Arterial pressure changes on cardiac function during hemodialysis

Transcription

1 2 Arterial pressure hanges on ardia funtion during hemodialysis Dimitrios I. Chaniotis *, Evangelos Papademitriou, Stavroula Galani- Triantaphyllidou, Petros Petropoulos, Frangiskos Chaniotis Tehnologial Eduational Institution (TEI) of Athens and Ioannina Foundation of Biomedial Researh, Cardiovasular Division, Aademy of Athens *( Address for orrespondene: Tel , ABSTRACT Left ventriular (LV) diastoli funtion has been ausally deteriorated on hypotensive episodes during hemodialysis (ΗD). The influene of intravasular volume deterioration and arterial pressure redution on LV funtion in patients without hypotensive episodes during ΗD has not been adequately studied. 23 patients on ΗD were studied for 48±3 months, whose mean age was 0±2 years, their mean body mass index was 24±4kg/m 2 and their mean fluid retention between ΗD sessions 2.2±. kgr. We used 2D and Doppler ehoardiography before and after the same HD session. The following parameters were measured: a) end-diastoli (LVED) and end-systoli LV diameters, left atrial diameter (LA) and fration shortening (FS) b) isovolumi relaxation (IVRT) and ontration (ICT) time, deeleration time (DT), Ε and Α waves of the mitral inflow and ejetion time (ΕΤ) of the LV outflow veloity. The following indies were alulated: E/A ratio, myoardial performane index (ΜΡΙ) using the (IVRT+ICT)/ET formula, mean arterial pressure (ΜΑΡ), the % redution in ΜΑΡ and the redution in intravasular volume after HD. Stroke volume (SV) and orresponding ardia output (CO), were alulated from the LV outflow veloity waveform. All patients demonstrated systoli arterial pressure at the level of 90Hg and normal FS before ΗD, while they had demonstrated restritive LV diastoli filling before ΗD. ΜΑΡ, SV, CO, LVΕD, LΑ, Ε wave and Ε/Α dereased while IVRT inreased after ΗD (p<0.0). After HD, low ΜΡΙ values (normal range <0.44) were related to greater ultrafiltration volume loss (UFV) (r=0.3, p<0.0) and greater % redution in ΜΑΡ (r=0.62, p<0.0). Conversely, abnormal ΜΡΙ values were related to high ΜΑΡ after ΗD (r=0,44, p<0.0). Inreased UFV was related to greater % inrease in IVRT (r=0.43, p<0.0) and % derease in Ε/Α (r=0.40, p<0.0) after HD. Patients with UFV >3kg (7/23) had lower ΜΡΙ (0.47± vs. 0.84±0.3, p<0.0) and greater % inrease in ΙVRT and % redution in Ε/Α (p<0.0 ) than those with <3kgr. Fluid retention between ΗD sessions leads to restritive LV diastoli filling as shown by an Ε/Α> and a short IVRT in patients before HD. Redution in the exess intravasular volume after ΗD normalises ΜΑΡ and thus, improves LV performane. KEY WORDS: Ehoardiography assessment, Cardia funtion, Heart rate, Arterial pressure, Intravasular volume, Ultrafiltration volume, Chroni renal failure, Hemodialysis. 2

2 26 INTRODUCTION Chronially hemodialysed patients demonstrates a high inidene of ardiovasular disease (). It is also known that while the majority of patients on HD have linial signs of heart failure only few of them demonstrate systoli dysfuntion in ehoardiography (2). In these patients a large variation of intravasular volume and arterial blood pressure (BP) ours during HD. The diastoli funtion of the left ventrile (LV) is important for keeping a normal stroke volume with low intraavitary pressures. The study of parameters that ould influene the balane of the ardiovasular system in patient on HD is very important. Doppler ehoardiography of the LV is a reliable method of measuring LV diastoli funtion. Diastoli dysfuntion of the LV indued by a redution in the intravasular volume is responsible for the hypotension of those patients during HD (3-). The effet of aute hanges of intravasular volume and of the variability of BP on the diastoli and systoli funtion of the LV in patients who did not demonstrate hypotension during HD has not been fully investigated. METHODS Study population The study inluded 23 patients (6 men and 7 women) aged 0±2 years with hroni renal failure (CHD) who were undergoing HD, aged 0±2 years and whose mean duration of HD was 48±3 months (Tab. I). They did not suffer from oronary artery disease, respiratory disease, ardia rhythm abnormalities or infetion and have not used any inotropi or other ardioative drugs for drug half-lives before the study. Glomerulonephritis was the primary renal disease in 2 patients, whereas polyysti kidney disease was diagnosed in 4, reflux nephropathy in 2, diabeti nephropathy in 2, nephrolithiasis in 2, renal TBC in one and hroni pyelonephritis in one patient. Hemodialysis was performed for 4 hours, three times weekly with the use of biarbonate dialysate, the blood flow rate ranging between ml/min and the dialysate flow rate ranging between 400 and 00 ml/min. Their hematorit was 3%. They were all reeiving erythropoeitin therapy. They were also reeiving phosphate binders, ferrum and foli aid per os. Parathyroid and thyroid funtion were within aeptable limits. Nine were smokers and had hypertension Moreover, these patients did not suffer from ardia valve disease, ardia musle disease or infetion. All patients had an ehoardiogram half an hour before and iediately after HD. Their body weight, systoli, diastoli and mean arterial pressure (MAP) were measured. Heart rates (HR) were also assessed before and after HD. The ultrafiltration volume loss (UFV) was alulated by the redution of body weight after HD. This hange in weight was onsidered to represent the orresponding hange of intravasular volume during HD. Institutional Ethis Coittee approved the protool and eah subjet gave an informed onept. Ehoardiographi measurements The ehoardiographi study was performed by means of a HP-Sonos 00 and a 2.MHz phase-array transduer. The following indies were measured: a) left ventriular end-diastoli (LVED) and systoli LV diameters, left atrial diameter (LA) and fration shortening (FS), b) isovolumi relaxation (IVRT) and ontration (ICT) time, deeleration time (DT), E 4 (2), April

