Introduction
Patients who have spastic esophageal motility disorders present with dysphagia, regurgitation,
chest pain, and weight loss. Esophageal achalasia is the best defined of the spastic
esophageal motility disorders and can be treated either endoscopically or surgically
with disruption of the lower esophageal sphincter (LES) [1 ]. Traditional surgical disruption of the LES with laparoscopic Heller myotomy has
been effective. Peroral endoscopic myotomy (POEM) is a conceptually similar but less
invasive approach that does not require thoracoscopy or laparoscopy [2 ]
[3 ]. Since its advent in 2010 [2 ], worldwide adoption of the POEM procedure has progressed at a rapid rate.
POEM at times may be technically challenging and time-consuming; the reported POEM
procedural times in most of the literature are longer than 1 hour [4 ]. A variety of modifications to improve the efficiency of the endoscopic approach
have been developed [4 ]
[5 ]
[6 ], and these modifications of technique require additional tools and expense. Submucosal
tunneling is an integral part of the POEM procedure. It usually takes a long time
to establish a complete submucosal tunnel by dissecting submucosal fibers with endoscopic
submucosal dissection knives.
To avoid perforation or mucosal injury during submucosal tunneling, accurate identification
of the mucosal, submucosal, and muscularis layers is required. This is accomplished
by creating a demarcation between the submucosal layer and the muscular layer with
repeated injections of dyed saline (saline mixed with indigo carmine or methylene
blue) during tunneling [7 ]. The process is time-consuming, and numerous exchanges of the injection needle and
dissection knife are required during each POEM procedure [6 ]; therefore, the time spent on submucosal tunneling may account for most of the POEM
procedural time. Reducing the time required to establish a long submucosal tunnel
may be the best way to reduce the entire procedural time.
Traditionally, myotomy is performed after a submucosal tunnel approximately 12 cm
long (10 cm above and 2 cm below the gastroesophageal junction [GEJ]), is completely
established. However, a completed submucosal tunnel may not be necessary for starting
a myotomy. Most recently, a video case report of a similar modified technique in which
submucosal tunneling and myotomy were performed concurrently suggested improved efficiency
[8 ]. We hypothesized that starting a myotomy when the submucosal tunnel is half completed
might significantly reduce the procedural time of POEM. To our knowledge, this is
the first case series of concurrent myotomy and tunneling, termed modified POEM, whose
results are presented here. We believe that this simple modification is inexpensive
and flexible and that it improves the efficiency of the procedure by reducing the
time necessary to establish a long submucosal tunnel.
Methods
Patients
Starting in December of 2013, all patients who were seen at our institution with an
esophageal motility disorder, including achalasia, and were candidates for laparoscopic
myotomy were offered POEM as part of a retrospective outcomes study approved by the
institutional review board. Between November 2014 and March 2015, a modified POEM
procedure was performed at the discretion of the endoscopist in six patients who opted
to be treated with POEM.
Patient exclusion criteria included an inability to tolerate general anesthesia and
prior endoscopic myotomy. Preoperative assessment included confirmation of a symptomatic
esophageal motility disorder as defined by standard high resolution manometry, standard
upper gastrointestinal endoscopy, barium swallow, and chest computed tomography. The
data collected during the procedure included Eckardt score, length of myotomy, total
duration of procedure, duration of submucosal tunneling, duration of myotomy, intraoperative
and postoperative complications, and types and doses of anesthetic agents. The Eckardt
score is a clinically accepted system for evaluating achalasia both before and after
treatment [9 ]. Data derived included time per unit length of myotomy. Similar data were collected
for six patients who underwent traditional POEM during the same period.
Peroral endoscopic myotomy procedures
Patient preparation and surgical technique have been described previously [10 ]. The same basic technique, proposed by others [2 ]
[7 ], was used for all cases. All surgeries were performed in the endoscopy suite with
the patient supine and under general anesthesia. Patients were given 4.5 g of piperacillin/tazobactam
intravenously or 500 mg of levofloxacin intravenously during the procedure. The esophagus
was cleared of any retained particulate matter with lavage and suction. A submucosal
wheal of normal saline dyed with methylene blue was created 10 cm above the endoscopically
visualized GEJ in the posterior esophagus. An endoscope (GIF-H190; Olympus, Tokyo,
Japan) with a transparent distal cap attachment (MH-588; Olympus) was used, and a
1.5 – to 2-cm mucosectomy was created with a triangle tip knife (Olympus).
The technique consists of four basic steps: (i) mucosectomy, (ii) submucosal tunneling,
(iii) myotomy, and (iv) mucosal resection closure [11 ] ([Fig. 1 ]). In the process of establishing a submucosal tunnel, repetitive cycles of dissection
and injection with dyed normal saline are necessary to delineate the submucosal layer
from the muscular layer and so avoid full-thickness perforation or mucosal injury.
