2021 Volume 85 Issue 8 Pages 1321-1328
Background: Sedation during pulmonary vein isolation (PVI) for atrial fibrillation often provokes a decline in left atrial (LA) pressure (LAP) under atmospheric pressure and increases the risk of systemic air embolisms. This study aimed to investigate the efficacy of adaptive servo-ventilation (ASV) on the LAP in sedated patients.
Methods and Results: Fifty-one consecutive patients undergoing cryoballoon PVI were enrolled. All patients underwent sedation using propofol throughout the procedure. After the transseptal puncture and the insertion of a long sheath into the LA, the LAP was measured. Then, the ASV treatment was started, and the LAP was re-measured. The LAP before and after the ASV support was investigated. Before ASV, the LAP during the inspiratory phase was significantly smaller than that during the expiratory phase (4.9±5.4 mmHg vs. 14.0±5.2 mmHg, P<0.01). The lowest LAP was −2.2±5.1 mmHg and was under 0 mmHg in 37 (73%) patients. After the ASV, the LAP during the inspiratory phase significantly increased to 8.9±4.1 mmHg (P<0.01), and lowest LAP increased to 4.7±5.9 mmHg (P<0.01). The negative lowest LAP value became positive in 30/37 (81%) patients. There were no statistical differences regarding obstructive sleep apnea (OSA), obesity, gender, or other comorbidities between patients with and without a negative lowest LAP after ASV support.
Conclusions: ASV is effective for increasing the LAP above 0 mmHg and might prevent air embolisms during PVI.
Pulmonary vein isolation (PVI) is a widely accepted procedure for catheter ablation of patients with atrial fibrillation (AF). To complete PVI, access to the left atrial (LA) is required, and a transseptal puncture has usually been performed. The procedure in the LA has a substantial risk of systemic embolisms, including cerebral and myocardial infarctions.1,2
PVI using a cryoballoon has emerged as an alternative ablation procedure tool for radiofrequency (RF) ablation, and its safety and effectiveness have been proven.3,4 However, thrombi and air embolic events during cryoballoon ablation have recently been reported.2,5 In terms of air embolic events during the procedure, the creation of procedure-related micro air bubbles has been thought to be the most common factor.6,7 The majority of micro air embolisms are silent, asymptomatic, and detected by brain magnetic resonance imaging after the procedure.6,8 In contrast, a large amount of an air embolism during the catheter ablation procedure is rare, but could be life-threatening.1,2 It is mainly caused by massive air intrusion through a long sheath located in the LA and is prone to occur at the time the intra LA pressure (LAP) drops to less than the atmospheric pressure.1,9 According to a recent study evaluating air embolisms during cryoballoon PVI, clinical manifestations of air embolisms such as ST elevation in the inferior leads occur in 1–3% of the patients during the procedure.10
Although the cryoballoon PVI can shorten the procedure time as compared to the PVI with RF catheter ablation, patients typically receive sedation during the PVI because the procedures often are invasive.3,4 Sedation of patients could inevitably result in an upper airway obstruction and subsequently provoke apnea and snoring, which could reduce the intra thoracic pressure and LAP. A decreased LAP to less than the atmospheric pressure increases the risk of air intrusion into the vasculature through a long sheath.
Adaptive servo-ventilation (ASV) (AutoSet CS; ResMed, Sydney, NSW, Australia) is a non-invasive positive pressure ventilation and is designed to treat sleep-disordered breathing.11–13 It provides a positive expiratory airway pressure and inspiratory pressure support, and automatically adjusts the airway ventilation volume based on the analysis of the patient’s breathing effort. Although the efficacy of ASV therapy in patients with sleep-disordered breathing has been widely accepted, the accurate efficacy of ASV for LAP in sedated patients remains unclear. The aim of this study was to investigate the LAP in sedated patients undergoing a cryoballoon PVI and to clarify the effect of ASV on LAP during the procedure.
From October 2018 to September 2020, a cryoballoon PVI was performed in patients with drug refractory AF. All patients received sedation and a subsequent ASV treatment was applied during the procedure. Consecutive patients undergoing a cryoballoon PVI with ASV support under sedation were enrolled in this study. The LAPs before and after ASV support were sequentially evaluated in all these patients.
Exclusion criteria were severe valvular disease, hemodialysis, severe coronary artery disease, an LA diameter >55 mm, and the existence of a thrombus in the LA.
Written informed consent was obtained from all patients. This study protocol was approved by the institutional review board of our institute and conformed to the ethical guidelines of the 1975 Declaration of Helsinki.
