Identification of slow anterograde conduction of excitation in patients with paroxysmal reciprocal atrioventricular nodal tachycardia

Basing on results of examination of a cohort of patients with typical paroxysmal reciprocal atrioventricular tachycardia a group of patients with continuous curve of anterograde conduction was distinguished. The use of incremental doses of adenosine triphosphate (ATP) during transesophageal atrial pacing allowed in some cases to identify slow conduction through atrioventricular node and to initiate paroxysmal nodal tachycardia. The dose of ATP causing conduction block over fast pathway depended on the duration of effective refractory period.     

'Uninterrupted' anterograde atrioventricular excitation conduction in patients with paroxysmal reciprocal atrioventricular nodal tachycardias

Different variants of anterograde atrioventricular conduction of excitation were distinguished basing on data obtained from 150 patients with paroxysmal reciprocal atrioventricular nodal tachycardias. Excitation conduction during programmed and accelerating atrial transesophageal pacing allowed to assess characteristics of excitation conduction along fast and slow conduction pathways in atrioventricular node. Some parameters were suggested that allowed to predict possibility of detection of different variants of anterograde atrioventricular conduction of excitation. Electrophysiological mechanisms of detection of various types of atrioventricular conduction curves are discussed.     

Parameters of central hemodynamics in patients with paroxysmal atrioventricular nodal reciprocal tachycardia before and after radiofrequency catheter ablation

We present in this article results of assessment of morphofunctional state of the myocardium in patients with typical form of paroxysmal atrioventricular nodal reciprocal tachycardia (AVNRT) before and during one year after radiofrequency catheter ablation of slow part of atrioventricular junction and their comparison with analogous parameters of control group. Participants of this study (n=81) were divided into 2 groups: main (study group) and control group. Main group comprised 61 (75.3%) patients with AVNRT in variant of typical course, mean age 45.3+/-15.1 years. All patients of study group were subjected to endocardial electrophysiological investigation and radiofrequency ablation (RFA) - modification of slow part of atrioventricular junction. Control group comprised 20 practically healthy persons aged 41.9+/-5.3 years in whom no structural pathology of cardiovascular system was found. Transthoracic echocardiography (EchoCG) was carried out before and in 2, 6, and 12 months after operation in patients of main group and once in control group. Analysis of parameters of central hemodynamics studied with the Echo method in patients of main group before and in 2, 6, 12 months after RFA demonstrated that before conduct of surgical intervention there were no significant differences between the parameters studied and analogous characteristics of the control group. It was established in the course of dynamic observation of patients of the study group that in 2, 6 and 12 months after RFA the studied parameters of central hemodynamics did not undergo substantial changes compared with initial values. According to EchoCG data so called minor anomalies of development of cardiac connective tissue were diagnosed in 28 cases (45%) among patients of study group and in 2 cases (10%) in control group.     

Effect of digitalis in patients with paroxysmal atrioventricular nodal tachycardia.

Atrioventricular (A-V) conduction, ventriculo-atrial conduction and mechanism of tachycardia were studied by programmed electrical stimulation before and after the administration of ouabain in 15 patients suffering from paroxysmal supraventricular re-entrant tachycardia. In 13 patients the tachycardia circuit was confined to the A-V node. In two patients the stimulation study showed that an accessory pathway was used in a ventriculo-atrial direction during tachycardia. Ouabain lengthened the effective and functional refractory period of the A-V node and A-V nodal transmission time in all patients in whom this could be studied. Only six patients showed lengthening in ventriculo-atrial conduction time or refractory period of the ventriculo-atrial conduction system. In seven patients no tachycardia could be initiated after ouabain. The width of the zone of atrial premature beats able to initiate tachycardia (the tachycardia zone) narrowed in five patients, showed no change in two patients, and increased in one patient. In these eight patients the tachycardia zone shifted to longer premature beat intervals. Ouabain resulted in slowing of cardiac rate during tachycardia. Both patients who used an accessory pathway during tachycardia showed no change in width of their tachycardia zone following ouabain administration. Seven patients were restudied two weeks after chronic oral administration of digoxin. The results were similar to those obtained following ouabain administration. This indicates that in patients suffering from paroxysmal A-V nodal tachycardia the effect of chronic oral digoxin administration can be predicted from the study of the effect of ouabain during programmed stimulation of the heart.     

