however , a few reports have described esophageal injury after pvi , including the development of lethal atrioesophageal fistulae . in addition ,
periesophageal nerve ( pen ) injury after pvi may rarely cause pyloric spasms and gastric hypomotility .
the c - acetate breath test has been used to diagnose delayed gastric emptying induced by gastric hypomotility and/or pyloric spasms .
the objectives of this study were to clarify the impact of pvi on gastric motility , the prevalence of gastric hypomotility after pvi , and the relationship between de novo esophageal injury and gastric hypomotility following pvi .
the c - acetate breath test and esophagogastroduodenoscopy ( egd ) were performed before and after the procedure to achieve these objectives .
thirty - one consecutive patients with symptomatic paroxysmal or persistent af were included in this prospective study .
patients with a history of pvi , the maze procedure , gastrostomy , an eating disorder , or episodes of acute coronary syndrome , emboli , or decompensated heart failure within 3 months before enrollment were excluded .
we enrolled 20 patients who underwent ablation procedures other than pvi as the control group .
egd was performed in all patients within 3 months before the ablation procedure and within 3 days after the procedure .
esophageal injury was defined as a de novo lesion detected on the anterior wall of the midthoracic esophageal region after pvi that had not been detected before the procedure .
administration of rabeprazole ( 30  mg / day ) was scheduled to start the day after pvi and was re - evaluated on the day of the gastric emptying test after pvi to avoid worsening any esophageal injury .
oral medications , other than rabeprazole , that affected gastric peristalsis were initiated or changed in all patients within a month before the ablation and in the hospital .
measurements of the gastroesophageal reflux disease symptoms scale and the gastrointestinal symptom rating scale were obtained before and after pvi .
these scales are used to evaluate common symptoms of patients with gastrointestinal digestive disorders such as reflux esophagitis , .
gastric emptying was evaluated using the c - acetate breath test with a slight modification , , .
gastric emptying is conventionally evaluated using the acetaminophen absorption test or technetium-99  m scintigraphy .
however , the acetaminophen absorption test requires repeated collection of blood samples , and scintigraphy requires specialized instrumentation .
both examination times are approximately 4  h. in contrast , the c - acetate breath test , which is an alternative method to the acetaminophen absorption test or scintigraphy , can be performed at the patients bedside .
a strong correlation is observed between gastric emptying time measured by scintigraphy and the time to peak co2 concentration in an expired breath ( tmax ) as well as half - dose recovery time ( t1/2 ) measured by the c acetate breath test .
tmax in patients with functional dyspepsia is significantly delayed compared with that in healthy controls . therefore , we chose the c - acetate breath test , which was modified by not measuring t1/2 , as described previously , , .
c - sodium acetate administered orally with a test meal moves from the stomach and is absorbed by the intestines , where it is subsequently metabolized to co2 , and finally expired by the lungs ( fig .
if a patient has gastric hypomotility , the duration between swallowing the test meal and the test meal reaching the intestines is longer than that in normal patients . as a result ,
tmax in a patient with gastric hypomotility is longer than that in a patient without gastric hypomotility .
this duration has been validated on the basis of a mean and standard deviation value of 43.910.3  min and a median value of 70  min in patients with advanced parkinsons disease , which is commonly associated with dyspepsia .
first , a breath sample was obtained after ingestion of a liquid test meal ( racol , 200  kcal/200  ml ; otsuka pharmaceutical co. , ltd . ,
otsuka , japan ) which contained 100  mg of c - sodium acetate ( sigma - aldrich , st .
the test meal was consumed in < 5  min , and breath samples were collected after 5 , 10 , 15 , 20 , 30 , 40 , 50 , 60 , 75 , and 90  min .
all breath samples were analyzed using infrared isotope spectrometry ( poc one ; otsuka electronics co. , ltd . ,
gastric emptying was evaluated by the peak time of co2 excretion ( tmax ) , .
the c - acetate breath test was conducted early in the morning before catheter ablation and was repeated early in the morning 13 days after catheter ablation .
cardiac - enhanced ct ( cct ) was performed before the procedure to obtain three - dimensional images of the heart , thoracic vessels , and esophagus .
