Plasma ANP and renin-angiotensin-aldosterone system as new parameters describing the hemodynamics of the circulatory system after implantation of stented or stentless aortic valves.

BACKGROUND AND AIM OF THE STUDY: Aortic valve replacement (AVR) in patients with a small aortic root involves the occurrence of patient-prosthesis mismatch (PPM). Recent reports have shown that a reduced effective orifice area index (EOAI) may not be the sole factor responsible for this complication. The study aim was to analyze the activity of atrial natriuretic peptide (ANP)/renin-angiotensin-aldosterone (RAA) after implantation of stented or stentless valves.

METHODS

Between 2001 and 2003, a total of 30 patients operated on at the authors' institution received either a stentless Freestyle bioprosthesis (group A; n = 15) or a stented Mosaic bioprosthesis (group B; n = 15). The demographics of both groups were similar, and all patients underwent echocardiography preoperatively, and at one, six and 12 months postoperatively. The activity of the RAA system and plasma ANP level were measured in all patients preoperatively and at one and six months postoperatively.

RESULTS

At one month after AVR, statistically significant inter-group differences were noted in plasma renin activity (group A, 3.7 +/- 2.1 ng/ml/h; group B, 5.6 +/- 0.8 ng/ml/h; p <0.05; control value 0.3-5.3 ng/ml/h). For ANP, statistically significant differences were present at one month after surgery (group A, 36.3 +/- 5.1 pg/ml; group B, 62.9 +/- 9.2 pg/ml; p <0.005; control value 27.3-37.2 pg/ml). On echocardiography, the ejection fraction, aortic valve gradient, EOAI and left ventricular mass index (LVMI) were assessed. A statistically significant difference was identified for the LVMI at 12 months postoperatively (group A, 216 +/- 13 g/m2; group B, 240 +/- 18 g/m2; p <0.05). In terms of other parameters both groups were similar.

CONCLUSION

The implantation of an aortic valve prosthesis affects the hemodynamics of the entire circulatory system, and thus the activity of natriuretic systems. Whilst stentless valves allowed much more rapid normalization of circulatory system hemodynamics (one month), no difference compared to preoperative was identified after six months. Natriuretic peptides appear to provide more sensitive (long-term) but less specific (short-term) assessment of circulatory system behavior than echocardiography.