Research indicates that patients receiving MHD are at an elevated risk of developing PH. Chronic PH can lead to right heart failure, ultimately contributing to increased mortality rates among these patients [5]. The underlying mechanisms that contribute to the development of PH in individuals undergoing hemodialysis are multifaceted and complex. Notably, the survival rate for patients with PH is significantly lower compared to those without this condition. Evidence suggests that the RVEF serves as an independent predictor of mortality in patients on MHD [6]. Therefore, timely attention to the right heart function in MHD patients with elevated PASP can help improve patient survival rates. This study found that patients with MHD have elevated PASP, and there are varying degrees of right heart dysfunction among the three groups. The incidence of severe RV systolic dysfunction in the group 3 is significantly higher than in the groups 1 and 2, accompanied by more pronounced RV remodeling and dysfunction [7, 8]. Compared to traditional ultrasound, real-time three-dimensional ultrasound provides a more accurate assessment of RV volume and function.The study observed a gradual increase in RVEDV and RVESV across all three groups, accompanied by a decrease in RVEF, indicates that as the severity of PASP increases, RV volume expands, RV systolic function diminishes, and RV remodeling ensues.

The findings of this study indicate that the RVFWLS is more effective than traditional echocardiographic parameters, such as TAPSE, FAC, and S', in assessing diminished right heart function. This observation is consistent with previous research. However, the assessment of right heart function is influenced by a greater number of factors due to the complexity of right heart structures, and the accuracy of these measurements also depends on the clinical expertise of the practitioner [9, 10]. Speckle tracking technology(STI) has been extensively utilized in the assessment of cardiac function [11, 12]. In Group 2, RVFWLS shows a declining trend, falling below established normative values. The use of speckle tracking technology enables the early detection of subtle changes in myocardial architecture, thereby partially overcoming the limitations associated with conventional assessments of right heart function.

This study shows that there are differences in LVEF among the three groups of subjects, and as PASP increases, LVEF gradually decreases. In patients undergoing hemodialysis, this phenomenon is likely attributable to a combination of multiple factors. The microenvironment of hemodialysis patients is notably complex, as individuals with chronic kidney failure often present with pre-existing cardiovascular disease and associated risk factors prior to the initiation of dialysis. As the disease progresses, a reduction in LVEF is observed, and the deterioration of left heart function may further compromise right heart function.

Echocardiography is a valuable tool for evaluating cardiac function and can provide insights into the volume of extravascular lung water [13]. Lung ultrasonography serves as a straightforward diagnostic tool that can effectively indicate the extent of pulmonary edema. The accumulation of excessive fluid in the body poses a significant and potential threat to cardiovascular health, especially in individuals with advanced kidney disease [14]. Patients undergoing hemodialysis may not exhibit overt lung conditions, yet they frequently experience fluid overload [15]. This research demonstrates a positive association between LUS findings and the progression of PASP, showing significant correlations with TAPSE, FAC, S', and RVFWLS. In this study, LUS is correlated with TAPSE, FAC, S’, and RVFWLS, which may pertain to a specific group of patients with PASP undergoing MHD. The causes of PH induced by MHD are complex and arise from various interrelated factors and interactions. Consequently, the reasons for pulmonary edema in hemodialysis patients are also diverse. Individuals undergoing MHD alongside PH are affected by both preload and afterload factors. Elevated preload levels can increase pulmonary venous pressure and pulmonary capillary wedge pressure, resulting in interstitial fluid accumulation, heightened extravascular lung water content, and pulmonary edema [16]. Current literature emphasizes a strong connection between LUS findings and the severity of pulmonary edema [17,18,19]. PH is associated with alterations in the hemodynamics of the pulmonary circulation, primarily characterized by the restructuring of pulmonary blood vessels, leading to a gradual increase in resistance over time [20]. PH results in elevated afterload on the right heart, leading to progressive structural changes in the right heart. The maintenance of pulmonary vein pressure is dependent on the pressure within the right heart, which also influences the development of pulmonary edema [21]. Consistent with the results of this study, LUS increases with the increase of PASP. Patients with MHD are prone to LV hypertrophy and LV diastolic dysfunction, which leads to an increase in LV filling pressure, resulting in an increase in LUS. In this study, almost all patients had LV diastolic dysfunction, which may contribute to the increase in LUS to some extent. At the same time, changes in volume load can also affect LUS, but in this study, patients underwent lung ultrasound examinations after hemodialysis, so the impact of volume load can be excluded.

The primary method for diagnosing PH is through right heart catheterization, although its clinical utility is constrained by its invasive nature. Studies have demonstrated a strong association between the PASP derived from the peak tricuspid regurgitation velocity assessed via ultrasound and the PASP obtained through right heart catheterization [22, 23]. In the context of predicting RV systolic dysfunction, research has shown that RVFWLS exhibits the highest prognostic value. This finding is attributed to the capability of speckle tracking technology to identify early myocardial microdamage. When integrated with other metrics, the combination of traditional right heart function parameters and LUS yielded a superior predictive capacity for RV systolic dysfunction compared to individual metrics. Notably, the predictive efficacy of RVFWLS in conjunction with LUS did not significantly differ from that of RVFWLS in isolation, although it did augment the predictive utility of LUS to some extent. The incorporation of LUS with conventional right heart function parameters has been shown to enhance diagnostic accuracy. Furthermore, considering preload maintenance in hemodialysis patients can offer valuable insights for optimizing their treatment strategies.

There are some limitations in this study: This investigation did not utilize a gold standard for diagnosing PH, which may introduce a degree of error. Research indicates that the most prevalent type is combined precapillary and post-capillary PH, followed by post-capillary PH. Additionally, the volume overload status significantly influences the types of PH observed in patients receiving hemodialysis. Consequently, this article does not specifically evaluate the various types of PH. In patients with pre-capillary PH, there may be an overestimation of the relationship between LUS and right heart function. However, the unique microenvironment of patients with both hemodialysis and PH simultaneously affects the heart and blood vessels, which may help explain the strong correlation found between LUS and right heart function in this study. Further analysis is needed on the relationship between LUS and right heart function in patients with different subtypes of PH. This study is a single-center investigation with a small sample size, which limits the generalizability of the results. Although cardiac magnetic resonance imaging was not utilized to assess right heart function, there is a strong correlation between RVEF measured by cardiac magnetic resonance and RVEF measured by real-time three-dimensional echocardiography.