this was to exclude the presence of a thrombus and to avoid transesophageal echocardiography , which may increase the burden in patients with a low chads2 score ( < 2 ) .
all antiarrhythmic drugs were discontinued for at least five half - lives before the day of the ablation procedure .
warfarin and dabigatran were discontinued for 5 days and on the day preceding the ablation procedure , respectively , and were substituted with intravenous unfractionated heparin ( 15,000 units / day ) .
when the baseline heart rhythm showed af , sinus rhythm was restored by external cardioversion .
after trans - septal catheterization , intravenous heparin was administered to maintain an activated clotting time of 250300  s. a three - dimensional reconstruction of the la was performed using an electroanatomical mapping system ( carto3 , biosense webster , diamond bar , ca , usa ) .
the electroanatomical map was integrated with the ct image ( carto merge , biosense webster ) .
a 7-fr ablation catheter with a 3.5-mm open - irrigated distal tip ( thermocool navistar , biosense webster ) was used for mapping and ablation .
an esophagram was obtained after oral administration of 10  ml of gastrografin before pvi .
paul , mn , usa ) with three metal thermocouple electrodes ( 5-mm distance ) was placed within the esophagus under fluoroscopic guidance , directly posterior to the la at a level covering the antra of the left pvs .
the ipsilateral left and right pvs were encircled at the antrum in a single lesion line by circumferential pvi using a dragging technique .
the end - point of pvi was defined as the elimination of all pv potentials on the circular mapping catheter during sinus rhythm , while an exit block was confirmed by pacing from inside the pv using the circular mapping catheter .
if pv potentials continued after creating the circumferential lesion , additional radiofrequency applications were delivered to the carina between the pvs . the radiofrequency generator ( biosense webster )
the power and duration of the radiofrequency applications were limited to 25  w and 30  s , respectively , on the posterior wall adjacent to the esophagus according to the esophagram or the merged ct image .
ablation energy was stopped when the let reached 40  c . after a period of waiting until the let decreased to 39  c ,
rf was resumed at 1520  w. if the lower and shorter applications did not create a lesion , another part of the linear lesion was dragged further from the esophagus .
all statistical analyses were carried out using spss 21 for windows software ( spss inc . ,
thirty - one consecutive patients with symptomatic paroxysmal or persistent af were included in this prospective study .
patients with a history of pvi , the maze procedure , gastrostomy , an eating disorder , or episodes of acute coronary syndrome , emboli , or decompensated heart failure within 3 months before enrollment were excluded .
we enrolled 20 patients who underwent ablation procedures other than pvi as the control group .
egd was performed in all patients within 3 months before the ablation procedure and within 3 days after the procedure .
esophageal injury was defined as a de novo lesion detected on the anterior wall of the midthoracic esophageal region after pvi that had not been detected before the procedure .
administration of rabeprazole ( 30  mg / day ) was scheduled to start the day after pvi and was re - evaluated on the day of the gastric emptying test after pvi to avoid worsening any esophageal injury .
oral medications , other than rabeprazole , that affected gastric peristalsis were initiated or changed in all patients within a month before the ablation and in the hospital .
measurements of the gastroesophageal reflux disease symptoms scale and the gastrointestinal symptom rating scale were obtained before and after pvi .
these scales are used to evaluate common symptoms of patients with gastrointestinal digestive disorders such as reflux esophagitis , .
gastric emptying was evaluated using the c - acetate breath test with a slight modification , , .
gastric emptying is conventionally evaluated using the acetaminophen absorption test or technetium-99  m scintigraphy .
however , the acetaminophen absorption test requires repeated collection of blood samples , and scintigraphy requires specialized instrumentation .
both examination times are approximately 4  h. in contrast , the c - acetate breath test , which is an alternative method to the acetaminophen absorption test or scintigraphy , can be performed at the patients bedside .
a strong correlation is observed between gastric emptying time measured by scintigraphy and the time to peak co2 concentration in an expired breath ( tmax ) as well as half - dose recovery time ( t1/2 ) measured by the c acetate breath test .
tmax in patients with functional dyspepsia is significantly delayed compared with that in healthy controls . therefore , we chose the c - acetate breath test , which was modified by not measuring t1/2 , as described previously , , .
c - sodium acetate administered orally with a test meal moves from the stomach and is absorbed by the intestines , where it is subsequently metabolized to co2 , and finally expired by the lungs ( fig .