Latent Clerc-Levy-Cristesco syndrome as an electrophysiologic basis for paroxysmal reciprocal atrioventricular nodal tachycardia

An intracardiac electrophysiological investigation was performed in 15 patients with frequent episodes of supraventricular tachycardias (SVT) which are regarded, in terms of the present electrophysiological criteria, as episodes of reciprocal atrioventricular nodal tachycardia. It was demonstrated that accessory atrionodal junctions functioning only in the retrograde direction formed the basis for arrhythmias in 6 patients. This electrophysiological phenomenon was proposed to be termed the latent Clerc-Lery-Cristesco (CLC) syndrome. The main electrophysiological criteria for diagnosing the syndrome are the following: a) during a SVT episode, retrograde atrial excitation is recorded before or concomitantly with the initiation of ventricular excitation; b) during a SVT episode, H-A interval is no greater than 5 ms; c) during programmed ventricular stimulation, H2-A2 interval values remain constant. The latent CLC syndrome was shown to be commonly associated with discrete conduction in the antegrade atrioventricular junctions. Rhytmilen and gilurytmal (ajmaline) are the most potent antiarrhythmic agents for patients with reciprocal SVT due to the latent CLC syndrome.     

Effectiveness and pharmacodynamics of tobanum in patients with paroxysmal reciprocal atrioventricular tachycardia]

The antiarrhythmic effects and pharmacodynamics of tobanum were evaluated in 28 patients wist paroxysms of reciprocal atrioventricular tachycardia, by using transesophageal cardiac pacing. The agent given in a single dose of 10 mg produced antiarrhythmic effects in 70% patients with paroxysms of atrioventricular nodal tachycardia and in 40% with atrioventricular tachycardia in the presence of the Wolff--Parkinson-White syndrome. After administration of the drug, its antiarrhythmic effect occurred on an average 1.5 h and retained for 27 h.     

Concept of the polyfascicular structure of the atrioventricular junction in patients with reciprocal paroxysmal nodal tachycardias

Intracardiac electrophysiologic studies were carried out in 41 patients with paroxysmal supraventricular tachycardias. Reciprocal atrioventricular tachycardia due to dissociated conduction through the atrioventricular junction was diagnosed in 29 patients. Electrophysiologic data suggested trifascicular atrioventricular conduction in 4 patients, and quadrifascicular conduction in 2. A concept of polyfascicular impulse conduction through the atrioventricular junction in some cases of reciprocal nodal tachycardia is proposed. It is demonstrated that combinations of congenital cardiac conduction abnormalities may be possible in the same individual.     

Demonstration of dual atrioventricular nodal pathways utilizing a ventricular extrastimulus in patients with atrioventricular nodal re-entrant paroxysmal supraventricular tachycardia.

In patients with atrioventricular (A-V) nodal re-entrant paroxysmal supraventricular tachycardia (PSVT), atrial extrastimulus technique frequently reveals discontinuous A1-A2, H1-H2 curves suggestive of dual A-V nodal pathways. To further test the hypothesis that these curves in fact reflect dual A-V nodal pathways, a ventricular extrastimulus (VS) was coupled either to A2 at a fixed A1-A2 interval which reliably produced an A-V nodal re-entrant atrial echo (E) with a constant A2-E interval in two patients, or to QRS complex (V) during sustained PSVT with a constant E-E interval in one patient. Three response zones were defined: at longer A2-VS or V-VS coupling interval, VS manifested no effect on the timing of E (Zone 1). At closer A2-VS or V-VS coupling interval, VS conducted to the atrium, shortening the apparent A2-E or E-E interval (Zone 2). At shortest A2-VS or V-VS coupling interval, VS was blocked retrogradely, and no E was induced (Zone 3). The ability of VS to preempt control of the atria (Zone 2 response) strongly suggests the presence of dual A-V nodal pathways in these PSVT patients. If only a single pathway were present, VS would of necessity collide with the antegrade impulse and could not reach the atria. The Zone 3 response occurs because of retrograde refractoriness of the fast pathway. Failure of the echo during Zone 3 probably reflects concealed conduction to the fast pathway, or possibly interference in the slow pathway.     

Second degree block during reciprocal atrioventricular nodal tachycardia.

Of 67 patients with reciprocal atrioventricular (A-V) nodal tachycardia consecutively studied by programmed electrical stimulation of the heart, nine patients showed second degree block toward the ventricle and one patient toward the atrium during tachycardia. In four patients the occurrence of block was critically related to the prematurity of the test stimulus initiating the tachycardia. In three patients block developed following increase in rate of tachycardia. In two patients block could be elicited by introducing premature ventricular stimuli during tachycardia. Our observations indicate that different mechanisms may be responsible for second degree block during reciprocal supraventricular tachycardia. The finding of second degree block during reciprocal supraventricular tachycardia excludes a tachycardia with A-V conduction over the A-V node - His pathway and V-A conduction over an accessory A-V pathway.     

