Biomedical subjects

Thomas Meinertz

Publications and source records attributed to Thomas Meinertz.

At least 55 records · Page 3Linked to original sources

PubMed2004

Sub-threshold stimulation in variants of atrioventricular nodal re-entrant tachycardia: electrophysiological effects and impact for guidance of slow pathway ablation.

AIM: Sub-threshold stimulation (STS) applied during atrioventricular nodal re-entrant tachycardia (AVNRT) of the common (slow-fast) type has been shown to effectively characterise target sites suitable for slow pathway (SP) ablation but has not been investigated in the setting of fast-slow and slow-slow variants. METHODS AND RESULTS: Seventeen consecutive patients (52+/-16 years, 12 female) with sustained uncommon type AVNRT (fast-slow: n = 13, slow-slow: n = 4) were investigated. Mapping of the SP was started postero-septally close to the coronary sinus ostium and continued toward mid-septal sites, if required. Target sites for STS were selected according to established criteria including the recording of the earliest retrograde atrial activation during AVNRT. Long duration (5 s) constant current STS during AVNRT variants was performed in a stepwise manner (max 5 mA) at each site eligible for SP ablation until termination or capture occurred. Radiofrequency current (RFC) was delivered following successful STS termination of tachycardia (65 degrees C, 60 s) and exclusion of catheter dislodgement. Uncommon AVNRT with a mean cycle length of 405+/-70 ms was induced without spontaneous termination in all patients. Interruption of AVNRT variants due to selective STS-induced block of the retrograde (n = 12) or anterograde (n =2) SP occurred without capture in 14/17 (82%) patients. This was exclusively observed at sites with successful subsequent RFC application. AVNRT was rendered non-inducible in all patients after a median of 1 (1-11) RFC pulses without complications. CONCLUSIONS: Uncommon AVNRT can be interrupted by STS delivered at subsequently successful target sites for SP ablation in most patients (82%). The high positive and negative concordance between the effects of STS and following RFC application indicates that STS-mapping is also useful in the setting of AVNRT variants.

Adult↗

PubMed2004

Suppression of paroxysmal atrial tachyarrhythmias--results of the SOPAT trial.

AIM: The indication to treat paroxysmal atrial fibrillation (PAF) is controversial. The Suppression of Paroxysmal Atrial Tachyarrhythmias (SOPAT) trial was designed to answer the following questions: (1) What is the average rate of spontaneous events of symptomatic PAF with and without anti-arrhythmic medication? (2) what is the prevalence of severe side-effects? and (3) is the fixed combination of Quinidine + Verapamil inferior to the efficacy of sotalol or not? METHODS AND RESULTS: Within 60 months 172 centres in Germany, Poland, and The Slovak Republic prospectively enrolled 1033 patients (mean age 60 years, 62% male) with documented frequent episodes of symptomatic PAF. Patients were randomised to either Quinidine + Verapamil 480/240 mg/d (high dose; 263 patients), Quinidine + Verapamil 320/160 mg/d (low dose; 255 patients), Sotalol 320 mg/d (264 patients) or placebo (251 patients), of which 1012 patients entered the intention-to-treat analysis. The primary endpoint was the time to first recurrence of symptomatic PAF or premature discontinuation. Secondary outcome parameters were the total number of symptomatic episodes and tolerability of the tested drugs. Patients were followed for a period of up to 12 months by daily and symptom-triggered trans-telephonic ECG-monitoring (Tele-ECG). The mean time under treatment was 233 +/- 152 days. Regarding the primary endpoint, all active treatments were superior to placebo and not different from each other. A total of 756 patients reached the primary endpoint within 105.7 +/- 8.7 d (mean +/- SEM) in the placebo group, vs. Quinidine + Verapamil (high dose) (150.4 +/- 10 d, p = 0.0061), vs. Quinidine + Verapamil (low dose) (148.9 +/- 10.6 d, p = 0.0006), vs. Sotalol (145.6 +/- 93 d, p = 0.0007). All three treatments were also effective in the reduction of AF burden (days with symptomatic AF [%] mean +/- SD, p vs. placebo): Quinidine + Verapamil (high dose) (3.4 +/- 12, p = 0.0001), Quinidine + Verapamil (low dose) (4.5 +/- 12.3, p = 0.008) and Sotalol (2.9 +/- 6.5, p = 0.026) compared to placebo (6.1 +/- 13.5). A total of four deaths, 13 syncopes, and one ventricular tachycardia (VT) occurred during the active study period, of which one death and one VT were related to Quinidine/Verapamil. CONCLUSION: Taken together, anti-arrhythmic therapy with the fixed combination of Quinidine + Verapamil is as effective as Sotalol in the reduction of the recurrence rate of symptomatic PAF with a low but definite risk of severe side-effects.

