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Aim of our study was to retrospectively evaluate atrioventricular conduction 24 hours after selective radiofrequency catheter ablation of the fast pathway or after selective ablation of the slow pathway of the atrioventricular nodal reentrant tachycardia circuit. Electrophysiologic modifications were retrospectively analyzed in 47/48 patients successfully submitted to fast pathway ablation and in 90/93 patients successfully submitted to slow pathway ablation. The atrioventricular conduction intervals (P-Q and A-H), both anterograde and retrograde Wenckebach point, the effective refractory period of atrioventricular node and the atrioventricular node function curve were evaluated before and after selective radiofrequency catheter ablation of slow and fast pathway. We identified the fast pathway ablation potential as: A:V ratio > or = 2:1, His electrogram < or = 150 microV. The slow pathway potential was identified as the widest, sharpest and latest atrial electrogram recorded during sinus rhythm in the posteroseptal region of the atrioventricular junction or as the widest, sharpest and earliest observed during retrograde conduction. We observed a significant increase in the P-Q and A-H intervals in patients submitted to fast pathway ablation, while no significant modification of these parameters was appreciated in patients submitted to slow pathway ablation. No significant modification of anterograde Wenckebach point (NS) was observed in patients submitted to successfully ablation of fast pathway while a statistically significant increase in anterograde Wenckebach point (p = 0.03) was observed in patients submitted to slow pathway ablation. After selective fast pathway ablation, retrograde conduction was absent in 82.9% of patients submitted to ablation; in the remaining 17.1% a significant increase of retrograde Wenckebach point was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical or catheter ablation of accessory pathways by means of high energy shock has been substantial associated with morbidity and mortality. On the contrary radiofrequency current, an alternative energy source for ablation, has a low incidence of complications and a very high success rate. Aim of this study was to relate about the results using catheter ablation of accessory pathways by radiofrequency current in our Electrophysiologic laboratory. Radiofrequency current (20-40 W) was delivered between a large-tip catheter electrode positioned against the mitral or tricuspid anulus and a standard adhesive electrosurgical dispersive pad applied to the left chest wall. When possible radiofrequency delivery was guided by catheter recordings of accessory pathway activation. Ablation was attempted in 181 patients with 191 accessory pathways. We obtained successful ablation of 187/191 accessory pathways and accessory pathway conduction was eliminated in 177/181 patients. During a mean follow-up of 14 +/- 10 months preexcitation returned in 7 patients (3.9%). All underwent a second successful ablation. In 1 patient, during the procedure, we observed a transient ischemic attack, with no complications. In accordance to other reports we conclude that radiofrequency ablation is highly effective in ablating accessory pathways, with low morbidity and no mortality.

Aim of this study is to suggest our methodological approach for transcatheter ablation of Kent bundles by radiofrequency energy as to the potential ablation sites, the need in unipolar or bipolar recording mode, single catheter or multiple catheters mapping of anomalous pathways, the vascular approach for both left sited and right sited anomalous pathways, and finally the duration and power to supply. The recording of Kent potential and/or a Va-QRS interval > or = 0 ms have been considered significant predictors of success (respectively p < 0.001 and p < 0.05). The unipolar recording mode has been considered critical in the choice of ablation site in 47 (29.9%) patients. A 6-catheter approach for both diagnostic electrophysiologic studies and mapping allowed us to easily localize accessory pathways and to record either a probable or possible Kent potential in a high percentage of patients and to reduce the permanence of the ablation catheter in the left ventricle. By transaortic retrograde approach in ablating left sited anomalous pathways, we obtained a high success rate, while right sited accessory pathway were approached from the inferior vena cava. In right sited anomalous pathway we delivered radiofrequency energy for a longer time in order to avoid a relapse soon after the procedure. We performed ablation of 174/178 (97.7%) anomalous pathways in 165/169 (97.6%) patients. We observed a 3.8% relapse during a mean follow up of 13 +/- 9 months.

Bowel resection for idiopathic megarectum and megacolon does not always predictably relieve symptoms and has a significant morbidity. We have therefore evaluated the results of stoma formation in this condition. All patients had a bowel frequency of less than one per week, and all had a dilated rectum or colon. Eight patients, six of who had had a previous unsuccessful operation for their constipation, had a colostomy--this relieved the constipation and the need for laxatives in all six patients with rectosigmoid dilatation, although one patient could not tolerate his stoma. Two patients with dilatation of the whole colon were not helped. An ileostomy was formed in four patients with previous colonic resection, with relief of constipation in all. However pain and abdominal distension were common persistent symptoms in both groups. Four patients with a colostomy and all four patients with an ileostomy felt subjectively improved with a stoma. Stoma formation is a viable alternative to more major surgery, either as a primary procedure or after previous surgery has failed.

Adult patients with an idiopathic megarectum or megacolon can experience severe constipation requiring surgical treatment. Some of these patients have a proximal colon of normal diameter, with dilatation involving only the left or distal colon and rectum. The results of partial colonic and rectal resection with coloanal anastomosis in such patients have been reviewed. Seven patients (two female and five male) underwent a coloanal anastomosis over a seven-year period. The median age at operation was 19 years, the mean age at onset of symptoms was five years, and the mean follow-up period was one year. Five patients experienced a return to normal bowel frequency with the loss of most symptoms. One patient has an ileostomy because of persistent constipation after the procedure. One subject died because of postoperative bleeding from the anastomosis and subsequent cardiac and respiratory complications. This operation may have a place in the treatment of severe constipation caused by idiopathic megarectum and megacolon, but careful preoperative motility studies and meticulous attention to operative technique are required for a good outcome.

The outcome in 40 patients who underwent colectomy for idiopathic megacolon and megarectum over an 18 year period was evaluated. All patients had a radiologically dilated bowel and a bowel frequency of less than two per week. Twenty two patients had a caecorectal anastomosis, 11 had an ileorectal anastomosis (including one with a previous caecorectal anastomosis and four with a previous sigmoid resection), and seven had a sigmoid resection. The mean (range) age at operation was 35 (17-69) years. All three operations resulted in a normal bowel frequency in more than 80% of patients but no patient with an ileorectal anastomosis experienced recurrent constipation. Thirty four patients experienced pain preoperatively and this was still present in 14 patients postoperatively. One patient died and four required subsequent laparotomy for bowel obstruction. The functional outcome in patients with dilatation of the whole colon and in those with dilatation of the left colon did not differ. Subsequent surgery for constipation was performed in three patients. Colectomy offers good results with few complications in the treatment of idiopathic megacolon, and an ileorectal anastomosis is the preferred operation.

The results of the Duhamel operation in patients with idiopathic megarectum and megacolon have been reviewed. Twenty patients (14 males, six females) underwent the Duhamel operation over a 17-year period for this condition. The mean age at operation was 25 years; the mean age of onset of constipation was 3 years; and the mean follow-up period was 4.5 years. All the resected colons were of enlarged diameter. There was agreement between the preoperative radiographs and the operative specimens with regard to which parts of the rectum and colon were dilated. Subjective feelings of well-being were generally improved by surgery, as was bowel frequency in ten patients. Soiling, straining, abdominal pain and distension were, however, common after operation. Early complications were also common and five patients required further surgery for constipation. The Duhamel operation for megarectum and megacolon is characterized by an improved sense of well-being and improved bowel frequency, but it is associated with the persistence of many symptoms and further surgery is often required.