Characterizing dual atrioventricular nodal physiology in pediatric patients with atrioventricular nodal reentrant tachycardia

INTRODUCTION: Dual atrioventricular (AV) nodal physiology, defined as an AH jump > or =50 msec with a 10 msec decrease in A1A2, is the substrate for atrioventricular nodal reentrant tachycardia (AVNRT) and yet it is present in a minority of pediatric patients with AVNRT. Our objective was to characterize dual AV nodal physiology as it pertains to a pediatric population. METHODS/RESULTS: We retrospectively reviewed invasive electrophysiology studies in 92 patients with AVNRT (age12.1 +/- 3.7 yrs) and in 46 controls without AVNRT (age 13.3 +/- 3.7 yrs). Diagnoses in controls: syncope (N = 31), palpitations (N = 6), atrial flutter (N = 3), history of atrial tachycardia with no inducible arrhythmia (N = 3), and ventricular tachycardia (N = 3). General anesthesia was used in 49% of AVNRT and 52% of controls, P = 0.86. There were no differences in PR, AH, HV, or AV block cycle length. With A1A2 atrial stimulation, AVNRT patients had a significantly longer maximum AH achieved (324 +/- 104 msec vs 255 +/- 67 msec, P = 0.001), and a shorter AVNERP (276 +/- 49 msec vs 313 +/- 68 msec P = 0.0005). An AH jump > or =50 msec was found in 42% of AVNRT versus 30% of controls (P = 0.2). Using a ROC graph we found that an AH jump of any size is a poor predictor of AVNRT. With atrial overdrive pacing, PR > or = RR was seen more commonly in AVNRT versus controls, (55/91(60%) vs 6/46 (13%) P = 0.000). CONCLUSIONS: Neither the common definition of dual AV nodes or redefining an AH jump as some value <50 msec are reliable methods to define dual AV nodes or to predict AVNRT in pediatric patients. PR > or = RR is a relatively good predictor of AVNRT.     

房室折返和房室结折返性心动过速患者的个性分析

目的探讨房室折返性心动过速(AVRT)和房室结折返性心动过速(AVNRT)患者的个性特征。方法采用龚耀先修订的艾森克个性问卷量表,对83例AVRT、105例AVNRT患者射频消融前后和50例对照组正常人的精神质(P)、内外向(E)、情绪稳定性(N)和掩饰倾向(L)值进行测量。结果射频消融前后,各组之间的P、E、N和L值相比较差异无显著性(P>0.05);射频消融前后AVNRT组内女性患者的N分值较男性高(分别为12.93±2.83vs9.88±2.61;12.84±2.87vs9.87±2.64;P均<0.05)。结论AVNRT女性患者具有神经质倾向,这可能是在AVNRT中女性占多数的原因之一。     

Effects of intravenous and oral disopyramide on paroxysmal atrioventricular nodal tachycardia

The effect of intravenous and oral disopyramide on the mechanisms of the arrhythmia were studied in 11 patients with the common type of atrioventricular (AV) nodal paroxysmal reentrant tachycardia. Programmed electric stimulation of the heart was used to initiate and terminate tachycardia and to evaluate the effect of disopyramide on mode of initiation and termination of tachycardia. Disopyramide was given intravenously to all patients during tachycardia. This resulted in termination of tachycardia, by block in the anterograde slow pathway in 1 and in the retrograde fast pathway in 3 patients. In all 4 patients, reinitiation of tachycardia was no longer possible. In these 4 patients, oral disopyramide prevented spontaneous and pacing-induced AV nodal tachycardia. In 4 of the remaining 7 patients in whom tachycardia was not terminated by intravenous disopyramide, reinitiation of the arrhythmia during programmed stimulation was prevented by the drug. In these 4 patients, oral disopyramide was also effective in preventing spontaneous occurrence of tachycardia. In 3 patients, tachycardia was not terminated and its reinitiation was not prevented by intravenous disopyramide. Only 1 of these 3 patients received disopyramide by mouth, and it failed to prevent reinitiation and spontaneous tachycardia. In conclusion, disopyramide is an effective drug in patients with AV nodal paroxysmal reentrant tachycardia. A good correlation was found between intravenous and oral effect of disopyramide on the mechanisms of the arrhythmia. The study of the effect of intravenous disopyramide predicted the outcome of oral disopyramide therapy.     