Adolescent↗

PubMed2004

Transmembraneous irrigation of multipolar radiofrequency ablation catheters: induction of linear lesions encircling the pulmonary vein ostium without the risk of coagulum formation?

INTRODUCTION: Pulmonary vein (PV) isolation for the curative treatment of atrial fibrillation using conventional radiofrequency ablation (RF) catheters with the point by point technique is time consuming and carries a remaining risk for thrombembolic complications. AIMS OF THE STUDY: Aim of the present in vivo study was to evaluate feasibility and safety of a novel multipolar irrigated ablation catheter designed to create contiguous lesions encircling the PV ostium in a single ablation position. METHODS: The entire ablation section (tripolar, length of each electrode 22 mm, interelectrode distance 2 mm, helix radius: 9 and 10 mm) of the 7F RF catheter (Encirclr, Medtronic, MN, USA) was covered by a porous membrane (pore size 30 micron) providing continuous irrigation. The helical formed catheter was used in two different experimental settings. Initially, a thigh muscle preparation has been performed in 7 anesthetized sheep in order to evaluate the development of lesions at different power level (40-80 W) and RF duration (30-90 sec). The ablation catheter was placed at the surface of the thigh muscle in a perpendicular position (0.1 N contact pressure) and perfused with heparinized blood (250 ml/min, 37C degrees ). Irrigation was provided with a flow rate of 10 ml/min. The resulted lesion morphology was evaluated with regard to coagulum or crater formation and lesion depth and diameter. Subsequently in 9 anesthetized sheep intracardiac ablation has been achieved with 50 W and an irrigation flow of 10 ml/min. Transseptal puncture and RF ablations were guided using fluoroscopy and intracardiac echocardiography (ICE, Acuson, USA). Endpoint of the intracardiac RF applications was the reduction of local electrogram amplitude >50%. RF applications were achieved at both atrial appendages and in the orifices of the coronary sinus (CS), the vena cava inferior (VCI) and PV. Following RF ablation all animals were sacrificed and following in vivo staining (2% TTC) macroscopically and histologically investigations of the lesions were performed. RESULTS: At the thigh muscle preparation 57 RF applications have been performed. The lesion depth was homogeneous without gaps between the ablation electrodes. There was a significant increase comparing 30 with 90 sec of RF duration for 40, 50 and 60 W applications respectively: 40 W: 1.1 +/- 0.4 vs. 3.6 +/- 0.5; 50 W: 1.2 +/- 0.3 vs. 4.6 +/- 0.4 mm and 60 W: 2.6 +/- 0.6 vs. 4.8 +/- 0.5 mm. All applications with 80 W (n = 3) had to be terminated due to immediate increase of impedance >150 omega. Late impedance rises (>60 sec) without occurrence of coagulum formation have been observed in 1 out of 4 RF applications with 60 W.A total of 85 RF applications could be achieved intracardiacally in the right atrium (right atrial appendage n = 18, ostium of the coronary sinus n = 12, ostium of the inferior caval vein: n = 12) and in the left atrium (left atrial appendage: n = 15, ostium of the PV: n = 28). ICE guided positioning of the catheter and showed during all applications no coagulum formation at the electrode or impedance rise (>150 Omega). Reduction of local electrograms (>50%) were observed following 48 out 85 (56%) RF applications. The lesions showed a homogeneous depth of 4 +/- 2 mm and a width 5 +/- 2 mm at the surface. No charring or crater formation could be observed in any of the lesions. CONCLUSIONS: In the present in vivo studies it could be demonstrated that long irrigated ablation electrodes induce continuous lesions without the risk of thrombus formation at the electrode. Increase of RF duration from 30 to 90 seconds with power setting of 40-60 W, respectively, created deeper lesions without the risk of thrombus formation. Thus, the helical formed irrigated ablation catheter appears to be appropriate for simplified PV isolation.

