Predictors of positive response to cardiac resynchronization therapy.

BACKGROUND: Approximately 30% of patients treated with cardiac resynchronization therapy (CRT) do not achieve favourable response. The purpose of the present study was to identify echocardiographic and clinical predictors of a positive response to CRT. METHODS: The study included 82 consecutive heart failure (HF) patients in New York Heart Association (NYHA) functional class III or IV with left bundle branch block (LBBB), QRS duration ≥ 120 ms and left ventricular ejection fraction (LVEF) ≤ 35%. Statistical analysis was performed using IBM SPSS statistical software (SPSS v.21.0 for Mac OS X). A p value < 0.05 was considered statistically significant. RESULTS: Echocardiographic response was established in 81.6% and clinical response was achieved in 82.9% of patients. Significant univariate predictors of favourable echocardiographic response after 12 months were smaller left ventricular end-diastolic diameter (LVEDD) (odds ratio [OR] 0.89; 95% confidence interval [CI] 0.82 - 0.97, p = 0.01), and smaller left ventricular end-systolic diameter (LVESD) (OR 0.91; 95% CI 0.85 - 0.98, p = 0.01). Lower uric acid concentration was associated with better echocardiographic response (OR 0.99; 95% CI 0.99 - 1.0, p = 0.01). Non-ischemic HF etiology (OR 4.89; 95% CI 1.39 - 17.15, p = 0.01) independently predicted positive clinical response. Multiple stepwise regression analysis demonstrated that LVEDD lower than 75 mm (OR 5.60; 95% confidence interval [CI] 1.36 - 18.61, p = 0.01) was the strongest independent predictor of favourable echocardiographic response. CONCLUSIONS: Smaller left ventricular end-diastolic and end-systolic diameters and lower serum uric acid concentration were associated with better response to CRT. Left ventricular end-diastolic diameter and non-ischemic heart failure etiology were the strongest independent predictors of positive response to CRT.

Radiofrequency catheter ablation of pulmonary vein roots results in axonal degeneration of distal epicardial nerves.

BACKGROUND: In treatment of atrial fibrillations (AF), radiofrequency ablation (RFA) at the pulmonary vein (PV) roots isolates AF triggers in the myocardial sleeves, but also can destroy PV ganglia and branches of the intrinsic cardiac nerve plexus. AIM: To determine the long-term impact of RFA at the PV roots on the structure of epicardial nerves located distally from the RFA site. METHODS: Five black-faced sheep underwent epicardial RFA of the left and middle PV roots. Two to 3 months after RFA, we obtained samples of epicardial nerves from remote locations of the left dorsal (LD) neural subplexus that extends along the roots of the superior PVs toward the coronary sinus (CS) and dorsal left ventricle (LV). Right atrial epicardial nerves from the right ventral (RV) neural subplexus of the ablated animals and epicardial nerves from LD neural subplexus of five additional intact sheep were used as control. Nerve morphology was examined using histochemical, immunohistochemical and transmission electron microscopy. RESULTS: Histochemical acetylcholinesterase staining did not reveal any epicardial nerve alterations. However, tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) staining showed clearly the reduced numbers of TH and ChAT immunoreactive (IR) nerve fibers within epicardial nerves derived from the remote LD subplexus; control samples from all examined animals were full of evenly distributed TH-IR and ChAT-IR nerve fibers. In sharp contrast to control nerves, numerous swollen or disintegrated axons and Schwann cells with pyknotic nuclei inside unmyelinated and myelinated nerve fibers were identified by electron microscopy of ultrathin sections of epicardial nerves from the CS and LV regions in all ablated animals. CONCLUSIONS: Degeneration of remote atrial and ventricular epicardial nerves is evident 2-3 months after epicardial RFA at the PV roots. Such nerves are likely to be non-functional. Therefore, long-term autonomic dysfunction is a potential risk of PV isolation by RFA.

Coagulation alterations in treating arrhythmias with radiofrequency ablation.