Procedural ManagementAll patients received oral anticoagulants prior to the procedure. In patients taking direct oral anticoagulants, the drugs were interrupted on the day of the procedure and re-administered on the next morning after the procedure. In patients taking warfarin, the warfarin therapy was continued without interruption.
During the procedure, a single transseptal puncture was performed with a RF needle (Baylis Medical Inc, Montreal, Quebec, Canada) and 8 Fr long sheath (SL0, Abbott, Minneapolis, MN, USA). Five thousand units of heparin were administered before the transseptal puncture and additionally given to maintain an activated clotting time between 300 and 350s. After the transseptal puncture, an 8 Fr long sheath was exchanged for a steerable 15 Fr sheath (Flexcath Advance, Medtronic, Minneapolis, MN, USA).
LAP Evaluation and ASV SupportThe atmospheric pressure was set as 0 mmHg for the reference at a beginning of the procedure. After the transseptal puncture and insertion of the 15 Fr long sheath (FlexCath) in the LA, the LAP via the sheath was recorded on a digital polygraph (RMC-5000, Nihon Corden, Tokyo, Japan) (Figure 1). The LAP was measured over >3 consecutive respiratory cycles. The LAP during 1 respiratory cycle was calculated as the average of the integral LAPs during 1 respiratory cycle, and the LAP was defined as the average value of that ≥3 consecutive cycles. The LAP during the inspiratory and expiratory phases also was defined in the same manner. The lowest LAP was the minimum LAP during those respiratory cycles. Afterward, the ASV treatment was initiated in all patients. As the default setting for ASV, an expiratory positive airway pressure of 5 cmH2O and inspiratory pressure support between 3 and 10 cmH2O were used according to previous reports.11–13 Following the ASV treatment and confirmation of stable breathing synchronized with ASV, the LAP was re-measured.
LAP waveform and measurement of the LAP during 1 respiratory cycle. Respiratory variations in the LAP waveform during the procedure were observed, and the inspiratory LAP prominently dropped to less than the atmospheric pressure (0 mmHg). The inspiratory and expiratory LAPs during 1 targeted respiratory cycle are highlighted by the red and blue diagonal lines, respectively. The respective LAPs were automatically calculated as the average of the integral LAP during each respiratory period. Exp, expiratory phase; Insp, inspiratory phase; LAP, left atrial pressure.
All patients received sedation throughout the procedure. At the beginning of the procedure, an intravenous propofol bolus of 0.5 mg/kg was administered, and an esophageal temperature probe was inserted and located in the esophagus to measure the esophageal temperature during the procedure. Maintenance of sedation was performed with a continuous intravenous propofol administration at a dosage of 1.25–2 mg/kg/h. As an analgesic, an intravenous drip infusion of buprenorphine with a dosage of 1.0 µg/kg was also administered at the beginning of the procedure and was appropriately added if patients complained of pain. The bispectral index (BIS) was continuously monitored by a BIS monitoring system (A-3000 BIS XP Platform; Aspect Medical Systems, Newton, MA, USA) to evaluate the sedation level of the patients. To maintain the BIS index level between 50 and 70, an intravenous propofol bolus of 0.5 mg/kg was additionally administered, and the dosage of the continuous intervenous propofol administration was also adjusted according to the sedation level of the patients, if necessary.14,15
Ablation ProcedureThe method of the cryoballoon ablation has been previously described.8 In brief, a steerable 15 Fr sheath (Flexcath) and second-generation 28-mm cryoballoon (Arctic Front Advance, Medtronic) were inserted into the LA and advanced to the orifice of the targeted PVs. Then, the cryoballoon PVI was started. The entire PVI procedure was performed under ASV support.
Statistical AnalysisThe data are expressed as the mean±SD, median (25th–75th percentile range), or count, according to the distribution of the variable. The LAP and BIS value before and after ASV support were compared by using a paired t-test, and the proportion of the negative lowest LAP was evaluated by using Fisher’s exact test. To compare each parameter between the patients with or without a negative lowest LAP, a Student’s t-test or Mann-Whitney U-test was used for the quantitative variables with a normal or non-normal distribution, respectively, and a Fisher’s exact test was used for the categorical variables. Statistical significance was set at a value of P<0.05. The statistical analyses were performed using a Bell curve for Excel (ver. 3.20; Social Survey Research Information Co., Ltd).
