Remodeling of sinus node function after catheter ablation of right atrial flutter

INTRODUCTION: The purpose of this study was to investigate the effect of ablation of right atrial flutter upon sinus node function in humans. METHODS AND RESULTS: This study enrolled 35 patients. Twenty-four patients (16 men and 8 women; age 68 +/- 11 years) were referred for ablation of persistent atrial flutter (duration 8 +/- 11 months). After ablation, there was abnormal sinus node function defined as a corrected sinus node recovery time (CSNRT) > or = 550 msec. The control group consisted of 11 patients who were undergoing pacemaker implantation for sinus node disease but did not have a history of atrial dysrhythmias or ablation. Within 24 hours of ablation or pacemaker implantation, baseline maximal CSNRT was measured through a permanent pacemaker by AAI pacing at six cycle lengths: 600, 550, 500, 450, 400, and 350 msec. CSNRT then was measured in the same manner at 48 hours, 14 days, and 3 months after ablation/pacemaker implantation. P wave amplitude and duration, and percent atrial sensing also were assessed at the same intervals. For patients undergoing atrial flutter ablation, there was progressive temporal recovery of CSNRT (1,204 +/- 671 msec at baseline vs 834 +/- 380 msec at 3 months; P < 0.001) and a significant increase in the percent atrial sensing and P wave amplitude at 3 months compared with baseline (P < 0.001). In control subjects, there was no change in the CSNRT, percent atrial pacing, or P wave amplitude. CONCLUSION: After ablation of persistent atrial flutter, there is temporal recovery of CSNRT and increase in spontaneous atrial activity. These findings suggest that atrial flutter induces reversible changes in sinus node function.     

Concordance of Collagen-Based Radiocarbon and Aspartic-Acid Racemization Ages

By determining the extent of racemization of aspartic acid in a well-dated bone, it is possible to calculate the in situ first-order rate constant for the interconversion of the L and D enantiomers of aspartic acid. Collagen-based radiocarbon-dated bones are shown to be suitable samples for use in "calibrating" the racemization reaction. Once the aspartic-acid racemization reaction has been "calibrated" for a site, the reaction can be used to date other bones from the deposit. Ages deduced by this method are in good agreement with radiocarbon ages. These results provide evidence that the aspartic-acid racemization reaction is an important chronological tool for dating bones either too old or too small for radiocarbon dating. As an example of the potential application of the technique for dating fossil man, a piece of Rhodesian Man from Broken Hill, Zambia, was analyzed and tentatively assigned an age of about 110,000 years.     

Vaginal Delivery After Ileal Pouch-Anal Anastomosis: A Word of Caution

PURPOSE This study was designed to evaluate the impact of childbirth on anal sphincter integrity and function, functional outcome, and quality of life in females with restorative proctocolectomy and ileal pouch-anal anastomosis.METHODS The patients who had at least one live birth after ileal pouch-anal anastomosis were asked to return for a comprehensive assessment. They were asked to complete the following questionnaires: the Short Form-36, Cleveland Global Quality of Life scale, American Society of Colorectal Surgeons fecal incontinence severity index, and time trade-off method. Additionally, anal sphincter integrity (endosonography) and manometric pressures were measured by a medical physician blinded to the delivery technique. Anal sphincter physiology also was evaluated with electromyography and pudendal nerve function by nerve terminal motor latency technique.RESULTS Of 110 eligible females who had at least one live birth after ileal pouch-anal anastomosis, 57 participated in the study by returning for clinical evaluation to the clinic and 25 others by returning the quality of life and functional outcome questionnaires. Patients were classified into two groups: patients who had only cesarean section delivery after ileal pouch-anal anastomosis (n = 62) and patients who had at least one vaginal delivery after ileal pouch-anal anastomosis (n = 20). The mean follow-up from the date of the most recent delivery was 4.9 years. The vaginal delivery group had significantly higher incidence of an anterior sphincter defect by anal endosonography (50 percent) vs. cesarean section delivery group (13 percent; P = 0.012). The mean squeeze anal pressure was significantly higher in the patients who had only cesarean section delivery (150 mmHg) after restorative proctocolectomy than patients who had at least one vaginal delivery (120 mmHg) after restorative proctocolectomy (P = 0.049). Quality of life evaluated by time trade-off method also was significantly better in the cesarean section delivery group (1) vs. vaginal delivery group (0.9; P < 0.001).CONCLUSIONS The risk of the sphincter injury and quality of life measured by time trade-off method are significantly worse after vaginal delivery compared with cesarean section in patients with ileal pouch-anal anastomosis. In the short-term, this does not seem to substantially influence pouch function or quality of life; however, the long-term effects remain unknown, thus obstetric concern may not be the only factor dictating the type of delivery in this group of patients. A planned cesarean section may eliminate these potential and factual concerns in ileal pouch-anal anastomosis patients.Podium presentation at the meeting of The American Society of Colon and Rectal Surgeons, Dallas, Texas, May 8 to 13, 2004.     

