Colonic pacing: a therapeutic option for the treatment of constipation due to total colonic inertia

HYPOTHESIS: The treatment of constipation caused by total colonic inertia is problematic and its results are unsatisfactory. We speculated that colonic pacing would initiate electric activity in the inertial colon and effect rectal evacuation. METHODS: Nine patients with constipation due to total colonic inertia (age range, 39-52 years; 7 women, 2 men) were enrolled in the study. One pacing electrode was applied to each of the 4 potential colonic pacemaker sites, and 2 to 3 temporary recording electrodes were applied distally. A stimulator was embedded subcutaneously in the inguinal area. Home pacing was practiced after patients were trained; the recording electrodes were removed before home pacing was started. RESULTS: Colonic pacing evoked electric waves, which effected defecation in 6 of the 9 patients. Three of these 6 patients had spontaneous defecation after a few months of pacing, and their electrodes and stimulators were removed. In the other 3 of these 6 patients, the pacemakers are still in place and continue to effect rectal evacuation. Colonic pacing did not produce rectal evacuation in 3 patients and is believed to have failed because of an advanced stage of colonic inertia. CONCLUSION: Colonic pacing induced rectal evacuation in 66.6% of the patients with total colonic inertia. No complications were encountered. We suggest that colonic pacing be considered as a new therapeutic option in the treatment of total colonic inertia.     

Vesical pacing in patients with overactive bladder: technique and results

OBJECTIVES: A recent study has demonstrated that the electric activity of the overactive bladder (OAB) is 'dysrhythmic'. The cause was attributed to a disordered vesical pacemaker which discharges these waves. In a subsequent study, the dysrhythmic waves have been 'normalized' by vesical pacing and the optimal parameters which are required to achieve normalization have been defined. We investigated the hypothesis that vesical pacing of the OAB might improve not only the vesical electric activity but also the symptoms. METHODS: Vesical pacing was used in 9 patients (age 39.2 +/- 10.3; 5 women, 4 men) with OAB. Under anesthesia, the pacemaker was implanted in an inguinal subcutaneous pocket and connected to 2 pacing electrodes implanted into the vesical vault. The normalization of the waves was tested by 2 recording electrodes which were temporarily applied to the vesical wall and removed post-testing. The pacemaker was then programmed for home pacing to be activated at given times. RESULTS: Vesical pacing effected normalization of the dysrhythmic electric waves with disappearance of the OAB symptoms in 7 patients and failed in 2. Vesical pacing was abandoned in 3/7 patients after a few months following the spontaneous disappearance of the symptoms. CONCLUSIONS: Vesical pacing has normalized the dysrhythmic electric activity and suppressed the symptoms of the OAB in 77.7% of patients. The pacemaker was removed in 5 patients: 2 failures and 3 after spontaneous waves normalization. No complications were encountered. Vesical pacing is suggested as a treatment for OAB when commonly used therapeutic modalities have failed.     

Study of the rectal electric activity of the uninhibited rectal detrusor (overactive rectum): a new concept of pathogenesis

BACKGROUND/OBJECTIVE: One of the causes of fecal incontinence is uninhibited rectal detrusor syndrome (URDS). Patients with this condition either perceived the first rectal sensation after the onset of involuntary rectal contraction or not at all. We investigated the hypothesis that the abnormal rectal contractility in URDS may be caused by deranged rectal electric activity. METHODS: Twenty-five patients with URD (14 women and 11 men; age, 44.7 +/- 10.3 years) and 10 healthy volunteers (6 women and 4 men; age, 42.8 +/- 8.7 years) were studied. URDS was diagnosed by rectometry and provocative test. A transcutaneous EMG was performed with one electrode placed lateral to each sacroiliac joint and the third one midway between the greater trochanter and the ischial tuberosity. Two 20-minute recording sessions were performed for each subject. RESULTS: Slow waves (SWs) with regular rhythm and similar parameters (frequency, amplitude, conduction velocity) from the 3 electrodes were recorded from the healthy volunteers. They showed a significant increase in the parameters on saline filling of the rectum. The SWs of patients with URDS exhibited a "dysrhythmic" pattern with irregular parameters, which were different in the 3 electrodes and inconsistent during recording. They showed areas of tachyrhythmia, bradyrhythmia, and arrhythmia. On provoking rectal overactivity, the SWs showed an increased dysrhythmic activity. CONCLUSIONS: The patients with URD exhibited a "dysrhythmic" electric pattern with areas of variable electric activity. The tachyrhythmic areas seem to initiate the urgency and fecal incontinence of URDS. It is suggested that a disordered rectosigmoid pacemaker causes the dysrhythmic waves.     