1 ) . if a patient has gastric hypomotility , the duration between swallowing the test meal and the test meal reaching the intestines is longer than that in normal patients . as a result ,
tmax in a patient with gastric hypomotility is longer than that in a patient without gastric hypomotility .
this duration has been validated on the basis of a mean and standard deviation value of 43.910.3  min and a median value of 70  min in patients with advanced parkinsons disease , which is commonly associated with dyspepsia .
first , a breath sample was obtained after ingestion of a liquid test meal ( racol , 200  kcal/200  ml ; otsuka pharmaceutical co. , ltd . ,
otsuka , japan ) which contained 100  mg of c - sodium acetate ( sigma - aldrich , st .
the test meal was consumed in < 5  min , and breath samples were collected after 5 , 10 , 15 , 20 , 30 , 40 , 50 , 60 , 75 , and 90  min .
all breath samples were analyzed using infrared isotope spectrometry ( poc one ; otsuka electronics co. , ltd . ,
gastric emptying was evaluated by the peak time of co2 excretion ( tmax ) , .
the c - acetate breath test was conducted early in the morning before catheter ablation and was repeated early in the morning 13 days after catheter ablation .
cardiac - enhanced ct ( cct ) was performed before the procedure to obtain three - dimensional images of the heart , thoracic vessels , and esophagus .
this was to exclude the presence of a thrombus and to avoid transesophageal echocardiography , which may increase the burden in patients with a low chads2 score ( < 2 ) .
all antiarrhythmic drugs were discontinued for at least five half - lives before the day of the ablation procedure .
warfarin and dabigatran were discontinued for 5 days and on the day preceding the ablation procedure , respectively , and were substituted with intravenous unfractionated heparin ( 15,000 units / day ) .
when the baseline heart rhythm showed af , sinus rhythm was restored by external cardioversion .
after trans - septal catheterization , intravenous heparin was administered to maintain an activated clotting time of 250300  s. a three - dimensional reconstruction of the la was performed using an electroanatomical mapping system ( carto3 , biosense webster , diamond bar , ca , usa ) .
the electroanatomical map was integrated with the ct image ( carto merge , biosense webster ) .
a 7-fr ablation catheter with a 3.5-mm open - irrigated distal tip ( thermocool navistar , biosense webster ) was used for mapping and ablation .
an esophagram was obtained after oral administration of 10  ml of gastrografin before pvi .
paul , mn , usa ) with three metal thermocouple electrodes ( 5-mm distance ) was placed within the esophagus under fluoroscopic guidance , directly posterior to the la at a level covering the antra of the left pvs .
the ipsilateral left and right pvs were encircled at the antrum in a single lesion line by circumferential pvi using a dragging technique .
the end - point of pvi was defined as the elimination of all pv potentials on the circular mapping catheter during sinus rhythm , while an exit block was confirmed by pacing from inside the pv using the circular mapping catheter .
if pv potentials continued after creating the circumferential lesion , additional radiofrequency applications were delivered to the carina between the pvs .
the radiofrequency generator ( biosense webster ) was set at 3035  w and 42  c .
the power and duration of the radiofrequency applications were limited to 25  w and 30  s , respectively , on the posterior wall adjacent to the esophagus according to the esophagram or the merged ct image .
ablation energy was stopped when the let reached 40  c . after a period of waiting
until the let decreased to 39  c , rf was resumed at 1520  w. if the lower and shorter applications did not create a lesion , another part of the linear lesion was dragged further from the esophagus .
all statistical analyses were carried out using spss 21 for windows software ( spss inc . ,
after obtaining informed consent , a thrombus was detected in the laa of one af patient by cct ; this patient was excluded from the study .
thirty out of 31 patients with af and all 20 patients in the control group completed the required procedures and were analyzed .
