Importance of preexcited QRS morphology during induced atrial fibrillation to the diagnosis and localization of multiple accessory pathways

The present investigation evaluates the ability of several electrocardiographic (ECG) and electrophysiologic methods to identify multiple accessory pathways in 47 patients in whom the presence and sites of multiple accessory pathways were confirmed intraoperatively. To establish ECG features that suggested the presence of multiple accessory pathways in these patients, we initially studied the 12-lead ECG during maximal preexcitation in 101 patients with single accessory pathways. Distinctive 12-lead ECG patterns were noted for six defined anatomic areas around the right and left atrioventricular groove. Multiple preexcited QRS morphologies, each typical for a separate accessory pathway, and atypical preexcited QRS morphologies were recorded during atrial fibrillation in 31 of 47 (66%) patients with multiple accessory pathways. By comparison, the ECG during sinus rhythm and rapid atrial pacing identified 14 (32%) and 26 (55%) of the patients, respectively. In 12 (26%) patients in whom evidence for multiple accessory pathways was absent from endocardial mapping data, atrial fibrillation provided the diagnosis. In five (11%) patients, atrial fibrillation was the only method that demonstrated the presence of multiple accessory pathways. A combination of ECG findings during atrial fibrillation and rapid atrial pacing plus endocardial mapping data identified 43 (91%) of the patients with multiple accessory pathways. There were two unique fusion patterns on the 12-lead ECG that were characteristic of specific multiple accessory pathway combinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of a revised procainamide test in the Wolff-Parkinson-White syndrome

A shortest preexcited RR interval less than 250 ms during atrial fibrillation identifies the patient with Wolff-Parkinson-White syndrome potentially at risk for ventricular fibrillation. Loss of preexcitation after infusion of up to 10 mg/kg of procainamide during sinus rhythm has been reported to correlate with a slow ventricular response during atrial fibrillation and has been proposed as a noninvasive test to establish risk of sudden death in these patients. Others have failed to establish this relation and have questioned the usefulness of the procainamide test. Such conflicting results were hypothesized to be a result of differing dosages and methodology. Consequently, this study tested the effect of incremental doses of procainamide (to a cumulative dose of 1 g) on the anterograde effective refractory period of the accessory pathway and related the reliability of the procainamide test to the dose at which preexcitation was lost. The effect of procainamide on the anterograde effective refractory period of the accessory pathway was dose dependent; patients who lost preexcitation had a steeper dose-response curve. Loss of preexcitation by a cumulative dose of 550 mg provided the best balance for sensitivity (60%) and specificity (89%) in identifying patients with preexcited shortest RR greater than 250 ms. Specificity fell steeply after this dosage and higher doses were not useful. The diagnostic accuracy of the procainamide test is critically related to dosage and method of infusion.

[Surgical treatment of Wolff-Parkinson-White syndrome--experiences with 87 surgically treated patients]

Since January 1984, 87 patients (pts) (57 male, 30 female; age 3 to 64 years) with Wolff-Parkinson-White syndrome were operated upon. The indication for surgical treatment was documented recurrent, paroxysmal tachycardia refractory to medical treatment in 85 cases. Eleven pts (13%) had additional heart disease. 87 pts had a total of 103 accessory pathways (AP). AP was localized at the left free wall in 68% (70 AP), at the right free wall in 16% (16 AP), and localized septally in 17% (17 AP). Thirteen pts (15%) had multiple AP (10 pts had two and three pts had three AP). 87 AP were known preoperatively, 96 were localized intraoperatively, and seven were diagnosed during reoperation. Twenty-seven pts were left lateral AP were operated by the epicardial approach and 37 pts by the endocardial approach. Patients with right lateral AP were approached by an epicardial technique in six cases, and by a transmural technique in five. Cryotechnique was applied additionally in 85 pts. Twelve pts suffered recurrences, 11 were reoperated. 101 AP (98%) were dissected successfully, of which 13 (13%) were ablated during reoperation. All pts survived the initial operation. Two pts died after reoperation. One pt is pacemaker-dependent due to a persisting postoperative AV block. We conclude that surgical dissection of accessory pathways can now be offered as an alternative to the non-surgical treatment modes, with low risk and yielding a high success rate.

Management of the patient with the Wolff-Parkinson-White syndrome

Patients with ventricular preexcitation may have symptomatic arrhythmias (Wolff-Parkinson-White syndrome) which can range from life-threatening, to disabling symptoms or minimal symptoms. Individuals may also be entirely asymptomatic. A rational approach to the management of these individuals is therefore dependent on the clinical circumstances. This review discusses the value and limitations of some of the available noninvasive and invasive investigations which may contribute to the successful management of these patients. In general, investigations are useful for establishing the diagnosis, identifying those patients at risk from life-threatening arrhythmias and providing a rational basis for therapy. The available pharmacologic and nonpharmacologic therapeutic options are discussed.