OBJECTIVE: To determine an influence of radiofrequency ablation on changes in coagulation system. MATERIAL AND METHODS: We investigated 30 patients with cardiac arrhythmias. Platelet aggregation, fibrinogen and D-dimer level were analyzed before, right after, 24 and 72 h after radiofrequency ablation. Platelet aggregation was explored in whole blood and platelet-rich plasma using adenosine diphosphate (ADP), epinephrine, and collagen for induction. RESULTS: Platelet aggregation induced by ADP and collagen in whole blood plasma increased significantly (P<0.01) (by 45% and 43%, respectively) in 24 h after radiofrequency ablation and remained increased in 72 h after radiofrequency ablation (by 11% and 35%, respectively) (P<0.01) as compared with baseline results. Spontaneous aggregation of platelet-rich plasma as well as ADP- and collagen-induced platelet aggregation tended to decrease right after radiofrequency ablation. Epinephrine-induced platelet aggregation significantly decreased by 17.5% after radiofrequency ablation (P<0.01) and started to increase in 24 h after radiofrequency ablation. In 72 h after radiofrequency ablation, platelet aggregation induced by different agonists increased by 7-45% significantly (P<0.05), and values were higher than baseline ones. Fibrinogen level after radiofrequency ablation did not differ from that of the baseline (3.08+/-0.7 g/L), but D-dimer level increased significantly (from 0.39+/-0.3 to 1.29+/-2.4 mg/L, P<0.01). In 24 h after radiofrequency ablation, an increase in fibrinogen level and a decrease in D-dimer level were found. Fibrinogen level increased to 3.32+/-0.6 g/L significantly in 72 h after radiofrequency ablation (P<0.05). Meanwhile, D-dimer concentration decreased to 0.78+/-0.8 mg/L, but it was still significantly higher (P<0.05) than the baseline value. CONCLUSION: Despite diminished platelet aggregation and increased D-dimer level right after radiofrequency ablation, a risk of thrombosis increased in the next few days after radiofrequency ablation.

Changes in electrophysiologic properties of the conductive system of the heart in children with atrioventricular nodal reentrant tachycardia after 2-8 years following radiofrequency catheter ablation of the slow pathway.

UNLABELLED: Radiofrequency ablation of the slow pathway is an effective method of treatment in children with atrioventricular nodal reentrant tachycardia. The aim of our study was to evaluate anterograde conduction properties in children before and after radiofrequency ablation of the slow pathway and to determine the efficacy and safety of this method. MATERIAL AND METHODS: Noninvasive transesophageal electrophysiological examination was performed in 30 patients at the follow-up period (mean duration, 3.24 years) after radiofrequency ablation of the slow pathway. RESULTS: The slow pathway function was observed in 13 patients one day after ablation, in 26 patients during the follow-up period, and in 28 patients after administration of atropine sulfate. Atrioventricular node conduction was significantly decreased the following day after ablation and at the follow-up versus the preablation (165.2 [30.2] bmp and 146.3 [28.5] bpm versus 190.9 [31.4] bpm; P<0.001). The atrioventricular node effective refractory period prolonged significantly the following day after ablation and at the follow-up versus the preablation (319.3 [55.3] ms and 351.0 [82.1] ms versus 248.3 [36.6] ms; P<0.001). Effective refractory period of the fast pathway prolonged significantly as compared with the preablation (from 408.0 [60.4] ms to 481.2 [132.9] ms; P=0.005). The prolongation of effective refractory period of the slow pathway was more significant than effective refractory period of the fast pathway at the follow-up (P<0.001). Two late recurrences occurred; one patient had atrial tachycardia. CONCLUSION: Children with atrioventricular nodal reentrant tachycardia can be effectively and safety cured by ablative therapy. The end-point during slow pathway ablation should be the abolition of tachycardia with preservation of dual atrioventricular nodal physiology.

Atrial tachyarrhythmias in infants.

This report describes clinical features and tactics of treatment of atrial tachyarrhythmias in infancy. Electrophysiologic study was performed in all 20 infants (2 weeks - 12 months old) in order to determine the mechanism of arrhythmia and to predict the clinical efficacy of management. Reciprocating mechanism was revealed in 12 infants. Atrial flutter was diagnosed for 10 infants among whom only 2 patients were older than two months. Six infants were found to have flutter conduction with a rate of 1:1. Four infants had congestive heart failure, 3 of them with a structurally normal heart. Half of the infants with atrial flutter needed long-term antiarrhythmic therapy. Electrotherapy for termination of atrial flutter was effective in all of them. Automatic atrial tachycardia in eight infants presented no major problems unless it became incessant and resistant to pharmacological treatment. The average tachycardia rate reached 171+/-7 beats/min. Atrial reciprocating tachycardia usually affects patients with diseased myocardium.

Idiopathic ventricular tachycardia in children: curative therapy with radiofrequency ablation.

