We discuss two cases of incessant atrial tachycardia (AT), including the presentation and clinical course. It is important to differentiate AT from other causes of supraventricular tachycardia, such as atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT), as it would have implications on clinical management. Electrocardiographic features of AT, especially the presence of an AV Wenckebach phenomenon with 'grouped beating', are critical for differentiating AT from AVRT and AVNRT. It is also vital to identify the P waves and their relations to QRS on electrocardiography, as this would aid in the differentiation of various supraventricular tachycardias.
Aged ; Diagnosis, Differential ; Electrocardiography ; Electrophysiology ; Female ; Heart Conduction System ; abnormalities ; Hemodynamics ; Humans ; Male ; Respiration ; Tachycardia ; diagnosis ; Tachycardia, Atrioventricular Nodal Reentry ; diagnosis ; Tachycardia, Supraventricular ; diagnosis ; Tricuspid Valve ; physiopathology

PURPOSETo evaluate and compare the effects of heart rate on conduction velocity in the cavotricuspid isthmus (CTI) and septum in patients with and without typical atrial flutter (AF) using electro-anatomic mapping (EAM) of the right atrium (RA).

METHODSTen patients (age 53+/-10 yrs, 7M/3F) with AF and 13 patients (age 51+/-11 yrs, 5M/8F) with atrioventricular nodal reentrant tachycardia (AVNRT) underwent conventional electrophysiological study, electro-anatomic mapping and radiofrequency ablation. Using EAMs obtained during coronary sinus pacing at pacing cycle length (PCL) 600 ms, 400 ms, and 300 ms, we evaluated conduction velocities in the CTI and septum of RA in 10 patients with AF and compared EAMs to 13 patients with AVNRT to determine whether the conduction slowing required to maintain AFL was related to changes in volume alone or altered RA electrophysiology.

RESULTSConduction velocities in CTI and septum were significantly slower at all PCL when AF was compared to AVNRT (*P<0.05). Additionally, in the AF group, septal conduction velocities were slower at PCL 600 ms and 400 ms, but not at 300 ms compared to CTI (*P<0.05). In AF, during PCL 300, conduction in CTI slowed significantly compared to PCL 600 and 400 ms such that there was no difference between CTI and septum at PCL 300.

CONCLUSIONSThere is slower conduction in the septum compared to the CTI in all patients. However, in patients with AF, there is significant slowing of conduction in the CTI and septum as well as decremental rate-dependent slowing of conduction in the CTI. These findings indicate that in addition to RA enlargement, changes in atrial electrophysiology distinguish AF patients from patients with AVNRT.

Adult ; Atrial Flutter ; physiopathology ; Female ; Heart Atria ; physiopathology ; Heart Conduction System ; physiopathology ; Heart Rate ; physiology ; Humans ; Male ; Middle Aged ; Tachycardia, Atrioventricular Nodal Reentry ; physiopathology ; Tricuspid Valve ; physiopathology

OBJECTIVETo map and compare the right atrium in patients with AF to those with atrioventricular nodal reentrant tachycardias (AVNRT, as control group) and to investigate the anatomical and electrophysiological abnormality of the right atrium in AF.

METHODSThe anatomy and electrophysiology of right atrium and cavotricuspid isthmus were evaluated in 20 patients with AF (16 M/4 F, mean age 55.9 +/- 10.68 years) and 26 patients with AVNRT (9 M/17 F, mean age 47.50 +/- 19.56 years) during coronary sinus pacing at 600 ms prior to ablation with electro-anatomical mapping system. Right atrial volume (RAV), the length and width of cavotricuspid isthmus (IsL, IsW), unipolar and bipolar voltage in the right atrium (UniV-RA, BiV-RA) were measured and compared between patients with AF and those with AVNRT.

RESULTSRAV, IsL, IsW, UniV-RA, and BiV-RA were 143.22 +/- 40.72 vs 104.35 +/- 21.06 ml, 39.31 +/- 8.10 vs 32.42 +/- 9.77 mm, 30.54 +/- 7.48 vs 23.15 +/- 6.61 mm, 1.96 +/- 1.24 vs 1.53 +/- 0.91 mv and 1.47 +/- 1.47 vs 1.29 +/- 1.12 mv in AF and AVNRT respectively.

CONCLUSIONThe right atrial volume is larger; both the length and width of cavotricuspid isthmus are greater. Unipolar and bipolar voltages in the right atrium are higher in AF than in AVNRT, suggesting that the enlarged right atrium, increased length and width of cavotricuspid isthmus, and concomitant atrial hypertrophy are important substrates for initiation and perpetuation of typical AF.

