International Journal of Cardiology 171 (2014) 78–81
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Don't move during ablation of atrial fibrillation!☆ Akinori Sairaku a,b,⁎,1, Yukihiko Yoshida a,1, Haruo Hirayama a,1, Yukiko Nakano b,1, Noriaki Kondo c,1, Yasuki Kihara b,1 a b c
Department of Cardiology, Cardiovascular Center, Nagoya Daini Red Cross Hospital, Nagoya, Japan Department of Cardiology, Graduate School of Medicine, Hiroshima University, Hiroshima, Japan Department of Clinical Laboratory, Nagoya Daini Red Cross Hospital, Nagoya, Japan
a r t i c l e
i n f o
Article history: Received 12 September 2013 Received in revised form 21 October 2013 Accepted 17 November 2013 Available online 23 November 2013 Keywords: Ablation time Atrial fibrillation Body movement Pressure sensor SD-101 Total radiofrequency energy
a b s t r a c t Background: Restless patient is recalcitrant during ablation of atrial fibrillation (AF). We aimed to assess the association between patient movements during AF ablation and its outcome. Methods: We examined the body movement during AF ablation in 78 patients with the use of a novel portable respiratory monitor, the SD-101, which also has the ability to quantify the frequency of body movements. Results: The body movement index, defined as the number of the units of time with body movement events divided by the recording time (11.4 ± 6.5 events/h), was significantly correlated with the ablation time defined as the time from the first point of the ablation to the end of the procedure (1.2 ± 0.3 h) (r = 0.35; p = 0.0014) and a total radiofrequency energy applied (56.6 ± 17.7 kW) (r = 0.36; p = 0.0015). A multiple linear regression analysis showed that non-paroxysmal AF (β = 0.25; p = 0.036) and the body movement index (β = 0.36; p = 0.0019) were independent determinants of the ablation time. The body movement index was similar in patients with and without recurrence of AF. Conclusions: Keeping patients motionless may be important to reduce the procedural duration of AF ablation. © 2013 Elsevier Ireland. Ltd All rights reserved.
1. Introduction During catheter ablation of atrial fibrillation (AF) with consciousness sedation, though a sufficient amount of sedatives or analgesics is given, patients often move their body unconsciously on the procedure table because of pain caused by the radiofrequency applications to the left atrium (LA) [1]. This annoys the operators, and sometimes even interrupts the procedure. However, this issue has not been discussed because it is difficult to know precisely how often and how seriously the patients move during the ablation. The SD-101 sleep recorder is a newly developed portable respiratory recorder [2], which can also assess the body movements of the examinee quantitatively with pressure sensors embedded in its sheet-shaped body. With the use of the SD-101, in this study we sought to answer the question, “Does the patient movement observed during AF ablation matter?”
☆ This work is not supported by any external funding. ⁎ Corresponding author at: Department of Cardiology, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. Tel.: +81 82 257 5540; fax: +81 82 257 5169. E-mail address: [email protected] (A. Sairaku). 1 This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. 0167-5273/$ – see front matter © 2013 Elsevier Ireland. Ltd All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.11.049
2. Methods 2.1. Patients This study was conducted by the Cardiovascular Center of Nagoya Daini Red Cross Hospital from May 2011 to April 2012. The study protocol was approved by the research committee of the institution. Patients were considered eligible for inclusion if they were scheduled to undergo radiofrequency catheter ablation of drug refractory AF for the first time. Patients were excluded from the study if they were scheduled in advance to undergo any additional procedure other than pulmonary vein (PV) isolation and cavotricuspid isthmus ablation. All the participants underwent transthoracic and transesophageal echocardiography prior to the ablation. The eligible patients were enrolled after giving informed consent. 2.2. Cather ablation All antiarrhythmic drugs (AADs) were discontinued 5 half-lives before the ablation procedure. The details of the double Lasso catheter-guided extensive encircling PV isolation performed in the present study have been described elsewhere [3]. In brief, two 7French decapolar circumferential catheters (Lasso, Biosense Webster, Diamond Bar, CA, USA) were placed within the ipsilateral superior and inferior PVs. After constructing 3dimensional electroanatomical maps using a non-fluoroscopic navigation system (CARTO3, Biosense Webster), circumferential ablation lines were created around the left- and right-sided ipsilateral PVs using a 3.5-mm irrigated tip catheter (ThermoCool, Biosense Webster). Radiofrequency energy was delivered with a maximum power of 35 W for 20 s at each site. The endpoint of the PV isolation was either the elimination or dissociation of the PV potentials recorded from the circular catheters placed within the PVs and exit block from the PVs. Transthoracic cardioversion was applied to restore sinus rhythm in the patients with persistent or longstanding persistent AF. Finally, the cavotricuspid isthmus was ablated with the use of a non-irrigated ablation catheter with an 8-mm tip (Fantasista, Japan Lifeline, Tokyo, Japan). Radiofrequency energy was delivered with a target temperature of 55 °C and power limit of 50 W. The ablation procedures were carried out by four different operators.