Vesical pacing in patients with overactive bladder: Technique and results

Objectives: A recent study has demonstrated that the electric activity of the overactive bladder (OAB) is `dysrhythmic'. The cause was attributed to a disordered vesical pacemaker which discharges these waves. In a subsequent study, the dysrhythmic waves have been `normalized' by vesical pacing and the optimal parameters which are required to achieve normalization have been defined. We investigated the hypothesis that vesical pacing of the OAB might improve not only the vesical electric activity but also the symptoms. Methods: Vesical pacing was used in 9 patients (age 39.2 ± 10.3; 5 women, 4 men) with OAB. Under anesthesia, the pacemaker was implanted in an inguinal subcutaneous pocket and connected to 2 pacing electrodes implanted into the vesical vault. The normalization of the waves was tested by 2 recording electrodes which were temporarily applied to the vesical wall and removed post-testing. The pacemaker was then programmed for home pacing to be activated at given times. Results: Vesical pacing effected normalization of the dysrhythmic electric waves with disappearance of the OAB symptoms in 7 patients and failed in 2. Vesical pacing was abandoned in 3/7 patients after a few months following the spontaneous disappearance of the symptoms. Conclusions: Vesical pacing has normalized the dysrhythmic electric activity and suppressed the symptoms of the OAB in 77.7% of patients. The pacemaker was removed in 5 patients: 2 failures and 3 after spontaneous waves normalization. No complications were encountered. Vesical pacing is suggested as a treatment for OAB when commonly used therapeutic modalities have failed. This revised version was published online in August 2006 with corrections to the Cover Date.     

A study of the effect of distension of the rectosigmoid junction on the rectum and anal canal with evidence of a rectosigmoid-rectal reflex

PURPOSE: To elucidate the role of the rectosigmoid junction (RSJ) in the mechanism of defecation. METHOD: Fourteen healthy volunteers were enrolled in the study (10 men, 4 women; mean age 38.2 +/- 10.6 years). The pressures in the rectum, anal canal, and RSJ as well as rectal balloon expulsion were recorded in response to balloon distension of the RSJ in increments of 10 ml of carbon dioxide (CO2) to 50 ml. The experiments were repeated after individual anesthetization of the RSJ, rectum, and anal canal. The expulsion of a 50-ml distended balloon located in the anesthetized rectum was tested. RESULTS: RSJ distension with 10 ml of CO2 produced no significant pressure changes in the RSJ, rectum, or anal canal. A 20-ml distension effected a significant pressure rise in the RSJ (P < 0.05) and the rectum (P < 0.01) and a decline in the anal canal (P < 0.05); the rectal balloon was expelled to the exterior. Similar pressure changes (P > 0.05) were recorded with a 30-, 40-, and 50-ml balloon distension. The mean latency for the RSJ response was 12.6 +/- 2.2 ms and for the rectum 15.8 +/- 2.6 ms. The balloon, distended with 50 ml of CO2 and located in the rectum, was not expelled to the exterior. Balloon expulsion occurred only with distension with volumes of above 80 ml. Individual anesthetization of the RSJ, rectum, and anal canal followed by RSJ distension produced no significant pressure changes in RSJ, rectum, and anal canal as well as no rectal balloon expulsion. CONCLUSION: The rectal contraction upon RSJ distension affirms the hypothesis of the possible involvement of a reflex, which we term "rectosigmoid-rectal reflex." This reflex relationship is evidenced by reproducibility and its absence on anesthetization of either the RSJ or the rectum, both presumably representing the two arms of the reflex arc. It is postulated that stools passing from the sigmoid colon to the rectum distend the RSJ and evoke the rectosigmoid-rectal reflex, which produces rectal contraction. The role of the reflex in defecation disorders needs to be studied.     

