Biomedical subjects

Alan Bulava

Publications and source records attributed to Alan Bulava.

12 recordsLinked to original sources

PubMed2006

Usefulness of bifocal pacing in patients with heart failure and intraventricular conduction delay.

BACKGROUND: Bifocal pacing (BFP) has been proposed as a feasible alternative to cardiac resynchronization therapy. AIM: To evaluate BFP in patients with severe heart failure and significant intraventricular conduction delay and to compare it with biventricular pacing (BVP). METHODS: Echocardiographic examination including TDI and invasive measurement of haemodynamics was performed under basal conditions, during BFP and during BVP. RESULTS: Fifty patients were included: 29 with ischaemic heart disease (IHD), 21 with idiopathic dilated cardiomyopathy (IDCM). LV dp/dt(max) increased during BFP compared to the basal state (13.4%, 95% CI 9.2-17.6%, p<0.0001) and a further increase was achieved during BVP (29.5%, 95% CI 23.7-35.4%, p<0.0001). A significant correlation was found between the distance of the right ventricular apical and outflow tract leads and percentage of dp/dt(max) increase in IDCM patients (r=0.72), but not in IHD patients. Interventricular mechanical delay (IVMD) decreased in BFP (43+/-22 ms vs. 53+/-31 ms, p=0.006), but BVP produced even shorter IVMD (22+/-19 ms, p<0.0001). In all patients, regional systolic contraction times were significantly shortened, corresponding with prolongation of the respective regional diastolic filling times during both BFP (p<0.05 for all segments) and BVP (p<0.001 for all segments). CONCLUSIONS: BFP improves LV haemodynamics by decreasing the inter- and intraventricular conduction delays. The leads in the right ventricle should be placed at the longest achievable distance. BVP is superior to BFP.

Aged↗

PubMed2006

Case report: Symptoms of advanced heart failure--a case for radiofrequency catheter ablation?

A sixty-year-old man with previous history of coronary artery disease was admitted due to progressive worsening of dyspnoea at exertion (NYHA III functional class) and no angina. Coronary angiography confirmed occlusion of the right coronary artery which was naturally bypassed by homocollaterals with TIMI 3 flow to the peripheral branches. The lesion was not technically suitable for percutaneous angioplasty. The left coronary artery was without stenosis. On echocardiography, both the left ventricle and the left atrium were dilated and hemodynamically significant mitral regurgitation was present. Surface ECG showed a left bundle branch block with repeated runs of monomorphic ventricular ectopic beats (PVC). Radiofrequency catheter ablation of the focus in the posteroseptal region of the left ventricle underneath the mitral valve was performed using electroanatomical mapping system. After the procedure, mitral regurgitation decreased and reverse remodeling of the left ventricle and the left atrium occurred with concomitant significant clinical improvement of the patient. The authors discuss several treatment strategies: mitral valve repair surgery combined with revascularization, implantation of a biventricular ICD system or elimination of the focus of monomorphic VT runs by radiofrequency catheter ablation as a possible causal approach in the treatment of PVC-induced cardiomyopathy.

Body Surface Potential Mapping↗

PubMed2005

Dramatically improved left ventricular function after biventricular pacemaker implantation--a case report.

A case study of a patient suffering from severe chronic congestive heart failure resulting from ischemic cardiomyopathy in whom a biventricular (BiV) pacing system was implanted is reported. After a 1-year follow-up, left ventricular (LV) ejection fraction improved dramatically from an initial 15% to 60%, left ventricular end-diastolic diameter decreased, as did left atrial dimension. Tissue Doppler data and acute hemodynamic measurements taken during the biventricular pacemaker implantation procedure are presented. The case represents an exceptional example of left ventricular reverse remodeling with practically normalized left ventricular function after 1 year of synchronized pacing.

Aged↗

PubMed2005

Postmortem anatomy of the coronary sinus pacing lead.

