Biomedical subjects

Jan Bytesník

Publications and source records attributed to Jan Bytesník.

6 recordsLinked to original sources

PubMed2006

Decrease in plasma B-type natriuretic peptide early after initiation of cardiac resynchronization therapy predicts clinical improvement at 12 months.

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+/-9 years, NYHA class 3.2+/-0.4, QRS duration 195+/-24 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+/-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+/-346 vs. 267.7+/-320.8 pg/ml, p<0.01, big ET-1 3.11+/-1.50 vs. 2.50+/-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.

Adult↗

PubMed2006

Optimization of right ventricular lead position in cardiac resynchronisation therapy.

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 (DeltaLVEDD) was observed in the RVS group only (-3.4+/-6.5 mm versus +1.7+/-6.4 mm in RVA group at 12 months, p=0.004). No significant correlation between the degree of DeltaLVEDD 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.

Cardiac Output, Low↗

PubMed2004

Technical aspects of implantation of LV lead for cardiac resynchronization therapy in chronic heart failure.

The goal of this study was to analyze total procedural and fluoroscopic time during initial experience with implantation of LV lead in a single center, and to assess the performance of electrophysiologically-guided approach for cannulation of the coronary sinus (CS) in a subsequent period. Over an initial period of 29 months, a total of 46 attempts to implant biventricular pacing system were revised. During the first phase, only one type of LV electrode was available for three implanters (11 attempts). The second phase covered their early experience with other stylet-controlled LV leads (10 attempts). Additional LV leads including the over-the-wire design were available in the third phase and 25 attempts were done by he most experienced implanter. In a period of advanced experience, 92 implant procedures performed by four implanters using an electrophysiologically-guided approach to CS cannulation were revised. In the first period, success rates for different phases reached 70%, 90%, and 96%, respectively. Significant decrease in both procedural and fluoroscopic times was achieved with increased experience (Phase I: 247.1 +/- 104.5 minutes and 31.2 +/- 34.3 minutes, Phase II: 219.4 +/- 85.6 minutes, and 22.9 +/- 19.1 minutes, Phase III: 116.4 +/- 89.9 minutes and 6.6 +/- 4.4 minutes, respectively, P < 0.05). Advanced experience with electrophysiologically-guided approach to CS cannulation allowed achievement of this target within a reasonable amount of time (15.4 +/- 16.3 minutes) and with minimum fluoroscopic time (2.1 +/- 2.9 minutes). In conclusion, both individual learning curve and technical advances significantly influence success rate, procedural, and fluoroscopic times for biventricular system implantation. Electrophysiologically-guided approach makes cannulation of the CS a highly reproducible procedure that requires minimum fluoroscopic time.

Adult↗

PubMed2004

The spectrum of inter- and intraventricular conduction abnormalities in patients eligible for cardiac resynchronization therapy.

Although cardiac resynchronization therapy (CRT) has clearly demonstrated its clinical benefit in patients with congestive heart failure (CHF) and intraventricular conduction abnormalities, selection of eligible patients and/or optimal pacing site are still a matter of debate. The aim of the study was to analyze the spectrum of conduction abnormalities in CRT candidates. A total of 26 patients (mean age 62 +/- 9 years) with CHF and conduction disturbances (QRS > or = 130 ms) were studied. The underlying heart disease was dilated cardiomyopathy (DCM) (n = 12) or coronary artery disease (CAD) (n = 14). High density, left ventricular endocardial activation maps were constructed using an electroanatomic mapping system (CARTO). Based on endocardial activation patterns, left ventricular conduction abnormalities were classified as left bundle branch block (LBBB) (n = 9), nonspecific intraventricular conduction disturbances (n = 10), and the bifascicular block (n = 7). In DCM patients the endocardial activation sequences corresponded with a 12-lead ECG pattern with a homogeneous spread of activation wavefront and the latest activation laterally (LBBB) or anteriorly (bifascicular block), respectively. CAD patients presented with variable activation patterns that reflected the location of the postinfarct scar, and the 12-lead ECG was less predictive. Although there was a trend for longer QRS durations for DCM subjects (170 +/- 23 vs 156 +/- 23 ms, P = NS), left ventricular activation time was significantly longer in the CAD group (115 +/- 21 ms vs 134 +/- 23 ms, P < 0.05). CRT candidates represent a broad spectrum of conduction abnormality patterns with variable inter- and intraventricular activation delays. CAD subjects have more pronounced intraventricular conduction abnormality. The standard ECG is less reliable in the characterization of complex conduction abnormalities.

Adult↗

PubMed2003

Catheter ablation of ventricular tachycardia following myocardial infarction using three-dimensional electroanatomical mapping.

One challenge encountered during catheter ablation of postinfarction ventricular tachycardia (VT) is the inducibility of multiple VT morphologies associated with variable hemodynamic instability. The clinical usefulness and safety of a three-dimensional electroanatomical mapping in guiding radiofrequency (RF) catheter ablation of VT, used in parallel with a multichannel recording system, was studied in 28 men (mean age = 63.8 +/- 10.6 years, mean left ventricular ejection fraction = 28% +/- 9%). Three-dimensional voltage maps of the left ventricle were obtained in sinus rhythm with annotation of areas of fractionated or late potentials, zones of slow conduction and/or dense scar with no pacing capture at 10 mA. RF lesions were created either in sinus rhythm or during hemodynamically stable VT within reconstructed critical zones of the circuit. A total of 82 VTs were induced (mean = 2.9 +/- 1.0/patient). Hemodynamically unstable clinical VTs were induced in 5 patients, and clinical or nonclinical unstable VT in 14. Clinical VT was rendered noninducible in 24/28 (85.7%) patients, and monomorphic VT was eliminated in 16/28 (57.1%) patients. The mean procedural time was 258 +/- 82 minutes, and fluoroscopic exposure 13.5 +/- 8.8 minutes. During a mean follow-up period of 10.6 +/- 6.4 months, catheter ablation was repeated in 6 patients for VT recurrences. No significant complications occurred except for a transient cerebral ischemic attack in one patient. In conclusion, electroanatomical mapping assisted the successful and safe catheter ablation of both mappable and nonmappable VTs in a significant proportion of patients after myocardial infarction.

Catheter Ablation↗

PubMed2003

Clinical application of electroanatomical mapping in the characterization of "incisional" atrial tachycardias.

UNLABELLED: Scar tissue after surgical procedures for congenital heart disease may create a complex arrhythmogenic substrate and expose patients to the risk of "incisional" tachycardia. We report the usefulness of electroanatomical mapping in the characterization of reentrant circuits and identification of sites of successful radiofrequency (RF) ablation. METHODS: Electroanatomical mapping was used to draw activation maps of the right atrium in 6 men and 4 women (mean age 45 +/- 13.7 years) with 21 atrial tachycardias after corrections of atrial septal defects (n = 6) or tetralogy of Fallot (n = 4). The critical isthmus of reentrant circuits was ablated by RF energy. RESULTS: Macroreentrant circuits were localized on the posterolateral wall of the right atrium in all cases. Scar tissue in that region often contained several pathways that allowed induction of different tachycardias. Interruption of all slow conducting pathways successfully abolished all inducible tachycardias. The cavotricuspid isthmus participated in a figure-of-eight reentrant circuit or in a typical flutter circuit in 6 patients. RF ablation was successful in all but one patient, without significant complications. CONCLUSION: Electrocanatomical mapping allows the precise description of macroreentrant circuits and the identification of all slow conducting pathways. It is a powerful tool for the planning of ablation lines, navigation of ablation catheter, and verification of conduction block.

Adult↗