the baseline characteristics of both the pvi and control groups are shown in table 1 .
no significant differences were observed in baseline characteristics between groups , except history of heart failure and stroke .
the mean chads2 score was 0.670.76 in the af group , with a maximum score of 2.0 .
the number of patients with abnormal tmax ( 75  min ) increased from seven ( 23% ) to 13 ( 43% ) after the procedure in the pvi group ( fig .
no significant differences were observed between the histories of these seven patients and those of the other patients ( table 2 ) .
the number of patients with abnormal tmax increased from three ( 15% ) to five ( 25% ) after the procedure in the control group ( fig .
the mean tmax was longer after pvi than before pvi ( 6414  min vs. 5715  min , p=0.006 ; fig .
2c ) . on the other hand , the mean tmax in the control group was not significantly different after the procedure ( 5616  min vs. 5316  min , p=0.35 ; fig .
proton pump inhibitor ( ppi ) administration was initiated between the first and second c - acetate breath test in five patients with af .
the mean tmax was significantly longer after pvi than before pvi when the effects of the ppi on gastric emptying were considered , even after excluding these five patients ( 5816  min vs. 6415  min , p=0.039 ) .
the mean difference between tmax before and after the procedure ( tmax ) was 7.7  min in the af group and 3.3  min in the control group ( p=0.27 ) .
no significant difference was observed in the quantity of the radiofrequency energy applied to the left side of the posterior wall of the la or the number of points of let > 39  c between the groups ( normal tmax to normal tmax vs. normal tmax to abnormal tmax ; table 2 ) .
in addition , there was no correlation between tmax and the quantity of radiofrequency energy applied to the left side of the posterior wall of the la ( p=0.82 ) or the number of points of let > 39  c ( p=0.30 ) .
reflux esophagitis and hernia were detected in seven ( 23% ) and nine ( 30% ) patients , respectively , before pv ( table 3 ) .
no patients had food residue in the stomach or esophageal mucous membrane lesions before the procedure . furthermore , no patient suffered from digestive symptoms such as nausea , vomiting , bloating , epigastric pain , or dyspepsia after the procedure .
food residue in the stomach was detected in another three patients , but only one had an abnormal tmax after pvi .
of the other 24 patients with no egd findings , 13 had an abnormal tmax .
furthermore , no patient developed a symptomatic pen injury after pvi during their hospital stay .
after obtaining informed consent , a thrombus was detected in the laa of one af patient by cct ; this patient was excluded from the study .
thirty out of 31 patients with af and all 20 patients in the control group completed the required procedures and were analyzed .
the baseline characteristics of both the pvi and control groups are shown in table 1 .
no significant differences were observed in baseline characteristics between groups , except history of heart failure and stroke .
the mean chads2 score was 0.670.76 in the af group , with a maximum score of 2.0 .
the number of patients with abnormal tmax ( 75  min ) increased from seven ( 23% ) to 13 ( 43% ) after the procedure in the pvi group ( fig .
no significant differences were observed between the histories of these seven patients and those of the other patients ( table 2 ) .
the number of patients with abnormal tmax increased from three ( 15% ) to five ( 25% ) after the procedure in the control group ( fig .
the mean tmax was longer after pvi than before pvi ( 6414  min vs. 5715  min , p=0.006 ; fig .
2c ) . on the other hand , the mean tmax in the control group was not significantly different after the procedure ( 5616  min vs. 5316  min , p=0.35 ; fig .
proton pump inhibitor ( ppi ) administration was initiated between the first and second c - acetate breath test in five patients with af .
the mean tmax was significantly longer after pvi than before pvi when the effects of the ppi on gastric emptying were considered , even after excluding these five patients ( 5816  min vs. 6415  min , p=0.039 ) .
the mean difference between tmax before and after the procedure ( tmax ) was 7.7  min in the af group and 3.3  min in the control group ( p=0.27 ) .
no significant difference was observed in the quantity of the radiofrequency energy applied to the left side of the posterior wall of the la or the number of points of let > 39  c between the groups ( normal tmax to normal tmax vs. normal tmax to abnormal tmax ; table 2 ) .