Study of the Rectal Electric Activity of the Uninhibited Rectal Detrusor (Overactive Rectum): A New Concept of Pathogenesis

Abstract

Background/Objective: One of the causes of fecal incontinence is uninhibited rectal detrusor syndrome (URDS). Patients with this condition either perceived the first rectal sensation after the onset of involuntary rectal contraction or not at all. We investigated the hypothesis that the abnormal rectal contractility in URDS may be caused by deranged rectal electric activity.

Methods: Twenty-five patients with URD (14 women and 11 men; age, 44.7 ± 10.3 years) and 10 healthy volunteers (6 women and 4 men; age, 42.8 ± 8.7 years) were studied. URDS was diagnosed by rectometry and provocative test. A transcutaneous EMG was performed with one electrode placed lateral to each sacroiliac joint and the third one midway between the greater trochanter and the ischial tuberosity. Two 20- minute recording sessions were performed for each subject.

Results: Slow waves (SWs) with regular rhythm and similar parameters (frequency, amplitude, conduction velocity) from the 3 electrodes were recorded from the healthy volunteers. They showed a significant increase in the parameters on saline filling of the rectum. The SWs of patients with URDS exhibited a “dysrhythmic” pattern with irregular parameters, which were different in the 3 electrodes and inconsistent during recording. They showed areas of tachyrhythmia, bradyrhythmia, and arrhythmia. On provoking rectal overactivity, the SWs showed an increased dysrhythmic activity.

Conclusions: The patients with URD exhibited a “dysrhythmic” electric pattern with areas of variable electric activity. The tachyrhythmic areas seem to initiate the urgency and fecal incontinence of URDS. It is suggested that a disordered rectosigmoid pacemaker causes the dysrhythmic waves.     

Effect of rectal distension on rectal electromechanical activity.

The rectum possesses electric activity in the form of pacesetter potentials (PPs) and action potentials (APs). The latter are associated with rectal pressure elevation and share in the rectal motile activity. A recent study has shown that electric waves are transmitted by the longitudinal but not the circular rectal muscle fibers. Rectal motile activity under normal physiologic conditions was suggested to be induced by the electric waves, that effect longitudinal muscle contraction, as well as by circular muscle stretch resulting from rectal distension. The current study investigated the effect of rectal overdistension on the rectal electromechanical activity aiming at assessing the effect of stool accumulation in the rectum on rectal motile activity. Under general anesthesia, the abdomen of 16 mongrel dogs was opened, the rectum exposed, and 3 electrodes were sutured to the rectal serosa. The rectal pressure was measured by a 10-F catheter connected to a pressure transducer. Rectal distension was achieved by a balloon inflated with carbon dioxide (CO2). Simultaneous recording of the electric activity and rectal pressure was performed during rectal inflation in increments of 10 mL CO2. There was significant increase of rectal pressure as well as of frequency, amplitude, and conduction velocity of PPs and APs on rectal distension. The more the rectal balloon was distended, the more was the increase in rectal pressure and waves variables; the increase was maximal just before balloon expulsion at 40 mL distension. Upon rectal overdistension (50 and 60 mL), no PPs or APs were recorded and the rectal pressure was 0; no balloon expulsion occurred. Rectal overdistension (pathologic distension) appears to abort the electromechanical activity of the rectum and lead to failure of the rectum to expel the balloon. This effect is suggested to be due to overstretch of rectal musculature with a resulting loss of the rectal electric waves and noncontraction of the muscle fibers. These findings appear to explain the cause of rectal atony, which occurs in rectal inertia and leads to constipation.     