Elimination of electronic offset and physiological background activity in magnetocardiographic localization

A method has been developed to eliminate disturbing magnetic signals in the biomagnetic localization of arrhythmogenic sources in the heart. The procedure consists of two steps: Superimposed background activity of the heart is eliminated by subtraction of a template of pure background activity. Systematic and electronic offset is subsequently eliminated by baseline-correction during periods of zero activity. The method was applied to several kinds of arrhythmias. It was demonstrated that elimination of background activity is the prerequesite for exact localization and that the proposed procedure yields correct results.

Localization of accessory pathways in the Wolff-Parkinson-White syndrome

Operative and ablative therapy in the Wolff-Parkinson-White syndrome requires accurate localization of accessory atrioventricular pathways. A reasonable first approximation to pathway location can be obtained by noninvasive techniques, the 12-lead electrocardiogram being the most readily available of these. Accurate characterization of the number and anatomic localization of accessory pathways still requires invasive electrophysiological assessment. The most useful technique for accessory pathway localization remains endocardial atrial mapping of the tricuspid and mitral (via the coronary sinus) ring during atrioventricular reciprocating tachycardia and ventricular pacing. Other techniques provide important confirmatory evidence and may be the only guides to accessory pathway location in selected individuals.

Long-term status and survival in Wolff-Parkinson-White syndrome

In a long-term follow-up study of 103 patients who had Wolff-Parkinson-White syndrome, four died suddenly; two men had previously experienced paroxysmal atrial fibrillation and two women, both elderly, had paroxysmal tachyarrhythmias, one documented as atrial paroxysmal tachycardia on one occasion. Sixty-six (64%) of the patients had histories of paroxysmal tachyarrhythmias. Of 88 survivors, 10 of the 35 (29%) who did not have a history of arrhythmias on entry developed tachyarrhythmias, and 20 of 33 (38%) who did have symptomatic arrhythmias on entry had no symptoms at last follow-up. Thirteen (15%) of the survivors had frequent attacks of symptomatic arrhythmias.

[Ebstein's anomaly of the tricuspid valve with the WPW syndrome]

Case-history of a four-year-old boy with Ebstein's anomaly of the tricuspid valve with WPW syndrome. Severe tricuspid insufficiency and repeatedly occurring tachydysrhythmias soon led to cardiac decompensation and death before the intended cardiac operation. Non-invasive clinical, ECG, X-ray and ECHO examinations correlated with catheterization, electrophysiological and pathological findings. In addition to the dislocated, malformed tricuspid valve the septal cusp of which was fused with the ventricular septum the authors found another additional atrioventricular muscular connection between the lower part of the septum of the right atrium and right ventricle.

Electrophysiological demonstration of anterograde concealed conduction in accessory atrioventricular pathways capable only of retrograde conduction

Anterograde concealed conduction into the concealed accessory atrioventricular (AV) pathway has been postulated to be one of the factors preventing the reciprocating process via the accessory pathway in patients with the concealed Wolff-Parkinson-White(WPW) syndrome but its presence has not been documented. To demonstrate the occurrence of anterograde concealment, 12 patients with the concealed WPW syndrome were selected for study. A pacing protocol was designed in which the retrograde conduction of the ventricular extrastimulus over the accessory pathway was assessed during ventricular pacing alone (conventional method) and during the AV simultaneous pacing (simultaneous method); the results were then compared. When the high right atrium was simultaneously paced, the effective refractory period of the concealed accessory pathway shortened as compared with the conventional method in five of 12 patients (from 341.7 +/- 110.8 to 312.5 +/- 108.2 msec, n = 12), whereas, it decreased in all patients studied when the coronary sinus near the accessory pathway was simultaneously paced (from 375.7 +/- 135.0 to 287.1 +/- 116.1 msec, n = 7). These results demonstrate that the AV simultaneous pacing frequently shortens the refractoriness of the concealed accessory AV pathway and such facilitation seems to be well explained by the probable anterograde concealment in it and peeling back of the refractory barrier.

Electrophysiologic evaluation of asymptomatic patients with the Wolff-Parkinson-White pattern

In the past 4 years, 34 asymptomatic patients with the Wolff-Parkinson-White (WPW) pattern underwent electrophysiologic study. The effective refractory period (ERP) of antegrade conduction over the accessory pathway was 288 +/- 29 msec. In three asymptomatic patients (9%), the antegrade ERP of the accessory pathway was shorter than 250 msec. The antegrade ERP of the accessory pathway became shorter than 250 msec in an additional 12 of 22 (55%) patients after isoproterenol administration. Nineteen (56%) of the asymptomatic patients showed the absence of retrograde conduction over the accessory pathway even after isoproterenol administration. The rate of induction of orthodromic reciprocating tachycardia in the asymptomatic WPW patients was 15% (5/34), which was significantly lower than that in the symptomatic patients. These data suggest that in the asymptomatic patients, the absence of retrograde conduction over the accessory pathway is the reason they remained asymptomatic, free of reciprocating tachycardia. However, even in the asymptomatic patients, some had the accessory pathway in which antegrade ERP was shorter than 250 msec. They may result in rapid ventricular conduction over the accessory pathway when atrial fibrillation develops.

