Background and aims of the study: The purpose of this study was to evaluate the hemodynamic performance after aortic valve replacement using different surgical options in small (19-mm diameter) annuli. Methods: Postoperative hemodynamics were assessed in three groups according to the surgical method. A 19-mm St. Jude Medical (SJM) valve was used in nine patients (group A), a 19-mm SJM HP in nine patients (group B), and annular enlargement was performed in eight patients (group C). Echocardiography was performed and percent fraction shortening, peak pressure gradient, effective orifice area and left ventricular mass were measured. Results: Postoperative peak systolic pressure gradient was decreased to 31.1 +/- 8.7 mmHg in group B, and to 22.3 +/- 11.7 mmHg in group C, but was 42.9 +/- 16.5 mmHg in group A (p <0.01). Percent fraction shortening and left ventricular mass index were improved in groups B and C, soon after surgery compared with group A(p <0.01). The effective orifice area significantly increased during exercise in group C, from 1.59 to 1.87 cm(2) (p <0.01), but was not increased in groups A and B (N.S.). Conclusions: The small SJM HP provides a better hemodynamic performance than the standard 19 mm SJM. However, annular enlargement may be beneficial in patients with poor ejection fraction and severe ventricular hypertrophy.