Doppler echocardiographic analysis of diastolic left ventricular function in dialysis patients and its relation to intradialytic hypotension

Diagnosis of left ventricular diastolic dysfunction in the setting of acute changes in loading conditions

Introduction

Conventional pulsed wave Doppler parameters are known to be preload dependent, whereas newly proposed Doppler indices may be less influenced by variations in loading conditions. The aim of the present study was to evaluate the effects of haemodialysis-induced preload reduction on both conventional and new Doppler parameters for the assessment of left ventricular (LV) diastolic function.

Methods

This prospective observational study was conducted in a medical-surgical intensive care unit (ICU) and nephrology department of a teaching hospital. In total, 37 haemodialysis patients with end-stage renal disease (age [mean ± standard deviation]: 52 ± 13 years) and eight ventilated ICU patients with acute renal failure receiving vasopressor therapy (age 57 ± 16 years; Simplified Acute Physiology Score II 51 ± 17) were studied. Echocardiography was performed before and after haemodialysis. Conventional pulsed wave Doppler indices of LV diastolic function as well as new Doppler indices, including Doppler tissue imaging early diastolic velocities (E' wave) of the septal and lateral portions of the mitral annulus, and propagation velocity of LV inflow at early diastole (Vp) were measured and compared before and after ultrafiltration.

Results

The volume of ultrafiltration was greater in haemodialysis patients than in ICU patients (3.0 ± 1.1 l versus 1.9 ± 0.9 l; P = 0.005). All conventional pulsed wave Doppler parameters were altered by haemodialysis. In haemodialysis patients, E' velocity decreased after ultrafiltration when measured at the septal mitral annulus (7.1 ± 2.5 cm/s versus 5.9 ± 1.7 cm/s; P = 0.0003), but not at its lateral portion (8.9 ± 3.1 cm/s versus 8.3 ± 2.6 cm/s; P = 0.37), whereas no significant variation was observed in ICU patients. Vp decreased uniformly after ultrafiltration, the difference being significant only in haemodialysis patients (45 ± 11 cm/s versus 41 ± 13 cm/s; P = 0.04). Although of less magnitude, ultrafiltration-induced variations in Doppler parameters were also observed in haemodialysis patients with altered LV systolic function.

Conclusion

In contrast to other Doppler parameters, Doppler tissue imaging E' maximal velocity measured at the lateral mitral annulus represents an index of LV diastolic function that is relatively insensitive to abrupt and marked preload reduction.

Preload dependence of new Doppler techniques limits their utility for left ventricular diastolic function assessment in hemodialysis patients

Left ventricular (LV) hypertrophy leads to diastolic dysfunction. Standard Doppler transmitral and pulmonary vein (PV) flow velocity measurements are preload dependent. New techniques such as mitral annulus velocity by Doppler tissue imaging (DTI) and LV inflow propagation velocity measured from color M-mode have been proposed as relatively preload-independent measurements of diastolic function. These parameters were studied before and after hemodialysis (HD) with ultrafiltration to test their potential advantage for LV diastolic function assessment in HD patients. Ten patients (seven with LV hypertrophy) underwent Doppler echocardiography 1 h before, 1 h after, and 1 d after HD. Early (E) and atrial (A) peak transmitral flow velocities, peak PV systolic (s) and diastolic (d) flow velocities, peak e and a mitral annulus velocities in DTI, and early diastolic LV flow propagation velocity (V(p)) were measured. In all patients, the E/A ratio after HD (0.54; 0.37 to 1.02) was lower (P < 0.01) than before HD (0.77; 0.60 to 1.34). E decreased (P < 0.01), whereas A did not. PV s/d after HD (2.15; 1.08 to 3.90) was higher (P < 0.01) than before HD (1.80; 1.25 to 2.68). Tissue e/a after HD (0.40; 0.26 to 0.96) was lower (P < 0.01) than before HD (0.56; 0.40 to 1.05). Tissue e decreased (P < 0.02), whereas a did not. V(p) after HD (30 cm/s; 16 to 47 cm/s) was lower (P < 0.01) than before HD (45 cm/s; 32 to 60 cm/s). Twenty-four hours after the initial measurements values for E/A (0.59; 0.37 to 1.23), PV s/d (1.85; 1.07 to 3.38), e/a (0.41; 0.27 to 1.06), and V(p) (28 cm/s; 23 to 33 cm/s) were similar as those taken 1 h after HD. It is concluded that, even when using the newer Doppler techniques DTI and color M-mode, pseudonormalization, which was due to volume overload before HD, resulted in underestimation of the degree of diastolic dysfunction. Therefore, the advantage of these techniques over conventional parameters for the assessment of LV diastolic function in HD patients is limited. Assessment of LV diastolic function should not be performed shortly before HD, and its time relation to HD is essential.