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2.3. Quantification of the body movement The SD101® (Kenzmedico, Saitama, Japan) is a newly developed portable respiratory monitor with a sheet-like shape (Fig. 1) [2]. Unlike conventional portable monitors, the device does not have any cords, tubes or belts, and therefore never restrains the examinee. All that the examinee needs to do is turn the device on and lie on it. The device recognizes the patterns of thoracic ventilatory efforts using 162 coin-shaped pressure sensors embedded in it, and creates respiratory waveforms. In addition, the device also can quantitatively assess the body movements of the examinee. Specifically, since the sensors can detect the pressure load in an all or none fashion, when the patients move any part of their body, the distribution of the sensors detecting the pressure load changes from that before the movement. When (the number of sensors that newly detect the pressure load and that no longer detect any pressure load after the change in the body position)/(the number of the sensors that detect the pressure load before the change in the body position) is more than 0.6, it is recognized as a body movement (Fig. 2). With the use of this criterion, the body movement events are checked automatically every 0.1 s. When the events are identified one or more times within a time window of 25.6 s, this unit of time is recorded as having a body movement event (Fig. 3). We put the SD-101 on an X-ray table in the cath lab (Fig. 1), and then the patients lied on it. The recording with the device was started when the radiofrequency energy was initially applied and the recording was stopped when the procedure was completed. All data recorded by the device were analyzed automatically with the use of the SD ANALYZER software (Kenzmedico) and were reviewed by experienced technicians. We defined the number of the units of time with body movements divided by the total recording time as the body movement index, and used it for the analyses. We excluded any recorded events of body movements resulting from electrical cardioversion from the analyses in patients with persistent or longstanding persistent AF (non-paroxysmal AF). Also, the time required for the cardioversion was subtracted from both the ablation time and recording time. 2.4. Sedation and analgesia The patients were sedated while monitoring the non-invasive blood pressure and oxygen saturation without intubation during the ablation procedure. A total of 30 mg of pentazocine was given in 2 separate injections at the beginning of the ablation procedure and just before mapping the LA. Thiamylal was then administered as an intravenous bolus of 1.25 mg/kg every 10 min during the radiofrequency applications to the atria. When the patients complained of chest pain or moved their body due to the pain, an additional infusion of thiamylal was administered. The patients were given 2 L/min of oxygen through a nasal canula throughout the procedure. 2.5. Follow-up Previously ineffective AADs were restarted the day after the ablation. The patients were discharged from the hospital 2 days after the ablation and were scheduled to be followed up at the outpatient clinic 3, 6, 9, and finally 12 months after the procedure to check for any AF recurrences defined in the current guidelines [1]. Twelve lead electrocardiograms were obtained at all clinical visits, and 24-hour Holter monitoring was performed at 3-month intervals during the follow-up period. The oral AADs were encouraged to be discontinued in patients who remained free of AF for 3 consecutive months. 2.6. Endpoints The endpoints of this study were (1) an association of the body movement index with ablation time defined as the time from the initial application of the radiofrequency energy
Fig. 2. Schema of the distribution maps of the pressure load. The black circles indicate the sensors detecting the pressure load before any change in body position. The red and blue circles show the sensors that newly detect the load and the ones that no longer detect the load after the body movement, respectively. The gray circles indicate the sensors that continue to detect the load even after the body movement.
to the completion of the ablation procedure and a total amount of radiofrequency energy applied to complete PV isolation and cavotricuspid isthmus block, and (2) a relationship between the body movement index and the occurrence of an AF recurrence.
2.7. Statistical analysis The continuous variables were summarized as the means ± SD or medians with interquartile ranges, and categorical variables as proportions. A Pearson's correlation analysis was used to access the correlations between the body movement index and ablation time or total radiofrequency energy. Multivariate linear regression analyses were performed to determine the independent determinants of the ablation time and the total radiofrequency energy using the body movement index and other potential clinical parameters as independent variables. The body movement index was compared between the patients with and without AF recurrences by means of an unpaired t-test. The statistical analyses were performed using JMP software version 8.0 (SAS Institute, Cary, NC, USA). For all analyses, a P value of b0.05 was considered statistically significant.