UNLABELLED: Idiopathic ventricular tachycardia is a rare condition, and there is a lack of clear guidelines for the necessity and indications for prophylactic antiarrhythmic or curative treatment. The aim of this study was to review the clinical picture of idiopathic ventricular tachycardia and evaluate the efficacy and safety of radiofrequency ablation therapy in children. MATERIAL AND METHODS: The subjects of this study were 16 children with idiopathic ventricular tachycardia. The mean age at onset of idiopathic ventricular tachycardia was 12 years. All patients underwent electrophysiological examination. Nonfluoroscopic mapping technology (Carto) was used in one case. Radiofrequency ablation was performed in all children (mean duration of follow-up was 46 months). RESULTS: Six children with idiopathic ventricular tachycardia were free of symptoms. Palpitation was the only complain in four patients, and six patients presented with symptoms of circulatory disorder (the tendency of the higher rate of ventricular tachycardia and more premature contractions and episodes of ventricular tachycardia in one day were noticed in five of them). All children after radiofrequency ablation were alive, and only one complication (complete right bundle branch block) occurred. Success at last follow-up included five children with left and six with right idiopathic ventricular tachycardia. CONCLUSIONS: Catheter ablation seems a promising therapeutic option with the outlook possible of the idiopathic ventricular tachycardia in children. It is safe enough and should be considered as the therapy of choice even in children without of symptoms if they wish to live active social and physical life.

Changes of electrophysiological parameters in patients with atrial flutter.

OBJECTIVES: The aim of the study was to study some anatomic and electrophysiological features of the right atrium, related to the presence of atrial flutter. MATERIALS AND METHODS: A total 23 patients with type I atrial flutter and 22 patients without atrial flutter were studied. Right atrium size was assessed using echocardiography before intracardiac examination and radiofrequency ablation. RESULTS: Effective refractory periods of coronary sinus, high right atrium, low right atrium were different comparing with the control group (P<0.05). A stimulus-response time between high right atrium and low right atrium positions in anterograde and retrograde ways, an impulse propagation speed along the lateral wall of the right atrium were statistically different comparing both groups (P<0.05). There was a significant correlation among effective refractory periods measured in different sites of the right atrium (r2=0.64, 0.44, 0.44, respectively). All measured effective refractory periods also correlated with stimulus-response time in anterograde way (P<0.05) and impulse propagation speed (P<0.05). Right atrium dimensions were significantly larger in atrial flutter group. There was no correlation between the right atrium dimensions and measured electrophysiological parameters in both groups. CONCLUSIONS: The presence of atrial flutter associates with diffuse alterations of the right atrium, but not the focal or single changes of refractoriness.

Alterations of platelet aggregation while treating cardiac arrhythmias with radiofrequency ablation.

OBJECTIVE: To find out if radiofrequency ablation as method of treatment of cardiac arrhythmia influences platelet aggregation and if intensity of this process depends on the number of radiofrequency ablation episodes for one patient. MATERIAL AND METHODS: We analyzed platelet aggregation before, right after and in 24 hours after radiofrequency ablation in whole blood and platelet rich plasma in 39 cases with cardiac arrhythmias. Adenosine diphosphate and adrenaline were used for aggregation induction. Three groups of patients were formed based on the number of radiofrequency ablation episodes: A-- <10, B--10-20, C-- >20 for one patient. RESULTS: We detected a decrease in spontaneous, adenosine diphosphate and adrenaline induced platelet aggregation in plasma right after radiofrequency ablation, and also the same tendency was noted in adenosine diphosphate induced aggregation in whole blood. In 24 hours after radiofrequency ablation platelet aggregation tended to return to pre-radiofrequency ablation levels. Based on the number of radiofrequency ablation episodes we detected significant changes in spontaneous and adrenaline-induced aggregation in plasma. In group A adrenaline induced aggregation after radiofrequency ablation increased by 0.4%, in group B it decreased by 15.7% and in group C it decreased by 19.4% from pre-radiofrequency ablation level (p<0.05, between groups A and C). Spontaneous platelet aggregation after radiofrequency ablation decreased in group A 41.9%, in group B--20.8% and in group C--18.4% from pre-radiofrequency ablation level (p<0.05 between groups A and C). The greater decrease in adenosine diphosphate induced aggregation in plasma and in whole blood was detected in the group with larger number of radiofrequency ablation episodes. CONCLUSIONS: This study found that platelet aggregation decreased in plasma and in whole blood after radiofrequency ablation. And this alteration was significant in groups B and C, when the number of radiofrequency ablation episodes were >10. In 24 hours platelet aggregation increased again to pre- radiofrequency ablation level.