in addition , there was no correlation between tmax and the quantity of radiofrequency energy applied to the left side of the posterior wall of the la ( p=0.82 ) or the number of points of let > 39  c ( p=0.30 ) .
reflux esophagitis and hernia were detected in seven ( 23% ) and nine ( 30% ) patients , respectively , before pv ( table 3 ) .
no patients had food residue in the stomach or esophageal mucous membrane lesions before the procedure . furthermore , no patient suffered from digestive symptoms such as nausea , vomiting , bloating , epigastric pain , or dyspepsia after the procedure .
food residue in the stomach was detected in another three patients , but only one had an abnormal tmax after pvi .
of the other 24 patients with no egd findings , 13 had an abnormal tmax .
furthermore , no patient developed a symptomatic pen injury after pvi during their hospital stay .
this study demonstrated significantly , although only slightly , prolonged gastric emptying after pvi compared with that before the procedure .
however , the average impact of pvi on gastric motility under monitoring of the let was small .
the vagus nerve modulates the secretion of gastric acid and gastric peristalsis . in the thoracic cavity , the left vagus nerve forms the mesh - like anterior esophageal plexus
after traveling behind the left pulmonary hilum and enters the abdomen through the esophageal diaphragmatic opening ( fig .
the anterior vagus nerve from the esophageal plexus lies extremely close to the outer muscle of the abdominal esophagus and divides near the esophageal end of the lesser curvature into the gastric and pyloric branches .
therefore , the anterior vagal nerve is responsible for coordinated relaxation of the pyloric sphincter and gastric peristalsis during gastric emptying . because radiofrequency energy may injure the esophagus , it is possible that the esophageal nerve plexus situated between the left atrium and esophagus can also be injured
however , if the radiofrequency energy injures any part of the plexus , although rare , pen injury may occur .
because the plexus surrounds the entire circumference of the esophagus , the nerve rarely becomes completely blocked .
they reported that patients with pen injuries were defined as those with symptoms of delayed gastric emptying , such as nausea , vomiting , postprandial fullness , and bloating , associated with gastric hypomotility as assessed by gastrointestinal fluoroscopy .
eleven of 3538 patients ( 0.3% ) were diagnosed with a periesophageal vagus nerve injury .
the average impact of rf energy on pen and the prevalence of asymptomatic or slight pen injury were previously unknown .
this study demonstrates the minimal average impact and shows a very low incidence of severe pen injury . using electrogastrography , lo et al
similar to the c - acetate breath test , electrogastrography is noninvasive and may be a surrogate measure of gastric emptying .
we observed a discrepancy between the presence of food residue as detected during egd and abnormal tmax in the gastric emptying test .
one reason is that we used a liquid meal for the test ; therefore , the results were representative of liquid gastric emptying .
the additive effect may result in the formation of solid residue , even when the pen is slightly affected by rf energy .
when a patient complains of gastroparesis - like symptoms but has normal findings of egd after af ablation , the c - acetate breath test may be helpful to diagnose the possible periesophageal vagal nerve injury .
in addition to the direct effects of rf energy , mental stress , fatigue , and other factors may also have a considerable influence . in the control group ,
this finding indicates that not only a direct effect of rf energy but also mental or other stress can influence gastric emptying after the procedure , including pvi .
takahashi et al . reported that rabeprazole may delay tmax to a greater extent than h2 receptor antagonists , although this difference was not significant .
rabeprazole suppresses gastric emptying of liquid nutrients after the ingestion of a meal . even after exclusion of patients
for whom ppi administration was initiated between the first and second c - acetate breath tests , the mean tmax was significantly longer after pvi than before pvi .
showed that dexmedetomidine administered at the upper limit of the recommended dose ( 0.7  g / kg / h ) inhibited gastric emptying , where as memis et al . reported that doses administered at the lower limit did not affect gastric emptying .