Biventricular pacing nowadays represents a recognized method of nonpharmacological treatment of severe congestive heart failure refractory to medication. A growing number of biventricular implants is likely to bring an increasing demand for the extraction of specially designed coronary sinus (CS) leads for left ventricular pacing. There is a lot of data regarding conventional pacing or defibrillation lead extractions, but only very limited experience with the CS lead extractions. We describe the pathological-anatomical findings of a woman who died after 26 months postimplantation due to refractory ventricular fibrillation with focus on the left ventricular pacing lead course and feasibility of extraction.

Aged↗

PubMed2004

Triple-site pacing in patients with biventricular device-incidence of the phenomenon and cardiac resynchronization benefit.

BACKGROUND: In patients with biventricular pacing (BIV), triple-site pacing (TSP), i.e. standard biventricular cathodal pacing of the right and the left ventricle plus additional anodal capture of the right ventricle, is sometimes present. AIMS: To evaluate the incidence of TSP phenomenon, to examine TSP-related QRS changes, and to assess the effect of TSP on intraventricular resynchronization by means of tissue Doppler imaging (TDI). METHODS AND RESULTS: 23 patients with a first generation biventricular device (Medtronic 8040) and 16 patients with a new generation device (Medtronic 8042) were evaluated to look for the presence of TSP. TSP was found in 6 patients (26%) with the Medtronic 8040 (group I) and in 13 patients (81%) with the Medtronic 8042 device (group II). QRS duration decreased by 10 to 20 ms and QRS amplitude of leads I and aVL increased in almost all patients in group I during TSP modality. In group II, QRS morphology, duration and amplitude did not change as obviously. TDI analysis of the left ventricular (LV) basal segments showed significant shortening of the systole, together with a corresponding prolongation of the diastole, at the inferior wall of the LV, during TSP compared to standard BIV in all patients ( p < 0.01). Other LV segments did not show any change. Qualitative TDI electro-mechanical activation pattern of all LV segments improved in 22%, while it remained unchanged in 72%. CONCLUSIONS: TSP phenomenon can be identified in approximately a quarter of patients with the first-generation biventricular devices on the basis of the QRS morphology changes. In the second-generation biventricular pacemakers it can be demonstrated in the vast majority of patients. TSP may increase the effectiveness of cardiac resynchronization therapy by counteracting the regional activation delay located at the inferior wall of the LV.

Aged↗

PubMed2004

Endothelial damage and activation of the hemostatic system during radiofrequency catheter isolation of pulmonary veins.

AIMS: To determine the systemic thrombogenic effect of radiofrequency catheter isolation of the pulmonary veins (PVI) in the treatment of atrial fibrillation. METHODS AND RESULTS: We studied endothelial damage marker (von Willebrand factor [vWf]), fibrinolysis markers (tissue plasminogen activator [t-PA], plasminogen activator inhibitor-1 [PAI-1]) and coagulation activation markers (D-dimer [DD]) in 30 patients (pts) undergoing PVI. Heparin was administered continuously after double transseptal puncture in all pts. Concentrations of vWf and t-PA were significantly increased after accomplishing PVI compared to the baseline values, and elevated levels persisted 24 hours later ( p < 0.01). PAI-1 levels decreased following PVI compared to the baseline levels ( p = 0.02). PAI-1 levels normalized 24 hours after the procedure. DD increased continuously during the procedure with the peak following PVI ( p < 0.01). Higher DD concentrations persisted 24 hours later ( p = 0.02). In a multivariate analysis, total procedure time correlated significantly with the peak vWf and DD concentrations, while total RF energy dose correlated only with peak vWf ( r = 0.82). Time to heparin administration correlated with DD levels prior to the first RF pulse ( r = 0.83, p < 0.01) as well as after PVI ( r = 0.75, p < 0.01). A group of patients heparinized within the first hour of the PVI procedure had normal preablation DD levels and significantly mitigated DD levels following PVI compared to the group of patients heparinized later ( p < 0.01). CONCLUSIONS: Pulmonary vein ablations cause an increased systemic procoagulant state as reflected by fibrin turnover, fibrinolysis activation and endothelial perturbation. The activation of the coagulation cascade could be decreased by early heparin administration.