The role of carnitine in myocardial dysfunction

L-Carnitine (carnitine) may have a role in the treatment of various cardiac disorders because of its actions on cardioprotection from hypoxia and oxidative stress. Studies on the role of carnitine administration to patients with myocardial infarction (MI), angina, and congestive heart failure generally have been positive. In general, treatment with carnitine (1.5 to 6 g/d for up to 1 year) results in a beneficial effect of fewer deaths and less heart failure when administered to patients after MI. Compared with placebo, carnitine use resulted in smaller increases in left ventricular end-systolic and end-diastolic volumes over time. In shorter term studies (1 to 3 months), carnitine therapy may have positive effects on symptoms of heart failure and angina in the post-MI period. Carnitine also seems to improve exercise tolerance and oxygen consumption in moderate to severe heart failure. Only preliminary results are available; results of a long-term (3-year) study should be reported soon. Studies specific to the dialysis population have generally shown that carnitine may have a beneficial effect on a number of cardiac parameters. Because cardiac disease is the most common form of death in patients with end-stage renal disease, these findings may be particularly important for this population. Moreover, because the relationship between conventional cardiac risk factors and cardiac disease is less clear in this population, the role of therapies that address pathological states specific to the dialysis population is worthy of study. Because a dialysis-related carnitine disorder is common among these patients, L-carnitine supplementation would be among these specific therapies.

Congestive heart failure in patients with chronic kidney disease and on dialysis

CHF is highly prevalent in ESRD and is a leading cause of death in such patients. Hypertension, renal anemia, and comorbid conditions such as coronary artery disease are particularly important risk factors for CHF in ESRD. Dialysis hypotension may be a marker of poor prognosis in such persons. Recent studies suggest that lipid peroxidation and L-carnitine deficiency may contribute to CHF in some patients with ESRD. All forms of renal replacement therapy are capable of ameliorating symptoms of CHF, but their effect on cardiovascular mortality has not been firmly established. Drug therapy, particularly angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers, is under-used in patients with ESRD and CHF. Heart/kidney transplantation may be a viable option for some patients with advanced CHF and ESRD.

Left ventricular diastolic function in end-stage renal disease and the impact of hemodialysis

Twenty-one patients (17 men and 4 women, aged 20 to 40 years) with end-stage renal disease (creatinine clearance persistently < 5 ml/min for > 3 months) were evaluated for left ventricular (LV) diastolic function by Doppler echocardiography before and after hemodialysis. Fifteen patients were on maintenance hemodialysis (group A) and 6 were studied before and after their first hemodialysis (group B). The following indexes of LV diastolic function were studied: (1) isovolumic relaxation time; and (2) Doppler indexes from mitral inflow signal--peak early velocity, peak late velocity (atrial), deceleration of early filling phase, and deceleration time of early filling phase. LV systolic function in groups A and B (LV ejection fraction 68 +/- 6 and 77 +/- 5%, fractional shortening 0.39 +/- 0.06 and 0.46 +/- 0.05%) was normal and did not change after hemodialysis. Group A had a prolonged isovolumic relaxation time of 80 +/- 22 ms, which decreased to 57 +/- 14 ms (p < 0.005). Deceleration time decreased from 248 +/- 58 to 184 +/- 38 ms (p < 0.00005) and the deceleration slope increased from 4.3 +/- 1.8 to 5.1 +/- 1.6 m/s2 (p < 0.005) after hemodialysis. In group B, isovolumic relaxation time decreased from 87 +/- 21 to 73 +/- 15 ms (p < 0.05), deceleration time decreased from 256 +/- 43 to 185 +/- 34 ms (p < 0.05), and deceleration slope increased from 3.5 +/- 0.8 to 4.2 +/- 1.1 m/s2 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of hemodialysis on left and right ventricular Doppler diastolic filling indices

Hemodialysis is associated with acute reduction in intravascular volume. To assess the impact of volume reduction on left and right ventricular diastolic filling indexes obtained by Doppler echocardiography, 24 patients on chronic hemodialysis were consecutively studied before, during, and immediately after one hemodialysis session. Twenty four normal sex and age-matched volunteers served as a control group. Study patients had abnormal diastolic indexes when compared to controls. At 2 hours of dialysis (mid dialysis) there was a significant decrease in peak early mitral flow velocity (E), no change in peak atrial filling velocity (A), and a reduction in the E/A ratio. The deceleration time of the mitral E wave also was prolonged compared to baseline. Similar findings were observed with respect to right ventricular filling indices. These changes occurred during the first 2 hours of dialysis and remained unaltered at end dialysis. When patients were subdivided according to weight loss, only the group that lost 1 or more kilograms had significant changes in the Doppler parameters of the left and right ventricle, as well as reduction of the left ventricular dimensions. These findings suggest that preload reduction is the main mechanism that accounts for acute changes in Doppler diastolic indices observed during hemodialysis.