Role of the rectosigmoidal junction in fecal continence: concept of the primary continent mechanism

HYPOTHESIS: At mass contraction of the descending colon, the colonic contents stop at the sigmoid colon (SC) and do not pass directly to the rectum. We investigated the hypothesis that a continent mechanism seems to exist at the rectosigmoidal junction (RSJ), preventing the direct passage of stools from the descending colon to the rectum. METHODS: The SC in 16 healthy volunteers (mean +/- SD age, 38.6 +/- 10.2 years; 9 men and 7 women) was distended with an isotonic sodium chloride solution-filled balloon, and the pressure response of the RSJ and the rectum was recorded at rapid and gradual filling of the balloon. The test was repeated after the SC and RSJ were anesthetized separately. RESULTS: Rapid SC balloon distension with a mean +/- SD of 52.1 +/- 3.6 mL of isotonic sodium chloride solution effected an RSJ pressure increase to a mean +/- SD of 67.8 +/- 18.4 cm H(2)O (P<.01) with no rectal pressure response (P>.05). Slow SC filling produced a progressive increase in RSJ pressure but no rectal pressure change. At a mean +/- SD SC distending volume of 86.3 +/- 4.1 mL, the RSJ pressure decreased to 9.6 +/- 2.8 (P<.01), and the balloon was dispelled to the rectum; rectal pressure increased (P<.001), and the balloon was expelled to the exterior. The RSJ pressure did not respond to distension of the anesthetized SC. CONCLUSIONS: Contraction of the RSJ at rapid SC distension with big volumes implies a reflex relationship that we call the RSJ guarding reflex. This reflex seems to prevent the descending colon contents from passing directly to the rectum. It is considered the first continent reflex and may serve as an investigative tool in the study of fecal incontinence.     

Human duodenal myoelectric activity after operation and with pacing

We sought to determine the influence of operation on the pattern of human duodenal myoelectric activity and to assess whether electrical pacing might correct any postoperative disturbances. Three pairs of temporary bipolar serosal electrodes were placed on the duodenums of ten patients undergoing cholecystectomy. Electrical recordings were obtained daily until the patients' discharge, at 3 to 7 days, after operation. On each postoperative day, a regular rhythmic pattern of pacesetter potentials (PPs) was detected in all patients. The PP frequency (mean +/- SEM) was greater at the proximal electrode than at the distal electrode on the first postoperative day (12.3 +/- 0.1 cpm vs 11.9 +/- 0.1 cpm, p less than 0.01) and on the day of feeding (12.0 +/- 0.2 cpm vs 11.6 +/- 0.2, p less than 0.01). Spontaneous periods when spike potentials accompanied each PP (phase III of the migrating myoelectric complex), were found in only one patient on the day after operation, while they were recorded in five patients after 3 to 7 days, when postoperative ileus had resolved (p less than 0.05). Pacing with electric pulses (50 msec, 5 to 15 mA, 11 to 13 cpm) did not alter the pattern of duodenal PPs or entrain them in the duodenum of any patient at any time after operation. In conclusion, the pattern of duodenal pacesetter potentials changed little during the period of postoperative ileus, while the incidence of phase IIIs of the migrating myoelectric complex was greatly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electric activity of the colon in subjects with constipation due to total colonic inertia: an electrophysiologic study

BACKGROUND: Idiopathic constipation may result from colonic inertia, which affects the whole colon or is localized to an area of the colon. The colon exhibits electric activity in the form of slow waves or pacesetter potentials (PPs) and action potentials (APs), which are coupled with elevated colonic pressure. The APs are claimed to be responsible for colonic motor activity. HYPOTHESIS: Colonic electric activity is disordered in patients with constipation due to colonic inertia. METHODS: Electric activity was studied in 11 patients with colonic inertia and constipation (mean +/- SD age, 42.8 +/- 6.6 years; 7 women) who underwent total colectomy. Eight volunteers who had no gastrointestinal complaints (mean +/- SD age, 40.6 +/- 5.8 years; 5 women) acted as controls. Control subjects underwent laparotomy for hernia repair (n = 7 patients) and for removal of a mesenteric cyst (n = 1 patient). During the operation, 2 monopolar silver-silver chloride electrodes were applied to the cecum and the ascending, transverse, descending, and sigmoid colon. RESULTS: Electric waves (PPs and APs) were recorded from all parts of the colon in control subjects. The waves were monophasic, negatively deflected, and had regular rhythm. The wave variables from the 2 electrodes of each segment of the colon were identical and reproducible. They progressively increased aborally. In the colonic inertia group, 5 patients had recorded waves from the cecum and ascending colon but no waves from the rest of the colon. The wave variables were significantly lower than those of the controls (P =.02). In the remaining 6 patients, no waves were registered from the whole colon. CONCLUSIONS: Regular electric waves were recorded from the colons of control subjects. The aboral increase of their frequency, amplitude, and conduction velocity suggests that colonic motile activity increases analward, reaching its maximum in the sigmoid colon to expel its solid contents. We postulate that constipation in patients with colonic inertia is attributable to weak or absent electric activity, the cause of which is unknown. A disorder of the interstitial cells of Cajal, which generate electric activity, is suggested to have a role in inducing diminished or absent colonic motor activity, a point that should be investigated.     

