Summary
Background
Treatment of atrial fibrillation (AF) by radiofrequency or cryoballoon ablation requires good sedation and effective analgesia to be carried out safely and successfully.
Aim
To compare analgesic and sedative drug usage during ablation procedures for paroxysmal AF.
Methods
The records of 60 patients hospitalized for ablation of paroxysmal AF were studied. Patients were divided into two groups, according to the technique used: radiofrequency ablation (group A) and cryoballoon ablation (group B). Anaesthetic and sedative medication usage was compared between groups.
Results
Patients’ mean age was 56.2 ± 1 years in the radiofrequency group and 57.0 ± 0.74 years in the cryoballoon group; mean duration of AF was 6.91 ± 2.36 and 6.77 ± 2.51 years, respectively. Twenty patients from group A and 18 from group B had transesophageal echocardiography. With regard to sedative use, 3.01 ± 1.3 mg/m 2 of midazolam was used in group A versus 3.5 ± 1.26 mg/m 2 in group B ( p = 0.14). Propofol was seldom used. For analgesia, 0.31 ± 0.26 g/m 2 of paracetamol was used in group A versus 0.73 ± 1.86 g/m 2 in group B ( p = 0.23). Mean morphine dose was higher in group A versus group B (3 ± 1.5 vs 2.09 ± 1.02 mg/m 2 , respectively; p = 0.01).
Conclusion
In this study, patients who underwent cryoballoon ablation required a lower dose of morphine compared with those who underwent radiofrequency ablation. Catheter cryoballoon ablation appears better tolerated than radiofrequency ablation for the treatment of paroxysmal AF.
Résumé
Justification
L’ablation par radiofréquence ou par cryo-énergie de la fibrillation auriculaire (FA) nécessite une bonne sédation et une analgésie efficace.
Objectif
Comparer les antalgiques et sédatifs durant les procédures d’ablation de FA paroxystique.
Méthodes
Une étude rétrospective a été réalisée sur 60 patients hospitalisés pour ablation de FA paroxystique, divisés en deux groupes ; groupe A : radiofréquence, groupe B : cryoablation. Nous avons comparé l’utilisation des anesthésiques et sédatifs.
Résultats
L’âge moyen était de 56,2 ± 1 ans pour le groupe A et 57 ± 2,51 pour le groupe B. L’ancienneté de la FA était de 6,91 ± 2,36 ans pour le groupe A et de 6,77 ± 2,51 pour le groupe B. Vingt patients du groupe A et 18 du groupe B ont eu une échocardiographie transœsophagienne. Concernant les sédatifs, les doses utilisées ont été : 3,01 ± 1,3 mg/m 2 de midazolam pour le groupe A et 3,5 ± 1,26 mg/m 2 pour le groupe B ( P = 0,135). Le propofol était peu utilisé. Concernant les analgésiques, les doses utilisées ont été : 0,31 ± 0,26 g/m 2 de paracétamol pour le groupe A, contre 0,73 ± 1,86 g/m 2 dans le groupe B ( P = 0,23) ; 3 ± 1,5 mg/m 2 de morphine dans le groupe A contre 2,09 ± 1,02 mg/m 2 dans le groupe B avec une différence significative ( p = 0,01).
Conclusion
La cryoablation nécessite moins d’analgésiques que la radiofréquence d’après notre étude. L’anesthésie légère offre une meilleure tolérance et assure un état de conscience vigile qui permet de détecter les complications de façon plus précoce.
Background
AF is the most frequent arrhythmia in clinical practice, affecting 5% of people aged 65 years and 10% of those aged over 80 years . PV isolation by RF or cryoballoon ablation enables effective treatment of paroxysmal AF .
Currently, RF is the gold standard ablation strategy for paroxysmal AF . However, this technique can be complicated by stenosis of the PVs, thromboembolism, pericardial effusion, complex left atrial flutters and atrio-oesophageal fistula. Cryoballoon ablation has emerged as a valuable alternative to RF ablation in the treatment of AF, with complications that seem to occur less frequently. There has been no description of atrio-oesophageal fistula with cryoballoon ablation, while thromboembolic accidents and PV stenosis are exceptional . This technique creates smaller, more circumscribed and reversible lesions, better stability for energy delivery, and greater patient comfort with a lower risk of pain .
In our experience, we can avoid and treat rapidly any complications that might arise while carrying out these techniques with the patient under conscious sedation, while maintaining appropriate pain management. We therefore initiated the present study to assess the requirements for pain control with the two ablation techniques; our aim was to compare the doses of analgesic and sedative drugs used during the treatment of paroxysmal AF by RF ablation and cryoballoon ablation.
Methods
Study population
We studied the case files of 60 successive patients who had ablations after we considered that our proficiency in performing both techniques was optimal. Thirty patients had RF ablation for paroxysmal AF while 30 had catheter cryoballoon ablation for the same indication. Paroxysmal AF is defined as recurrent episodes of AF that self-terminate in less than 7 days. Patients who required a hybrid technique with additional RF at the end of a catheter cryoballoon ablation procedure were excluded.
Our retrospective study included the following variables: epidemiological data (age, sex, prior history); clinical data (weight, height, body surface area, duration of AF); ancillary data (whether TEE was used or not); and therapeutic data (ablation procedure [type of procedure, need for external cardioversion, results, complications], medication dosage [the medications used are expressed in mg/m 2 ]).
Two groups were identified: group A (patients who had RF ablation) and group B (patients who had catheter cryoballoon ablation).
