (CTI) via the IVC/AZV and placement of an ablation catheter to the CTI through the left subclavian vein. He was discharged in sinus rhythm on dofetilide and warfarin. DISCUSSION: The unusually large AZV can be confused with retrocural adenopathy or right-sided paratracheal mass2. It has been reported with Scimitar syndrome3 and non-compaction cardiomyopathy4. Recognition of this anatomic anomaly is of paramount importance in invasive procedures like radiofrequency catheter ablation and during cardiopulmonary bypass. CONCLUSIONS: A high index of suspicion shoud be present for patients requiring ablation procedures if operator feels a resistance during procedure and use of sophisticated imaging is definitely helpful recognizing this abnormality and can be helpful in avoiding complications.Our case is unique because AZV drained directly into the coronary sinus which has not been reported before in literature to our knowledge so far. Reference #1: Mamidipally S, Rashba E, McBrearty T, Poon M. Azygous continuation of inferior vena cava. J Am Coll Cardiol. 2010; 56(21):e41. Reference #2: J. Edward Bass, MD, Michael D. Redwine, MD, Larry A. Kramer, MD, Phan T. Huynh, MD, John H. Harris Jr, MD, DSc. Spectrum of Congenital Anomalies of the Inferior Vena Cava: Cross-sectional Imaging Findings. RadioGraphics, 2000; 20,639-652. Reference #3: Celik M, Celik T, Iyisoy A, Ayten O. Scimitar syndrome and azygos continuation of the inferior vena cava diagnosed in an adult--an unusual association. Congenit Heart Dis. 2012: E85-8. DISCLOSURE: The following authors have nothing to disclose: Ali Ghani, Sadaf Mirrani, Ghazi Mirrani, Rizwan Sardar, Ahsan Raza No Product/Research Disclosure Information