, we used a low to medium dose of dexmedetomidine and evaluated the effect 13 days after the intravenous injection . because the half - life of dexmedetomidine is extremely short ( 2  h )
, we predicted that it would barely influence gastric emptying in our study . before pvi ,
as already described in table 2 , ppi was administered at the time of enrollment in 20% patients with af and may potentially have led to a risk of symptomatic delayed gastric emptying and esophageal injury after pvi .
the possibility that the ppi may have influenced gastric emptying in some of the patients with af at baseline also can not be ruled out .
however , this was transient and patients recovered by decreasing sedation dose . adaptive servo ventilator or airway devices were not used , but it can not be denied that these patients might have potential sleep apnea syndrome ( sas ) .
continuous positive airway pressure ( cpap ) reduces reflux esophagitis with respiratory failure . respiratory support device such as cpap
therefore , it is necessary to evaluate a larger number of patients from multiple centers with a longer follow - up for further clarification of the clinical implications .
second , because we used the modified c acetate breath test , we measured excretion only up to 90  min . in patients with peak times of co2 excretion
> 90  min , tmax may be considered as 90  min . in our study ,
two patients out of 30 had a tmax of 90  min before ablation . in both patients ,
if patients have a greater degree of gastric hypomotility than this , we may overestimate the impact of rf energy .
one of them marked 60  min before ablation and the other 75  min .
if they had more gastric hypomotility , we may underestimate the impact of rf energy .
third , the precise number of patients who underwent transmural ablation in this study remains unknown .
some papers have inferred that sas is related to reflux esophagitis . however , another paper has found that sas is not related to reflux esophagitis . in this
paper , ju et al . reported that poor subjective sleep and depressive symptoms are associated with the presence of reflux esophagitis with no association between sas , bmi and reflux esophagitis .
this study demonstrated significantly , although only slightly , prolonged gastric emptying after pvi compared with that before the procedure .
however , the average impact of pvi on gastric motility under monitoring of the let was small .
the vagus nerve modulates the secretion of gastric acid and gastric peristalsis . in the thoracic cavity , the left vagus nerve forms the mesh - like anterior esophageal plexus
after traveling behind the left pulmonary hilum and enters the abdomen through the esophageal diaphragmatic opening ( fig .
the anterior vagus nerve from the esophageal plexus lies extremely close to the outer muscle of the abdominal esophagus and divides near the esophageal end of the lesser curvature into the gastric and pyloric branches .
therefore , the anterior vagal nerve is responsible for coordinated relaxation of the pyloric sphincter and gastric peristalsis during gastric emptying . because radiofrequency energy may injure the esophagus , it is possible that the esophageal nerve plexus situated between the left atrium and esophagus can also be injured
however , if the radiofrequency energy injures any part of the plexus , although rare , pen injury may occur .
because the plexus surrounds the entire circumference of the esophagus , the nerve rarely becomes completely blocked .
they reported that patients with pen injuries were defined as those with symptoms of delayed gastric emptying , such as nausea , vomiting , postprandial fullness , and bloating , associated with gastric hypomotility as assessed by gastrointestinal fluoroscopy .
eleven of 3538 patients ( 0.3% ) were diagnosed with a periesophageal vagus nerve injury .
the average impact of rf energy on pen and the prevalence of asymptomatic or slight pen injury were previously unknown .
this study demonstrates the minimal average impact and shows a very low incidence of severe pen injury . using electrogastrography , lo et al
similar to the c - acetate breath test , electrogastrography is noninvasive and may be a surrogate measure of gastric emptying .
we observed a discrepancy between the presence of food residue as detected during egd and abnormal tmax in the gastric emptying test .
one reason is that we used a liquid meal for the test ; therefore , the results were representative of liquid gastric emptying .
the additive effect may result in the formation of solid residue , even when the pen is slightly affected by rf energy .
when a patient complains of gastroparesis - like symptoms but has normal findings of egd after af ablation , the c - acetate breath test may be helpful to diagnose the possible periesophageal vagal nerve injury .
in addition to the direct effects of rf energy , mental stress , fatigue , and other factors may also have a considerable influence . in the control group ,
this finding indicates that not only a direct effect of rf energy but also mental or other stress can influence gastric emptying after the procedure , including pvi .
takahashi et al . reported that rabeprazole may delay tmax to a greater extent than h2 receptor antagonists , although this difference was not significant .
rabeprazole suppresses gastric emptying of liquid nutrients after the ingestion of a meal . even after exclusion of patients
for whom ppi administration was initiated between the first and second c - acetate breath tests , the mean tmax was significantly longer after pvi than before pvi .
showed that dexmedetomidine administered at the upper limit of the recommended dose ( 0.7  g / kg / h ) inhibited gastric emptying , where as memis et al . reported that doses administered at the lower limit did not affect gastric emptying .