Anaesthesia and analgesia
Conscious sedation was administered by a nurse at the direction of the physician. Initially, the patient received: sedatives (midazolam [Hypnovel ® ], 2–5 mg if TEE; propofol [Diprivan ® ], 20 mg if TEE difficult); analgesics (paracetamol [Perfalgan ® ], 1 g at the start of the procedure; morphine, 3 mg). These doses were titrated by the physician to achieve an adequate comfort level throughout the procedure. The use of morphine is not systematic and depends on the response to pain expressed by the patient through motion or verbal communication. Electrocardiographic tracing and continuous monitoring of heart rate, and respiratory and oxygen saturation were performed. Blood pressure was monitored non-invasively every 5 minutes. The doses of anaesthetic products were referenced to body surface area using the Boyd calculation formula (used most frequently in clinical research) : body area (m 2 ) = 0.0003207 × (weight) 0.7285-0.0188 × log (weight) × (height) 0.3 ; weight is in g (limit, 15–200 kg), height is in cm (limit, 99–250 cm) and the log is decimal.
Anaesthetic and sedative medication dosages were compared between the two groups.
Radiofrequency procedure
For RF ablation, we used the same procedure as that described by Haïssaguerre and coworkers . After placing diagnostic catheters into the coronary sinus, the interatrial septum was punctured as described before, and venography of all four PVs was performed by introducing contrast material through the transseptal sheath or through a 6-French multipurpose catheter into the proximal PVs. Next, a circumferential mapping catheter (Lasso, Biosense Webster Inc., Diamond Bar, CA, USA) was introduced into the proximal PVs. An irrigated tip ablation catheter (ThermoCool, Biosense Webster Inc., Diamond Bar, CA, USA) delivering RF energy was introduced into the same hole. RF was applied in a power-controlled mode with a power limit of 30 W and a maximum temperature of 48 °C. Ablation was performed at the atriovenous junction proximal to the circumferential mapping catheter at sites showing the earliest PV potentials, performing a segmental ablation of the PV ostia.
As in the cryoballoon group, acute isolation success was confirmed by the circumferential Lasso catheter in all patients. Also, 20 minutes after the last PV was ablated, ablation success was verified again in all PVs. Periprocedural and postprocedural anticoagulants were administered.
Cryoballoon procedure
All patients were treated with a double-lumen cryoballoon (Arctic Front, CryoCath Technologies, Montreal, Quebec, Canada), either 23 mm or 28 mm in size, as appropriate for the diameter of the PVs. Both femoral veins were used for venous access. A multipolar catheter (Woven, Bard Electrophysiology Inc., Lowell, MA, USA) was placed in the coronary sinus via the left femoral vein. Via the right femoral vein, we used a single standard transseptal approach with a Brockenbrough needle (BRK Needle, St Jude Medical, St. Paul, MN, USA) guided by fluoroscopy and TEE, as required. We introduced an 8-French SL1 sheath (FAST-CATH, St. Jude Medical, St. Paul, MN, USA) into the left atrium, then performed angiography of the PV with the catheter. We advanced and positioned a 10-pole Lasso catheter (Lasso 2515, Biosense-Webster Inc., Diamond Bar, CA, USA) in the antrum of each vein to demonstrate the presence of electrical activity in the veins. For the left PV, pacing in the distal coronary sinus was necessary to confirm PV potentials. After this confirmation, we proceeded with the ablation without continuous Lasso monitoring.
We removed the SL1 sheath and advanced a 12-French steerable sheath (FlexCath, CryoCath Technologies, Montreal, Quebec, Canada) “over the wire” (0.032 inch, 180 cm Super Stiff G.W., St Jude Medical, St. Paul, MN, USA) into the left atrium. The Arctic Front balloon catheter was introduced inside the 12-French sheath and positioned over a wire guide (Amplatz Extra Stiff Wire Guide, 0.032 inch, Cook Group Incorporated, Bloomington, IN, USA). We selected either a 23 mm or a 28 mm Arctic Front cryoballoon in accordance with PV diameters. The cryoballoon catheter was positioned in such a way as to occlude the ostium of each PV after inflation. Cryoablation was applied for 4 minutes at least twice for each vein and directed toward the major side branches with the use of the guide wire. We tried for at least one cryoablation application with full occlusion (grade 4) on each targeted vein. When the extent of occlusion was not optimal, we changed the position of the balloon or flexion of the sheath to achieve better occlusion. The ablation procedure was always started in the left superior PV, then proceeded to the left inferior PV, followed by the right inferior PV, and finally, the right superior PV.
Whenever we targeted the right PVs, we positioned the Lasso catheter in the superior caval vein for continuous phrenic nerve stimulation during cryoablation application. As the proximity of the phrenic nerve to the right-sided veins cannot be ascertained, this vigilance is essential in order to prevent phrenic nerve palsy. If phrenic nerve capture ceased, the ablation was stopped instantly due to the operator’s continuous monitoring. After targeting all the PVs, we reintroduced the Lasso catheter into the veins to verify that complete electrical disconnection was achieved during sinus rhythm and pacing. The procedure was performed under full anticoagulation with heparin.
Statistical analysis
Statistical analysis was done using the SPSS software program, version 10.0 (SPSS Inc., Chicago, IL, USA). The variables studied were expressed as means ± standard deviations.
Continuous data were compared between the two groups by the unpaired t -test and ordinal data were compared in both groups using the chi-square test. A value of p < 0.05 was considered to be statistically significant.
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