The "opening time" and "pelvic floor electromyographic lag time": two novel tools in the assessment of the anorectal evacuation time.

Rectal evacuation necessitates rectal contraction and pelvic floor muscles relaxation; it is not known which action precedes the other. We investigated the hypothesis that pelvic floor muscles relaxation precedes rectal contraction so that rectal contents find the anal canal already opened. Electromyographic activity of the external anal sphincter as well as anal and rectal pressures were recorded during rectal balloon distension and evacuation. Pelvic floor muscles electromyographic lag time (time from start of pelvic floor muscles relaxation to start of evacuation) and opening time (time from start of rectal contraction to start of evacuation) were measured. Rectal balloon distension in increments of 20 mL up to 100 mL effected progressive increase of both external anal sphincter electromyography and anal pressure. At 120 mL balloon distension up to 180 mL, external anal sphincter electromyography and anal pressure exhibited gradual decrease whereas rectal pressure showed no changes. At 200 to 220 mL rectal balloon distension, rectal pressure increased and anal pressure decreased, while external anal sphincter showed no electromyographic activity; rectal balloon was expelled. The opening time recorded a mean of 1.8 +/- 0.7 s and pelvic floor muscles electromyographic lag time of 2.2 +/- 0.9; the two recordings showed no significant difference (p > .05). These, two diagnostic tools in anorectal investigations are presented: the opening time and pelvic floor muscles electromyographic lag time. Pelvic floor muscles relaxation preceded rectal contraction. As there is no significant difference between opening time and pelvic floor muscles electromyographic lag time, it appears easier to apply the latter as it is simple, objective, and noninvasive.     

Ectopic jejunal pacemakers and gastric emptying after Roux gastrectomy: effect of intestinal pacing

The aims of this study were to determine whether ectopic pacemakers are present after meals in the Roux limbs of dogs after vagotomy and Roux gastrectomy, whether these pacemakers slow gastric emptying of liquids or solids, and whether abolishing the pacemakers with electric pacing might speed any slow emptying that occurs. In six dogs that underwent vagotomy and Roux gastrectomy and in four dogs that underwent vagotomy and Billroth gastrectomy (controls), myoelectric activity of the Roux limb or duodenum was measured during gastric emptying of a 500 kcal mixed meal of 99mTc-labeled cooked egg and 111In-labeled milk. Roux dogs were tested with and without pacing of the Roux limb. Roux dogs showed ectopic pacemaker in the Roux limb that drove the pacesetter potentials of the limb in a reverse, or orad, direction during 57% of the postprandial recordings. Billroth dogs had no ectopic pacemakers (p less than 0.05). Liquids emptied more slowly in Roux dogs (half-life (t1/2) = 121 +/- 15 minutes) than in Billroth dogs (t1/2 = 43 +/- 9 minutes; p less than 0.05), but solids emptied similarly in both groups of dogs (t1/2 approximately 8 hours). Pacing the Roux limb abolished the ectopic pacemakers, restored the slow emptying of liquids to the more rapid rate found in the Billroth dogs (t1/2: paced Roux, 72 +/- 15 minutes; Billroth, 43 +/- 9 minutes; p greater than 0.05) and did not change emptying of solids. The conclusion was that ectopic pacemakers present in the Roux limb after vagotomy and Roux gastrectomy drove the limb in a reverse direction and slowed emptying of liquids after the operation. The defect was corrected by pacing the Roux limb in a forward direction.     