Retrograde block during dual pathway atrioventricular nodal reentrant paroxysmal tachycardia

There are limited reported data regarding the occurrence of retrograde block during dual pathway atrioventricular (A-V) nodal reentrant paroxysmal tachycardia. This study describes two patients with this phenomenon. The first patient had 2:1 and type 1 retrograde ventriculoatrial block during the common variety of A-V nodal reentrance (slow pathway for anterograde and fast pathway for retrograde conduction). Fractionated atrial electrograms suggested that the site of block was within the atria. The second patient had type 1 retrograde block (between the A-V node and the low septal right atrium) during the unusual variety of A-V nodal reentrance (stow pathway for retrograde and fast pathway for anterograde conduction). The abolition of retrograde block by atropine suggested that the site of block was within A-V nodal tissue. Both cases demonstrate that intact retrograde conduction is not necessary for the continuation of A-V nodal reentrant paroxysymal tachycardia. Case 2 supports the hypothesis that the atria are not a requisite part of the A-V nodal reentrant pathway.     

Cycle length in atrioventricular nodal reentrant paroxysmal tachycardia with observations on the lown-ganong-levine syndrome

Sixty-five patients with dual pathway atrioventrlcular (A-V) nodal reentrant paroxysmal tachycardia were studied. Of these 65 patients, 11 (17 percent) had a short P-R interval (0.12 second or less) and 3 (5 percent) had a short A-H interval (53 ms or less) during sinus rhythm, suggesting the Lown-Ganong-Levine syndrome. Frequency distribution analyses of P-R and A-H intervals In the 65 patients demonstrated continuous unimodal functions, suggesting a continuum of A-V nodal properties. Regression analyses of P-R and A-H (fast pathway) intervals versus cycle length of paroxysmal tachycardia revealed an r value of 0.11 and 0.10, respectively (not significant). The cycle length of paroxysmal tachycardia did not differ between the 11 patients with a short P-R Interval (370 ± 20 ms) and the 54 patients without a short P-R interval (382 ±11 ms). Regression analysis of the slow pathway A-H interval versus cycle length of paroxysmal tachycardia revealed an r value of 0.68 (p <0.001).

The cycle length of dual pathway A-V nodal reentrant paroxysmal tachycardia is a function of the slow pathway A-H Interval and not the P-R or A-H Interval during sinus rhythm. Identification of short P-R intervals in patients with A-V nodal reentrant paroxysmal tachycardia has little significance.     

Gender-related differences in patients with atrioventricular nodal reentry tachycardia

The present study sought to assess the extent of gender differences in electrophysiologic parameters in patients with atrioventricular nodal reentrant tachycardia (AVNRT). The study population consisted of 203 patients (women/men ratio 2:1) who underwent slow pathway ablation. Patients with associated heart disease experienced the first episode of tachycardia at a significantly older age than patients with lone AVNRT (women 50 +/- 18 vs 29 +/- 15 years, p < 0.0001; men 45 +/- 20 vs 31 +/- 17 years, p = 0.01). Sinus cycle length (797 +/- 142 vs 870 +/- 161 ms, p = 0.0001), HV interval (41 +/- 7 vs 45 +/- 8 ms, p = 0.0001), atrioventricular (AV) block cycle length (348 +/- 53 vs 371 +/- 75 ms, p = 0.01), slow pathway effective refractory period (ERP) (258 +/- 46 vs 287 +/- 62 ms, p = 0.006), and tachycardia cycle length (354 +/- 58 vs 383 +/- 60 ms, p = 0.001) were shorter in women. No gender differences were noted in fast pathway ERP and ventriculoatrial (VA) block cycle length. In women, an AV block cycle length <350 ms along with a VA block cycle length <400 ms predicted tachycardia induction without the need for autonomic intervention, with a positive predictive value of 93% (sensitivity 71%, specificity 82%). No such cut-off values could be found in men. The acute success rate (100% vs 98%) and the recurrence rate (3% vs 6%) were similar for the 2 genders. In conclusion, in patients with lone AVNRT, the onset of symptoms occurred at a younger age than in patients with concomitant heart disease. Women had shorter slow pathway refractory periods, AV block cycle lengths, and tachycardia cycle lengths. No gender differences were noted in the fast pathway ERP. Therefore, women have a wider "tachycardia window" (i.e., the difference between the fast and slow pathway refractory periods), a finding that may explain their greater incidence of AVNRT.