Fifty-one consecutive patients underwent the cryoballoon PVI and were enrolled in the present study. Two patients with hemodialysis and 1 with severe coronary artery disease were excluded. The mean age of those 51 patients was 65.8±10.4 years and 41 (80.4%) patients had a male gender. The proportion of paroxysmal and non-paroxysmal AF was 27 (53.0%) and 24 (47.0%) patients, respectively. Two patients were diagnosed with obstructive sleep apnea (OSA) and were introduced to continuous positive airway pressure therapy. The patient characteristics are shown in Table 1.
| Number of patients (n) | 51 |
| Age (years) | 65.8±10.4 |
| Male gender (%) | 41 (80.4) |
| BMI (kg/m2) | 24.4±3.6 |
| Obesity (BMI >25 kg/m2) (%) | 20 (39) |
| Obstructive sleep apnea (%) | 2 (3.9) |
| Non-paroxysmal AF (%) | 24 (47.0) |
| CHADS2 score | 1.0±0.8 |
| Hypertension (%) | 25 (49.0) |
| Diabetes mellitus (%) | 6 (11.8) |
| Heart failure (%) | 8 (15.7) |
| Old cerebral infarction and TIA (%) | 2 (3.9) |
| BNP on the day before ABL (pg/mL) | 78.6 (34.8–142.7) |
| LA diameter (mm) | 41.2±7.1 |
| LVEF (%) | 63.4 (59.8–67.4) |
ABL, ablation; AF, atrial fibrillation; BNP, brain natriuretic peptide; BMI, body mass index; LA, left atrium; LVEF, left ventricular ejection fraction; TIA, transient ischemic attack.
The LAPs were sequentially measured before and after ASV support in a total of 51 enrolled patients. The BIS value at the time of the LAP measurement was similar between that before and after ASV support (67.7±13.1 vs. 68.5±12.7, P=0.26). Out of 27 patients with paroxysmal AF, the LAP was measured during sinus rhythm in 25 and during AF in the remaining 2. In all 24 patients with non-paroxysmal AF, the LAP was measured during AF or atrial flutter. There was no significant difference in the average LAP between that before and after ASV support (10.9±4.8 mmHg vs. 11.6±3.7 mmHg, P=0.14) (Table 2).
| Before ASV | After ASV | P value | |
|---|---|---|---|
| Average LAP (mmHg) | 10.9±4.8 | 11.6±3.7 | 0.14 |
| LAP during the inspiratory phase (mmHg) | 4.9±5.4 | 8.9±4.1 | <0.01 |
| Lowest LAP (mmHg) | −2.2±5.1 | 4.7±5.9 | <0.01 |
| Number of lowest LAPs ≤0 mmHg (%) | 37 (72.5) | 7 (13.7) | <0.01 |
| LAP during the expiratory phase (mmHg) | 14.0±5.2 | 12.7±4.3 | <0.01 |
| BIS value at the time of the LAP measurement | 67.7±13.1 | 68.5±12.7 | 0.26 |
ASV, adaptive servo-ventilation; BIS, bispectral index; LAP, left atrial pressure.
The LAP during the inspiratory phase was 4.9±5.4 mmHg and was significantly lower than that during the expiratory phase (14.0±5.2 mmHg, P<0.01). The average lowest LAP was −2.2±5.1 mmHg (from 7 to −17 mmHg), which was recorded during the inspiratory phase in all patients. Out of a total of 51 patients enrolled, 37 (72.5%) had a lowest LAP value of ≤0 mmHg. A male gender was frequently observed in patients with a lowest LAP value of ≤0 mmHg (negative lowest LAP) than in those with a lowest LAP value of >0 mmHg (33/37 vs. 8/14, P=0.02). There were no significant differences regarding the BIS index, body mass index (BMI), prevalence of OSA, obesity (BMI >25 kg/m2), and other comorbidities between the patients with and without a negative lowest LAP value (Table 3A). The BIS value at the time of the LAP measurement was similar between the 2 groups (67.4±12.5 vs. 68.7±14.4, P=0.54).