Study of the role of the second defecation reflex: anorectal excitatory reflex in the pathogenesis of constipation

BACKGROUND: Previous studies have shown that anal distension caused rectal contraction, an action mediated through the anorectal excitatory reflex. Anal anesthetization aborted rectal contraction and rectal evacuation was induced by excessive straining. We investigated the hypothesis that inhibition or absence of the anorectal excitatory reflex could lead to constipation. METHODS: We studied 18 patients (mean age +/- SD: 40.6 +/- 5.8 years, 14 women) with rectal inertia, 14 (41.7 +/- 6.6 years, 12 women) with puborectalis paradoxical syndrome, and 10 healthy volunteers (37.9 +/- 4.8 years, 8 women). The rectum was filled with normal saline until urge and then evacuated; residual fluid was calculated. The anal and rectal pressure response to anal balloon distension in increments of 2 mL of saline was recorded by a two-channel microtip catheter. RESULTS: In the healthy volunteers, saline was evacuated as a continuous stream without straining except occasionally at the start of evacuation; no residual fluid was encountered. Anal balloon distension effected notable rectal pressure increase. In rectal inertia patients, evacuation occurred in small fluid gushes produced with excessive straining; residual fluid of large volume was collected. Anal balloon distension up to 10 mL produced no notable rectal pressure changes. The patients with PPS failed to evacuate more than a few mL of fluid despite excessive straining; the volume of residual fluid was considerable. Anal balloon distension caused a notable rectal pressure rise. The results were reproducible. CONCLUSIONS: These results suggest that the defecation reflexes (rectoanal and anorectal) are absent in rectal inertia patients and this presumably denotes a neurogenic disorder. The anorectal reflex is active in puborectalis paradoxical syndrome, but the rectoanal reflex is not, indicating a possible myogenic defect in the puborectalis muscle.     

Ectopic jejunal pacemakers and enterogastric reflux after Roux gastrectomy: effect of intestinal pacing

The aims of this study were to determine whether ectopic pacemakers are present in the Roux limb of dogs after vagotomy and Roux gastrectomy, whether these pacemakers lead to enterogastric reflux, and whether abolishing the pacemakers with electric pacing might correct such reflex, were it to occur. In five dogs that had undergone gastric vagotomy and Roux gastrectomy and five dogs that had undergone gastric vagotomy and Billroth I gastrectomy (controls), myoelectric activity of the Roux limb or duodenum was recorded during saline infusion (154 mmol/L NaCl) or nutrient (Meritene) infusion into the limb or the duodenum. Reflux of infusate into the stomach was determined via a gastric cannula. Tests in Roux dogs were done with and without limb pacing. Roux dogs showed ectopic pacemakers in the Roux limb that drove the pacesetter potentials of the limb in a reverse, or orad, direction during 76% of the recordings; Billroth dogs rarely had such pacemakers (p less than 0.001). Enterogastric reflux occurred in both groups of dogs but was greater during phase III of the interdigestive migrating myoelectric complex in Roux dogs (12% +/- 6%) than in Billroth dogs (3% +/- 1%; p less than 0.05). Pacing abolished the ectopic pacemakers in the Roux dogs and reduced enterogastric reflux from 12% +/- 6% to 3% +/- 2% when phase III was present (p less than 0.05). In conclusion, the Roux limb was driven by ectopic pacemakers that contributed to, but were not solely responsible for, jejunogastric reflux. Pacing abolished the ectopic pacemakers and decreased reflux when phase III was present in the limb.     

Permanent pacing following cardiac transplantation.