Animals↗

PubMed2004

Effect of atrial tachyarrhythmia duration on percentage of time with atrial pacing in pacemaker patients with paroxysmal atrial fibrillation.

UNLABELLED: Atrial pacing can prevent the recurrence of paroxysmal atrial tachyarrhythmia (AT) in pacemaker patients. The aim of the study was to determine in pacemaker patients the effect of AT duration on the percentage of time with atrial pacing by programming the same setting twice. METHODS: In 14 pacemaker patients with paroxysmal AT the dual-chamber pacemaker was programmed to identical parameters for two consecutive follow-up periods. The pacemakers were interrogated after three months to determine the percentage of time with atrial pacing relative to the total time of follow-up periods and the AT duration (atrial rates >150 bpm). The two three-month follow-up periods were compared to each other. The differences between the two follow-up periods were determined for the percentage of time with atrial pacing as well as for the AT duration. To assess the relationship between atrial pacing and AT duration, the differences between the two follow-up periods for atrial pacing and AT duration were correlated to each other. In addition, the percentage of atrial pacing was corrected for AT duration. RESULTS: Median percentage of atrial pacing relative to the complete follow-up period was 73% after the first and 76% after the second period and median AT duration 21% and 18%, respectively (not significantly different). The differences between the first and second study period were 1% for atrial pacing and -2% for AT duration. The percentage of atrial pacing and AT duration were inversely related together with a significant correlation coefficient of r = 0.95 ( p = 0.0001). After atrial pacing was corrected for AT duration, the percentage of atrial pacing relative to the time in sinus rhythm was significantly higher with a median of 93% for the first and second period ( p = 0.005). The correlation coefficient between the percentage of atrial pacing relative to the time in sinus rhythm and AT duration was r = 0.08 (not significant). CONCLUSIONS: The percentage of time with atrial pacing can be underestimated in patients with paroxysmal atrial fibrillation and should be carefully interpreted in relation to AT duration.

Aged↗

PubMed2004

Catheter ablation of common-type atrial flutter guided by three-dimensional right atrial geometry reconstruction and catheter tracking using cutaneous patches: a randomized prospective study.

INTRODUCTION: EnSite NavX (NavX) is a novel mapping and navigation system that allows visualization of conventional catheters for diagnostic and ablative purposes and uses them to create a three-dimensional (3D) geometry of the heart. NavX is particularly suitable for ablation procedures utilizing an anatomic approach, as in the setting of common-type atrial flutter (AFL). The aim of this study was to compare NavX-guided and conventional ablation procedures for AFL. METHODS AND RESULTS: Forty consecutive patients (32 male, 59 +/- 12 years) with documented AFL were randomized to undergo fluoroscopy-guided (group I, 20 patients) or NavX-guided (group II, 20 patients) ablation, including 3D isthmus reconstruction. The same catheter setup was used in both groups. The endpoint of bidirectional isthmus block was obtained in all patients. Compared to conventional approaches, NavX-guided procedures significantly reduced fluoroscopy time (5.1 +/- 1.4 min vs 20 +/- 11 min, P < 0.01) and total x-ray exposure (5.1 +/- 3.1 Gycm2 vs 24.9 +/- 1.6 Gycm2, P < 0.01). Isthmus geometry reconstruction could be performed in all patients of group II. In 4 patients (20%) of group II, anatomic isthmus variations were detected by NavX. No significant differences in radiofrequency current applications and procedural times were found between the two groups. CONCLUSION: NavX technology allows geometry reconstruction of the cavotricuspid isthmus. NavX-guided ablation of AFL reduces total x-ray exposure compared to the fluoroscopy-guided approach but does not prolong procedure time.

