Background and Objectives: Cardiac Resynchronization Therapy (CRT) has, besides its benefits, various limitations. For instance, atrial fibrillation (AF) has a huge impact on the therapy efficacy. It usually reduces the overall BiV pacing percentage and leads, inevitably, to lack of fusion beats. In many patients with heart failure that could benefit from resynchronization, the QRS morphology is often IVCD and atypical, or non-LBBB, which further diminishes the CRT response. In those cases, we established His pacing combined with LV pacing as a feasible option to reduce the impact of AF on the CRT response and regain partially physiological ventricular activation to improve the electromechanical sequence. Materials and Methods: We implanted two patients with AF, HF, EF < 35%, NYHA II-III and QRS > 150 ms with CRT-D systems modified to HOT-CRT and observed their clinical, ECG and echocardiographic improvements over a follow-up period of three months. Results: In both patients we observed improvements of the initial parameters. We were able to shorten the QRS duration to approx. 120 ms, improve NYHA functional class, increase the EF by approximately 12% and distinctly reduce mitral regurgitation. Conclusion: Since the conventional CRT reaches its limits within this specific patient group, we need to consider alternative pacing sites and the effective combination of them. Our results and respectively other studies that are also mentioned in the current guidelines, support the feasibility of HOT-CRT in the above mentioned patient group.

No abstract

We present a case of dual chamber cardioverter-defibrillator placement with atrial lead implanted in His-bundle area, resulting in current of injury and accelerated nodal rhythm recorded in pacing system analyzer, rarely seen in clinical practice. Such presentation resulted in excellent pacing and sensing conditions, despite primarily doubtful setting.

The heart rate regularization is crucial for proper treatment of patients with atrial fibrillation and congestive heart failure. The standard resynchronization can be applied, but in patients with narrow QRS this procedure is of no use. The aim of our study is to assess the efficacy of direct His-bundle pacing in patients with congestive heart failure and chronic atrial fibrillation using dual chamber ICD implanted for prevention of sudden cardiac death. Methods The study population included 78 patients with CHF and chronic AF: group A - 56 pts treated with direct His-bundle pacing using atrial port of dual chamber ICD and group B - 22 patients implanted with single chamber ICD as recommended by the guidelines. The patients in group B constituting clinical controls were derived from the Heart Failure Outpatients Clinic with established clinical status and pharmacotherapy. Results The demographic data, clinical characteristics and echocardiography measurements at baseline and during follow-up were presented in the table: Table 1 Group A Group B P value Age (years) 69.7±6.9 66.7±11.3 n.s. Sex (% of male sex) 84.0 86.4 n.s. Ventricular pacing (%) – 46.3±31.2 – His-bundle pacing (%) 81.7±9.2 – – pre post pre post pre vs. post LVEDD (mm) 66.9±4.9 59.9±4.7 64.8±8.0 64.7±8.1 <0.01 n.s. EF (%) 29.6±3.8 43.6±5.9 28.1±6.1 28.8±7.3 <0.01 n.s. NYHA class 2.7±0.6 1.4±0.6 2.5±0.6 2.0±0.2 <0.05 n.s. B-blocker dose (metoprolol equivalent dose) 104.6±41.6 214.3±82.6 78.3±56.6 103.1±49.2 <0.001 <0.05 During 12-months of follow-up the mean values of NYHA functional class, EF and LV dimensions did not change in group B but significantly improved in group A. The physiological His-bundle based pacing enabled optimal beta-blocker dosing. The studied groups had no tachyarrhythmia at baseline so the presumable atrial fibrillation-related harm depends on the rhythm irregularity. Conclusions His-bundle-based pacing in CHF-chronic AF patients contributes to significant echocardiographic and clinical improvement. Standard single-chamber ICD implantation in CHF-chronic AF patients yields only SCD prevention without influence on remodeling process. The CHF-patients with narrow QRS and chronic AF benefit from substantially higher beta-blockade which can be instituted in His-bundle pacing group.

The influence of Dopamine on microcirculation during hemorrhagic shock was investigated by means of the pancreas chamber technique (HEISIG, 1967). Parameter of microcirculation was the corpuscular flow velocity measured with the "flying spot" method. Simultaneously arterial and venous blood pressure, heart rate, blood gases and pH-status were registered. While a Dopamine-dosage of 5 mug/kg/min did not markedly effect perfusion of the pancreas, application of 10 as well as 20 mug/kg/min Dopamine caused a significant improvement of microcirculation. There was no difference between 10 and 20 mug/kg/min Dopamine. The increase of capillary perfusion can certainly not be explained by the small rise of blood pressure that was found under treatment with Dopamine. The results support the statement of the existence of Dopamine-specific receptors in pancreatic vessels. Compared to a group of animals treated with 5 mug/kg/min Dopamine and an untreated control group, survival rate of animals treated with 10 as well as 20 mug/kg/min Dopamine was significantly increased.