Permanent pacemakers were inserted in 20 of 439 patients who had received 453 orthotopic cardiac allografts since 1980 at the Columbia-Presbyterian Medical Center. Mean age at transplantation was 45 +/- 4 (SEM) years (range 10 to 64). Pacemakers were inserted an average of 2.4 +/- 1 months after transplantation (range 0.4 to 29), 16 of 20 (80%) within the first month. Indications included sinus bradycardia or sinus arrest in 15 (75%), third-degree heart block in 2 (10%), and both sinus node and atrioventricular node dysfunction in 3 (15%). Rejection episodes and pacemaker insertion were associated in 8 patients (40%). Pacing modes included DDD (7 patients, 35%), AAI,R (7 patients, 35%), VVI,R (3 patients, 15%), DDD,R (2 patients, 10%), and VVI (1 patient, 5%). There was no pacing-related morbidity or mortality. Fourteen of 20 patients (70%) are alive and well 3 to 48 months (mean 24 +/- 4) after transplantation. Late follow-up indicated that atrioventricular node dysfunction resolved in one of two patients, sinoatrial node dysfunction improved or resolved in 7/13 patients, and no atrioventricular block developed in 11 (8 to 37 months, mean 22 +/- 3). Permanent pacing can be safely performed following orthotopic cardiac transplantation, predominantly for sinus node dysfunction. The requirement for pacing may reflect ongoing or new onset rejection and patients should therefore be evaluated accordingly. Dual-chamber pacing is probably not necessary unless atrioventricular node dysfunction is coexistent. Further, as most transplant recipients return to an active life-style, AAI,R may be the preferred mode of pacing.     

Detrusor sphincter dyssynergia syndrome. A new syndrome and its treatment by external sphincter myotomy

A new syndrome in which there was persistent external anal sphincter contraction on rectal distension is described in 18 patients. 12 were females and 6 males. Average age was 38.3 years. The main complaint was chronic constipation and straining at stool. Rectal evacuation was performed manually or by enemas. Investigations comprised manometric and EMG studies of external anal sphincter. The average number of stools per week was 2.1. Rectal neck pressure recorded normal values at rest and on squeeze. The rectoinhibitory reflex registered high rectal neck pressure on rectal distension [average 136 +/- (SD) 12.3 mm Hg] which was lowered (average 13 +/- 2.2 mm Hg) after pudendal nerve block. External sphincter showed persistent high EMG activity during rectal distension. External sphincter myotomy was performed in 16 patients. Myotomy specimens showed no histologic abnormalities. The patients were followed up for 2-4 years after the operation. The stool frequency approached the normal range, and straining at stool disappeared. Rectal neck pressure during rectal distension dropped to normal values (average 36 +/- 10.3 mm Hg). Control disorders occurred in 2 patients but disappeared within 6 months after myotomy. External sphincter contraction on rectal distension leads to rectal neck obstruction with a resulting constipation and straining at stool. The cause of this contraction is unknown. Myopathy is excluded by the normal muscle integrity as evident from the normal EMG and biopsy findings. A disorder of the reflex arc may be considered.     

Interstitial cells of cajal in patients with constipation due to total colonic inertia.

Colonic wall contains interstitial cells of Cajal. In view of studies demonstrating that Cajal cells generate electric waves which are presumably responsible for colonic motor activity, and that these waves are absent in total colonic inertia, we investigated the hypothesis that colonic Cajal cells might be disordered in patients with total colonic inertia. The study comprised 28 patients (age 41.6 +/- 8.2 SD years, 19 women, 9 men) with total colonic inertia in whom total colectomy was performed. Colonic specimens obtained from normal segments of the excised colon of 24 cancer patients acted as controls. Specimens were subjected to c-kit immunohistochemistry. Controls for antisera specificity consisted of tissue incubated with normal rabbit serum that had been substituted for the primary antiserum. C-kit-positive branched Cajal-like cells were detected in the musculature of the normal colonic segments. They were distinguishable from the C-kit-negative smooth muscle cells and the C-kit-positive but unbranched mast cells. No Cajal cells were detected in colon of total colonic inertia patients. The absence of Cajal cells in patients with total colonic inertia can be assumed to explain the absence of electric waves and motile activity previously reported in these patients. Further studies are needed to investigate the cause of Cajal-cell absence.     

Gastrointestinal myoelectric and clinical patterns of recovery after laparotomy.

