Cardiovascular diseases (CVD) are the leading cause of mortality in patients undergoing chronic hemodialysis. Patients with chronic renal insufficiency are exposed to a 10 to 20 times higher risk of developing CVD compared to the general population. In patients with chronic kidney diseases, apart from the usual, traditional CVD risk factors (age, diabetes, smoking, arterial hypertension, positive family history), the importance is also attached to additional risk factors typical for uremic syndrome (anemia, arteriovenous fistula, permanent changes in blood volume, acquired valvular disease, hyperparathyroidism, increased product of calcium with phosphorus, aluminum overload, iron deficiency, malnutrition, inadequate dialysis, and chronic inflammatory syndrome), which on the one hand additively or synergistically accelerate the clinical course of the kidney disease, and on the other hand significantly increase the risk of developing CVD. (1)

Valvular heart disease is relatively common in dialyzed patients. (2) Echocardiography is an invaluable diagnostic tool for detecting valvular heart disease even in patients with present renal failure and without it. The detected abnormalities include valvular and annular thickening and calcification of any of the heart valves, causing regurgitation and/or stenosis. (3) Valvular thickening or sclerosis most commonly affects aortic (55% to 69%) and mitral valve (40% to 60% of dialyzed patients).

Calcification of the mitral and aortic valve is a common finding in patients undergoing chronic dialysis with the prevalence four to five times higher than in the general population. The calcification of the mitral annulus occurs in 10% to 50% of patients in the end-stage of kidney disease. Aortic valve calcification is recorded in 25 to 55% of hemodialyzed patients, occurring from 10% to 20 years earlier than in the general population. According to the study by Roberts et al (4) the calcification of mitral annulus was found in 42% and aortic valve calcification was found in 35% of dialyzed patients. Calcification of tricuspid and pulmonary valve is rare.

The presence of heart valve calcification is an important negative prognostic factor. Mortality in patients with valvular calcification is higher than in patients without calcification. Valve calcification in dialyzed patients determined by echocardiography is associated with a 2.5 to 5.4 times higher risk of cardiovascular death. Valve calcification is associated with other markers of atherosclerosis, such as carotid intima- media thickness. (5)

According to the study by Raggi et al (6) the cells accountable for the calcifications in the heart valves could be myofibroblasts. The most important factor in the development of cardiac calcification is the secondary hyperparathyroidism. Calcifications in the heart valves are etiologically associated with hyperphosphatemia, increased product of calcium and phosphorus, hypercalcemia, and calcifications in the blood vessels. (7) Valvular calcification progression can be slowed down by the treatment of altered metabolism of calcium, phosphorus and parathyroid hormone in patients undergoing hemodialysis and the use of statins in the general population. (8)

Main valvular abnormalities with clinical consequences observed in dialyzed patients are regurgitant and stenotic lesions. Aortic stenosis is recorded in 15% to 20% of dialyzed patients, while hemodialysis is an important risk factor for the progression of aortic stenosis. (9) A high incidence of mitral (95%), tricuspid (65%) and aortic (38%) regurgitation has been observed.

The aim of the article was to determine the incidence of valvular heart disease in asymptomatic patients undergoing chronic dialysis.

At the Department of Internal Medicine at the University Clinical Center in Tuzla a prospective trial was conducted involving 50 patients who were treated by applying the methods of chronic dialysis (hemodialysis and continuous ambulatory peritoneal dialysis). Conventional two-dimensional echocardiography was performed according to guidelines using a commercial ultrasound system (Schiller AT-2 plus).

The study included 50 patients, 22 men (44%) and 28 women (56%). Of the total number of involved patients, 35 (70%) of them were treated by hemodialysis, and 15 (30%) by the method of continuous ambulatory peritoneal dialysis (CAPD). The average age of patients was 47.3 ± 12.7 years. The average length of chronic dialysis treatment was 42.6 ±17.2 months. From the risk factors, hypertension was recorded in 62%, hyperlipidemia in 60% and diabetes in 25% of patients.

Echocardiography detected valvular thickening or sclerosis in 20 patients (40%), whereas sclerosis of mitral in 9 and sclerosis of aortic cusps in 11 patients.

The calcification of heart valve was diagnosed in 12 (31%) patients, whose average age were 53.4 ± 8.6 years. Mitral calcification was diagnosed in 8 patients, while calcification of aortic cusps was diagnosed in 4 patients. Left ventricular hypertrophy was recorded in all patients with calcified heart valves, while the dilation of the left-sided heart chambers was recorded in 5 out of 8 patients.

Mild aortic stenosis was diagnosed in 3, while mild mitral stenosis in one patient. Mitral regurgitation was detected in 38 (76%) patients, mild regurgitation was detected in 13 (26%), moderate in 19 (38%), medium severe in 4 (8%), and severe in 2 (4%) patients. Aortic regurgitation was diagnosed in 14 (28%) patients, whereas mild regurgitation was diagnosed in 9 (18%) and moderate in 5 (10%) of subjects. Tricuspid regurgitation was recorded in 24 (48%) patients, mild in 20 (40%), and moderate in 4 (8%) patients.

In this study, congestive heart failure was present in 17% of subjects.

This study determined a high prevalence of morphological and functional abnormalities of heart valves in patients undergoing chronic dialysis program. Degenerative valvular heart diseases are associated with the length of hemodialysis and changes in the metabolism of calcium and phosphorus.

Heart valve calcifications were diagnosed in 31% patients. Roberts et al (4) determined calcification of mitral annulus in 42%, while the calcification of the aortic valve was determined in 35% of patients undergoing chronic dialysis.

In comparison with the trials conducted by other authors, a higher prevalence of mitral regurgitation (76%) and aortic regurgitation (28%) was recorded. Straumann et al (10) found the incidence of mitral regurgitation of 11%, and the incidence of aortic regurgitation of 12% in the dialyzed patients.

This study has confirmed the fact that the left ventricular hypertrophy is common in patients undergoing chronic hemodialysis. The main risk factors for its development are elevated values of blood pressure, arteriosclerosis, aortic stenosis, anemia, increased extracellular fluid volume (retention of sodium and water), and increased blood flow through the vascular access for hemodialysis. (11)

The incidence of congestive heart failure in this group of subjects was lower than in patients undergoing dialysis in the USA (46%) and Europe (25%) and higher than those in Japan (6%). (12)

The incidence of valvular heart disease in patients undergoing chronic dialysis program is high. The calcifications of heart valves were diagnosed in almost one third of subjects, while 3 of the 4 patients undergoing chronic dialysis mitral regurgitation suffer from mitral regurgitation.

Echocardiographic examination is the golden standard for the assessment of morphology and function of heart valves. This non-invasive and cost-effective method needs to be applied in all patients treated by chronic dialysis.