3. Results 3.1. Patients We included 83 patients. However, 5 patients were not analyzed because an unplanned superior vena cava isolation and LA linear ablation were performed in addition to the PV isolation and cavotricuspid isthmus ablation in 3 and 2 patients, respectively. Therefore, we analyzed 78 patients. The mean age of the patients was 63 ± 10 years old, and two-thirds of them were men and had paroxysmal AF (Table 1).
3.2. Association of the body movement index with ablation time and total radiofrequency energy
Fig. 1. SD-101 sleep recorder; a sheet shaped portable respiratory monitor which has 162 pressure sensors in its body to detect events of disordered breathing and changes in body position.
The body movement index (11.4 ± 6.5 events/h, Fig. 4) was significantly correlated with the ablation time (1.2 ± 0.3 h) (r = 0.35; p = 0.0014, Fig. 5) and total radiofrequency energy (56.6 ± 17.7 kW) (r = 0.36; p = 0.0015, Fig. 6). A multiple linear regression analysis including the age, male gender, body mass index, non-paroxysmal AF, LA diameter and body movement index as independent variables showed that non-paroxysmal AF (β = 0.25; p = 0.036) and the body movement index (β = 0.36; p = 0.0019) were independent determinants of the ablation time (Table 2). Another multiple model including the same parameters as explanatory variables also revealed the body movement index as the only independent determinant of the total radiofrequency energy (β = 0.37; p = 0.002) (Table 3).
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A. Sairaku et al. / International Journal of Cardiology 171 (2014) 78–81
Fig. 3. A polygraphic recording from the SD-101 in a patient. In the upper panel, the waveform represents the thoracic ventilatory efforts and the gray bars indicate the units of time when body movement events occurred. The blue line in the lower panel shows the body position.
3.3. Body movement index and the outcome of AF ablation During a mean follow-up period of 12.4 ± 4.5 months, 60 patients (76.9%) remained free from AF recurrence without any AADs. The body movement index was similar in the patients with and without AF recurrences (13.4 ± 6.6 vs. 10.5 ± 6.8; p = 0.27). We identified a patient who had a giant hematoma at the femoral puncture site with a 22% decrease in her hematocrit, and her body movement index was 28.0 events/h. No other major periprocedural complications were observed. 4. Discussion We for the first time demonstrated that patients with frequent body movements during AF ablation were more likely to have a prolonged procedural duration and greater total radiofrequency energy. We suggest the following potential mechanisms for this. (1) Considering the criterion used for the SD-101 to determine whether the examinee moves or not, the device seemed to detect relatively large body movements. When the large body movement of the patient occurred, the operators presumably had to stop the ablation procedure to guarantee the procedural safety. Also, they may have had to reposition the patient's body back to its original location and to infuse additional sedatives, which would have consequently resulted in a prolonged procedure. (2) The non-fluoroscopic 3dimensional navigation system, CARTO3, has the excellent ability to correct for patient movement [4]. The correction however needs some time, during which the procedure must be interrupted.
Furthermore, its ability is still limited to only minor movements [4], and therefore it is possible that when the electro-anatomical maps constructed with much time and effort are made unusable due to coarse patient movements, further time is needed to create another map or to complete the procedure without the help of the navigation system. Accordingly, the issue of the navigation system should be taken into account. (3) The patient movement during application of radiofrequency energy must have led to a difficulty to manipulate the ablation catheter, and which consequently may have resulted in excessive applications of radiofrequency energy. (4) Restless patients will annoy the operator, which presumably would decrease the concentration level of the operator, possibly leading to a prolonged procedural time. We also found that another independent determinant of the ablation time was non-paroxysmal AF even after the impact of intraprocedural electrical cardioversion was left out. Although there is no clear data supporting this finding, the difficulty of ablating non-paroxysmal AF may be common knowledge among interventional electrophysiologists [1]. We were unable to show that an enlarged LA was an independent determinant of the ablation time, however, the electrical and structural remodeling other than the dilation occurring in the LA of patients with non-paroxysmal AF [5] may have resulted in a tough procedure. In addition, electronic potentials within the PVs are hard to identify during AF. Those characteristics observed in the patients with non-paroxysmal AF may have contributed to the difficulty of the ablation and therefore resulted in a longer procedural time. We failed to show any association between the frequency of body movement events and the freedom from AF recurrence. This indicated that indeed restless patients mattered, however that was not problematic enough to worsen the major outcomes of AF ablation.