3 27 and A waves of the mitral inflow and ejetion time (ET) of the LV outflow veloity. The following indies were alulated: E/A ratio, myoardial performane index (MPI) using the (IVRT + ICT)/ET formula, mean arterial pressure (MAP), the % redution in MAP and the redution in intravasular volume after HD. Stroke volume (SV) and orresponding ardia output (CO), were alulated from the LV outflow veloity waveform utilizing the mahine s software. Statistial analysis The distribution of the parameters examined was not normal, thus Mann-Whitney s non-parametri test was used for omparisons between groups. Spearman's orrelation was used to assess relations between variables. A p value <0.0 was onsidered as statistially signifiant. All values are expressed as means ± SD. RESULTS The linial harateristis of our patients population are shown in Table I. Hemodialysis indued a signifiant redution in MAP, SV, CO, LVED, LA, E, E/A, ET, with a onomitant inrease in DT and IVRT, while A and MPI remained unhanged (Tab. II). The perentage (%) inrease in IVRT and derease in E/A orrelated with a redution in intravasular volume (r=0.60, p<0.0 (Fig. ), r=0., p<0.0, respetively). After HD, low MPI values (n value <0.44) were assoiated with greater UFV (r=0.3, p<0.0), greater % redution in SV (r=0.4, p<0.0) and greater % redution in MAP (r=0.62, P<0.0) (Fig. 2). Conversely, abnormal MPI values were related to high MAP after HD (r = 0.44, p < 0.0). Patients with UFV loss > 3kg (7/23) had lower MPI and greater % inrease in IVRT and % redution in E/A (p<0.0) than those with < 3kg after HD (Tab. III, p<0.0). The two groups did not differ in age, duration of HD, hematorit, history of hypertension, heart rate, ardia output and in % redution in BP after HD and baseline values of the ehoardiographi indies before HD. Τable. Clinial harateristis of HD patients studied Age (years) 0 ± 2 Sex (M/F) 6 / 7 BMI (kg/m 2 ) 24.4 ± 4 Time on HD (in months) 48 ± 3 UFV (kg) 2.2 ± ΜΑP (Hg) 98 ± 4 HR (/min) 73 ± 0 Ht (%) 36 ± 2 Hypertension Smoking 9 UFV= ultrafiltration volume, MAP=mean arterial pressure, HR=heart rate 27

4 28 HD PR E PO ST ΜΑP H g TABLE 2. Results in all patients HR pulse s/min SV ml CO l/min 99± 76± 92±2 2 86±2 83±2 73±2 7 p <0.0 NS <0.0 <0.0 LVE D LV ES 7±2 2±6 3± 4 6±2 48±6 30± <0.0 TABLE 3. Patients with post-hd UFV LA FS % Ε m/se 0.8± 0.6± 43± 40± 40± 38± NS <0.0 NS <0.0 A m/se E/A 0.8±0.2.2± 0.8±0 0.8±.2 NS <0.0 DT mse IVRT mse ET mse MPI 84± 2 62± 4 298± 8 0.6±0.3 2± 89± 24± 0.7± <0.0 <0.0 NS UFV <3 kg n=6 3 kg n=7 ΜΑP Hg HR pulse s/min 90± 83±3 76±0 84± 6 SV ml 79± 20 60± 9 p <0.0 NS <0.0 % DS V ± 9 30± 6 <0.0 CO l/min 6.4± 3 LVE D 0± 6 ± 44± 6 LV ES 3.6 ±4 27. ± LA 4± 36± NS <0. 0 % FS 37 ±4 39 ±7 Ε m/se 0.6± 0.± 0. A m/se 0.8± 0.7± E/A % DE/ A 0.9± ± 0. 2± 20 44± 0 NS NS NS NS <0.0 DT mse 223 ±8 84 ±60 IVR T mse 92± 2 8± 9 % DIV RT 2± 2 40± 3 ET mse 239 ±6 244 ±37 M PI 0.8± ± NS NS 0.02 NS <0.0 %DSV: % differene SV,% DE/A : % differene E/A, %DIVRT=% differene IVRT. Figure. Correlation between ultrafiltration volume loss (UFV) and % inrease IVRT-post-HD. 4 (2), April

