Internodal conduction. Immediate and long-term effects of transverse circular incision of right atrium including atrial septum.

Immediate and long-term effects of a transverse circular incision of the entire right atrium, including the atrial septum, on internodal conduction were studied in 7 dogs. Electrocardiograms were followed up to 35 weeks, and the atrial epicardial excitation sequence was evaluated in all 7 dogs. The findings were compared with data from 3 normal dogs and 3 other dogs which underwent total atrial transverse incisions. All dogs with total atrial separation developed complete atrioventricular (A-V) block immediately after the operation and died within 3 days. All dogs with right atrial interruption exhibited persistent sinus rhythm with slight extension of P-R intervals and a normal QRS immediately after the operation. The mean P-R interval reached its maximum at the fourth day (50 per cent increase), remained prolonged through the first week, but returned to near control valves after 12 weeks. Three days later developed transient arrhythmia; sinus arrhythmia; sinus arrhythmia in 2 dogs and second-degree block in 1 appeared between the tenth and fourteenth postoperative days. Postoperative P vectors migrated toward the left. Atrial excitation sequence studies demonstrated prolongation of atrial epicardial conduction intervals (2.3 times) between the sinus node and distal right atrial wall. The presence of an interatrial conduction mechanism (whether by specific pathways or not), through which sinus node excitation was transmitted to the A-V node was demonstrated.

Cumulative clinical experience with the Symbion J7 TAH.

As of March 1, 1988, 92 patients have received the Symbion J7 pneumatic TAH as a bridge to cardiac transplantation. All implantee's were Category 6 (Urgent Need) patients, exhibiting functional Class IV symptoms or facing imminent death, in the judgment of their physician prior to obtaining a suitable cardiac allograft. Sixty-three of these patients, (68%) were transplanted. Of the 56 transplants 35 (56%) patients are currently alive, with most returning home and back to work. Implant duration ranged from 1 to 243 days of support, with an average of 24 days. Implantee average age was 42 years, with a range of 15-60 years. Male/female distribution was 80/12, with the females requiring longer periods of pump support and exhibiting lower survival rates. Several main implant categories have surfaced during the study, with the collective disease category of cardiomyopathy constituting 66% of the study population. This broad category may be subdivided into ischemic cardiomyopathy 52%, idiopathic 25%, viral 7%, and miscellaneous 16%. Acute rejection of donor organ (17%) and unweanable patients (11%) constitute the other major implant categories. Postoperative complications observed in a population cohort of 70 patients include bleeding in 44%, infection in 34%, reoperation in 27%, neurologic dysfunction in 13%, and device failure in none. Standardized device explant analysis results indicate a trend in thrombus reduction concurrent with increased investigator experience and improved patient management techniques. The concept of bridging in a specific group of patients in which the prognosis is otherwise hopeless continues to demonstrate therapeutic value.