Table 1 Clinical characteristics of the study population (n = 78). Variables Age (years) Male Body mass index (kg/m2) Duration of AF (months) No. of failed antiarrhythmic drugs Type of AF Paroxysmal AF Persistent AF Longstanding persistent AF Transient ischemic attack/stroke Hypertension Diabetes Heart failure Left ventricular ejection fraction (%) Left atrial diameter (mm)
63 ± 10 58 (74) 24.0 ± 4.1 26 [9, 55] 1.2 ± 1.1 57 (73) 19 (24) 2 (3) 3 (4) 38 (49) 10 (13) 5 (6) 62 ± 7 40 ± 6
Value are the mean ± SD, n (%), or median [interquartile range] as appropriate. AF = atrial fibrillation.
Fig. 4. The distribution of the body movement index.
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Table 2 Multiple linear regression analysis of the ablation time. Variables
t
β
p Value
Age Male Body mass index Non-paroxysmal AF Left atrial diameter Body movement index
−0.44 0.28 0.08 2.13 0.87 3.22
−0.053 0.033 0.01 0.25 0.12 0.36
0.66 0.78 0.94 0.036 0.38 0.0019
Adjusted R2 = 0.11, β = standardized coefficient, non-paroxysmal AF = persistent or longstanding persistent atrial fibrillation.
Table 3 Multiple linear regression analysis of the total radiofrequency energy.
Fig. 5. Scatter plots of the ablation time and body movement index.
4.1. Clinical implications This study is of importance in that we provided objective data on what had been considered to be impossible to be assessed quantitatively. Prolongation of the procedural duration forces patients to endure discomfort resulting from lying motionless for a long time, increases the radiation exposure and even decreases the patient-turnover at highvolume centers [6]. Excessive amount of radiofrequency energy delivered to the LA often causes an LA wall edema, which may increase thrombogenicity and further could result in heart failure [7]. Our study thus implies that keeping the patients motionless during the AF ablation procedure is important in order to avoid those potential detriments. In order to do that thoroughly, however, a large amount of sedatives may be needed and which frequently results in apnea or poses the potential risk of aspiration when used with consciousness sedation. Accordingly, in this respect, general anesthesia may be superior to consciousness sedation for AF ablation [8], however, the former appears to be somewhat like “taking a sledgehammer to crack a nut”. This dilemma is a future challenge.
Variables
t
β
p Value
Age Male Body mass index Non-paroxysmal AF Left atrial diameter Body movement index
−0.44 −0.04 0.26 1.75 1.25 3.22
−0.055 −0.005 0.033 0.21 0.17 0.37
0.66 0.97 0.8 0.085 0.22 0.002
Adjusted R2 = 0.10, abbreviations are as in Table 1.
operator's skill, and importantly most of them cannot be quantified. We were unable to determine whether restless patients are likely to have periprocedural complications, because the number of patients recruited was limited, and therefore we rarely encountered major complications. Acknowledgment The authors thank Mr. John Martin for his grammatical assistance. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. References
4.2. Limitations The body movement index was found to have only weak correlations with ablation time and total radiofrequency energy. Furthermore, the multiple linear regression models we used explained no more than 11% and 10% of the variations in the ablation time and total radiofrequency energy, respectively. Those findings indicate that the time required for the ablation and an amount of radiofrequency energy needed to create the complete lesions depend on many factors such as the anatomical variations in the patients, equipment used and
Fig. 6. Scatter plots of the total radiofrequency energy and body movement index.
[1] Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632–96 (e21). [2] Kobayashi M, Namba K, Tsuiki S, et al. Validity of sheet-type portable monitoring device for screening obstructive sleep apnea syndrome. Sleep Breath 2013;17: 589–95. [3] Ouyang F, Antz M, Ernst S, et al. Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the pulmonary veins: lessons from double Lasso technique. Circulation 2005;111:127–35. [4] Hameedullah I, Chauhan VS. Clinical considerations for allied professionals: understanding and optimizing three-dimensional electroanatomic mapping of complex arrhythmias—part 1. Heart Rhythm 2009;6:1249–52. [5] Sairaku A, Nakano Y, Oda N, et al. Prediction of sinus node dysfunction in patients with long-standing persistent atrial fibrillation using the atrial fibrillatory cycle length. J Electrocardiol 2012;45:141–7. [6] Khaykin Y, Zarnett L, Friedlander D, et al. Point-by-point pulmonary vein antrum isolation guided by intracardiac echocardiography and 3D mapping and duty-cycled multipolar AF ablation: effect of multipolar ablation on procedure duration and fluoroscopy time. J Interv Card Electrophysiol 2012;34:303–10. [7] Okada T, Yamada T, Murakami Y, et al. Prevalence and severity of left atrial edema detected by electron beam tomography early after pulmonary vein ablation. J Am Coll Cardiol 2007;49:1436–42. [8] Di Biase L, Conti S, Mohanty P, et al. General anesthesia reduces the prevalence of pulmonary vein reconnection during repeat ablation when compared with conscious sedation: results from a randomized study. Heart Rhythm 2011;8:368–72.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Don't move during ablation of atrial fibrillation!☆ Akinori Sairaku a,b,⁎,1, Yukihiko Yoshida a,1, Haruo Hirayama a,1, Yukiko Nakano b,1, Noriaki Kondo c,1, Yasuki Kihara b,1 a b c