For traditional POEM, careful electrocauterization was used to extend a submucosal
tunnel from 10 cm above the GEJ to approximately 2 cm past the GEJ into the gastric
cardia. After a 12-cm tunnel had been completed, a distal-to-proximal or proximal-to-distal
circular myotomy was performed ( [Fig. 2b ]). For modified POEM, a proximal-to-distal circular myotomy was initiated after about
half of the submucosal tunnel (4 – 6 cm long) had been created and was then continued
concurrently with extension of the submucosal tunnel ([Fig. 2a ], [Video 1 ]).
Fig. 1 The basic steps of endoscopic myotomy. a Mucosectomy. b Submucosal tunneling. c Myotomy. d Closure.
Fig. 2 a Modified approach. Submucosal tunneling and myotomy are performed concurrently. b Traditional approach. Submucosal tunneling is completed, and then a distal-to-proximal
or proximal-to-distal myotomy is performed. The red arrows indicate initiation of
the myotomy.
All procedures were performed by an attending physician experienced in POEM and an
advanced endoscopy trainee. The attending physician had performed more than 50 POEM
procedures before initiation of the study. Patients underwent modified or traditional
POEM at the discretion of the endoscopist. The trainee’s participation was fixed at
20 minutes per case, including 5 minutes for tunneling and 2 minutes for myotomy.
The modified peroral endoscopic myotomy procedure.
Outcomes and follow-up
The patients were admitted to the hospital after the procedure and followed in the
clinic after discharge. At 1 and 3 months, their Eckardt scores were calculated. Immediate
postoperative adverse events were recorded. Per protocol, all patients had a clinic
visit at 1 month, and it was recommended that they undergo high resolution manometric
analysis and a follow-up clinic visit at 3 months. In the entire cohort, 3 patients
in the modified POEM group and 3 in the traditional POEM group returned for manometric
evaluation.
Statistics
The paired Student’s t test was applied with Excel (Microsoft) to analyze the total length of the procedure,
submucosal tunneling time, myotomy time, and submucosal endoscopic time (tunneling
plus myotomy); the paired Student’s t test was also applied to compare the total time per unit length of myotomy and the
submucosal endoscopic time per unit length of myotomy in the two groups. P values of 0.05 or less were considered significant.
Results
Patient characteristics
The modified POEM procedure, consisting of short tunneling followed by myotomy, was
performed in 6 patients (1 male patient, 5 female patients; mean age 58 ± 13.3 years,
range 42 – 66; [Table 1 ]). Of these patients, 5 had a preoperative diagnosis of achalasia based on high resolution
manometry; all had type II achalasia. In 1 patient, the manometric examination was
not tolerated despite multiple attempts; achalasia was diagnosed based on expert opinion
after clinical review and endoscopic, thoracic computed tomographic, and barium swallow
examinations and was termed esophageal dysmotility ( [Table 2a ]). The baseline information for the patients who underwent traditional POEM is presented
in [Table 2b ].
Table 1
Characteristics of the patients included in a study of modified and traditional peroral
endoscopic myotomy (POEM).
Modified POEM (n = 6)
Traditional POEM (n = 6)
Age, mean ± SD, y
58 ± 13.3
53 ± 19.7
Gender (M:F)
1 : 5
3 : 3
Manometric diagnosis (achalasia:dysmotility)
5 : 1
5 : 1
SD, standard deviation; M, male; F, female
Table 2
Characteristics of the patients included in a study of modified and traditional peroral
endoscopic myotomy (POEM).
Patient No.
Age, y
Manometric diagnosis
Eckardt score
a Patients undergoing modified POEM
1
63
Type II achalasia
10
2
51
Type II achalasia
10
3
47
Type II achalasia
12
4
53
Esophageal dysmotility
12
5
22
Type II achalasia
10
6
82
Type II achalasia
9
b Patients undergoing traditional POEM
1
66
Type II achalasia
8
2
42
Esophageal dysmotility
10
3
79
Type II achalasia
10
4
60
Type II achalasia
7
5
48
Type II achalasia
8
6
53
Type II achalasia
10
Procedure times
Total procedure time, tunneling time, and myotomy time
The mean total procedure time was defined as the time elapsed from intubation of the
esophagus to removal of the scope from the patient’s mouth. The mean total procedure
time (± SD) was 47 ± 8 minutes for modified POEM and 67 ± 13 minutes for traditional
POEM ([Table 3 ]). Tunneling time was defined as the time elapsed from the initiation of tunneling
to the completion of tunneling. Myotomy time was defined as the time elapsed from
the initiation of myotomy to the completion of myotomy. The mean tunneling time (±
SD) was 10 ± 4 minutes for modified POEM and 27 ± 7 minutes for traditional POEM.
