PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Atrioventricular Node”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1997

Complex electrophysiological characteristics in atrioventricular nodal reentrant tachycardia with continuous atrioventricular node function curves.

BACKGROUND: Although typical atrioventricular nodal reentrant tachycardia (AVNRT) with discontinuous AV node function curves has been well studied, there has been a lack of any significant information about AVNRT without evidence of dual AV nodal pathway physiology during atrial extrastimulus testing or atrial pacing. METHODS AND RESULTS: Group 1 included 9 patients with continuous curves during atrial extrastimulus testing but without a jump (> or = 50 ms) of the atrial-His bundle (AH) interval during incremental atrial pacing. The maximal AH interval during atrial pacing (266 +/- 61 versus 168 +/- 27 ms, P = .007) or extrastimulus testing (290 +/- 60 versus 176 +/- 18 ms, P = .005) shortened significantly after ablation. Antegrade and retrograde AV node properties were similar before and after ablation. Group 2 included 14 patients with continuous curves and a jump of the AH interval during incremental atrial pacing. The atrial pacing cycle length with 1:1 AV conduction and effective refractory period (ERP) of the antegrade AV node increased significantly, whereas the maximal AH interval during atrial pacing (358 +/- 70 versus 203 +/- 28 ms, P = .001) or extrastimulus testing (338 +/- 75 versus 196 +/- 34 ms, P = .002) shortened significantly after ablation. Group 3 included 24 patients with discontinuous curves. The maximal AH interval during atrial pacing or extrastimulus testing and the ERP of the antegrade fast AV node shortened, whereas the ERP of the antegrade AV node increased significantly after ablation. The maximal AH interval before ablation, extent of decrease in maximal AH interval after ablation, ERP of the retrograde AV node before ablation, and tachycardia cycle length were significantly shorter in group 1 than groups 2 and 3. CONCLUSIONS: In AVNRT with continuous AV node function curves, dual AV nodal pathway physiology may or may not be demonstrated during atrial pacing. Significant shortening of the maximal AH interval during atrial pacing after radiofrequency ablation suggests successful elimination of AVNRT.

Catheter Ablation↗
PubMed1994

A report on selective radiofrequency ablation of dual atrioventricular node pathways in 34 cases.

Selective ablation of slow pathway by radiofrequency (RF) current in 34 patients with atrioventricular (AV) node pathways and tachycardia was performed with two methods in our section; posterior approach was used in the first 12 patients, the slow pathways were ablated successfully. Inferior approach was performed in the other 22 patients. Slow pathways were interrupted in 14 patients. Retrograde fast pathways and/or slow pathways were ablated in 6 patients. Retrograde fast pathways and slow pathways were abolished and antegrade fast pathways were injured transitorily in 2 cases. The total procedure time was shorter, RF applications were fewer by inferior approach than by posterior approach (P < 0.05). Both antegrade and retrograde conduction of fast pathways had not been affected after slow pathways were ablated (P > 0.05). After a mean of 8 months follow-up, two patients recurred and were ablated successfully again. We come to the conclusion that inferior approach might be a preferable method compared with posterior approach; the slow pathways is the compact node and its posterior input of transitional cells; the retrograde fast pathway may be the anterior superficial group of transitional cells and is not always in the same location of antegrade fast pathway.

Adult↗
PubMed1993

Radiofrequency ablation for atrioventricular node reentrant tachycardia: comparison between fast (anterior) and slow (posterior) pathway ablation.