Department of Cardiology, Cardiovascular Center, Nagoya Daini Red Cross Hospital, Nagoya, Japan Department of Cardiology, Graduate School of Medicine, Hiroshima University, Hiroshima, Japan Department of Clinical Laboratory, Nagoya Daini Red Cross Hospital, Nagoya, Japan
a r t i c l e
i n f o
Article history: Received 12 September 2013 Received in revised form 21 October 2013 Accepted 17 November 2013 Available online 23 November 2013 Keywords: Ablation time Atrial fibrillation Body movement Pressure sensor SD-101 Total radiofrequency energy
a b s t r a c t Background: Restless patient is recalcitrant during ablation of atrial fibrillation (AF). We aimed to assess the association between patient movements during AF ablation and its outcome. Methods: We examined the body movement during AF ablation in 78 patients with the use of a novel portable respiratory monitor, the SD-101, which also has the ability to quantify the frequency of body movements. Results: The body movement index, defined as the number of the units of time with body movement events divided by the recording time (11.4 ± 6.5 events/h), was significantly correlated with the ablation time defined as the time from the first point of the ablation to the end of the procedure (1.2 ± 0.3 h) (r = 0.35; p = 0.0014) and a total radiofrequency energy applied (56.6 ± 17.7 kW) (r = 0.36; p = 0.0015). A multiple linear regression analysis showed that non-paroxysmal AF (β = 0.25; p = 0.036) and the body movement index (β = 0.36; p = 0.0019) were independent determinants of the ablation time. The body movement index was similar in patients with and without recurrence of AF. Conclusions: Keeping patients motionless may be important to reduce the procedural duration of AF ablation. © 2013 Elsevier Ireland. Ltd All rights reserved.
1. Introduction During catheter ablation of atrial fibrillation (AF) with consciousness sedation, though a sufficient amount of sedatives or analgesics is given, patients often move their body unconsciously on the procedure table because of pain caused by the radiofrequency applications to the left atrium (LA) [1]. This annoys the operators, and sometimes even interrupts the procedure. However, this issue has not been discussed because it is difficult to know precisely how often and how seriously the patients move during the ablation. The SD-101 sleep recorder is a newly developed portable respiratory recorder [2], which can also assess the body movements of the examinee quantitatively with pressure sensors embedded in its sheet-shaped body. With the use of the SD-101, in this study we sought to answer the question, “Does the patient movement observed during AF ablation matter?”
☆ This work is not supported by any external funding. ⁎ Corresponding author at: Department of Cardiology, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. Tel.: +81 82 257 5540; fax: +81 82 257 5169. E-mail address: [email protected] (A. Sairaku). 1 This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. 0167-5273/$ – see front matter © 2013 Elsevier Ireland. Ltd All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.11.049
2. Methods 2.1. Patients This study was conducted by the Cardiovascular Center of Nagoya Daini Red Cross Hospital from May 2011 to April 2012. The study protocol was approved by the research committee of the institution. Patients were considered eligible for inclusion if they were scheduled to undergo radiofrequency catheter ablation of drug refractory AF for the first time. Patients were excluded from the study if they were scheduled in advance to undergo any additional procedure other than pulmonary vein (PV) isolation and cavotricuspid isthmus ablation. All the participants underwent transthoracic and transesophageal echocardiography prior to the ablation. The eligible patients were enrolled after giving informed consent. 2.2. Cather ablation All antiarrhythmic drugs (AADs) were discontinued 5 half-lives before the ablation procedure. The details of the double Lasso catheter-guided extensive encircling PV isolation performed in the present study have been described elsewhere [3]. In brief, two 7French decapolar circumferential catheters (Lasso, Biosense Webster, Diamond Bar, CA, USA) were placed within the ipsilateral superior and inferior PVs. After constructing 3dimensional electroanatomical maps using a non-fluoroscopic navigation system (CARTO3, Biosense Webster), circumferential ablation lines were created around the left- and right-sided ipsilateral PVs using a 3.5-mm irrigated tip catheter (ThermoCool, Biosense Webster). Radiofrequency energy was delivered with a maximum power of 35 W for 20 s at each site. The endpoint of the PV isolation was either the elimination or dissociation of the PV potentials recorded from the circular catheters placed within the PVs and exit block from the PVs. Transthoracic cardioversion was applied to restore sinus rhythm in the patients with persistent or longstanding persistent AF. Finally, the cavotricuspid isthmus was ablated with the use of a non-irrigated ablation catheter with an 8-mm tip (Fantasista, Japan Lifeline, Tokyo, Japan). Radiofrequency energy was delivered with a target temperature of 55 °C and power limit of 50 W. The ablation procedures were carried out by four different operators.