The mean myotomy time (± SD) was 16 ± 8 minutes for modified POEM and 8 ± 2 minutes
for traditional POEM ([Table 3 ]).
Table 3
Peroral endoscopic myotomy (POEM) procedural endpoints.
Modified POEM
Traditional POEM
Total procedure time, mean ± SD, min
47 ± 8
67 ± 13
Myotomy length, mean ± SD, cm
7.5 ± 0.8
6.8 ± 0.4
Tunneling time, mean ± SD, min
10 ± 4
27 ± 7
Myotomy time, mean ± SD, min
16 ± 8
8 ± 2
Tunneling time + myotomy time, mean ± SD, min
26 ± 8
36 ± 8
SD, standard deviation.
Total time per centimeter of myotomy
The total time per centimeter of myotomy was calculated as mean procedure time (min)/mean
length of myotomy (cm). The mean myotomy length (± SD) was 7.5 ± 0.8 cm for modified
POEM and 6.8 ± 0.4 cm for traditional POEM ([Table 3 ]). When the time per unit length of myotomy was calculated, modified POEM required
6 min/cm and traditional POEM required 10 min/cm. This was calculated as follows:
47 min/7.5 cm = 6.3 min/cm (modified POEM); 67 min/6.8 cm = 9.9 min/cm (traditional
POEM) ( [Table3 ], [Fig. 3a ])
Fig. 3 a Total time per length of myotomy (minutes per centimeter). b Submucosal time per length of myotomy (minutes per centimeter). Black, modified myotomy;
white, traditional myotomy.
Submucosal time per centimeter of myotomy
Other factors, such as clearing the esophageal lumen, making the initial incision,
and closing the incision, may affect the length of the procedure, and these factors
are not associated with tunneling and myotomy. Therefore, we also calculated the submucosal
time per centimeter of myotomy. The submucosal time (tunneling time plus myotomy time)
was defined as time from the initiation of tunneling to the completion of myotomy.
The mean tunneling time plus myotomy time (± SD) was 26 ± 8 min for modified POEM
and 36 ± 8 min for traditional POEM ([Table 3 ]). The submucosal time per centimeter of myotomy was calculated as mean submucosal
time (min)/mean length of myotomy (cm), so that the following values were obtained:
27 min/7.5 cm = 3.6 min/cm (modified POEM); 37 min/6.8 cm = 5.4 min/cm (traditional
POEM). Therefore, modified POEM saved 1.8 min/cm for myotomy and tunneling within
the submucosal space ([Fig. 3b ]).
Sedative medication
Only three anesthetic agents were consistently used across all the cases: fentanyl,
propofol, and succinylcholine. The mean doses used for modified POEM and traditional
POEM are listed [Table 4 ]. They were lower with modified POEM than with traditional POEM, although the difference
was not statistically significant. Based on the time saved with modified POEM, we
calculated the potential reduction in the cost of anesthetic agents. Again, because
many factors may affect the total procedure time, we calculated the reduction in the
amount of medication if the modified method was used in the patients who underwent
traditional POEM. To calculate the potential savings for medication (e. g., propofol)
if we used the modified method in the patients who underwent traditional POEM, we
first calculated the amount of propofol used during each minute of traditional POEM:
306 mg/67 min = 4.5 mg/min. With use of the modified method, we could save 1.8 minutes
for each centimeter of myotomy; therefore, we could save 12.24 minutes for each patient
who underwent traditional POEM (1.8 min/cm × 6.8 cm = 12.24 min). Then, we calculated
the amount of medication that could be saved for each patient if we used the modified
method in the patients who underwent traditional POEM (12.24 min × 4.5 mg/min = 55.08 mg),
with a saving of $330.48 in 6 patients ([Table 5 ]). Using the same method, we also calculated the savings for the other medications
([Table 5 ]).
Table 4
Amounts of agents most commonly used for general anesthesia during the procedures.
Anesthetic agent
Modified approach
Traditional approach
Fentanyl, mean ± SD, µg
191.7 ± 66.5
237.5 ± 77.1
Propofol, mean ± SD, mg
255 ± 104.3
306.7 ± 152.4
Succinylcholine, mean ± SD, mg
75 ± 62.5
90 ± 77.7
Eckardt score, mean ± SD
8.8 ± 1.3
10.5 ± 1.2
Table 5
Potential anesthesia savings with change from traditional to modified peroral endoscopic
myotomy (POEM).
Average savings per dose with modified POEM
Total savings with six patients
Fentanyl, µg
$ 43.40
$ 260.40
Propofol, mg
$ 55.08
$ 330.48
Succinylcholine, mg
$ 16.40
$ 98.40
Outcomes and complications
One adverse event occurred in the modified POEM group, in which a patient developed
thyrotoxicosis due to undiagnosed primary hyperthyroidism. No adverse events were
reported in the traditional POEM group. All patients in both the modified POEM group
and the traditional POEM group reported significant clinical improvement based on
their Eckardt scores at 1 and 3 months after endoscopic myotomy ( [Fig.4 ]). There were 3 patients in the modified POEM group and 3 in the traditional POEM
group who returned for manometric evaluation following myotomy ([Table 6 ]).
