ATRIAL-NATRIURETIC-PEPTIDE (ANP) AND CYCLIC GUANOSINE-MONOPHOSPHATE (CGMP) AFTER DIRECT-CURRENT CARDIOVERSION

We investigated atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) in patients undergoing elective direct current cardioversion (CV group) due to atrial fibrillation (n = 9) or atrial flutter (n = 3). Anesthesia for cardioversion (CV) was induced with propofol 1.5 mg/kg. Conversion was achieved in all patients. Before CV all patients had elevated ANP and cGMP plasma levels. After CV the concentrations of ANP and cGMP decreased significantly within 15 and 30 minutes (p < 0.01), respectively. Only one patient in the CV group showed increasing ANP and cGMP levels although his heart rate had decreased after CV and his blood pressure remained stable. High concentrations of ANP and cGMP might possibly be a compensatory mechanism of cardiac dysfunction. To study the influence the anesthetic agent on plasma levels of ANP and cGMP, we investigated six patients anesthetized with propofol for high-density radiation (HDR group). The data from this control group showed that propofol did not influence the plasma levels of ANP and cGMP. ANP correlated statistically significantly (p < 0.05) with cGMP in both groups (r = 0.88 and 0.76 in the HDR and CV groups, respectively). In addition, we found a cGMP release of 149.6 +/- 17.6 per mol ANP in the HDR group, in the CV group the release was 109 +/- 54.2 cGMP per mol ANP. This phenomenon could be due to minor response of target cells to ANP stimulation (receptor down-regulation) in patients with heart disease. In conclusion, ANP and cGMP levels decreased after successful cardioversion. Despite restoration of sinus rhythm, measurements of ANP and cGMP plasma concentrations were useful in controlling patients with atrial arrhythmias, as increasing ANP and cGMP levels in one patient had shown. But measurement of ANP is too complicated in daily medical routine. We suggest the sole measurement of cGMP because cGMP is a useful and specific parameter for ANP and easier to measure.