Esophageal high pressure zones : Effect of periesophageal structures on esophageal rnanornetric recording

During the course of esophageal motility studies, short zones of elevated esophageal baseline pressure are occasionally noticed. The aim of this study is to determine their frequency and their cause. Among 77 consecutive esophageal manometries (group 1), 17 cases (22%) of ‘esophageal high pressure zones’ (EHPZs) were recorded. Thirty-three additional patients (group 2) were evaluated and 18 other cases of EHPZ were found; in the latter group, a miniature sound microphone was positioned on a carotid artery. When a high pressure zone was identified, the manometric catheter was immobilized; the patient underwent a chest x-ray, with the radiopaque marker imbedded in the catheter used to locate the thoracic structures adjacent to EHPZs. In both groups, indentations (pressure spikes) over the high pressure zones occurred synchronously with the patients’ radial or carotid pulse. Results suggest that EHPZs are caused by the compression and pulsations of vascular or cardiac periesophageal structures; the aortic arch is responsible for the manometric EHPZ when it is found between 10 and 14 cm above the lower esophageal sphincter whereas the left auricle is the cause of the EHPZ if it is located between 4 and 7 cm above the lower esophageal sphincter.

Segments resophagiens hypertensifs; effet des structures peri, resophagiennes sur l' enregistrement de la manometrie resophagienne RESUME : Au cours d'ewdes de la motilite cesophagienne, n ous remarquon s occasionnell ement !'elevation de la pression de base sur de courts segments du corps ccsophagien .Cetce etude a eu pour but Je determiner leur frequen ce et leur M ANOMETRIC STUDIES OF THE esophagus have become indispensable in evaluating esophageal motility.Many studies have been published to help in the analysis and interpretation of manometric recordings.
Dalton (1) recently reported esophageal high pressure zones (EHPZS) surmounted by repetitive pressure spikes in different parts of the esophageal body, and suggested chat these indentations might be caused by the heart o r by an electric interference.Berenzweig et al ( 2) and M ittal et al (3) described this phenomenon in rare cases of dysphagia lusoria and aorcica.The latter group showed that it could be fou nd in normal volunteers.Cappell ( 4) recently demonstrated a m id-EHPZ with superimposed cyclic pressure waves produced by left aerial di lation.T he aim of this study was to look for a nd study these EHPZS systematically, determine their frequency a nd attempt to identify the meJiastinal structures causing them; the fo llowing is a presentation of our find ings.

PAT IENTS AND METHODS
Seventy-seven consecutive patients (group l) who presented to the Hotel-Dieu de Sherbrooke motility laboratory were prospectively evaluated from March co September 1990.During this period 17 patients presented a high pressure zone in t he region of the avons relevc 17 cas (22%) de «segments resphagiens hypertensifs» (SOH).Trente-trois patients additionnels (gro upe 2) furent evalues et 18 autres cas de SOH furent retrouves; clans ce dernier gro upe , un microphone miniatue fut positio nne sur une carotide.Lo rsqu'un segme nt hypertensif etait identifie, le catheter manometrique etait immo bilise; le patient subissait une rad iographie pulmonaire et le cath eter muni de marqueurs radioopaques servait a identtfier !es structures thoraciques adjacences au SOH.Dans les deux groupes, des indentations (pointes depression) au sommet des SOH apparaissaient de fa~on synch rone avec le pouls radial o u carotidien des malades.En conclusion, no tre e cude suggere que lcs SOH rcsultent de la compression et des pulsations provenant des structures pcri-cesophagiennes vasculaires ou cardiaques; lacrosse aortique est responsable du SOI-I lorsque ce dernier est retrouve entre 10 et 14 cm au-dessus du sphincter resophagien inferieur alors quc l'oreillette gauche !'est lorsque le SOH est localise entre 4 et 7 c m au-dessus de sphincter cesophagien infcrieur.apart.The catheter is equipped with radiopaque markers located immediately below each side hole.Each capillary was continuously perfused with disti lled water at the rate of 0.6 mL/min usi ng a pneumoh ydraulic capillaryinfusion pump powered by compressed nitrogen (Arndorfer Inc ).The catheter was connected to external pressure transducers (Beckman model 4-327 C, Georgia) that, in tum, were connected to a SensorMedics model R-611 dynograph (SensorMedics Corps, California).This system has a pressure rise rate greater th an 300 mmH.g/s.ln group l, a min iature sound mic rophone (Sen-sorMedics) taped to the patient's neck recorded swallows; in group 2, the microphone was located on a carotid artery to record arterial pulsations and the patient's swallows simulta neo usly.