OBJECTIVES: We compared the electrophysiologic effects on atrioventricular (AV) node physiology of selective "fast" versus selective "slow" pathway radiofrequency ablation in 42 patients with drug-resistant AV node reentrant tachycardia who underwent 51 ablation attempts to prevent tachycardia recurrence while preserving AV conduction. BACKGROUND: The recent introduction of radiofrequency ablation to treat AV node reentrant tachycardia allows the opportunity to study the effects of selective elimination of the different limbs involved in AV node reentrant tachycardia. METHODS: Selective fast pathway ablation was attempted in 13 patients by delivering radiofrequency energy anteriorly across the tricuspid valve anulus. Selective slow pathway ablation was attempted in 29 patients by delivering radiofrequency energy posteriorly across the tricuspid valve anulus at sites where putative slow pathway potentials were recorded. RESULTS: Selective fast pathway ablation eliminated AV node reentrant tachycardia without AV block in 6 (46%) of 13 patients after one ablation session and in an additional 3 patients (69% of total) after repeat ablation sessions. Slow pathway ablation eliminated AV node reentrant tachycardia without AV block in 26 (90%) of 29 patients after one radiofrequency ablation session and in an additional 2 patients (97% of total) after repeat ablation sessions. Selective fast pathway ablation increased the PR interval (140 to 220 ms, p = 0.0001) and AH interval (66 to 153 ms, p = 0.0001), whereas slow pathway ablation did not change these intervals. Fast pathway radiofrequency ablation caused retrograde block in 7 (64%) of 11 patients, whereas no patients undergoing slow pathway ablation developed selective retrograde block. Single AV node echo beats were commonly induced after slow but not fast pathway ablation (17 of 29 patients vs. 1 of 11 patients, respectively, p = 0.01) and did not predict recurrence of AV node reentrant tachycardia. CONCLUSIONS: Successful selective radiofrequency ablation of fast or slow pathways in patients with AV node reentrant tachycardia resulted in different electrophysiologic properties after ablation. Slow pathway ablation produced more successful outcomes, with a decreased prevalence of recurrent AV node reentrant tachycardia or AV block.

Atrioventricular Node↗
PubMed1993

A method for isolating rabbit atrioventricular node myocytes which retain normal morphology and function.

This report describes a method for isolating single rabbit atrioventricular (AV) node myocytes which retain their normal morphology when exposed to millimolar levels of calcium. Previous attempts to isolate cells from the AV node have produced myocytes that "round up" (i.e., go into contracture) when exposed to calcium. We show that the cells isolated with our technique possess properties similar to those described for intact AV nodal tissue. We find that single AV node myocytes are shorter and thinner (mean dimension = 103.5 +/- 2.3 by 7.8 +/- 0.2 microns; mean +/- SE, n = 90) than atrial or ventricular cells. Many of the cells produced by this isolation procedure generate spontaneous action potentials (188 +/- 9 beats/min; n = 6), which resemble action potentials recorded previously from the intact AV node. Voltage-clamp recordings from spontaneously active cells revealed similar membrane currents to those seen in intact tissue: fast sodium current and a L-type calcium current, followed by a delayed outward current. However, we found little evidence for the hyperpolarization-activated current (I(f)). Because the cells responded normally to concentrations of acetylcholine and isoproterenol within the physiological range, their cholinergic and adrenergic receptors appear to be well preserved by the isolation procedure. The ability to isolate morphologically and functionally normal AV myocytes may represent a significant advance for the investigation of nodal physiology at the cellular level.

Acetylcholine↗
PubMed2002

Sudden death after radiofrequency ablation of the atrioventricular node in patients with atrial fibrillation.

OBJECTIVES: We evaluated the incidence and predictors of sudden death after atrioventricular (AV) node ablation and pacemaker implantation. BACKGROUND: Sudden death may occur after radiofrequency catheter ablation of the AV node and pacemaker implantation in patients with atrial fibrillation (AF). Whether it is related to the procedure or to pre-existing heart disease remains unclear. METHODS: All patients who had radiofrequency catheter ablation of the AV node and pacemaker implantation for rate control of medically refractory AF were identified retrospectively and observed prospectively. All patients with sudden death after ablation were identified. The relationship between the procedure and sudden death was defined on the basis of the time between the two as "likely," "possibly" or "unlikely." RESULTS: Of 334 consecutive patients with AF who underwent AV node ablation, nine had sudden death after the ablation. Four patients (1.2%) had sudden death likely related to the procedure: in 3 patients, arrest occurred within 48 h after the procedure; in one patient, arrest occurred four days after the procedure. In three other patients (0.9%), sudden death was possibly related to the procedure because the event occurred within three months afterward. The remaining two deaths were unrelated to the procedure. Diabetes, New York Heart Association functional class (>or=II), preprocedure ventricular arrhythmia, mitral or aortic stenosis, aortic regurgitation and chronic obstructive pulmonary disease were independent predictors for sudden death. CONCLUSIONS: Sudden death likely or possibly related to catheter ablation occurred in 7 of 334 patients (2.1%). Risk of sudden death is highest within two days after the procedure.

