T. Sodolski

The effect of a single dialysis session on spatial QRS-T angle in haemodialysis patients

BACKGROUND Abnormal values of the spatial angle between the directions of ventricular depolarization and repolarization (QRS-T) reflect the action potential inhomogeneities and predict cardiac events and mortality in various patient groups. The study was designed to (i) compare QRS-T in haemodialysis (HD) patients and healthy subjects, (ii) assess the influence of HD on QRS-T and (iii) evaluate the possible associations between QRS-T and echocardiography, haemodynamic as well as biochemical parameters. METHODS The angular differences between the maximum spatial QRS and T vectors were measured in 73 HD patients and in 57 controls. QRS-T in patients was estimated pre- and post-dialysis together with the evaluation of blood chemistry and haemodynamic parameters. RESULTS Pre-dialysis QRS-T was higher compared with controls (30.18 ± 9.84 and 13.65 ± 7.23, respectively; P < 0.001). HD induced an increase of QRS-T (41.09 ± 11.74; P < 0.001). Pre-dialysis QRS-T adjusted for left ventricular mass index correlated with troponin T (r = 0.398, P = 0.001) and HDL (r = -0.270, P = 0.043). The differences between pre- and post-dialysis (Δ) QRS-T correlated with Δ potassium (r = 0.453, P < 0.001), Δ calcium (r = -0.309, P = 0.011) and Δ stroke index (SI; r = 0.311, P = 0.017). On multivariate analysis, troponin T was found to be an independent predictor of pre-dialysis QRS-T, whereas independent predictors of the HD-induced increase in QRS-T were potassium and cardiac index changes. CONCLUSIONS QRS-T is high in HD patients. HD enhances the inhomogeneities of action potential. Pre-dialysis QRS-T is mainly associated with troponin T elevation. HD-induced increase in QRS-T is mainly associated with potassium and SI changes. The possible clinical importance of the higher QRS-T in HD patients remains to be confirmed in further studies.

Comparison of the acute hemodynamic effect of right ventricular apex, outflow tract, and dual-site right ventricular pacing.

Background: We studied the acute effect of pacing at the right ventricular outflow tract (RVOT), right ventricular apex (RVA) and simultaneous RVA and RVOT—dual‐site right ventricular pacing (DuRV) in random order on systolic function using impedance cardiography.

CRT47: WHAT FACTORS INFLUENCE HEMODYNAMIC IMPROVEMENT AFTER RIGHT VENTRICULAR TO BIVENTRICULAR PACING SYSTEM UPGRADE?

It is still hard to predict hemodynamic effects after biventricular pacing system (BiVp) implantation despite established inclusion criteria for CRT and left ventricular pacing (LVp) techniques. The aim of the study was to find the predictors of acute hemodynamic improvement after right ventricular (RVp) to biventricular pacing system upgrade. Methods: The study group consisted of 69 patients with permanently implanted BiV pacing system with standard CRT criteria. Hemodynamic effect was determined using impedance cardiography (BioZ.com; Cardiodynamics). Cardiac Index (CI) and other indirect parameters were determined during 3 min periods of RV and BiV pacing in turn. Correlations were searched among clinical, echocardiographic, ECG and initial hemodynamic parameters and multivariate analysis was performed as well. Results: Cardiac contractility was higher during BiVp than RVp and LVp: CI (l/min/m2): RVp 2,29* LVp 2,20∧ BiVp 2,56*∧ [*∧ANOVA-LSD p>0,05]. Increase of CI after RV to BiV reprogramming correlated with CI during RVp (r=−0,50 p>0,001), Thoracic Fluid Index (TFI) (r=−0,32 p>0,01) and with difference of CI between RVp vs LVp (r=0,57 p>0,001) and LVp vs BiVp (r= 0,30 p>0,05). Values of CI during LVp, BiVp, echocardiographic parameters, NYHA class, RVp-, LVp-, BiVp- QRS durations and axis, and their changes did not correlated with differences of CI during RVp and BiVp. Multivariate analysis showed that only CI during RVp and RVp vs LVp CI difference determined acute hemodynamic effect of BiVp in comparison to RVp. Conclusions: Increase of CI after RVp to BiVp upgrade depends mainly on cardiac performance during right ventricular pacing and its improvement caused by change from RVp to single site LVp.

705 Rright ventricular apex or outflow tract for biventricular pacing

It was proved that RVOT pacing makes less ventricular asynchrony than RVA pacing. Recently better LV leads permits pacing more distal part of cardiac veins. For avoidance of apical region pacing of both of ventricles we implanted RV lead in RVOT position in every second patient with BiV pacing system. The aim of the study was to compare acute hemodynamic effects of BiV pacing in patients with RV lead in RVA and RVOT position. The study group consisted of 18 patients with permanently implanted biventricular pacing system (atrio-ventricular pacing 12 pts, ventricular only pacing 6 pts). RV lead positions: RVA 10 pts., RVOT 8 pts. LV lead positions: lateral CV 7 pts., postero-lateral CV 10 pts., posterior CV 1 pt. Hemodynamic measurements were performed using impedance cardiography (BioZ.com ICG; Cardiodynamics). Indices of contractility: Acceleration Index (ACI), Velocity Index (VI) and Stroke Volume (SV) were determined. Six consecutive measurements were collected after the adaptation period of 2 minutes throughout RV and BiV pacing in turn. The data for each pacing mode were averaged and compared. Results: ACI, VI and SV values were significantly higher during BiV pacing in comparison to RV pacing.