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2.3. Quantification of the body movement The SD101® (Kenzmedico, Saitama, Japan) is a newly developed portable respiratory monitor with a sheet-like shape (Fig. 1) [2]. Unlike conventional portable monitors, the device does not have any cords, tubes or belts, and therefore never restrains the examinee. All that the examinee needs to do is turn the device on and lie on it. The device recognizes the patterns of thoracic ventilatory efforts using 162 coin-shaped pressure sensors embedded in it, and creates respiratory waveforms. In addition, the device also can quantitatively assess the body movements of the examinee. Specifically, since the sensors can detect the pressure load in an all or none fashion, when the patients move any part of their body, the distribution of the sensors detecting the pressure load changes from that before the movement. When (the number of sensors that newly detect the pressure load and that no longer detect any pressure load after the change in the body position)/(the number of the sensors that detect the pressure load before the change in the body position) is more than 0.6, it is recognized as a body movement (Fig. 2). With the use of this criterion, the body movement events are checked automatically every 0.1 s. When the events are identified one or more times within a time window of 25.6 s, this unit of time is recorded as having a body movement event (Fig. 3). We put the SD-101 on an X-ray table in the cath lab (Fig. 1), and then the patients lied on it. The recording with the device was started when the radiofrequency energy was initially applied and the recording was stopped when the procedure was completed. All data recorded by the device were analyzed automatically with the use of the SD ANALYZER software (Kenzmedico) and were reviewed by experienced technicians. We defined the number of the units of time with body movements divided by the total recording time as the body movement index, and used it for the analyses. We excluded any recorded events of body movements resulting from electrical cardioversion from the analyses in patients with persistent or longstanding persistent AF (non-paroxysmal AF). Also, the time required for the cardioversion was subtracted from both the ablation time and recording time. 2.4. Sedation and analgesia The patients were sedated while monitoring the non-invasive blood pressure and oxygen saturation without intubation during the ablation procedure. A total of 30 mg of pentazocine was given in 2 separate injections at the beginning of the ablation procedure and just before mapping the LA. Thiamylal was then administered as an intravenous bolus of 1.25 mg/kg every 10 min during the radiofrequency applications to the atria. When the patients complained of chest pain or moved their body due to the pain, an additional infusion of thiamylal was administered. The patients were given 2 L/min of oxygen through a nasal canula throughout the procedure. 2.5. Follow-up Previously ineffective AADs were restarted the day after the ablation. The patients were discharged from the hospital 2 days after the ablation and were scheduled to be followed up at the outpatient clinic 3, 6, 9, and finally 12 months after the procedure to check for any AF recurrences defined in the current guidelines [1]. Twelve lead electrocardiograms were obtained at all clinical visits, and 24-hour Holter monitoring was performed at 3-month intervals during the follow-up period. The oral AADs were encouraged to be discontinued in patients who remained free of AF for 3 consecutive months. 2.6. Endpoints The endpoints of this study were (1) an association of the body movement index with ablation time defined as the time from the initial application of the radiofrequency energy
Fig. 2. Schema of the distribution maps of the pressure load. The black circles indicate the sensors detecting the pressure load before any change in body position. The red and blue circles show the sensors that newly detect the load and the ones that no longer detect the load after the body movement, respectively. The gray circles indicate the sensors that continue to detect the load even after the body movement.
to the completion of the ablation procedure and a total amount of radiofrequency energy applied to complete PV isolation and cavotricuspid isthmus block, and (2) a relationship between the body movement index and the occurrence of an AF recurrence.
2.7. Statistical analysis The continuous variables were summarized as the means ± SD or medians with interquartile ranges, and categorical variables as proportions. A Pearson's correlation analysis was used to access the correlations between the body movement index and ablation time or total radiofrequency energy. Multivariate linear regression analyses were performed to determine the independent determinants of the ablation time and the total radiofrequency energy using the body movement index and other potential clinical parameters as independent variables. The body movement index was compared between the patients with and without AF recurrences by means of an unpaired t-test. The statistical analyses were performed using JMP software version 8.0 (SAS Institute, Cary, NC, USA). For all analyses, a P value of b0.05 was considered statistically significant.