Atrial Flutter↗

PubMed2004

Pattern of isthmus conduction recovery using open cooled and solid large-tip catheters for radiofrequency ablation of typical atrial flutter.

INTRODUCTION: Open cooled-tip and solid 8-mm-tip catheters have demonstrated safety and effectiveness for radiofrequency current (RFC) ablation of typical atrial flutter (AFL). However, data from prospective and randomized studies in this setting are lacking. METHODS AND RESULTS: One hundred thirty consecutive patients (104 men; 61 +/- 11 years) with AFL were randomized to undergo RFC catheter ablation either using a solid 8-mm-tip catheter (group A, 65 degrees C, 70 W, 60 s) or an open irrigated-tip catheter (group B, 65 degrees C, 50 W, 60 s, 17 mL/min flow). Endpoint was bidirectional conduction isthmus block. In cases of repeated (two times) transient isthmus block, the catheter was changed (crossed over) to the catheter used in the other randomization arm, but patients remained in the original group following intention-to-treat analysis. The selected endpoint could be achieved in all patients after 12 +/- 6 RFC pulses in group A and 10 +/- 7 RFC pulses in group B (P = 0.11). Procedure times were longer (159 +/- 38 min vs 138 +/- 37 min, P = 0.002) and x-ray exposures higher in group A (fluoroscopy time 25 +/- 17 min vs 21 +/- 10 min, P = 0.08; x-ray dosage 3,133 +/- 2,576 cGy.cm2 vs 2,326 +/- 1,405 cGy.cm2, P = 0.03). Transient isthmus block was observed in 23 group A patients and 12 group B patients (P = 0.03). Onset time of transient isthmus block ranged from 0.5 to 27 minutes. Repeated transient isthmus block occurred in 8 of the 23 patients in group A after 19 +/- 3 RFC applications. After crossover to the cooled-tip catheter, the endpoint was reached another 5 +/- 1 RFC pulses. In group B, all patients could be treated without change of ablation catheter. After a follow-up of 14 +/- 2 months, 2 patients (3%) in group A and 1 patient (1.5%) in group B presented with AFL recurrence. CONCLUSION: Open cooled-tip catheters are more effective than solid large-tip catheters for AFL ablation. The greater effectiveness is evident in cases showing repeated conduction recovery within the cavotricuspid isthmus. Primary use of open irrigated-tip catheters should be considered for AFL ablation.

Atrial Flutter↗

PubMed2004

Arrhythmogenic right ventricular cardiomyopathy with left ventricular involvement and aortic dissection.

Ten years ago, a 59-year-old patient presented with ventricular fibrillations. The resting ECG showed findings typical for ARVC. Echocardiography and ventriculography confirmed the diagnosis of ARVC showing a dilated right ventricle with aneurysms. MRI showed additional fatty replacement of the LV. Furthermore, the diagnosis of a chronic aortic dissection was established. Two years after ICD implantation, the patient died of progressive right heart failure. On autopsy, most of the RV and parts of the LV were replaced by fatty tissue, and the media of the aorta showed degenerative changes. A pathogenetic link between the two diseases remains speculative at this time.

Aortic Dissection↗

PubMed2004

Radiofrequency catheter ablation of a macroreentrant ventricular tachycardia late after surgical repair of tetralogy of Fallot using the electroanatomic mapping (CARTO).

This case report describes a patient with a sustained monomorphic VT after surgical repair of a tetralogy of Fallot (TOF). In combination with the three-dimensional electroanatomic mapping system, CARTO, and conventional mapping techniques the VT was identified as a macro-reentrant tachycardia circling around the border between pulmonary graft and right ventricular outflow tract (RVOT). A y-shaped ablation line crossing this zone was created. The VT terminated during RF application and was not inducible again. This case underlines the use of a combined conventional and three-dimensional electroanatomic mapping technique can be helpful for catheter ablation of ventricular arrhythmias in TOF patients.

Adult↗

PubMed2004

Ten-year follow up after autologous rectus abdominis fascia sheath patch repair of aortic root abscess.

