DISCUSSION
In the present study, we investigated the impact of different dialysis modalities on echocardiographic RV function in ESRD patients with preserved left ventricular function. We demonstrated that patients on HD with AVF have poorer RV function compared with the patients undergoing PD and HD treatment is an independent risk factor for developing RV dysfunction.
Heart failure is associated with significant morbidity and mortality in ESRD patients on dialysis, however it remains poorly investigated. RV dysfunction has been reported as a significant indicator of mortality in heart failure patients, regardless of left ventricular systolic dysfunction and valvular disease. 12 A survival analysis including echocardiographic parameters reported that RV dysfunction is significantly associated with impaired survival in ESRD patients. 13 There is data suggesting that RV dysfunction is more common in patients on HD. 14Several pathophysiological mechanisms may be responsible for the deterioration of RV function: sympathetic activation, anemia, secondary hyperparathyroidism, inflammation and left-to-right shunt caused by AVF.15AVF leads to chronic volume overload, causing left to right shunt. Data from several studies suggest that mortality and heart failure prevalence may be increased in AVF patients.16,17 In a study by Reddy et al., it was reported that AVF creation for the initiation of HD in patients with ESRD, is associated with modest impairment in LV function and remodeling in the RV. 18 Another study using strain echocardiography, demonstrated that patients with ESRD and preserved LV EF undergoing HD have higher prevalence of LV diastolic dysfunction and reduced RV longitudinal function and deformation parameters, compared with healthy controls. 19 Sun et al. suggested that patients on HD endure the deterioration of RV function and demonstrated RV morphological and dysfunction, compared with control group.20 Karavelioglu et al. also stated that RV functions were deteriorated in ESRD patients on HD compared to healthy subjects.21
There is, however, a lack of data on the impact of different dialysis modalities on RV function. In the present study, we compared the long-term impacts of PD and HD with AVF on RV function in ESRD patients with preserved LV systolic function and demonstrated the deterioration of RV function in HD patients, compared with the patients on PD. TAPSE and tricuspid lateral annulus Sa values, which reflect the systolic function of RV, were found to decrease; additionally, RV MPI, an indicator of global RV function, was found to increase in patients on HD compared with PD patients. Logistic regression analysis demonstrated HD treatment as an independent predictor of RV dysfunction and also Ea velocity of tricuspid lateral annulus, as associated with RV dysfunction. Our results were consistent with a previous, similar study by Paneni et al., that investigated RV function in different dialysis modalities. They demonstrated a higher prevalence of RV dysfunction among HD patients when compared to patients on PD and also noted that RV dysfunction was more prevalent in brachial AVF patients, compared to the patients with radial AVF. 22 Different from Paneni’s study that evaluated RV MPI and tricuspid lateral annulus Sa velocities, we also investigated TAPSE and RV FAC, and defined a classification score, indicating RV function of the patients, by using these four echocardiographic parameters. The results of the present study emphasize the deterioration of RV function in patients undergoing HD, regardless of LV function and PASP, compared with the subjects on PD; this suggests the deterioration of RV independent of LV dysfunction and pulmonary hypertension.
Considering the vital role of RV dysfunction in the development of heart failure in ESRD patients, the choice of dialysis treatment modality is of great importance for patients at high risk for heart failure. Additionally, close follow-up of HD patients for RV function is necessary for detection, prevention and early treatment of heart failure in this patient group.
The lack of gold standards, such as magnetic resonance imaging or strain echocardiography for the assessment of RV and LV function is the main limitation of the present study. However, despite the difficulties in the evaluation of RV due to its complex anatomy and retrosternal position, transthoracic echocardiography is an accurate, easy, rapid, reproducible and noninvasive method to assess RV function. Further larger scale studies are needed to confirm these results and also evaluate the clinical importance and prognostic value of the results.
In conclusion, this study has demonstrated that RV function assessed by echocardiography was poorer in patients undergoing HD with AVF compared to the patients on PD, regardless of LV function and pulmonary hypertension. Accordingly, HD patients should be evaluated frequently for the development of RV dysfunction. The echocardiographic parameters reflecting RV function, should be examined and reported in patients on HD.