3. Results 3.1. Patients We included 83 patients. However, 5 patients were not analyzed because an unplanned superior vena cava isolation and LA linear ablation were performed in addition to the PV isolation and cavotricuspid isthmus ablation in 3 and 2 patients, respectively. Therefore, we analyzed 78 patients. The mean age of the patients was 63 ± 10 years old, and two-thirds of them were men and had paroxysmal AF (Table 1).
3.2. Association of the body movement index with ablation time and total radiofrequency energy
Fig. 1. SD-101 sleep recorder; a sheet shaped portable respiratory monitor which has 162 pressure sensors in its body to detect events of disordered breathing and changes in body position.
The body movement index (11.4 ± 6.5 events/h, Fig. 4) was significantly correlated with the ablation time (1.2 ± 0.3 h) (r = 0.35; p = 0.0014, Fig. 5) and total radiofrequency energy (56.6 ± 17.7 kW) (r = 0.36; p = 0.0015, Fig. 6). A multiple linear regression analysis including the age, male gender, body mass index, non-paroxysmal AF, LA diameter and body movement index as independent variables showed that non-paroxysmal AF (β = 0.25; p = 0.036) and the body movement index (β = 0.36; p = 0.0019) were independent determinants of the ablation time (Table 2). Another multiple model including the same parameters as explanatory variables also revealed the body movement index as the only independent determinant of the total radiofrequency energy (β = 0.37; p = 0.002) (Table 3).
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Fig. 3. A polygraphic recording from the SD-101 in a patient. In the upper panel, the waveform represents the thoracic ventilatory efforts and the gray bars indicate the units of time when body movement events occurred. The blue line in the lower panel shows the body position.
3.3. Body movement index and the outcome of AF ablation During a mean follow-up period of 12.4 ± 4.5 months, 60 patients (76.9%) remained free from AF recurrence without any AADs. The body movement index was similar in the patients with and without AF recurrences (13.4 ± 6.6 vs. 10.5 ± 6.8; p = 0.27). We identified a patient who had a giant hematoma at the femoral puncture site with a 22% decrease in her hematocrit, and her body movement index was 28.0 events/h. No other major periprocedural complications were observed. 4. Discussion We for the first time demonstrated that patients with frequent body movements during AF ablation were more likely to have a prolonged procedural duration and greater total radiofrequency energy. We suggest the following potential mechanisms for this. (1) Considering the criterion used for the SD-101 to determine whether the examinee moves or not, the device seemed to detect relatively large body movements. When the large body movement of the patient occurred, the operators presumably had to stop the ablation procedure to guarantee the procedural safety. Also, they may have had to reposition the patient's body back to its original location and to infuse additional sedatives, which would have consequently resulted in a prolonged procedure. (2) The non-fluoroscopic 3dimensional navigation system, CARTO3, has the excellent ability to correct for patient movement [4]. The correction however needs some time, during which the procedure must be interrupted.
Furthermore, its ability is still limited to only minor movements [4], and therefore it is possible that when the electro-anatomical maps constructed with much time and effort are made unusable due to coarse patient movements, further time is needed to create another map or to complete the procedure without the help of the navigation system. Accordingly, the issue of the navigation system should be taken into account. (3) The patient movement during application of radiofrequency energy must have led to a difficulty to manipulate the ablation catheter, and which consequently may have resulted in excessive applications of radiofrequency energy. (4) Restless patients will annoy the operator, which presumably would decrease the concentration level of the operator, possibly leading to a prolonged procedural time. We also found that another independent determinant of the ablation time was non-paroxysmal AF even after the impact of intraprocedural electrical cardioversion was left out. Although there is no clear data supporting this finding, the difficulty of ablating non-paroxysmal AF may be common knowledge among interventional electrophysiologists [1]. We were unable to show that an enlarged LA was an independent determinant of the ablation time, however, the electrical and structural remodeling other than the dilation occurring in the LA of patients with non-paroxysmal AF [5] may have resulted in a tough procedure. In addition, electronic potentials within the PVs are hard to identify during AF. Those characteristics observed in the patients with non-paroxysmal AF may have contributed to the difficulty of the ablation and therefore resulted in a longer procedural time. We failed to show any association between the frequency of body movement events and the freedom from AF recurrence. This indicated that indeed restless patients mattered, however that was not problematic enough to worsen the major outcomes of AF ablation.
Table 1 Clinical characteristics of the study population (n = 78). Variables Age (years) Male Body mass index (kg/m2) Duration of AF (months) No. of failed antiarrhythmic drugs Type of AF Paroxysmal AF Persistent AF Longstanding persistent AF Transient ischemic attack/stroke Hypertension Diabetes Heart failure Left ventricular ejection fraction (%) Left atrial diameter (mm)
63 ± 10 58 (74) 24.0 ± 4.1 26 [9, 55] 1.2 ± 1.1 57 (73) 19 (24) 2 (3) 3 (4) 38 (49) 10 (13) 5 (6) 62 ± 7 40 ± 6
Value are the mean ± SD, n (%), or median [interquartile range] as appropriate. AF = atrial fibrillation.