The infection of aortic annular tissue is a life-threatening complication of aortic valve endocarditis, the survival of which is usually with immediate surgical intervention. Optimal surgical techniques include aortic valve replacement with an aortic or pulmonary homograft, and reconstruction of cardiac structures with autologous pericardium. Here, two cases are reported with extensive aortic root infection and partial left ventricular-aortic dehiscence, who underwent left ventricular outflow tract reconstruction using a rectus abdominis fascia patch and aortic valve replacement with a Carpentier-Edwards porcine bioprosthetic graft. Both patients did well perioperatively and for 10 years postoperatively. The results may encourage alternative surgical strategies to be used when aortic valve homografts or autologous pericardium are unavailable. Notably, autologous rectus fascia patches showed excellent performance in the reconstruction of left ventricular outflow tract destruction associated with aortic root abscess.

Abscess↗

PubMed2003

Myeloperoxidase serum levels predict risk in patients with acute coronary syndromes.

BACKGROUND: Polymorphonuclear neutrophils (PMNs) have gained attention as critical mediators of acute coronary syndromes (ACS). Myeloperoxidase (MPO), a hemoprotein abundantly expressed by PMNs and secreted during activation, possesses potent proinflammatory properties and may contribute directly to tissue injury. However, whether MPO also provides prognostic information in patients with ACS remains unknown. METHODS AND RESULTS: MPO serum levels were assessed in 1090 patients with ACS. We recorded death and myocardial infarctions during 6 months of follow-up. MPO levels did not correlate with troponin T, soluble CD40 ligand, or C-reactive protein levels or with ST-segment changes. However, patients with elevated MPO levels (>350 microg/L; 31.3%) experienced a markedly increased cardiac risk (adjusted hazard ratio [HR] 2.25 [1.32 to 3.82]; P=0.003). In particular, MPO serum levels identified patients at risk who had troponin T levels below 0.01 microg/L (adjusted HR 7.48 [95% CI 1.98 to 28.29]; P=0.001). In a multivariate model that included other biochemical markers, troponin T (HR 1.99; P=0.023), C-reactive protein (1.25; P=0.044), vascular endothelial growth factor (HR 1.87; P=0.041), soluble CD40 ligand (HR 2.78; P<0.001), and MPO (HR 2.11; P=0.008) were all independent predictors of the patient's 6-month outcome. CONCLUSIONS: In patients with ACS, MPO serum levels powerfully predict an increased risk for subsequent cardiovascular events and extend the prognostic information gained from traditional biochemical markers. Given its proinflammatory properties, MPO may serve as both a marker and mediator of vascular inflammation and further points toward the significance of PMN activation in the pathophysiology of ACS.

Abciximab↗

PubMed2003

Platelet glycoprotein IIb/IIIa receptor blockade improves vascular nitric oxide bioavailability in patients with coronary artery disease.

BACKGROUND: Platelet glycoprotein IIb/IIIa receptor blockade not only enhances epicardial flow but also improves microvascular perfusion. Inhibition of abnormal platelet-endothelial interactions may contribute to this beneficial effect. The present study was designed to determine whether glycoprotein IIb/IIIa receptor blockade influences endothelial vasomotor function and NO bioactivity in patients with coronary artery disease. METHODS AND RESULTS: Forty patients with symptomatic coronary artery stenosis were studied before planned percutaneous coronary intervention. By using venous occlusion plethysmography, endothelium-dependent and -independent vasodilation was determined by measuring forearm blood flow responses to acetylcholine with and without NG-monomethyl-L-arginine (L-NMMA) and sodium nitroprusside. Vascular function tests were repeated during glycoprotein IIb/IIIa receptor blockade by tirofiban in 27 patients and by eptifibatide in 13 patients. A subgroup of 10 patients was retested 6 hours after stopping infusion of tirofiban. Glycoprotein IIb/IIIa receptor blockade by both substances improved acetylcholine-induced vasodilation and L-NMMA responses. Six hours after withdrawal of tirofiban infusion, the beneficial effects were not evident. Sodium nitroprusside-induced vasodilation was not changed by glycoprotein IIb/IIIa receptor blockade. CONCLUSIONS: These findings support the concept that abnormal platelet-endothelial interactions contribute to endothelial dysfunction and impaired NO bioactivity in patients with symptomatic coronary artery disease.