Adult ; Aged ; Atrial Flutter ; etiology ; pathology ; physiopathology ; Cardiomegaly ; complications ; Female ; Heart Atria ; pathology ; physiopathology ; Humans ; Male ; Middle Aged ; Tachycardia, Atrioventricular Nodal Reentry ; pathology ; physiopathology

A multipoint and computerized intraoperative mapping system has been known to be of value in improving the results of surgery for cardiac arrhythmia. It shows great potential as a new tool in the surgical intervention of the more common and lethal types of supraventricular tachyarrhythmias such as atrial flutter and atrial fibrillation. In addition, it also enhances the ability of the investigators to map and ablate the sometimes fleeting automatic atrial tachycardia. The authors developed a 64 channel computerized cardiac mapping system using a microcomputer (Macintosh IIx) and this has been used for basic research in cardiac electrophysiology as well as in arrhythmia surgery. In this system, bipolar electrograms are obtained from 64 different cardiac sites simultaneously at a sampling rate of 1 Ksample/sec and with a continuous and total data storage of up to 30 seconds. When the reference electrode is selected, delay time from the reference point is displayed on a two dimensional diagram of the heart. This system was used in one patient who underwent a surgical ablation of a ventricular tachycardia in whom we observed a ventricular activation sequence involving a variety of rhythms over several minutes. The system design permits easy expansion to a simultaneous sampling from 256 sites. This 64-channel mapping appeared to have the potential to be of great help in our understanding of cardiac arrhythmia as well as in its diagnosis and surgical treatment.
Arrhythmia/*physiopathology/*surgery ; *Cardiac Surgical Procedures ; *Diagnosis, Computer-Assisted ; Electrophysiology/*methods ; Heart/*physiopathology ; Heart Septal Defects, Atrial/surgery ; Human ; Support, Non-U.S. Gov't ; Tachycardia, Atrioventricular Nodal Reentry/surgery

BACKGROUNDTypical accessory pathways (APs) of Wolf-Parkinson-White syndrome have been widely discussed in recent decades. However, the characteristics of the special AP, Mahaim fibre, are not so clear. It is known that these fibres have antegrade conduction only, long conduction time, decremental node-like conduction and automaticity properties. This study was to elucidate the automaticity of Mahaim fibre and its response to effective ablation.

METHODSThirteen patients with Mahaim fibre (ten atrioventricular and three atriofascicular accessory pathways) were subjected to electrophysiological study and radiofrequency ablation via catheter. The incidence and characteristics of anautomatic rhythm originating from Mahaim fibre were observed during the whole procedure, especially during radiofrequency current delivery.

RESULTSRepetitive and short-run automatic rhythm (rate: 65-72 beats per minute), with a QRS morphology similar to that of clinical pre-excited atrioventricular re-entrant tachycardia (AVRT), occurred in two patients during sinus rhythm. Conduction via Mahaim fibre was successfully eliminated by radiofrequency current. Fourteen applications of RF were associated with irregularly accelerated automatic tachycardia of Mahaim fibre (with a sensitivity of 78%), lasting for 1.2-14 seconds. However, such automatic tachycardia of Mahaim fibre did not occur during 54 failed applications of radiofrequency current.

CONCLUSIONSMahaim fibre has the function of automaticity. The accelerated automatic tachycardia of Mahaim fibre occur red during radiofrequency catheter ablation can be used as a predictor for successful procedure.

Adolescent ; Adult ; Catheter Ablation ; Child ; Female ; Humans ; Male ; Middle Aged ; Pre-Excitation, Mahaim-Type ; physiopathology ; surgery ; Tachycardia, Atrioventricular Nodal Reentry ; physiopathology ; surgery

This study was designed to investigate the clinical and electrophysiologic characteristics of WPW syndromes in Korea. A total of 400 symptomatic WPW syndrome patients were consecutively recruited. The most common documented symptomatic tachyarrhythmia was orthodromic atrioventricar reentrant tachycardia (75.3%), followed by atrial fibrillation (31.3%), and antidromic atrioventricular reentrant tachycardia (6.2%). There was a higher incidence of multiple bypass tract in patients with antidromic tachycardia than in those with orthodromic tachycardia (30.4 vs 4.3%, P < 0.001). The inducibility of tachyarrhythmia with electrophysiologic study in this study population was 95.8%. The most frequent location of the accessory pathway was the left free wall (48.0%), followed by the right free wall (29.1%), posterior septum (17.5%) and anterior septum (3.5%). These results indicated that 1) clinical and electrophysiological characteristics of Korean patients with WPW syndrome were similar to those of western countries and 2) the electrophysiologic study was important in the evaluation of patients with WPW syndrome.
Adolescence ; Adult ; Atrial Fibrillation/physiopathology ; Atrial Fibrillation/complications ; Child ; Child, Preschool ; Electrocardiography ; Electrophysiology ; Female ; Human ; Korea ; Male ; Middle Age ; Tachycardia/physiopathology ; Tachycardia/complications ; Tachycardia, Atrioventricular Nodal Reentry/physiopathology ; Tachycardia, Atrioventricular Nodal Reentry/complications ; Wolff-Parkinson-White Syndrome/physiopathology* ; Wolff-Parkinson-White Syndrome/complications