, we used a low to medium dose of dexmedetomidine and evaluated the effect 13 days after the intravenous injection . because the half - life of dexmedetomidine is extremely short ( 2  h )
, we predicted that it would barely influence gastric emptying in our study . before pvi ,
as already described in table 2 , ppi was administered at the time of enrollment in 20% patients with af and may potentially have led to a risk of symptomatic delayed gastric emptying and esophageal injury after pvi .
the possibility that the ppi may have influenced gastric emptying in some of the patients with af at baseline also can not be ruled out .
however , this was transient and patients recovered by decreasing sedation dose . adaptive servo ventilator or airway devices were not used , but it can not be denied that these patients might have potential sleep apnea syndrome ( sas ) .
continuous positive airway pressure ( cpap ) reduces reflux esophagitis with respiratory failure . respiratory support device such as cpap
therefore , it is necessary to evaluate a larger number of patients from multiple centers with a longer follow - up for further clarification of the clinical implications .
second , because we used the modified c acetate breath test , we measured excretion only up to 90  min . in patients with peak times of co2 excretion
> 90  min , tmax may be considered as 90  min . in our study ,
two patients out of 30 had a tmax of 90  min before ablation . in both patients ,
if patients have a greater degree of gastric hypomotility than this , we may overestimate the impact of rf energy .
one of them marked 60  min before ablation and the other 75  min .
if they had more gastric hypomotility , we may underestimate the impact of rf energy .
third , the precise number of patients who underwent transmural ablation in this study remains unknown .
some papers have inferred that sas is related to reflux esophagitis . however , another paper has found that sas is not related to reflux esophagitis . in this
paper , ju et al . reported that poor subjective sleep and depressive symptoms are associated with the presence of reflux esophagitis with no association between sas , bmi and reflux esophagitis .
. however , the average impact of pvi on gastric motility under monitoring of the let was minimal .
 backgroundpulmonary vein isolation ( pvi ) has become an important option for treating patients with atrial fibrillation ( af ) . 
 periesophageal nerve ( pen ) injury after pvi causes pyloric spasms and gastric hypomotility . 
 this study aimed to clarify the impact of pvi on gastric motility and assess the prevalence of gastric hypomotility after pvi.methodsthirty consecutive patients with af underwent pvi under luminal esophageal temperature ( let ) monitoring . 
 the 13c - acetate breath test was conducted before and after the procedure for all patients ( pvi group ) . 
 gastric emptying was evaluated using the time to peak concentration of 13co2 ( tmax ) . 
 this test was also conducted in another 20 patients who underwent catheter ablation procedures other than pvi ( control group).resultsthe number of patients with abnormal tmax ( 75  min ) increased from seven ( 23% ) to 13 ( 43% ) and from three ( 15% ) to five ( 25% ) after the procedure in the pvi group and control group , respectively . 
 the mean tmax was longer after pvi than before pvi ( 6414  min vs. 5715  min , p=0.006 ) , whereas there was no significant difference before and after the procedure in the control group . 
 however , no significant difference in tmax was observed between the two groups ( p=0.27 ) . 
 no patients suffered from symptomatic gastric hypomotility.conclusionsasymptomatic gastric hypomotility occurred more often after pvi . however , the average impact of pvi on gastric motility was minimal . 
Introduction
Material and methods
Patient population
None
Computed tomography (CT)
Ablation procedure and monitoring of luminal esophageal temperature (LET)
Statistical analysis
Results
Patient characteristics
The 
EGD findings and clinical symptoms
Discussion
Major findings
Study limitations
Conclusions
Conflict of interest