Adult↗

PubMed2003

Atrioventricular nodal reentrant tachycardia: anatomical and electrophysiological considerations.

Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common regular narrow QRS tachycardias. Although the principal understanding of the physiology of dual atrioventricular conduction as a substrate for the reentry mechanism in AVNRT has not changed during the last 25 years, there is still some uncertainty with regard to the exact circuit delineation. At least four forms of AVNRT have been described and several possible circuits have been proposed. Although the refinement of our knowledge about AVNRT seems to be purely academic since further insight will probably not increase the success rate of treatment by radiofrequency catheter ablation, AVNRT continues to puzzle both clinical and basic electrophysiologists. The authors summarize our present knowledge about AVNRT and stress the unique features of the atrioventricular junction anatomy and the current opinions on the reentrant impulse propagation.

Catheter Ablation↗

PubMed2003

Relations between monophasic action potential duration and refractoriness after cardioversion of persistent atrial fibrillation: results in wash-out and amiodarone-treated patients.

BACKGROUND: The relation between repolarization and refractoriness has been clinically evaluated both in the atrium and ventricle. However, this relation has not been carefully investigated in the atria of patients with persistent atrial fibrillation after cardioversion. METHODS: We determined the refractoriness and monophasic action potential duration at 90% of repolarization (MAP90), at 5 pacing cycle lengths (300 to 700 ms) and in 5 right atrial sites after internal cardioversion of persistent atrial fibrillation in 27 patients. RESULTS: The effective refractory periods (ERPs) were longer in amiodarone-treated patients (group 1) than in wash-out patients (group 2) (211.3 +/- 26.4 vs 199.1 +/- 24.3 ms, p < 0.002) as well as the MAP90 (243.6 +/- 36.8 vs 223.1 +/- 29.2 ms, p < 0.001). Linear regression analysis showed a direct relation between the MAP90 and ERP changes induced by different pacing cycle lengths (r = 0.77 and r = 0.92 in the amiodarone and wash-out patients, respectively). The ERP/MAP90 ratio was similar at all pacing cycle lengths in both wash-out and amiodarone groups and was always < 1. The mean ERP and MAP90 were shorter in the lateral right atrial sites than in the atrial roof and septum in both group 1 and group 2 patients (p < 0.001). CONCLUSIONS: A linear correlation was found between ERP and MAP90 in response to changes in pacing cycle lengths. Postrepolarization refractoriness was not observed after cardioversion of persistent atrial fibrillation. Pretreatment with oral amiodarone does not affect these electrophysiological features or the dispersion of ERP and MAP90 in the right atrium after sinus rhythm restoration.

Action Potentials↗

PubMed2003

Transesophageal low-energy cardioversion of atrial fibrillation without fluoroscopy outside the electrophysiology laboratory.

BACKGROUND: Low-energy internal cardioversion (LEIC) is a safe and effective procedure for the restoration of sinus rhythm in patients with atrial fibrillation refractory to external cardioversion. However, the procedure needs fluoroscopy and the use of the electrophysiology laboratory, even when the esophageal approach is utilized. The aim of this study was to assess the efficacy, safety and tolerability of a new simplified procedure of esophageal LEIC performed without fluoroscopy, outside the electrophysiology laboratory. METHODS: Thirty consecutive patients (23 males, 7 females) with persistent atrial fibrillation were submitted to LEIC using a step-up protocol (by steps of 50 V, starting from 200 V). Twenty (66%) were resistant to external cardioversion. A large surface area lead (cathode) was positioned within the esophagus, 45 cm from the nasal orifice. A second large surface area lead (anode) was positioned in the right atrium via the right internal jugular vein without fluoroscopic control. Synchronization of delivery of the shock with the QRS was achieved by means of two cutaneous electrodes positioned on the thoracic wall. RESULTS: Sinus rhythm was restored in 28 patients (93%) with a mean delivered energy of 15.2 +/- 7.5 J (range 5-27 J) and a mean impedance of 48.3 +/- 5.6 Ohm. No complication occurred during and after the procedure that was well tolerated under sedation. CONCLUSIONS: This new technique of performing esophageal LEIC is effective and seems to be safe and well tolerated. In this way internal cardioversion can be performed without fluoroscopy, outside the electrophysiology laboratory.