Acetylcholine↗

PubMed2003

Nebivolol prevents vascular NOS III uncoupling in experimental hyperlipidemia and inhibits NADPH oxidase activity in inflammatory cells.

OBJECTIVE: Nebivolol, in contrast to other selective beta1-adrenergic receptor antagonists like atenolol, improves endothelial function in patients with oxidative stress within vascular tissue. With the present studies we sought to determine whether beta receptor blockade with nebivolol may improve endothelial function in hyperlipidemia and whether this is attributable to reductions in vascular oxidative stress. METHODS AND RESULTS: Watanabe heritable hyperlipidemic rabbits (WHHL) were treated with nebivolol (10 mg/kg per day for 8 weeks). New Zealand white rabbits (NZWR) served as controls. Nebivolol improved endothelial function, reduced vascular superoxide and vascular macrophage infiltration, and prevented NO synthase uncoupling in WHHL. Nebivolol treatment did not modify the expression of sGC or cGK-I but improved cGK-I activity (assessed by the phosphorylation state of the VAsodilator Stimulated Phosphoprotein at serine239, P-VASP). NAD(P)H oxidase activity in whole blood and isolated neutrophils was dose-dependently inhibited by nebivolol, whereas atenolol, metoprolol, and carvedilol were markedly less effective. CONCLUSIONS: Nebivolol therapy effectively prevents NO synthase III uncoupling and prevents activation of the neutrophil NAD(P)H oxidase and infiltration of inflammatory cells. These novel antioxidative stress actions of this compound may explain partly the beneficial effects on endothelial function in patients with enhanced vascular oxidative stress.

Adrenergic beta-Antagonists↗

PubMed2003

Intramural hematoma of the aorta: predictors of progression to dissection and rupture.

BACKGROUND: Aortic intramural hematoma (IMH) is a variant of overt aortic dissection. The predictors of progression of IMH to dissection and rupture are still unknown, and strategies for management are not established. METHODS AND RESULTS: A multicenter study was conducted comprising 66 patients with IMH and hospital admission <or=48 hours after onset of initial symptoms. Among these, progression to aortic dissection or rupture occurred in 30 (45%) and death occurred in 13 (20%) patients within 30 days. Late progression was noted in 14 (21%) and death in 11 (17%) patients, yielding a 1-, 2-, and 5-year survival of 76%, 73%, and 43%, respectively. In a set of 9 variables, multivariate analysis identified IMH location in the ascending aorta (type A; P=0.02) and moderately ectatic aortic diameters (49+/-13 mm with progression versus 57+/-16 mm without progression; P=0.03) as independent predictors of early progression. In type A IMH, early mortality was 8% with swift surgery versus 55% without surgery (P=0.004). The risk of late progression of IMH was independently associated with age at index diagnosis (P=0.01) and absence of beta-blocker therapy during follow-up (P=0.03). Kaplan-Meier analysis confirmed improved 1-year survival of IMH with beta-blocker therapy (95% versus 67% without beta-blockers; P=0.004). CONCLUSIONS: Regardless of aortic diameter, IMH of the ascending aorta (type A) is at high risk for early progression, and, thus, undelayed surgical repair should be performed. Moreover, oral beta-blocker therapy may improve long-term prognosis of IMH independent of anatomical location.

Adult↗

PubMed2003

Large tip electrodes for successful elimination of atrial flutter resistant to conventional catheter ablation.