Patients fasted for 5 h before evaluation.The catheter was introd uced transnasally, all patients lying supine.
Patients were given 5 ml of room-temperature tap water to swallow.Lower esophageal sph incter (LES) pressures were recorded with t he three distal side holes by the station and rapid pullthrough techniques.The cath eter was positioned in the esophageal body, the side holes being located 3, 8 and 13 c m above the LES.The amplitude, duration and velocity of the esophageal contraction waves were evaluated fo llowing 10 swa llows, each spaced by abou t 20 to 25 s.Th e motility study was continued, pulling back the catheter in l cm increments.This technique allowed all EHPZs to be revealed.
Each high pressure zone was evaluated using the three distal side holes of the manometric catheter.The ports' radial orientation ( 120° angles) showed that the EHPZs have an asymmetric pressure profil e; on e of the three plateaus was always more e levated as recorded by one of the three distal side holes.When the cathete r was pulled back, pressure spikes appeared over the high pressure zones.The dynograph's freq uency response was increased to sharpen the definition of the pressure spikes.At the condusion of the manometric study, the catheter was pushed down to position th e three distal side holes over the EHPZ for further eval uat ion .Thereafter the patient underwent a posteroanterior a nd lmeral chest x-ray to localize the cathete r's radiopaque markers and thus faci litate identification of t he med iastinal struc-  cures facing the cath eters distal side ho les.The x-rays were read blindly by a radiologist a nd the mediastinal structures were identified according to the esophageal segments described by Brombart (5) (Figure 1 ).Each EHPZ was evaluated by determining its position (cm above the LES), its length (cm) a nd its 'plateau pressure' (mmHg).The EHPZ plateau pressure wa established by asking the patient to stop breaching in midexpiration for 5 to 10 s.A horizontal line was drawn on the manometric trac ing at the centre of the pressure spikes' vertical excursions; although the line could have been drawn at the base of the pressure spikes, we felt chat placing it midway through the spikes' vertical excursion represented the 'mean' intraesophageal pressure.The plateau pressure va lue was obtained by subtracting the mean intrathoracic baseline pressure from the value obtained at the h orizontal line.In group 1, when clinically indicated, a Bernstein test and 24 h ambulatory esophageal pH monitoring were perfo rmed.
As the determination of the corre lation of the pressure spikes with the radial pulse appeared subjective, the mmtature sound microphone was moved over a carotid artery.In most patients, swallowing could simultaneously be recorded with the arterial pulsations; it thus became easier to corre late these arteria l pulsations precisely with the pressure spikes surmounting the EHPZs on the same tracing.T hirty-three additional pat ie nts (group 2) were eval uated from May to June 1992 inclusively; 18 pat ients with EHPZs were identified and were studied using the same protocol as The results of the manomecric find ing5 are presented in Table 3.