Aged↗
PubMed1976

Action potential changes under varied [Na+]0 and [Ca2+]0 indicating the existence of two inward currents in cells of the rabbit atrioventricular node.

In the perfused rabbit heart,the upstroke of the transmembrane action potential of fibers of the atrioventricular (AV) node presents two distinct components. The first depends strongly on extracellular sdoium concentration, but the degree to which it is activated is influenced by extracellular calcium, as indicated by the correlation between its Vmax and [Ca2+]0. The second component depends on calcium and sodium concentrations and is blocked by Mn ions. An analysis comparing action potentials from atrial (A), atrionodal (AN), and nodal (N) fibers shows that the second component of the upstroke of the action potential contributes 12%, 27%, and 34% to the total depolarization. The results suggest that the upstroke of the nodal action potential results from the activation of two inward currents, as in ordinary cardiac fibers. We postulate that (1) the degree of steady state inactivation of gNa is larger in N than in A fibers because of the low resting potential of the former, and (2) the contribution of the second channel to the upstroke depends on the time course of the previous depolarization and the potential level at which this component is activated.

Action Potentials↗
PubMed1988

[Catheter-induced modulation of the electric conductivity of the atrioventricular node by high-frequency current].

A radio-frequency current was delivered via a catheter to the atrioventricular (AV) node in 13 patients with supraventricular arrhythmias (maximal heart rate 215/min). In nine patients with atrial fibrillation, three with AV nodal re-entry tachycardia and one with AV re-entry tachycardia, AV node conduction time was prolonged from 95 +/- 43 ms to 168 +/- 72 ms. In three patients the radio-frequency current had no lasting effect, necessitating AV node ablation with a direct-current shock. During a mean observation period of five months, all ten patients in whom the radio-frequency current had been successfully applied remained free of symptoms without any anti-arrhythmia treatment. There were no complications during or after treatment.

Adult↗
PubMed1996

Regulation by acetylcholine of Ca2+ current in rabbit atrioventricular node cells.

Effects of acetylcholine (ACh) on L-type Ca2+ current (ICa) were examined in isolated atrioventricular (AV) node cells exhibiting spontaneous contractions and pacemaker current (If). ACh at a saturating concentration of 10 microM reduced basal ICa by 48 +/- 6%. The ACh effect was abolished by dialysis with 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), an adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase inhibitor, or guanosine-5'-O-(2-thiodiphosphate). Dialysis with guanosine 3',5'-cyclic monophosphate (cGMP) or NG-monomethyl-L-arginine (L-NMMA) and application of the cGMP-dependent protein kinase inhibitor KT-5823 (1 microM) did not affect ACh inhibition of ICa. Nitric oxide donor 3-morpholinosydnonimine (100 microM) and type III phosphodiesterase (PDE) inhibitor trequinsin (10 nM) enhanced basal ICa by 10-20%, whereas type IV PDE inhibitor Ro-20-1724 (30 microM) together with trequinsin caused a large ICa stimulation comparable to that by 3-isobutyl-1-methylxanthine (IBMX). These findings indicate that ACh inhibits basal ICa primarily by suppressing cAMP synthesis and that these cells have a potent type III and IV PDE activity to determine the basal cAMP concentration. When ICa was stimulated by IBMX (100 microM), the inhibitory effect of ACh was slightly reduced by L-NMMA, cGMP, and methylene blue but not by KT-5823 or Ro-20-1724. ACh hardly inhibited, or even enhanced, IBMX-stimulated Ica when forskolin (3 microM) was coapplied or the IBMX concentration was increased to 500 microM. These findings suggest that cAMP is degraded in the presence of 100 microM IBMX to some extent. Type II PDE, for which IBMX has a relatively high inhibitor constant, seems to contribute partially to the cAMP degradation.

1-Methyl-3-isobutylxanthine↗
PubMed1995

Modulation of atrioventricular conduction by ablation of the "slow" atrioventricular node pathway in patients with drug-refractory atrial fibrillation or flutter.