The most widely accepted criterion for successful radiofrequency catheter (RFC) ablation of typical atrial flutter is the development of bi-directional isthmus block. In a subset of patients, conventional RFC ablation fails to achieve this endpoint because deeper and wider lesions are required. We investigated the efficacy of a long 8-mm tip catheter in these cases. One hundred and seventy-four consecutive patients (137 male; 61 +/- 9 years) with recurrent typical atrial flutter underwent conventional RFC ablation first with a standard 4 mm tip catheter. In resistant cases (n = 52), ablation was continued using a large tip 8-mm catheter when the 4-mm tip catheter failed. Resistant atrial flutter was identified when 21 RFC pulses failed to reach the selected endpoint of bi-directional isthmus block or in cases of transient bi- directional block (at least 3 episodes). In 122 of the 174 patients (70%) conventional atrial flutter ablation was successfully performed with 13 +/- 5 RFC applications. In the remaining 52 subjects (30%), the ablation procedure was completed using the large tip electrode catheter. In 30 of these 52 patients (58%), the catheter was changed because of persistent intra-atrial conduction after 21 RFC pulses and in 22 (42%) because of intermittent conduction block after 11 +/- 5 applications. Using the large tip electrode catheter, the selected endpoint was achieved in all patients of both groups with 3 +/- 2 RFC pulses (power output of 50-60 W, pulse duration of 60 sec). No post-procedure complications were observed. After 15 +/- 5 months of follow-up, 16 patients (9%) had recurrence of atrial flutter. Five of the patients had been in the resistant group. In patients with atrial flutter resistant to conventional ablation therapy, the long tip (8-mm) catheter appears to be a safe and effective alternative to use of the conventional 4-mm tip catheter.

Atrial Flutter↗

PubMed2003

Feasibility of atrial sensing via a free-floating single-pass defibrillation lead for dual-chamber defibrillators.

BACKGROUND: Detection and misclassification of rapidly conducted atrial fibrillation (AF) and marked sinus tachycardia by implantable cardioverter defibrillators (ICD) can result in the delivery of inappropriate therapies. Continuous atrial sensing may improve the differentiation between supraventricular and ventricular tachycardia. The present approach is to implant a separate atrial pacing lead connected to a dual-chamber defibrillator. We hypothesized that a free-floating single-pass defibrillation lead reliably senses the atrial electrical activity. The aim of the study was to assess during implantation the efficacy of a custom-built free-floating single-pass defibrillation lead and to record sinus rhythm (SR), induced AF, and atrial flutter (Afl). METHODS: The free-floating single-pass defibrillation lead (Biotronik, Berlin, Germany) had an atrial bipole with 10 mm spacing and a distance between the atrial bipole and the electrode tip of 13.5, 15 or 17-cm. The lead was temporarily implanted in 15 patients during an ICD implantation. Fifteen seconds recordings were made during SR and after the induction of AF and Afl as well as during induced ventricular fibrillation. The amplitude and the time that the amplitude was less than 0.3 mV were assessed. RESULTS: The amplitude during SR (2.1 +/- 1.4 mV) was significantly higher compared with the amplitudes for Afl (1.3 +/- 0.5 mV; p < 0.02) and AF (0.7 +/- 0.5 mV; p < 0.001). Low amplitudes were not observed during SR and rarely during Afl (1.6 +/- 3.1%), but they were observed 19.9 +/- 15.9% of the time during AF (p < 0.05). The correlation coefficients between SR and AF amplitudes were r = 0.25, between SR and Afl amplitudes r = 0.31, and between AF and Afl amplitudes r = 0.41. During the ventricular fibrillation conversion test 9 patients were in continuous SR. The P-wave amplitude before the induction of ventricular fibrillation was 2.1 +/- 1.4 mV. The signal during ventricular fibrillation decreased to 1.1 +/- 0.7 mV and increased immediately after the termination of ventricular fibrillation to 1.6 +/- 0.8 mV. CONCLUSIONS: The recorded unfiltered signals indicate that SR as well as AF and Afl can immediately be detected after the implantation of the new free-floating single-pass defibrillation lead. High signal amplitude during SR did not predict high amplitude during AF or Afl. During induced ventricular fibrillation the P-wave amplitude decreased intermittently.

Aged↗

PubMed2003

Dissociated activity and pulmonary vein fibrillation following functional disconnection: impact for the arrhythmogenesis of focal atrial fibrillation.