Most of these patients presented with only one El IPZ (Figure 2); interestingly, two distinct and simultaneous zones were fou nd in four cases (23.5%) (Figures 3,4 ).The length of the El IP? vaned from 1.0 to 5.0 cm (average 2. 7 cm fo r t he l 7 cases).When the patient was asked co stop breathing in midexpiration, a pressure pla teau formed above the intrathoracic baseline and measured from 14 co 134 mmllg (mean 48.l ).This high pressure zone could be found any time the catheter was moved back to where it was first observed.El IPZs were mo~t often located at the level of the aortic segment (eight cases) and of the retrocardial segment (six cases) of the esophagus; the esophageal segment with the highest mean plateau pressure 242 CAN J 0ASTR0ENTER0L VOL 8 No 4 JULY/AUGUST 1994 (74.25 mmHg ) was che aortic segm ent (Table 4).
Repetitive pressure spi kes rose above every pressure plateau anJ occurred synchro nously with chc radial pulse (Figures 2,3).Following a wee swallow, the esophageal contractio n wave crossed rhro ugh the high pressure :one; preceding the arrival of the contraction wave, a transient relaxat io n of the El IP7 pressure plateau was o bse rved.
C hest x-rays were read blindly by one author; no s ignificant patho logypu lmo nary, mediascinal or cardiacwm, found.The x-rays showed chat the hypertensive zone~.indicated by ra-<l1opaque marke rs, were contiguous to the mediascinal struccures described in Table 4.
Group 2 : In group 2 patients, the sound microphone was positioned on che carotid a rtery to demonstrate even fu rthe r the simulcancicy between the pressure spikes above the El IPZs and the vascular (carotid) pulsations (Figure 5).The motility stud ies o f these pat ients are reported in Table 5.Their EHPZ characteristics are summa rized in Table 6.The frc4ue ncy of mediascinal structures fou nd beside che EHPZs reported in these patients vc1 riecl from chat reported for group l ; this may hm 1 e been relc1ted to the difficul ty in picking up a carotid pulsation with the sound mic rophon e 111 obese patien ts.A simultaneous eleccrocardiogram (ECG) would pro bably have demonstrat ed ch i~ simultaneity even better.
When values from patients in both group~ arc combined, mean length o f EIIPZs is 2.6 cm and mean pressure of EI IPZs is 52 .8mmHg.When the high pressure zone is found between 10 and 14 cm above Lhe LES it can be assumed that it is adjacent co the aortic arch ; when it is locared between 4 and 7 c m above Lhe LES, it sho uld be heside the left auricle.
Symptoms, endoscopic findings, barium meal results, overall mano metric findings, Bernstein tests and 24 h ambulacory pl-I mo nitoring results could nm he related to a ~pec ific esophageal conditio n (Tables l ,2,3, 5).Furthermore, bc1rium mea ls did no t show any mcdiastinal scruc cure abnormally compressing the esophagus.

DISCUSSION
EHPZs have been observed by several investigators in normal volunteers as well as in conditions in which mediastinal structures significantly compress a segment of the esophagus (1 -4).This study systematically evaluated their occurrence in a population presenting at a motility laboratory.Furthermore, the study aimed to determine which anatomical structures were responsible for their appearance.
EHPZs were consiste ntly found beside a vascular structure or a cardiac chamber.This observation suggests that these structures compress the esophagus and produce an in trnluminal high pressure zone or a loca lized h igh pressure plateau; moreover, the pressure spikes overlying the plateau appear to resu lt from vascular pulsations or from t he contraction of adjacent cardiac c hambers (Tables 4,6).l ndeed, t he radial or carotid pulse occurred synch ronously with the pressure spikes surmounting the high pressure zon es; when the recording frequency of the dynograph increased from 0.3 to 30 Hz and h igher, the spikes' amplitude increased and their synchrony with the radial and carotid pulse became more evident.EHPZs were arbitrarily defined as a rise of the intrathoracic baseline of at least JO mmHg; however, we also obse rved instances where the high pressure zone was inferior to this predefined limit.
