Assessment of the Physiologic Contribution of Right Atrial Function to Total Right Heart Function in Patients with and without Pulmonary Arterial Hypertension

Abstract

Total right heart function requires normal function of both the right ventricle and the right atrium. However, the degree to which right atrial (RA) function and right ventricular (RV) function each contribute to total right heart function has not been quantified. In this study, we aimed to quantify the contribution of RA function to total right heart function in a group of pulmonary arterial hypertension (PAH) patients compared to a cohort of normal controls without cardiovascular disease. The normal cohort comprised 35 subjects with normal clinical echocardiograms, while the PAH cohort included 37 patients, of whom 31 had echocardiograms before and after initiation of PAH-specific therapy. Total right heart function was measured via tricuspid annular plane excursion (TAPSE). TAPSE was broken down into two components, the excursion occurring during RA contraction (TAPSE RA ) and that occurring before RA contraction (TAPSE RV ). RA fractional area change (RA-FAC) was also compared between the two groups. In the PAH cohort, more than half of the total TAPSE occurred during atrial systole, compared to less than one-third in the normal cohort (51.0% vs. 32.1%; P < 0.0001). There was a significant correlation between RA-FAC and TAPSE in the PAH cohort but not in the normal cohort. TAPSE improved significantly in the posttreatment cohort (1.7 vs. 2.1 cm), but TAPSE RA continued to account for about half of the total TAPSE after treatment. RA function accounts for a significantly greater proportion of total right heart function in patients with PAH than in normal subjects. Pulmonary arterial hypertension (PAH) is characterized by marked increases in right ventricular (RV) afterload, which if left untreated leads to progressive RV dysfunction, exercise intolerance, and potentially death.1-3 As recently emphasized by the International Right Heart Foundation Working Group, the right ventricle (also RV) is only one part of the total right heart system, and the other components, including the right atrium (RA), contribute importantly to total right heart function. 4It has been recognized that in the setting of RV failure, preserved right atrial (also RA) function is essential to maintain adequate total right heart function. After RV infarction, for example, preserved RA function has been shown to improve RV filling and performance, whereas diminished RA function compromises cardiac output. 5,6 Loss of atrial function, in the form of supraventricular arrhythmias with resulting atrioventricular dyssynchrony, is also known to be poorly tolerated among patients with PAH and chronic thromboembolic pulmonary hypertension (CTEPH). 7,8 Moreover, animal models have shown that RA systolic function is, in fact, augmented in the setting of RV ischemia and that if there is a subsequent ischemic insult to the RA, RV function is significantly reduced. 7 Taken together, these studies suggest that RA function must not only be maintained but at times augmented, in order to optimize total right heart function in the setting of RV c...

Differences in right ventricular morphology, not function, indicate the nature of increased afterload in pulmonary hypertensive subjects with normal left ventricular function

“…It was important to note that 2D parameters of RV morphology outperformed measures of RV function (TAPSE and RV FAC) in their ability to predict pulmonary vascular disease. These findings are both clinically relevant and logical, as right heart function and filling pressures are influenced by right heart preload, afterload, intrinsic RV contractile function, and even right atrial function . As such, depressed RV function is a final common pathway of any insult of preload, afterload, and intrinsic contractile function.…”

Maximal systolic excursion of the tricuspid annulus is independent of right atrial size and function in chronic pulmonary hypertension

“…In a recent study, Sivak and associates showed that RA function contributes approximately 32% to total TA displacement. 16 This is in agreement with findings previously documented by our laboratory. 1,19 In our study, although most of RA measures were significantly associated with TAPSE, after adjusting for possible confounders, none of them were found to have any significant influence over maximal TA excursion.…”

“…1 Consequently, as the TA is both anatomically and functionally related to this right atrioventricular dependence, the main objective of this study was to determine whether changes in RA size and function alter the motion of the TA in cPH in view of recent data showing that RA function accounts for a significantly greater proportion of total right heart function in patients with cPH than in normal subjects. 16 …”

Right ventricular base/apex ratio in the assessment of pediatric pulmonary arterial hypertension: Results from the European Pediatric Pulmonary Vascular Disease Network

“…Therefore, parameters of RV morphology outperformed measures of RV function (eg, TAPSE) in their ability to predict PAH in the current study. Our finding will likely be clinically significant, as RV systolic function and filling pressures are influenced by RV preload, afterload, and RV contractile function, and they become abnormal much later in PAH progression than RVSP, N‐terminal pro‐brain natriuretic peptide, or as we show here, the RVES b/a ratio.…”