Aged↗

PubMed2003

Atrial flutter: arrhythmia circuit and basis for radiofrequency catheter ablation.

The term atrial flutter was introduced 90 years ago for an arrhythmia with a unique electrocardiographic pattern. The development of endocardial mapping techniques in the last decade allowed the detailed characterization of the tachycardia circuit and the identification of the cavotricuspid isthmus as its critical part. This review stresses the position of atrial flutter in the new classification of atrial tachycardias and focuses on its unique electrophysiological characteristics and different variants described in humans. Transcatheter radiofrequency ablation across the cavotricuspid isthmus constitutes a feasible and safe therapy, which prevents flutter recurrences during the long-term follow-up. This paper describes the different techniques that validate bidirectional isthmus block, which is an important endpoint for successful ablation.

Arrhythmias, Cardiac↗

PubMed2003

Risk stratification for arrhythmic events in patients with idiopathic dilated cardiomyopathy: a review of the literature and current perspectives.

The prognosis for patients with idiopathic dilated cardiomyopathy (DCM) has markedly improved during the last decade, mainly because of advancements in therapeutic strategies. However, sudden death still accounts for a significant part of the total mortality in patients with moderate disease. Recent primary prophylactic trials failed to demonstrate any benefit of cardioverter-defibrillator implantation in an unselected group of idiopathic DCM patients and thus the identification of the subgroup of patients at high arrhythmic risk is crucial. Although different risk stratification methods have been evaluated in risk assessment, the reported clinical value differs in studies, mainly because of differences in either methodology and/or patient selection. The present review focuses on arrhythmic events in idiopathic DCM and on the value of noninvasive methods and electrophysiological study in the risk stratification of this group of patients.

Arrhythmias, Cardiac↗

PubMed2003

The importance of indicators of the initial phase of atherosclerosis in patients with microvascular angina.

Endothelial dysfunction (ED) is generally considered to be the initial step in the progression to atherosclerosis but there is still much uncertainty about the role of the microvascular form of angina in patients with a normal coronary angiogram with regard to ED. The authors investigated the extent of endothelial perturbation and thereby whether the microvascular form of angina precedens macroscopic atherosclerosis by means of non-invasive ultrasound measurement of the intima-media thickening (IMT) in common carotid artery and flow mediated dilatation (FMD) in the brachial artery. 28 patients with stable angina with positive exercise test and ST segment depression (22 females, 6 males, average age 54 years) were compared with a control group consisting of 28 patients with no clinical signs of coronary artery disease (18 females, 10 males, average age 53 years). No significant difference in FMD% (7.3 vs. 10.8, p = 0.07) was found between the groups, though specific measurements (average dilatation of the brachial artery induced by ischemic insult, peak blood flow and peak hyperemic flow) differed considerably. Also IMT did not vary significantly between the groups (0.74 vs. 0.65, p = 0.08). In patients with IMT > 0.8 mm (6 patients in each group) a significant decrease of FMD was found as compared with patients with normal IMT (p < 0.05). It was concluded that in patients with increased IMT an inverse relationship between FMD and IMT exists both in patients with microvascular angina and in the healthy control subjects whereas in the group of patients with normal IMT no ED was demonstrated. This supports the hypothesis that the microvascular form of angina is the early stage of coronary artery atherosclerosis and this escapes angiographic recognition.

Adult↗