The objective of this study was to define the patterns of myoelectric activity that occur throughout the gastrointestinal tract during normal recovery from laparotomy. Electrodes were placed on the stomach, jejunum, and transverse colon of 44 patients undergoing laparotomy. Basal electric rhythms in all areas showed no changes in frequency after operation (up to 1 month). Gastric spike wave activity showed a gradient of increasing activity from fundus to antrum. Antral spike activity was unchanged during the study. Jejunal spike activity was present in the earliest recordings and occurred in 45.9% +/- 3.5% to 59.9% +/- 5.5% of slow waves. Recovery of normal colon discrete and continuous electric response activity occurred on postoperative day 5.9 +/- 1.5. Bowel sounds returned on day 2.4 +/- 0.5 and passage of flatus and stool occurred on day 5.1 +/- 0.2. The myoelectric parameters measured are not absolutely predictive of uneventful recovery from postoperative ileus but they are, as a group, more informative than any currently available clinical criteria.     

Staged anterior resection and TEM to preserve rectal function in synchronous malignant and benign rectal lesions

BACKGROUND: Traditionally patients with a high rectosigmoid carcinoma and a synchronous large distal rectal adenoma would be treated by low anterior resection with associated loss of rectal function. METHOD: Four patients with a carcinoma of the upper rectum or distal sigmoid colon and a synchronous distal rectal adenoma were treated by high anterior resection followed by staged Transanal Endoscopic Microsurgery (TEM) thus conserving the distal rectum. Preoperative and postoperative rectal function was assessed using the St. Mark's incontinence score. RESULTS: The proximal carcinomas and distal adenomas were 12-18 cms and 0.5-9 cms respectively from the dentate line. The mean surface area of the distal adenomas was 9.7 cms2. There were no deaths or major complications. There were no recurrences after a mean follow-up of 31.5 months. Rectal function was unchanged in three patients with a minor increase in the score in one. CONCLUSION: Staged high anterior resection and 'rEM offers effective treatment of synchronous rectosigmoid carcinoma and distal rectal adenoma with preservation of rectal function.     

Preservation of continence after ileoanal anastomosis by the coordination of ileal pouch and anal canal motor activity.

Nocturnal incontinence may occur after ileoanal anastomosis and may be related to loss of an effective anal canal pressure barrier during sleep; how pressure and contractions in the proximal bowel influence this barrier is unknown. Our aim was to evaluate the relationship between anal canal pressure and contractions and contractile activity of the pouch in continent subjects after ileal pouch-anal anastomosis (IPAA) and of the rectum in normal controls. A fully ambulatory system for 24-hour pressure recording was used. A flexible transducer catheter was introduced endoscopically so that sensors were at 2, 3, 8, 12, 16, and 24 cm from the anal orifice in 12 healthy controls (7 men, 5 women, mean age: 35 years) and 7 fully continent IPAA patients (4 men, 3 women, mean age: 34 years) more than 12 months postoperatively. Twenty-four hour spontaneous motor activity was stored in a 2.5 megabyte (MB) digital portable recorder. Mean anal canal pressure was calculated, and rectal motor complexes and ileal pouch large pressure waves were characterized. During sleep, resting anal canal pressures were similar in the two groups (72 +/- 12 mm Hg in controls versus 66 +/- 9 mm Hg in IPAA patients [mean +/- standard deviation (SD)], p = NS), but anal canal pressure showed cyclic relaxations (periodicity: 95 +/- 11 min in controls, 54 +/- 18 min in IPAA patients, p less than 0.05), during which the mean pressure trough was 15 +/- 4 mm Hg in controls and 14 +/- 5 mm Hg in IPAA patients (p = NS). In the control patients, during sleep, a mean of six rectal motor complexes were identified (range: 3 to 9). In patients with IPAA, during sleep, a mean of eight large pressure waves per hour were identified (range: 2 to 20). Importantly, in both controls and patients, rectal motor complexes or large pressure waves were always accompanied by rapid return of anal canal pressure from trough to basal values and increased contractile activity. We concluded that, in healthy patients and in continent patients after IPAA, motor activity of the rectum and of the ileal pouch was associated with changes in pressure and contractile activity of the anal canal so that rectal- and neorectal-anal canal pressure gradient, and, in turn, fecal continence were preserved.