B-type natriuretic peptide infusions in acute myocardial infarction.

BACKGROUND: Natriuretic peptides have actions likely to ameliorate cardiac dysfunction. B-type natriuretic peptide (BNP) is indicated as treatment for decompensated cardiac failure. OBJECTIVE: To determine the utility of BNP in acute myocardial infarction (MI). DESIGN: Double-blind randomised placebo-controlled trial. SETTING: Tertiary hospital coronary care unit. PATIENTS: 28 patients with acute MI with delayed or failed reperfusion and moderate left ventricular dysfunction. INTERVENTIONS: Infusion of BNP or placebo for 60 hours after MI. MAIN OUTCOME MEASURES: Neurohormonal activation and renal function in response to BNP infusion, secondary end points of echocardiographic measures of left ventricular function and dimension. RESULTS: BNP infusion resulted in a significant rise in BNP (276 pg/l vs 86 pg/l, p = 0.001). NT-proBNP levels were suppressed by BNP infusion (p = 0.002). Atrial natriuretic peptide (ANP) and NT-proANP levels fell with a significant difference in the pattern between BNP infusion and placebo during the first 5 days (p<0.005). C-type natriuretic peptide (CNP) and NT-proCNP levels rose during the infusion with higher levels than placebo at all measurements during the first 3 days (p<0.01). Cyclic guanosine monophosphate (cGMP) was raised during the infusion period showing a peak of 23 pmol/l on day 2 (placebo 8.9 pmol/l, p = 0.002), with a correlation between BNP and cGMP levels (p<0.001). Glomerular filtration rate (GFR) fell with BNP infusion but was not significantly lower than with placebo (71.0 (5.6) vs 75.8 (5.4) ml/min/1.73 m2, p = 0.62). Patients receiving nesiritide exhibited favourable trends in left ventricular remodelling. CONCLUSIONS: Nesiritide, given soon after MI, induced increments in plasma cGMP and CNP and decrements in other endogenous cardiac peptides with a neutral effect on renal function and a trend towards favourable ventricular remodelling.

Monomorphic ventricular tachycardia related to Wolff-Parkinson-White surgery.

Monomorphic ventricular tachycardia (MVT) is well described in patients who have had a ventricular scar due to repair of congenital heart disease. A 54-year-old woman presented with MVT 20 years after WPW surgery for a left-sided accessory pathway. The circuit was mapped to an area at the base of the left ventricle consistent with the incision described in the operation report. Entrainment confirmed the re-entrant circuit. Successful radiofrequency ablation was performed in a zone of slowed conduction consistent with the circuit isthmus. Any iatrogenic ventricular scar may form the substrate for MVT and be treated with standard electrophysiology techniques.

Radiofrequency ablation for common atrial flutter using an 8-mm tip catheter and up to 150 W.

The formation of bi-directional block in atrial flutter can be adversely affected by problems with the delivery of effective energy related to isthmus anatomy and contact. Higher energies can produce larger and more effective lesions. The optimum setting for power delivery using temperature controlled ablation has not been established, with the maximum reported being 100 W. This is a retrospective review of the first 50 new cases assessing the efficacy and safety of using temperature controlled (60-65 degrees C) flutter ablation with an 8mm tip electrode catheter and up to 150 W. All cases had either typical flutter alone (34%) or predominant flutter as the indication, no combined procedures were included. Acute procedural success was 94% and long-term success of 88%. Median number of ablations required was 11 (interquartile range 10-19), median procedure time 120 min (IQR 102-164), fluoroscopy time 22 min (IQR 17-36), radiation dose 17 Gy cm(2) (IQR 10-27), median number of lines 1 (IQR 1-2). Six patients achieved 150 W, but 42 achieved >100 W (median watts 142 W, IQR 104-147). Patients (12%) experienced an uncomplicated pop during the procedure. None experienced a significant complication. There were three late relapses. The setting of 150 W maximum delivered energy in temperature regulated ablation allowed higher energies (>100 W) to be delivered in most patients. This resulted in acute and long-term success rates that compare well with the literature but is associated with a 12% rate of pop. Subsequent to this series our 54th patient sustained a pop due to high energy ablation that resulted in perforation and tamponade, from which there was survival.