| Lowest LAP ≤0 | Lowest LAP >0 | P value | |
|---|---|---|---|
| (A) Before ASV support | |||
| Number of patients (n) | 37 | 14 | |
| Age (years) | 66.8±9.9 | 63.3±3.9 | 0.37 |
| Male gender (%) | 33 (89) | 8 (36) | 0.02 |
| BMI (kg/m2) | 24.2±2.7 | 24.8±3.9 | 0.84 |
| Obesity (BMI >25 kg/m2) (%) | 15 (41) | 5 (36) | 1.0 |
| Obstructive sleep apnea (%) | 2 (5) | 0 (0) | 1.0 |
| Non-paroxysmal AF (%) | 19 (51) | 5 (36) | 0.36 |
| CHADS2 score | 1.03±0.75 | 0.93±0.96 | 0.57 |
| Hypertension (%) | 19 (51) | 6 (43) | 0.76 |
| Diabetes mellitus (%) | 5 (14) | 1 (7) | 1.0 |
| Heart failure (%) | 5 (14) | 3 (21) | 0.67 |
| Old cerebral infarction and TIA (%) | 1 (3) | 1 (7) | 0.48 |
| BNP (pg/mL) | 79.1 (34.6–143.7) | 78.6 (39.3–167.4) | 0.74 |
| LA diameter (mm) | 41.0±7.3 | 42.2±6.4 | 0.70 |
| LVEF (%) | 64.1 (59.5–67.8) | 62.2 (59.0–66.9) | 0.42 |
| (B) After ASV support | |||
| Number of patients (n) | 7 | 44 | |
| Age (years) | 69.0±13.9 | 65.3±9.6 | 0.85 |
| Male gender (%) | 7 (100) | 34 (77) | 0.32 |
| BMI (kg/m2) | 24.6±4.9 | 24.3±3.3 | 0.47 |
| Obesity (BMI >25 kg/m2) (%) | 4 (57) | 16 (36) | 0.41 |
| Obstructive sleep apnea (%) | 1 (14) | 1 (2) | 0.26 |
| Non-paroxysmal AF (%) | 4 (57) | 20 (45) | 0.69 |
| CHADS2 score | 1.1±0.8 | 0.98±0.8 | 0.66 |
| Hypertension (%) | 3 (43) | 22 (50) | 1.0 |
| Diabetes mellitus (%) | 2 (29) | 4 (9) | 0.19 |
| Heart failure (%) | 1 (14) | 7 (16) | 1.0 |
| Old cerebral infarction and TIA (%) | 0 (0) | 2 (5) | 1.0 |
| BNP (pg/mL) | 105.5 (5.8–146.6) | 72.6 (35.1–143.1) | 0.92 |
| LA diameter (mm) | 42.3±6.9 | 41.0±7.1 | 0.44 |
| LVEF (%) | 64.9 (62.1–67.3) | 63.3 (57.7–67.5) | 0.53 |
Abbreviations as in Table 1.
After ASV, the LAP during the inspiratory phase significantly increased to 8.9±4.1 mmHg as compared to that before the ASV (4.9±5.4 mmHg) (P<0.01) (Figure 2). The ∆ lowest LAP between that before and after ASV support was 6.6±5.2 mmHg. The lowest LAP increased in 47/51 (92.2%) patients with ASV, and remained unchanged in the other 4 patients (Figure 3). Out of 37 patients with a negative lowest LAP value before ASV, in 30 (81.1%) patients, the lowest LAP value turned out to be positive after ASV. Even in the remaining 7 patients, the lowest LAP increased to 4.6±3.5 mmHg, but it did not reach more than 0 mmHg (from −6 to 0 mmHg). There were no significant differences regarding the patient characteristics or comorbidities between the patients with and without a negative lowest LAP value after ASV (Table 3B). The BIS value at the time of the LAP measurement was similar between the 2 groups (65.0±13.6 vs. 69.0±12.5, P=0.75). A male gender also was not observed very frequently in the patients with a negative lowest LAP value (7/7 vs. 34/41, P=0.32).
Representative case of the LAP between that before (A) and after (B) ASV support. The steep decline in the LAP during the inspiratory phase completely resolved and the lowest LAP increased to a positive value after ASV support. ASV, adaptive servo-ventilation; LAP, left atrial pressure.
Change in the lowest LAP between that before and after the ASV support. ASV, adaptive servo-ventilation; LAP, left atrial pressure.
After ASV, the expiratory LAP slightly decreased from 14.0±5.2 mmHg to 12.7±4.3 mmHg (P<0.01). The ∆expiratory LAP difference between that before and after ASV support was −1.3±3.3 mmHg.
Results of the Cryoballoon PVIOut of a total of 204 PVs for which the cryoballoon ablation was performed, all PVs were successfully isolated. Although temporary right phrenic nerve paralysis was observed in 2 patients during the cryoballoon ablation at the right superior PV, the motion of the diaphragm fully recovered by the first outpatient visit. A groin hematoma was observed in 3 patients. There were no other complications during the procedure including systemic embolic events such as cerebral and myocardial infarctions.
