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Cardiovascular disease is the leading cause of mortality in chronic renal failure patients. The higher cardiovascular risk in the CKD group is caused by the interaction between conventional risk factors of cardiovascular disease and those related to CKD. CKD is a fluid overload state, which in its longer course causes left ventricular hypertrophy. This LV hypertrophy leads on to impaired ventricular relaxation. Thus, even a small increase in preload can result in significantly raised left ventricular end-diastolic pressure, thereby causing pulmonary edema even with normal LV systolic function. As LV diastolic dysfunction seems to be impaired even in those asymptomatic patients, LVFP may be useful in cardiovascular risk stratification. CKD patients are frequently hospitalized with flash pulmonary edema. This occurs in presence of symptomatic diastolic dysfunction. The patients with CKD develop a stepwise reduction in diastolic function according to eGFR and, more importantly, that this happens before the onset of clinical heart failure. In recent decades, Doppler echocardiography has been extensively used to evaluate cardiac structure and function, and thus has played a key role in selecting individuals at higher cardiovascular risk. As LV diastolic function seems to be impaired in most CKD patients, even in those asymptomatic individuals, we speculate that LVFP (left ventricular filling pressure) may be useful in assessing cardiovascular risk in this group. Given this background, we performed this study to assess the left ventricular filling pressure (LVFP) in chronic renal failure patients and correlated LV filling pressure with eGFR and also to evaluate the relationship between LVFP and severity of CKD.
This prospective clinical observational study analyzed 100 chronic kidney disease patients. The age group ranged from 30–80 years with 40% female and 60% male CKD patients. These subjects were divided into 5 subgroups (CKD stage I to stage V) depending upon their estimated glomerular filtration rate (eGFR) calculated by MDRD equation (Modification of Diet in Renal disease study equation). All these patients were subjected to standard echocardiography (IE33 with 4 MHz transducer) and the new modality of tissue Doppler imaging (TDI). The detailed echocardiographic study assessing both systolic and diastolic function was performed in these patients. The Left ventricular filling pressure is calculated with E/e’ ratio (early diastolic mitral inflow velocity-E to early diastolic mitral annulus velocity–e’). The grading of diastolic dysfunction is done with E/e’ ratio (Grade 1 – E/e’<8, Grade 2 – E/e’=9-12, Grade 3 –E/e’ ratio>13).
The analysis of echocardiographic parameters (E-early diastolic mitral inflow velocity, e’-early diastolic mitral annulus velocity) showed that in CKD patients the stage of renal failure was associated with the significant increase in LV filling pressure (LVFP) with (p<0.001). There was a significant correlation between LV filling pressure and estimated GFR with (r value=-0.467) and (P value<0.001). These verities of renal dysfunction increased significantly in parallel with the rise in e’ (p=0.001) and LVFP (p<0.001). 98% of CKD patients invariably had diastolic dysfunction, only 2% had a normal diastolic function. In this study, it is noted that 2% of the population had Grade 1 diastolic dysfunction, 13% had Grade 2 diastolic dysfunction, and 85% had Grade 3 diastolic dysfunction. There is a linear correlation of increased left ventricular filling pressure with the worsening stage of chronic kidney disease.
Chronic kidney disease patients invariably have increased left ventricular filling pressure. The severity of increase in left ventricular filling pressure is directly proportional to the severity of chronic kidney disease. As eGFR decreases, the left ventricular filling pressure increases leading on to decrease in LV diastolic function. Increased left ventricular filling pressure is the important cause of increased cardiovascular mortality and diastolic heart failure (HFpEF) in Chronic kidney disease population. In chronic kidney disease, patients not only the fluid overload state but also the significant elevation of LV filling pressure due to concomitant LV dysfunction plays a vital role in the development of recurrent pulmonary edema. Left ventricular filling pressure (LVFP) can be used as an independent and practical predictor of diastolic dysfunction in patients with chronic kidney disease. Increased left ventricular filling pressure (LVFP) occurs even in patients with early stage of chronic kidney disease causing clinically significant LV diastolic dysfunction.