Proarrhythmic ECG Deterioration Caused by Myocardial Ischemia of the Conus Branch Artery in Patients with a Brugada ECG Pattern

The Brugada‐type electrocardiogram (ECG) is characterized by ST‐segment elevation in the right precordial ECG leads and has been reported to have the potential of sudden death. Right ventricular outflow tract supplied from the conus branch of the coronary artery (CB) is considered as the anatomopathologic substrate of Brugada syndrome. We experienced two asymptomatic patients with a saddleback Brugada‐type ECG who exhibited a dynamic ECG conversion to a coved type following a ventricular fibrillation/ventricular tachycardia (VT/VF) episode when myocardial ischemia occurred exclusively at the CB. Some types of Brugada syndrome might be caused VT/VF by selective myocardial ischemia at the CB. (PACE 2011; 34:e26–e29)     

Relationship between obstruction of arteriovenous fistula and plasma level of endothelin-1 in long-term haemodialysis patients

Summary: The relationship between the patency status of the autogenous arteriovenous (A-V) fistula and the plasma level of endothelin-1 (ET-1) was studied in 41 patients who had been receiving routine longterm haemodialysis for more than 10 years. the ET-1 level in the haemodialysis patients (mean ± s.d.=2.1 ± 0.9 pg/mL) was significantly elevated compared with that in healthy controls ( n =16; 1.1 ± 0.4 pg/mL; P < 0.01). the patients were classified into two groups according to whether the original A-V fistula had remained patent for more than 10 years or had been repaired due to frequent (more than twice) obstruction. Among all 41 patients, 21 were receiving recombinant human erythropoietin (rHuEpo) intravenously (i.v.). In the rHuEpo-treated group, the plasma ET-1 ( n =21; 2.4 ± 0.8 pg/mL) was significantly elevated than that in the rHuEpo-untreated group ( n =20; 1.9 ± 0.9 pg/mL; P<0.05). After exclusion of the 21 rHuEpo-treated patients, the ET-1 level in the repaired fistula group ( n =11; 2.3 ± 0.9 pg/mL) was significantly higher than that in the patent original fistula group ( n =9; 1.3 ± 0.7 pg/mL; P <0.02). Based on these results, we conclude that ET-1 shows a close relation to venous stenosis of the A-V fistula which may be due to its vasoconstrictive and smooth muscle cell-proliferating effects.