OBJECTIVES: We hypothesized that modulation of atrioventricular (AV) node conduction, allowing a reduction in ventricular rate during atrial fibrillation or flutter without affecting AV conduction during sinus rhythm, might be achieved through ablation of the "slow" AV node pathway. BACKGROUND: In patients with atrial fibrillation or flutter not amenable to a direct atrial approach, ablation of the His bundle is performed to induce complete AV block. This procedure causes pacemaker dependence. METHODS: Fourteen patients with drug-refractory paroxysmal atrial flutter or fibrillation underwent ablation of the slow AV node pathway. Radiofrequency current was delivered in six patients during sinus rhythm, in six during atrial flutter and in two during atrial fibrillation. RESULTS: The anterograde effective refractory period of the AV node was prolonged from 270 +/- 50 (mean +/- SD) to 390 +/- 87 ms (p = 0.005) and the Wenckebach cycle from 346 +/- 33 to 458 +/- 75 ms (p = 0.004) in six patients during sinus rhythm. Mean AV ratio increased from 1.6 +/- 0.5 to 3.0 +/- 0.6 (p = 0.02) in six patients with atrial flutter. Mean ventricular rate decreased from 157 +/- 38 to 67 +/- 10 beats/min in two patients with atrial fibrillation. Complete AV block was induced in two patients (transient in one, permanent in one). During a follow-up period of 5.8 +/- 3.5 months, 11 patients experienced a recurrence of atrial fibrillation at 60 to 95 beats/min. No patient had progression to any degree of AV block. CONCLUSIONS: Ablation of the slow AV node pathway allows reduction of ventricular rate during atrial fibrillation or flutter while maintaining intact AV conduction during sinus rhythm. Modulation of AV node conduction is effective in most patients as an alternative to His bundle ablation for control of ventricular rate in paroxysmal atrial fibrillation or flutter.

Adult↗
PubMed1995

Radiofrequency ablation of atrioventricular node reentrant tachycardia: experience in 302 patients.

Radiofrequency catheter ablation was performed in 302 consecutive patients with drug refractory atrioventricular (AV) node reentrant tachycardia. Fast pathway ablation was attempted in 167 patients and was successful in 161 patients (96.4%). At a mean follow-up of 24 +/- 12 months, there were 21 tachycardia recurrences (12.5%). A second fast pathway ablation was attempted in 17 patients and was successful in all but 1 patient. Permanent complete AV block occurred in 12 patients (7.2%). Among the latter, late AV block was noted in 5 patients. Final success without pacemaker implantation was accomplished in 151 patients (90.4%). Slow pathway was attempted in 135 patients and was successful in 130 patients (96.3%). Three patients in whom slow pathway ablation failed underwent successful fast pathway ablation during the same session. At a mean follow-up of 14 +/- 11 months, there were 16 tachycardia recurrences (11.8%). A second slow pathway ablation was attempted in 16 patients and was successful in all but 1 patient. Permanent complete AV block occurred in 3 patients (2.2%). An additional patient developed 2 : 1 AV block during exercise, 3 months after ablation. Final success without pacemaker implantation was achieved in 129 patients (95.5%). Fast and slow pathway ablation had similar success and recurrence rates, procedure and fluoroscopy times, and number of radiofrequency pulses. However, the incidence of permanent complete AV block was higher following fast pathway ablation (p = 0.049). Although equally effective, slow pathway ablation is safer than fast pathway ablation, therefore, should be the first choice approach for treatment of AV node reentrant tachycardia.

Adolescent↗
PubMed1997

Electrotonic modulation of electrical activity in rabbit atrioventricular node myocytes.

Electrotonic effects of electrically coupling atrioventricular (AV) nodal cells to each other and to real and passive models of atrial and ventricular cells were studied using a technique that does not require functional gap junctions. Membrane potential was measured in each cell using suction pipettes. Mutual entrainment of two spontaneously firing AV nodal cells was achieved with a junctional resistance (Rj) of 500 M omega, which corresponds to only 39 junctional channels, assuming a single-channel conductance of 50 pS. Coupling of AV nodal and atrial cells at Rj of 50 M omega caused hyperpolarization of the nodal cell, decreasing its action potential duration and either slowing or blocking diastolic depolarization in the AV node myocyte. Opposite changes occurred in the atrial action potential. When AV nodal and ventricular cells were coupled at Rj of 50 M omega, nodal diastolic potential was markedly hyperpolarized and diastolic depolarization was completely blocked with little change in ventricular diastolic potential. However, coupling did elicit marked changes in the action potential duration of both cells, with prolongation in the nodal cell and shortening in the ventricular cell. Nodal maximum upstroke velocity was increased by both atrial and ventricular coupling, as expected from the hyperpolarization that occurred. With an Rj of 50 M omega, spontaneous firing was blocked in all single AV nodal pacemaker cells during coupling to a real or passive model of an atrial or ventricular cell. These results demonstrate that action potential formation and waveform in a single AV nodal cell is significantly affected by electrical coupling to other myocytes.