Comparison Between the Cryoballoon PVI With and Without ASV SupportIn our institute, the ASV support during the cryoballoon PVI started from October 2018, and before that, the procedure was performed without ASV support in 111 patients. During this period, systemic air embolisms with manifested symptoms or collapse of one’s vital signs was not be observed; however, temporary ST elevation in the inferior leads was observed in 2 (1.8%) patients during the cryoballoon PVI without ASV support. However, no air embolisms, including temporary ST elevation, were observed in 51 patients with ASV support in the present study (2/111 vs. 0/51, P=1.0).
The major findings in the present study were: (1) the lowest LAP in sedated patients dropped to less than the atmospheric pressure in approximately 73% of patients; (2) ASV increased the lowest LAP value to a positive value in 81% of the patients who had a negative lowest LAP value before ASV support; (3) there were no significant differences regarding the patient characteristics, including the prevalence of OSA, BMI, and a male gender between the patients with and without a negative lowest LAP value after ASV support.
A drop in the LAP of less than the atmosphere pressure during the PVI increases the risk of massive air intrusion during the procedure. The hemostasis valve of the sheath plays an important role in the prevention of air intrusion into the vasculature through a long sheath. However, the valve could become open to the atmosphere while inserting a catheter into the sheath via the valve, especially when inserting catheters with complicated tip shapes such as circular mapping catheters or multipolar catheters.1,2,5 If the timing of the insertion of the catheter is synchronized with a drop in the LAP to less than atmospheric pressure, a massive air embolism is prone to occur. The continuous maintenance of the LAP above the atmospheric pressure during the procedure could absolutely decrease the risk of air intrusion. The present study confirmed that the majority of the sedated patients undergoing AF ablation had a negative LAP during the procedure, and to the best of our knowledge, this is the first clinical study that has demonstrated the efficacy of ASV in the prevention of a LAP drop to less than the atmospheric pressure. Although the present study evaluated the LAP in patients undergoing a cryoballoon PVI, this result could be applicable to all types of percutaneous catheter procedures that require access into the LA.
The LAP decline in sedated patients was mainly caused by an upper airway collapse during the inspiratory phase, and this phenomenon could be reproduced by a Mueller maneuver, as a previous study revealed.16 During ASV support, an expiratory positive airway pressure plays a main role in the prevention of an upper airway obstruction. Further, an upper airway opening could subsequently prevent a decrease in the intra thoracic pressure and LAP during the inspiratory phase.
Although the inspiratory positive pressure is not directly thought to improve an upper airway obstruction, the supply of an automatically adjusted inspiratory positive pressure under sedation is effective for the alleviation of feeble and decreased respirations such as central sleep apnea. It could provide a stable respiration pattern. Although bronchial intubation could certainly more effectively reduce the risk of air intrusion and contribute to a stable LAP, it is invasive and requires general anesthesia; however, ASV treatment is easy to start and finish. Therefore, an evaluation of the effect of ASV on the LAP could be worthwhile. Although a statistical difference could not be observed regarding the temporary ST elevation between the patients undergoing a cryoballoon PVI with and without ASV support, the incidence of temporary ST elevation could not be observed after the ASV support was introduced during the cryoballoon PVI. This result suggested the efficacy of ASV support for the prevention of air embolisms.
AF Ablation With SedationThe feasibility and safety of deep sedation during AF ablation has been previously reported.17,18 However, intravenous sedation with an anesthetic agent such as propofol causes respiratory suppression due to upper airway collapse, and the anesthetic depth is associated with the respiratory status.19
In terms of sedation depth, anesthetic dosing was adjusted to maintain the BIS value within a target range of 50–70, and the actual average BIS value before ASV support was approximately 68, suggesting that the sedation depth was a nearly moderate sedation.14,15 In patients under a moderate sedation depth, it is generally considered that no interventions are required to maintain a patent airway and that spontaneous ventilation is adequate.20 However, the present study revealed that 73% of the sedated patients had a negative lowest LAP value before ASV support. That suggested that the LAP could become negative even in patients under moderate sedation. During the procedure, the sedation level often resulted in a deeper sedation level than initially intended; therefore, the fact that the risk of air intrusion might change depending on the sedation continuum should be noted.
Additionally, the introduction and maintenance of the sedation was performed with an intravenous propofol administration. For an intravenous anesthetic agent during AF ablation, propofol, midazolam, and dexmedetomidine are commonly used. Out of those anesthetic agents, dexmedetomidine has a relatively lesser propensity for the induction of an upper air way collapse in comparison to propofol.14 If dexmedetomidine is administered for the anesthesia, the prevalence of a negative LAP under sedation could be lower.