The present study sought to investigate the electrophysiological properties of isolated pulmonary veins following successful radiofrequency (RF) catheter ablation in patients with paroxysmal atrial fibrillation (PAF). Overall, 71 pulmonary veins in 37 consecutive patients (age: 56 +/- 9 years) with recurrent PAF were targeted for RF ablation at the ostial region in order to achieve a complete functional block. Following disconnection, the incidence of dissociated pulmonary vein (PV) activity and its response to orciprenalin were studied. RF ablation abolished conduction in 67 (94%) of 71 potentially arrhythmogenic PVs after a mean of 10.7 +/- 6.4 RF applications for each PV. After ablation, spontaneous dissociated automatic activity (9 to 52 beats/min, median 27) was found in 6 out of 67 isolated PVs (left superior: n = 1, left inferior: n = 1, right superior: n = 2, common left PV: n = 2). Slight acceleration (13 to 68 beats/min, median 29) of dissociated PV activity was observed during infusion of orciprenalin. Following isolation, initiation of sustained or nonsustained local fibrillation was recorded in only two cases of the common left sided PV with preceding automatic activity. In one patient PV fibrillation occurred during orciprenalin infusion following a repetitive response to a dissociated automatic rhythm with increasing duration as well as destabilization. In the other patient, PV fibrillation occurred immediately after the occurrence of PV automaticity. Slow dissociated automatic rhythms are detectable within 9% of disconnected PVs. The unique anatomic substrate of common left PVs seem to favor the occurrence of local fibrillation following isolation. The initiation pattern of fibrillation within the isolated PV has pathophysiological implications and underlines the contribution of multiple factors to the onset and sustenance of PAF.

Aged↗

PubMed2003

Electrical disconnection of an arrhythmogenic superior vena cava with discrete radiofrequency current lesions guided by noncontact mapping.

This case describes a 54-year-old patient with paroxysmal atrial fibrillation and atrial flutter. Conventionally recorded local electrogram demonstrated a cycle length of 245 ms in the SVC which was conducted to the right atrium in a 2:1 fashion. The analysis of the virtual unipolar local electrogram from the noncontact mapping system demonstrated slow conduction between SVC and right atrium orthogonal to the atrial breakthrough in the upper part of the crista terminalis. RF ablation at the atrial breakthrough induced the electrical disconnection between the CVC and the right atrium.

Atrial Fibrillation↗

PubMed2003

Diagnostic yield of external electrocardiographic loop recorders in patients with recurrent syncope and negative tilt table test.

External electrocardiographic loop recording permits extended cardiac rhythm monitoring and ECG storage before and after device activation. The purpose of the study was to assess the diagnostic yield of external loop recorders in patients with more than two syncopal events within the last 6 months and a negative tilt table test. Twenty-four consecutive patients (51 +/- 14 years, male n = 9) were enrolled with 3 +/- 4 recurrent syncopal events within the last 6 months and no overt structural heart disease. The loop recorder CardioCall continuously records a two-channel ECG via skin electrodes. When activated, up to 4.5 minutes of the ECG preceding activation is stored. The time between tilt table testing and monitoring was 5 +/- 4 weeks. The average monitoring period covered 50 +/- 22 days. Recording was either unsuccessful or terminated prematurely in 5 patients. The reasons were skin irritation secondary to the electrodes in two patients, cable damage in one patient, and two patients inadvertently erased the stored data when replacing the batteries. Fourteen patients activated the loop recorder at least once. Symptoms leading to device activation were syncope (n = 1), dizziness (n = 11), feeling unwell (n = 7), palpitations (n = 5), headaches (n = 1), and chest pain (n = 1). The loop recorder documented sinus tachycardia during the syncopal event. Sinus tachycardia was also observed in 7 other patients, and atrial flutter in two patients. Eight patients had recurrent syncope with two patients experiencing syncope prior to the monitoring period, one syncope occurred in a patient who inadvertently erased the stored data, one event coincided with sinus tachycardia, and 4 (17%) patients had syncope during 15 +/- 10 months after termination of loop monitoring. The external loop recorder was not very useful for arrhythmia detection in patients with syncopal events, no overt heart disease, and a negative tilt table test because the cardiac rhythm was stored in only 1 of 8 (13%) patients with recurrent syncope. Reasons for the low diagnostic yield of external loop recorders were infrequent syncopal events after the baseline evaluation, with rare events during the limited monitoring period in particular, and premature termination or unsuccessful recording in 21% of patients.

Arrhythmias, Cardiac↗