[Mitral prosthesis dysfunction--report of 3 clinical cases with unusual ultrasonography features].

Prosthetic valve obstruction is one of the most serious complications of mechanical cardiac valves. Clinicians must be aware of this diagnosis in patients with a worsening of functional NYHA class. Over the past years, echocardiography has imposed itself as the method of choice to diagnose and evaluate patients with suspected prosthetic valve obstruction. We present three clinical reports of prosthetic valve malfunction that have unusual echocardiographic features.