Background: The benefit of biventricular pacing (BiV) may be substantially affected by optimal lead placement. Aim: To evaluate the importance of right ventricular (RV) lead positioning on clinical outcome of BiV. Methods and results: A total of 99 patients with symptomatic heart failure and implantation of BiV system were included. Position of the left-ventricular (LV) lead was selected based on timing of local endocardial signal within the terminal portion of the QRS complex. RV lead was preferably positioned at the midseptum (n = 74, RVS group) where the earliest RV endocardial signal was recorded. A subgroup of patients had RV lead placed in the apex (n = 25, RVA group). NYHA class, maximum oxygen-uptake (VO 2 max), LV end-diastolic diameter (LVEDD, mm) and ejection fraction were assessed every third month.A trend towards greater improvement in NYHA class and significant increase in VO 2 max was present in the RVS group. Moreover, a significant decrease in LVEDD (DLVEDD) was observed in the RVS group only (À 3.4 T 6.5 mm versus + 1.7 T 6.4 mm in RVA group at 12 months, p = 0.004). No significant correlation between the degree of DLVEDD and QRS narrowing induced by BiV was found. LVEDD reduction was predominantly present in dilated cardiomyopathy. Conclusions: Midseptal positioning of the RV lead appears to promote reverse LV remodelling during cardiac resynchronisation therapy.

Restoration of the atrioventricular (AVD) and interventricular (VVD) delays increases the hemodynamic benefit conferred by biventricular (BiV) stimulation. This study compared the effects of different AVD and VVD on cardiac output (CO) during three stimulation modes: BiV-LV = left ventricle (LV) preceding right ventricle (RV) by 4 ms; BiV-RV = RV preceding LV by 4 ms; LVP = single-site LV pacing. We studied 19 patients with chronic heart failure due to ischemic or idiopathic dilated cardiomyopathy, QRS >/= 150 ms, mean LV end-diastolic diameter = 78 +/- 7 mm, and mean LV ejection fraction = 21 +/- 3%. CO was estimated by Doppler echocardiographic velocity time integral formula with sample volume placed in the LV outflow tract. Sets of sensed-AVDs (S-AVD) 90-160 ms, paced-AVDs (P-AVD) 120-160 ms, and VVDs 4-20 ms were used. BiV-RV resulted in lower CO than BiV-LV. S-AVD 120 ms and P-AVD 140 ms caused the most significant increase in CO for all three pacing modes. LVP produced a similar increase in CO as BiV stimulation; however, AV sequential pacing was associated with a nonsignificantly higher CO during LVP than with BiV stimulation. CO during BiV stimulation was the highest when LV preceded RV, and VVD ranged between 4 and 12 ms. The most negative effect on CO was observed when RV preceded LV by 4 ms. Hemodynamic improvement during BiV stimulation was dependent both on optimized AVD and VVD. LV preceding RV by 4-12 ms was the most optimal. Advancement of the RV was not beneficial in the majority of patients.

Background: Decrease in neurohormonal activation during pharmacotherapy for chronic heart failure (CHF) is associated with haemodynamic and clinical improvement. We tested the hypothesis that changes in neurohormonal activation after initiation of cardiac resynchronization therapy (CRT) predict its long-term clinical effect. Methods: The study group included 43 patients with CHF (37 males, mean age 62 T 9 years, NYHA class 3.2 T 0.4, QRS duration 195 T24 ms) who underwent successful implantation of a CRT system. Pharmacotherapy remained stable during the first 3 months of follow-up. Plasma levels of B-type natriuretic peptide (BNP) and big endothelin-1 (big ET-1) were evaluated before and 3 months after implantation. Clinical, echocardiographic and exercise parameters were monitored for a mean period of 25.8 T 6.7 months. Results: At 12 months of follow-up 13 non-responders were identified (no improvement in NYHA class (n = 10), urgent heart transplantation (n = 2) and death due to progressive heart failure (n = 1)). CRT resulted in a significant reduction in neurohormone levels (BNP 345.4 T 346 vs. 267.7 T 320.8 pg/ml, p < 0.01, big ET-1 3.11 T1.50 vs. 2.50 T 1.56 fmol/ml p < 0.05), especially in responders. Percentage change in BNP level was a stronger predictor of long-term clinical improvement than clinical, echocardiographic and exercise parameters at 3 months of follow-up. Conclusions: Percentage change in plasma BNP levels from baseline to 3 months was the strongest predictor of long-term response to CRT and may have potential to predict outcome.

Acute hemodynamic studies suggest that resynchronization therapy using single-site left ventricular pacing (LVP) is equivalent to biventricular pacing (BIVP). The aim of this study was to assess the performance of LVP versus BIVP during exercise by means of stress echocardiography. A total of 28 patients (25 men and 3 women, mean age 60.9 +/- 8 years) with advanced chronic heart failure and impaired ventricular conduction (QRS > 150 ms) were studied. Patients were randomly allocated to either BIVP or LVP mode with a crossover on the next day and cardiac output was estimated at rest and during each stage of bicycle ergometry in supine position by means of velocity time integral formula. Maximum exercise level was comparable for both pacing modes (up to 100 W) and no significant differences were revealed either in heart rate or in blood pressure at rest and during any step of exercise. LVP was associated with significantly higher cardiac output at rest (3.2 +/- 0.5 vs 2.8 +/- 0.6 l/min, P < 0.01) and during low level exercise (4.4 +/- 0.8 vs 3.9 +/- 0.8 l/min at 25 W, P < 0.05) as compared with BIVP. There was a trend towards higher cardiac output for LVP even at higher levels of exercise. These effects were predominantly confined to patients with idiopathic dilated cardiomyopathy. It is concluded that cardiac resynchronization therapy using single-site LVP results in better hemodynamic response as compared with BIVP, both at rest and during physical exercise.

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