Right atrial contractile dynamics are impaired in patients with postcapillary pulmonary hypertension

Left ventricular (LV) dysfunction in conjunction with postcapillary pulmonary hypertension (PH) is frequently associated with right ventricular (RV) dysfunction, determining the patient prognosis. Compensatory mechanisms for RV dysfunction have not been previously evaluated in detail. Since calcium dependent right atrial (RA) dynamics are a surrogate for RA contractile properties, the present study examined the calcium dependency of RA tissue obtained from patients with or without postcapillary PH. In total, 15 patients with PH (PH group; mean age, 70.7 +/- 7.2 years) and 10 patients without postcapillary PH (non-PH group; mean age, 55.7 +/- 11.8 years) who were scheduled to undergo elective left heart valve surgery were included in the current study. Calcium concentration (pCa; shown as the negative log10) against force curves were generated, while LV and RV function was evaluated by echocardiography. Echocardiography data revealed a significantly reduced LV function in the PH group, while the RV function was preserved in the two groups, precluding overt RV dysfunction. In the PH group, significantly reduced force values were detected at high pCa values when compared with the non-PH group force, indicating impaired RA function. Furthermore, reduced calcium sensitivity was observed (which was determined as the pCa at half maximal activation) in the PH group, and the presence of a compensatory mechanism for reduced force capacity was hypothesized. In conclusion, the preliminary results of the current study showed impaired RA contractile properties in postcapillary hypertension with preserved RV function. The diminished RA compensatory mechanisms may lead to accelerated RV dysfunction in the clinical course of postcapillary PH.