Fig. 4 Clinical outcomes at 1 and 3 months after modified (black) and traditional (white)
peroral endoscopic myotomy.
Table 6
Manometric analysis of lower esophageal sphincter (LES) pressures before (n = 3) and
after (n = 3) peroral endoscopic myotomy (POEM) for the two approaches.
Resting LES pressure
Modified POEM
Traditional POEM
Before POEM, mean ± SD, mmHg
34.2 ± 5.1
34.6 ± 16.3
After POEM, mean ± SD, mmHg
13.5 ± 1.9
16.3 ± 9.1
Discussion
As in laparoscopic surgical myotomy, an endoscopic submucosal tunnel is created in
POEM to allow dissection of the inner circular muscles [2 ]. Potential complications are likely to be minimized as the overall duration of the
procedure, exposure to anesthesia, and time within the submucosal space are decreased.
A large portion of the procedure is devoted to establishing the submucosal tunnel;
therefore, techniques to improve the efficiency of this step have emerged [4 ]
[8 ]
[12 ]
[13 ]. The current case series demonstrates a new, inexpensive modification of the current
POEM technique that improves efficiency and may be used as an adjunctive measure combined
with other modifications [4 ]
[12 ] to expedite tunnel creation. To our knowledge, this is the first report of a series
of patients undergoing modified POEM with concurrent tunneling and myotomy rather
than traditional POEM with long tunneling before myotomy.
In the patients treated with modified POEM, the procedure was safe, and they experienced
good relief from the symptoms of achalasia as evidenced by improvement in their Eckardt
scores and manometric parameters. The modified approach consists of the initial creation
of a short submucosal tunnel, followed by myotomy, before the completion of submucosal
tunneling; the benefit of the modified technique is directly related to the length
of the myotomy. We observed a decrease in the submucosal time with the modified approach,
and decreasing the total procedure time as well as the submucosal time may have important
implications in reducing such adverse events as mediastinitis, submucosal infection,
and symptomatic pneumoperitoneum. Furthermore, a reduction in the total procedure
time may reduce the duration of exposure to anesthesia, thereby decreasing the complications
of sedation and achieving secondary cost savings.
The adjustment in technique did not alter the clinical effectiveness of the procedure
at 3 months. Clinical improvement, as measured by the Eckardt score, was similar in
the modified and traditional approaches at 1 month and was sustained at 3 months after
the procedure. Concurrently, the LES pressure after myotomy was significantly lower
than the resting LES pressure before myotomy in both groups. This finding confirms
that the modification in technique preserves the fundamental goal of reducing the
LES pressure and relieving the clinical symptoms of achalasia.
A posterior approach was used, as is practiced at our institution. Many practices
may use an anterior myotomy or a myotomy in other locations during POEM. The feasibility
of applying this modification with other approaches is unknown. The strength of modified
POEM is its simplicity. The modified approach requires no additional resources and
can be used as an adjunct to other techniques that improve efficiency. The myotomy
was of the circular muscle fibers, not a full-thickness myotomy. This may also affect
the safety and feasibility of the modified approach.
In this study, a triangle tip knife was used. This technique may be combined with
other modifications (i. e., water jet – assisted dissecting knife or hybrid knife)
to improve efficiency further [4 ]
[6 ]
[12 ]. There are limited data suggesting that the use of a hybrid knife in expert hands,
with the capability of injection and dissection, can save time during POEM by decreasing
the frequency of accessory exchange; this needs to be confirmed in further studies,
which will provide more answers on the benefits of the hybrid knife with modified
POEM. In addition, the time saved per centimeter of myotomy (1.8 minutes) has important
implications for POEM. As the technique has been extended to other types of spastic
motility disorders, the myotomy lengths have also increased. Therefore, the modified
approach may assist with further reductions in total time and submucosal time.
Considered as a whole, this case series demonstrates that the creation of a short,
partial tunnel, followed by concurrent myotomy and tunneling, significantly reduces
total procedure time, total time per unit length of myotomy, and total time within
the submucosal space. Liu et al. [8 ] briefly demonstrated the feasibility of the technique of simultaneous tunneling
and myotomy in a video case report, but further study is required to evaluate the
safety and efficacy of modified POEM. Our case series demonstrates not only its safety
and feasibility but also improvements in short-term clinical outcomes. Randomized
controlled studies in larger number of patients are also needed to demonstrate significant
reductions in the administration of sedative medication and complications with the
use of this modified approach to POEM, in addition to secondary cost savings.
