Alteration of right ventricular contractile performance in mitral valve incompetence

Objectives: Severe alterations of intracellular Calcium handling and contractile performance have been illustrated in left ventricular myocardium of patients operated upon for mitral valve incompetence (MVI) even in NYHA II-patients. Corresponding investigations of right ventricular myocardium in MVI are not available. Material and Methods: Right ventricular trabeculae of patients operated upon for MVI (NYHA I: n=3; NYHA II: n=6, NYHA III: n=11; NYHA IV: n=5) were loaded with the fluorescent dye FURA-2/AM for Calcium measurements and electrically stimulated. Force development was analysed as a function of the stimulation frequency (30–180 beats per minute, bpm). Resting force, twitch force, diastolic and systolic Calcium and Calcium amplitude (ratio method 340/380 nm) were continuously recorded (measurement conditions: 37°C, supramaximal stimulation, Krebs-Henseleit-solution, optimal length). Right ventricular trabecuale of normal normal donor hearts (NDH, n=15) were used as control. Results: Increased stimulation frequencies were associated with increased force output up to an optimum between 150–180 bpm in NDH. In MVI the frequency associated with an optimum force output shifted significantly towards lower values with increasing NYHA stadium (p