Berenzweig et al (2 ) described a case of dysphagia lusoria whe rein a cine esophagogram and a bari um swallow elem-244 onstrated an external compression above the aortic arch.An esophagoscopy revealed an excraluminal defect appearing as a pulsating bandlike abnormally at 24 cm from the incisors.A contrast study with barium tablets and a steak meal under fluoroscopy reproduced the patient's dysph agia a nd confirmed that both of these meals 'hung up' at the level of the subclavian artery.An angiography demonstrated an aberrant right subclavian artery and a simultaneous barium swallow confirmed the a nomalous vessel as coinciding with the site of esophagea l compression.An esophageal motility study in the same region showed a zone of e levated intraluminal pressure of 10 mmHg higher than the adjacent esophageal baseline pressure; superimposed on this hypertensive zone, they found changes suggesting pulsations compatible with arterial pressure.
Similarly, Mitcal and co-workers (3) reported three patients with clysphagia resulting from t he compression of t he distal esophagus; a nonaneurysmal descending thoracic aorta was fou nd in the first case and an e nlarged heart in the two latter cases.A barium esophagogram demonstrated extrinsic compression on the distal esophagus; esophagoscopy was performed in the first case only and confirmed the radiographic findings.Vascular compression of the esophagus was assessed by esophageal man o metry in all three cases and showed an area of increased resting intraesophageal pressure of 10 to 20 mmHg, varying in length from 3 to 5 cm.Promine nt arterial pulsations were superimposed on this part of the tracing.
Furthermore, Mittal et al (3) analyzed esophageal manomctric tracing~ of 4 7 normal subjects, 39 males and eight females, mean age 3 1 years ( range 24 to 56).In 10 of these subjects they fo und a hypertensive zon e greater than 5 mmHg at the site of a vascular compression; they did not elaborate any further on these sites.T he resting pressure ranged from 5 to 65 mmHg a nd, as in this study, they noticed that the El IP7 was not circumferential (it was seen in only one Lead).Again, as was shown in this study (Figures 2,3,5), the plateau pressure dropped to intraesophageal pressure prior to swallow-induced esophageal contractions, thus behaving like a sphincter.The mechanism of the pressure drop was not clear but was thought to represent movement of the recording orifice away from the compressing structure.These findings were similar to chose described in the three previous patients with dysphagia.H owever, these investigators d id nor attempt to determine which mcdiastinal structures were producing these high pressure zones.
Recently Cappell ( 4) reported a case of Left atrial dilation producin g esophageal compression and dysphagia; using esophageal manometry and simu ltaneous ECG he demonstrated a localized mid-EHPZ with superimposed cyclic pressure waves and showed a one-coone correspondence between these pressure oscillations and the elcctrocardiographic QRS complex.He concluded that this high pressure zone re presented a di stinctive manometric find ing in a patient with left atrial dilation, and that it resulted from mechanical compression on the esophagus.Furthermore, his study showed that su-peri mpose<l cyclic pressure waves corresponded co transmitted mural pulsations.
The findings o ( Berenzweig, Micca l and Cappel!(2-4), combined with this m 1dy's results, suggest that EHPZs reflect ~ compressio n created by the proximity of vascula r or cardiac structu res o n the esophagea l body.The work of Cappe l! and this study provides strong c ircumstantial evidence to suggest that the pressure spikes sunnouncing the high pressure zones correspond to sys co lic pulsations induced by these same struccurcs.Mittal's observat ions as we ll as those provided in this study suggest char EHPZs may be found in norma l subjects and in patients with various esophageal conditio ns.