5 29 Figure 2. Correlation between % redution MAP and MPI post-hd. DISCUSSION In the present study we have shown that patients with end-stage renal failure (ESRF) and normal systoli LV funtion before HD, demonstrate a restritive LV diastoli fill possibly due to fluid retention between sessions. MAP, LVED, LA, E wave and E/A dereased, IVRT inreased after HD, while the systoli BP has remained 90Hg throughout eah session. Patients with a UFV of >3kg (7/23) had better MPI and greater % inrease in IVRT and % redution in E/A than those with <3kg. Relaxation of the ontrated myoardium ours at the onset of diastole. The rapid pressure deay and the onomitant untwisting and elasti reoil of the LV produe a sution effet that augments the LA to LV pressure gradient, thereby promoting diastoli filling. During the later phases of diastole, the normal LV is omposed of ompletely relaxed myoytes and is very ompliant and easily distensible, offering minimal resistane to LV filling over a normal volume range. This an normally be aomplished by very low filling pressures in the left atrium and pulmonary apillary pressure (<2 Hg) and the ontribution of atrial ontration is relatively small. Loss of normal LV diastoli relaxation and distensibility due to either strutural (eg, LVH) of funtional (ishemia, volume overload) auses impairs LV filling. This results in inreases in LV diastoli, LA and pulmonary venous and pulmonary apillary pressures. The net effet is a relative shift of LV filling to the later part of diastole, with a greater dependene on atrial ontration. They also present left ventriular hyperthrophy and dilatation. Coronary artery disease is also oon in this population. For these reasons patients with ESRF may demonstrate systoli and diastoli dysfuntion of the left ventrile (2). Other studies 29

6 30 doumented the presene of the LV filling abnormalities in patients on HD and orrelated them with the linial ourrene of hypotensive episodes during dialysis. This is possible due to the requirement of a higher preload to maintain adequate filling and ardia output in a stiff ventrile (). The redution in intravasular volume during HD auses a onomitant redution in pre and after load of LV. An inordinate derease in preload ould ause deterioration of LV diastoli filling and hypotension. Our findings are in agreement with those of Punzengruber et al (3) who found prolonged isovolumi relaxation time and inreased peak veloity of the late ventriular filling, in patients on hroni maintenane HD. Rozih et al reported a signifiant prolongation of isovolumi relaxation time and redution in early filling after HD. This appears to be so due to the redution in preload suggested by these investigators. Previous studies have evaluated the influene of HD indued altered loading onditions on Doppler ehoardiographi indies of the LV in patients with CRF. It has been proposed that most of Doppler-derived indies of diastoli dysfuntion are preload dependent. The use of MPI as a Doppler index of the global myoardial performane in diastoli dysfuntion patients was introdued in 99 by Tei et al. In a reent publiation by Koga et al it was suggested that the MPI index is a reliable diagnosti tool in the evaluation of myoardial performane in dialysis patients (9). This index is preload dependent. MPI is a new Doppler index (0), ombining systoli and diastoli time intervals as an expression of global myoardial performane, has been shown to be of prognosti value in patients with dilated ardiomyopathy (6), ardia amyloidosis, primary pulmonary hypertension (3) and Ebstein anomaly (4). This Doppler index of ardia funtion was proposed and defined as the sum of isovolui ontration and relaxation times divided by the ejetion time. In addition, this index is not influened by hanges in ventriular geometry, in heart rate or blood pressure, whih might alter the left ventriular filling pattern and affet the assessment of diastoli Doppler indies (3,6). MPI is an important inremental measurement in a omprehensive hemodynami workup of patients with ardia dysfuntion sine it is reproduible and easy to use (7-20). After HD, low MPI values (n values <0.44) (2) were related to greater UFV loss and greater % redution of MAP, thus onfirming the benefiial role in the redution of pre and afterload in LV funtion. Conversely, abnormal MPI values were related to high MAP after HD, suggesting the exaerbating effet on afterload in diastoli LV funtion. In onlusion, fluid retention between ΗD sessions leads to restritive LV diastoli filling as shown by a Ε/Α> and a short IVRT in patients before HD. Redution in the exess intravasular volume after ΗD normalises the ΜΑΡ and thus, improves diastoli LV performane. REFERENCES. De-Lima JJ, Sesso R, Anensur H, et al. Preditors of Mortality in Long-Term Hemodialysis Patients with a Low Prevalene of Comorbid Conditions. Nephrol Dial Transplant 99;0: Tükek T, Yildiz A, Akkaya V, et al. Systoli Time Intervals in Hemodialysis Patients with Normal Ejetion Fration: An Ehoardiographi Study. Nephrology 2002;7: (2), April

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