Radiofrequency catheter ablation for atrial flutter following orthotopic heart transplantation.

A 26 year old woman with a diagnosis of limb girdle muscular dystrophy and peripartum cardiomyopathy underwent orthotopic heart transplantation using standard atrial anastomoses. Recurrent atrial flutter was demonstrated in the absence of histological evidence of cellular rejection. Radiofrequency ablation of the flutter circuit was successfully performed allowing the avoidance of long term antiarrhythmic therapy. Ten weeks following ablation and cessation of amiodarone, presyncopal symptoms were found, associated with daytime and nocturnal sinus pauses of 2.9 seconds and 4.2 seconds, respectively. There was no evidence of AV node conduction impairment. In view of the continued absence of cellular rejection and the evident denervated state of the heart, the pauses reflected significant donor sinus node dysfunction; therefore, an AAIR permanent pacing system was implanted. At the time of pacemaker implantation atrial pacing at 150 beats/min did not produce significant PR interval prolongation or AV block. This case serves to advise rigorous follow up in such patients to continue to seek evidence of sinus node dysfunction potentially requiring permanent pacemaker implantation.

The natural history of thoracic aortic aneurysm disease: an overview.

Relatively little is known of the natural history of thoracic aortic aneurysms (TAA). The limited data available suggests that survival is at best equivalent to that observed for abdominal aortic aneurysm (AAA), and probably significantly worse. Patients with an AAA > 6 cm diameter have a 5-year survival of 10%, with a cumulative risk of rupture over 10 years of 43%. Rupture is also responsible for death in 25% of patients with 4-7 cm AAA. Natural history studies of TAA report a 1- and 5-year survival of 39%-52% and 13%-19%, respectively, but many studies include data on acute type A dissection. Although most mortality in patients with TAA is related to aneurysm rupture, data on the relationship between aneurysm size and rupture risk remains scarce. TAA is a highly lethal condition warranting consideration of elective, prophylactic surgical repair. However, the timing of surgery is often a difficult clinical decision, particularly in asymptomatic patients or those with comorbid conditions. Surgery for TAA carries a significant mortality and potentially permanently crippling morbidity. A recommendation of surgery represents a balance, weighing estimates of TAA natural history and rupture risk against operative mortality and complication rate, while carefully considering the impact of important comorbid conditions, e.g., ischemic heart disease, obstructive pulmonary disease, and renal dysfunction. When to intervene is a critical question facing cardiovascular surgeons and is based upon an assessment of the risk of rupture. This risk is related to the site, aetiology, size, and expansion rate of the aneurysm.