Animals↗
PubMed2006

Clinical anatomy of the atrioventricular node artery.

BACKGROUND AND AIM OF THE STUDY: The study aim was to describe the topographical relationship of the atrioventricular (AV) node artery and mitral valve annulus fibrosus with regard to AV node dysfunction following mitral valve replacement or ring annuloplasty. METHODS: The anatomy of the AV node artery was analyzed in 55 human hearts without previous pathological alterations. Selective coronary angiograms were performed to identify the AV node origin. Run-off of the AV node artery and its topographical relationship to the mitral valve attachment was analyzed in dry-dissected hearts. The position of the AV node was verified by histological sectioning. RESULTS: The AV node artery originated from the right coronary artery in 73% of examined cases, and from the left coronary artery in 27% of cases. The left AV node artery was closely related to the mitral valve attachment, especially at the area of the left proximal part of the posterior leaflet. CONCLUSION: These morphological data were compared to clinical reports emphasizing the postoperative incidence of AV block after mitral valve implantation and ring annuloplasty. The occurrence of early postoperative AV node block ranged from 20% to 37%. By comparing the present data with available literature, it can be stated that there is a high risk of intraoperative damage to the left AV node artery during manipulation of the mitral valve annulus fibrosus.

Adult↗
PubMed1997

Electrophysiologic properties of the atrioventricular node in pediatric patients.

OBJECTIVES: The purpose of this study was to characterize anterograde and retrograde properties of the atrioventricular (AV) node in children and to determine the presence of ventriculoatrial (VA) conduction and dual AV node pathways. BACKGROUND: Although AV node reentry is common in adults, it accounts for 13% of pediatric supraventricular tachycardia (SVT). The age-related changes in the AV node with development are poorly understood. The incidence of dual AV node pathways and VA conduction in the pediatric population is unknown. METHODS: Electrophysiologic studies were performed in 79 patients with normal hearts and no evidence of AV node arrhythmias. Patients were classified into two groups by age: group I = 49 patients (0.39 to 12.8 years old, mean [+/- SD] age 8.5 +/- 3.6); group II = 30 patients (13.4 to 20.0 years old, mean age 15.6 +/- 1.8). RESULTS: There was a significant difference (p < 0.05) in the cycle length (CL) at which anterograde AV block occurred between group I (305 +/- 63 ms) and group II (350 +/- 91 ms). Sixty-one percent of children had VA conduction with no age-related differences. There was no significant difference in the mean CL of retrograde VA block (360 ms). The incidence of dual AV node pathways in group I was 15% and 44% in group II (p < 0.05). CONCLUSIONS: These findings suggest that AV node electrophysiology undergoes maturational changes. The increase in AV node reentrant tachycardia in adults may relate to changes in the relative refractoriness and conduction of the AV node or to differences in autonomic input into the AV node that allow dual pathway physiology to progress to SVT.

Adolescent↗
PubMed1991

Transcoronary chemical ablation of atrioventricular node for the treatment of paroxysmal supraventricular tachycardia--a case report.

We applied transcoronary chemical ablation of the atrioventricular (AV) node to a patient with uncontrollable paroxysmal supraventricular tachycardia (PSVT). Through an angioplasty dilatation catheter. 99% ethanol at a dose of 1.0 ml was selectively infused into the AV nodal artery. Complete AV block with junctional escape rhythm occurred. Two weeks later, the treadmill exercise test was performed according to a modified Bruce protocol. The patient tolerated for 12 min, and the heart rate increased to 85 beats/min. His bundle electrocardiogram showed that the AV block resulted from atrio-Hisian block. Neither atrial nor ventricular extrastimulus could induce the tachycardia. It appeared that chemical ablation was a good method for controlling medically resistant PSVT. Elevation of serum creatine kinase was observed when ethanol overflowed during the ablation procedure. Occlusion of branches of the AV artery and mild hypokinesis in the inferobasal wall of the left ventricle were seen.

Aged↗