Evaluation of a Negative Lowest LAP Even After ASV SupportThe present study revealed the ability of ASV treatment to increase the LAP above the atmospheric pressure. In contrast, the lowest LAP was still negative in 7 patients even with ASV support. Previous reports demonstrated that OSA has been associated with a LAP decline during sleep.16 Furthermore, obesity, a male gender, hypertension, diabetes mellitus, and heart failure are thought to be important risk factors for OSA.21,22 However, those specific patient characteristics could not frequently be observed in patients with a negative LAP after ASV. In the present study, there were only 2 patients who had been diagnosed with OSA before the ablation procedure, and that might have influenced the results.
We should be aware that a negative LAP after ASV could be provoked even in patients without OSA, obesity, or other risk factors. Complications due to massive air intrusion could be fatal, and therefore, not only the efficacy but the limitations of ASV on the LAP must be taken into consideration. In patients with a negative LAP after ASV, the use of a water bucket when inserting catheters into the sheath could prevent an accidental air intrusion into the sheath and reduce the incidence of air embolisms during the cryoballoon PVI.10 Needless to say, in addition to avoiding inserting catheters into the sheath during the inspiratory phase, it is also important to flush the sheath with heparinized saline just after inserting the catheter into the sheath.1 If further study reveals and predicts the characteristics of patients with a high risk of an ASV refractory negative LAP, selective and prophylactic bronchial intubation before the procedure could be effective in preventing air intrusion.
Expiratory LAPFor patients under sedation, the inspiratory LAP was easily influenced by a decline in the intra thoracic pressure; however, the expiratory LAP theoretically would not be. Therefore, the expiratory LAP in patients under sedation was thought to be almost identical to the LAP in those in an awake state.
The expiratory LAPs after ASV were slightly lower than those before ASV. From the aspect of the mechanism for non-invasive positive pressure ventilation, a positive expiratory pressure might reduce the venosus return and decrease the LAP. However, whether a positive expiratory pressure influences the LAP immediately after the initiation of ASV remains unclear and requires further investigation in terms of the hemodynamic status.
Study LimitationsThis study was a single center trial and the study population was relatively small. The LAP was not evaluated continuously because it was necessary to insert the cryoballoon into the long sheath in order to perform the PVI, and an accurate LAP could not be evaluated during the cryoballoon ablation. The sedation status was variable even with the same dose of an anesthetic agent, and the collapsibility of the upper airway also changed during the procedure. An additional propofol bolus administration as the patient status dictated easily deepens the sedation status for a certain length of time; therefore, the efficacy of ASV for the LAP could be variable and labile.
The patients’ hemodynamic status such as hypo- or hypervolemia might have influenced the LAP value. The central venous pressure, which represents the amount of the circulating plasma volume, was not measured in the present study. Thus, the details of the plasma volume status of the patients and its influence on the LAP could not be evaluated.
In the present study, polysomnography was not performed to evaluate the extent of the OSA before the ablation procedure. Therefore, the prevalence of OSA might have been underestimated. Further prospective studies that enroll larger numbers of patients with OSA and investigates the LAP change after ASV treatment are expected.
The settings of ASV were not changed according to the patients’ respiration status. Therefore, whether an increase in the expiratory positive pressure could improve the LAP could not be evaluated.
The cryoballoon PVI is less painful and has a shorter procedure time in comparison to the PVI with RF catheter ablation, and exact 3D mapping is not required. Therefore, milder sedation than in the present study could be adequate for performing the cryoballoon PVI.
From the standpoint of the cost benefit, an ablation procedure with deeper sedation and ASV support is costly. A simple cryoballoon PVI with mild sedation is more economical in terms of reducing the medical cost.
The ASV treatment in sedated patients undergoing a PVI was effective for increasing the LAP above the atmospheric pressure and might prevent fatal air embolisms during the procedure. This finding could be universal for all types of procedures in the LA. Furthermore, the LAP could drop and become negative in patients under sedation, even in those without OSA, obesity, or other comorbidities.
We would like to thank Mr. Kento Watanabe for data collection and Mr. John Martin for the grammatical correction of the English. We also are grateful to Dr. Kenji Okubo for his helpful advice about the present study.
The authors have no conflicts of interest to declare.
The local ethics committee of our institute, the Tokyo Yamate Medical Center, approved this study (Reference number: J-094).
The deidentified participant data will not be shared.