Fig. 4. The distribution of the body movement index.
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Table 2 Multiple linear regression analysis of the ablation time. Variables
t
β
p Value
Age Male Body mass index Non-paroxysmal AF Left atrial diameter Body movement index
−0.44 0.28 0.08 2.13 0.87 3.22
−0.053 0.033 0.01 0.25 0.12 0.36
0.66 0.78 0.94 0.036 0.38 0.0019
Adjusted R2 = 0.11, β = standardized coefficient, non-paroxysmal AF = persistent or longstanding persistent atrial fibrillation.
Table 3 Multiple linear regression analysis of the total radiofrequency energy.
Fig. 5. Scatter plots of the ablation time and body movement index.
4.1. Clinical implications This study is of importance in that we provided objective data on what had been considered to be impossible to be assessed quantitatively. Prolongation of the procedural duration forces patients to endure discomfort resulting from lying motionless for a long time, increases the radiation exposure and even decreases the patient-turnover at highvolume centers [6]. Excessive amount of radiofrequency energy delivered to the LA often causes an LA wall edema, which may increase thrombogenicity and further could result in heart failure [7]. Our study thus implies that keeping the patients motionless during the AF ablation procedure is important in order to avoid those potential detriments. In order to do that thoroughly, however, a large amount of sedatives may be needed and which frequently results in apnea or poses the potential risk of aspiration when used with consciousness sedation. Accordingly, in this respect, general anesthesia may be superior to consciousness sedation for AF ablation [8], however, the former appears to be somewhat like “taking a sledgehammer to crack a nut”. This dilemma is a future challenge.
Variables
t
β
p Value
Age Male Body mass index Non-paroxysmal AF Left atrial diameter Body movement index
−0.44 −0.04 0.26 1.75 1.25 3.22
−0.055 −0.005 0.033 0.21 0.17 0.37
0.66 0.97 0.8 0.085 0.22 0.002
Adjusted R2 = 0.10, abbreviations are as in Table 1.
operator's skill, and importantly most of them cannot be quantified. We were unable to determine whether restless patients are likely to have periprocedural complications, because the number of patients recruited was limited, and therefore we rarely encountered major complications. Acknowledgment The authors thank Mr. John Martin for his grammatical assistance. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. References
4.2. Limitations The body movement index was found to have only weak correlations with ablation time and total radiofrequency energy. Furthermore, the multiple linear regression models we used explained no more than 11% and 10% of the variations in the ablation time and total radiofrequency energy, respectively. Those findings indicate that the time required for the ablation and an amount of radiofrequency energy needed to create the complete lesions depend on many factors such as the anatomical variations in the patients, equipment used and
Fig. 6. Scatter plots of the total radiofrequency energy and body movement index.
[1] Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632–96 (e21). [2] Kobayashi M, Namba K, Tsuiki S, et al. Validity of sheet-type portable monitoring device for screening obstructive sleep apnea syndrome. Sleep Breath 2013;17: 589–95. [3] Ouyang F, Antz M, Ernst S, et al. Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the pulmonary veins: lessons from double Lasso technique. Circulation 2005;111:127–35. [4] Hameedullah I, Chauhan VS. Clinical considerations for allied professionals: understanding and optimizing three-dimensional electroanatomic mapping of complex arrhythmias—part 1. Heart Rhythm 2009;6:1249–52. [5] Sairaku A, Nakano Y, Oda N, et al. Prediction of sinus node dysfunction in patients with long-standing persistent atrial fibrillation using the atrial fibrillatory cycle length. J Electrocardiol 2012;45:141–7. [6] Khaykin Y, Zarnett L, Friedlander D, et al. Point-by-point pulmonary vein antrum isolation guided by intracardiac echocardiography and 3D mapping and duty-cycled multipolar AF ablation: effect of multipolar ablation on procedure duration and fluoroscopy time. J Interv Card Electrophysiol 2012;34:303–10. [7] Okada T, Yamada T, Murakami Y, et al. Prevalence and severity of left atrial edema detected by electron beam tomography early after pulmonary vein ablation. J Am Coll Cardiol 2007;49:1436–42. [8] Di Biase L, Conti S, Mohanty P, et al. General anesthesia reduces the prevalence of pulmonary vein reconnection during repeat ablation when compared with conscious sedation: results from a randomized study. Heart Rhythm 2011;8:368–72.