Retransplantation for severe accelerated coronary artery disease in heart transplant recipients

Development of accelerated coronary artery disease (CAD) in the cardiac allograft is one of the major causes of late graft failure in heart transplant recipients. At the Stanford University Medical Center 356 heart transplant procedures were performed in 329 patients by the end of January 1985. Eighty-nine of these patients developed evidence of transplant CAD. Twenty retransplant procedures, including 2 third transplants, were performed in 19 of the 89 patients because of transplant CAD. The graft survival rates after the second transplant were 55%, 25% and 10% after 1, 2 and 5 years, respectively. Nine of these retransplant patients currently survive, the longest for 5.5 years. To examine potential risk factors for development of severe transplant CAD, these 20 retransplant procedures were compared with 113 transplant recipients who had no evidence of transplant CAD on annual coronary arteriograms. An excess of rejection episodes (3 +/- 2 vs 2 +/- 1 episodes/patient, p = 0.02), elevated total cholesterol (266 +/- 78 vs 225 +/- 47 mg/dl, p = 0.002) and higher low-density lipoprotein levels (176 +/- 88 vs 137 +/- 46 mg/dl, p = 0.009) were noted in the transplant CAD retransplant group. Five of 11 retransplant recipients who survived greater than 1 year again developed transplant CAD. Characteristic morphologic features and rapid progression of CAD in the second graft were similar to those in the primary graft.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of the renal concentration capacity following intravenous administration of dDAVP in healthy humans

The synthetic AVP analogue 1-desamino-8-d-arginine-vasopressin (dDAVP) is used for treatment of polyuric disorders. Lack of commercially available assays limits the usefulness of dDAVP as a diagnostic tool in the assessment of renal concentrating capacity. We aimed to develop a specific radioimmunoassay (RIA) for determination of plasma dDAVP (pdDAVP) in order to investigate the relationship between pdDAVP levels and urine osmolality (Uosm). Further, we aimed to determine the onset, duration, and maximum concentrating capacity following intravenous (i.v.) bolus dDAVP injection. The dDAVP assay was based on a well-established RIA for measurements of AVP. Fourteen healthy subjects (aged 15–18 years) participated. Blood and urine samples were collected prior to and after i.v. bolus of 0.03?µg/kg dDAVP. Diuresis and Uosm was measured for nine hours following dDAVP administration. PdDAVP and Uosm were analyzed.We established a specific RIA for the measurement of pdDAVP. All subjects reached maximal pdDAVP concentration (C_max) 30 minutes following infusion, and a rise in Uosm after 60 minutes. Maximal Uosm varied between subjects, with no direct correlation to the achieved pdDAVP levels. We found no significant intra-individual variation between two dDAVP infusions and the effect was reproducible in terms of C_max and maximal Uosm. We characterized the relationship between pdDAVP and Uosm after dDAVP bolus injection in healthy adolescents using our dDAVP assay. Maximal Uosm achieved correlated with the baseline Uosm levels and seemed unrelated to achieved pdDAVP levels. The urine concentrating response was maintained at least eight hours.     

Abnormalities of pulmonary artery wedge pressures in sleep-induced apnea

Six patients with sleep apnea syndrome were studied with continuous hemodynamic monitoring during sleep. Sleep apnea had been previously documented with an average number of apneas per hour of sleep ranging from 23 to 93 (mean 63). There was a significant decrease in heart rate during sleep (82 ± 5 to 69 ± 6, P < 0.01). There was a significant rise in systemic blood pressure (103 ± 2 mm Hg to 116 ± 6 mm Hg, P < 0.05) and pulmonary artery pressure (20 ± 1 mm Hg to 32 ± 5 mm Hg) during sleep. In addition, pulmonary artery wedge pressure increased (12 ± 2 mm Hg to 20 ± 3 mm Hg, P < 0.05) during sleep and 5 of the 6 patients developed an abnormal pulmonary wedge pressure. There was a significant decrease in P_O2 during sleep (71 ± 3 mm Hg to 49 ± 2 mm Hg, P < 0.005). These findings suggest that increases in pulmonary wedge pressures may be contributing to increase in pulmonary artery pressures in these patients during sleep.