Figure 4 )
Figure 4) Chest x-rays of patient3.A (left) Posteroanteric>r view; B (righ t) Lateral view.Arrows show radiopaque markers in the manometry catheter; lower arrow indicates the marker adjacent to the high pressure zone and the recrocardial segme111 of the esophagus; upper arrow is adjacent co the aonic segment of the eso/Jhagus

TABLE 2
Clinical characteristics of g roup 2 patients O Normal; 1 Hlotal hernia; 2 Gostroesophogea/ Junction Incompetency: 5 Esophageal ulceration: B Bulb/tis: CP Chest pain; D Dysphoglo; G Gastritis: GER Gostroesophogeol reflux; ND Not done HMlrmi"' J~ ~---, . . ..-" " "' -, . ., , . . ., , ., , ._ , . ., RESULTSGroup 1: Seveney-seven esophageal motility studies were performed in group l; 17 cases (22%) presented with at least one EHPZ.A ch est x-ray could not be obtained in three of these cases.CAN J GASTROENTEROL VOL 8 No 4 JULY/Aucus-r 1994 ,t.Figure2) Single esophageal high pressure zone.Manometry tracing from patient 11 recorded with the distal side holes of the manometric catheter; the side holes are locared at the same Lewi.The neck microphone indicates swallowing of 5 mL water; the high />ress11re zone is located at the level of t/1e retrocardial segment, 8 cm above the lower esophageal sphincter (LES), and is recorded from 36 to 34 cm from the 11ares.Notice at the top of che tracing that the /)(lticnt scops breathing in mtdexp1ratio11.A line is drawn che middle of the St'llet 's exC11rsion.The pressure of the high /m?.mtre zone Jilarcau 1.1 obtained 11)• subcracung the mlue ac the adjacent -Figure3) Two ad1acent esophageal high presmre zones.Manomecry tracing from /iacient 3. The first high pressure zone is located between 29 and 28 cm ( aornc segment) and the second between 35 and 31 cm from the nares ( retrocardial segment).No rice a fall of the /ilateau pressure when the esophageal contraction crosses rhe high premtre zone.The esophageal high pressure zane ap/>ears w behave as a sphincter.LES Lower esophageal sJ>hmcter

Esophageal high pressure zones manometric
. Bcrenzweig H, Baue AE, McCallum RW.Dysph agia lusoria.Report of a case and review of the diagnostic and necessarily have a functio na l significance since th is manometric enti.ty was reporred more often in normal subj ects than in cases where hindrance to the passage of barium or a n endoscope could be demonstrated in the esophagus.To show more clearly a localized high pressure zone, one needs only to decrease the filtration frequency of the dynograph and check if the pressure spikes occur synchronously with the patient's radial pulse; o therwise, one may tape a sensitive sound recorder o n a ca rotid artery and obtain, on the same trace, a simultaneous recording of swallows, arterial pulsations and EHPZs.Cappell's "locali zed midesophageal high pressure zone" should be termed "esophageal high pressure zone".This surgical approach.Dig Dis Sci 1980;25 :630-6.3. Mitrnl RK, S isk ind BN, Hongo M, Flye MW, McCallum RW.Dysphagia aortica.Clinical, radiological and manomctric findings.Dig Dis Sci 1986;3 I :379-84.4. Cappell MS, Manomctric findings in dysphagia secon dary to left at rial entity is due to cardiovasc ula r phenomena and should be recognized by all those involved in performing and interpreting esophageal manometric swdies.EHPZs have clinical significance only in patients where obstruction to esophagea l transit can be demonstra ted as in dysphagia lusoria and aortica (2,3 ) and in patients with mitra l va lve disease complicated by left atrial dilation ( 4 ); it may be related, in future stud ies, to other pathological entities.ACKNOWLEDGEMENTS: The authors thank Claudine and Jocelyne Poupnrt for assi~tance in preparing t h e manu script and Denis Tremblay for I he ph otographic work.dilatation.Gi,mr, cyclic midesophageal pressure w,wes occurring with every heart hear.Dig Dis Sci l 99 1;36:693-8. 5. Brombart M .Roentgenology of the esophagus.In: Margulis AR, Burhenne HJ , eds.Alimentary Tract Radiology, vol I. Sc Louis: The CV Mosby Co, 2CAN J GASTilOENTEROL VOL 8 No 4 JULY/AUGUST 1994 1967:277-83.