[A case of WPW syndrome with slow Kent documented by ATP injection]

A 46-year-old woman with chest tightness and palpitation at exercise was admitted to Sapporo Medical College Hospital for the evaluation of the ST-T changes on stress electrocardiogram. In this patient, PQ time was 0.14 second and pre-exitation was not clearly documented on electrocardiogram at rest. Bolus injection of 10 mg of adenosine-5'-triphosphate (ATP) demonstrated deltawave through the elongation of antegrade conduction of atrio-ventricular (AV) node. Electrophysiological study also showed left lateral accessory pathway with slow antegrade conduction, slow Kent. Stress 201-T1 myocardial scintigraphy using bicycle ergometer did not show the existence of ischemic region in spite of the ST-T changes on electrocardiogram. In this case, it seemed that a false positive ST-T changes might be caused by ventricular pre-exitation through slow Kent fiber. From these findings, it was suggested that the transient interruption on conduction through AV node by ATP bolus injection may be a useful diagnostic method in borderline pre-exitation syndrome.

[Intrauterine tachycardia--differential diagnosis from fetal death]

A case of intrauterine tachycardia is presented. The case was primarily diagnosed as one of foetal death. The correct diagnosis was established by ultrasonic scanning. During the neonatal period, the Wolff-Parkinson-White syndrome was diagnosed. This is a common cause of intrauterine tachycardia.

Utility of introducing ventricular premature complexes during reciprocating tachycardia in specifying the location of left free wall accessory pathways

The usefulness of the response to single and double ventricular premature complexes (VPCs) introduced during reciprocating tachycardia (RT) in predicting the location of a left free wall accessory pathway was studied in 55 patients with the Wolff-Parkinson-White syndrome. One VPC introduced from the right ventricle into narrow QRS RT when the His bundle was refractory resulted in retrograde atrial preexcitation in 25 of 55 (45%) patients, while 30 (55%) showed no preexcitation. Double VPCs produced retrograde atrial preexcitation in 9 of 26 patients not responding to a single VPC. No difference in RT cycle length, AH, HV or ventriculoatrial intervals was found between those patients who did or did not show retrograde atrial preexcitation. The response to single and double VPCs during RT was related to the location of the AP. The average distance of the AP from the crux determined by intraoperative epicardial mapping in the 41 patients who underwent surgery was 2.7 +/- 0.7 mapping units (left posterolateral region) in patients showing retrograde atrial preexcitation with a single VPC, 3.6 +/- 0.7 units (at the lateral left ventricular margin) in those responding to double VPCs and 4.3 +/- 0.8 units (beyond the LV margin) in those showing no response. Left bundle--branch block (LBBB) aberrancy during RT resulted in an average 60 +/- 14 ms prolongation of the ventriculoatrial interval in 40 patients, including 5 in whom LBBB was seen only after procainamide infusion. VPCs introduced into LBBB RT resulted in significant retrograde atrial preexcitation in 6 additional patients in whom no response during normal QRS RT was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of abrupt cycle length changes on the refractoriness of accessory pathway, His-Purkinje system, atrial and ventricular myocardium in Wolff-Parkinson-White syndrome

We compared the response of the accessory pathway (AP), the atrial myocardium, the His-Purkinje system (HPS) and the ventricular myocardium during steady state (constant cycle length) and following an abrupt alteration in cycle length in 23 patients with Wolff-Parkinson-White syndrome. The durations of the anterograde and retrograde refractory periods were measured during constant drive cycle lengths of 600 and 400 ms (Method I) and during an abrupt change in cycle length of either short-to-long (400 to 600 ms) (Method II) or long-to-short (600 to 400 ms) (Method III) just before the extra stimulus. The mean durations of the anterograde effective refractory periods of the APs were 295 +/- 43, 243 +/- 39 and 273 +/- 37 ms at 600, 400 and 400 to 600 ms cycle lengths, respectively. For the atrial effective refractory periods at the three cycles, they were 238 +/- 18, 217 +/- 11 and 241 +/- 17 ms, respectively. During ventricular stimulation, the mean durations of the retrograde effective refractory periods of the APs were 263 +/- 25, 245 +/- 19 and 253 +/- 21 ms at cycle lengths of 600, 400 and 400 to 600 ms, respectively. For the relative refractory periods of the HPS, they were 335 +/- 29, 239 +/- 23 and 367 +/- 38 ms, respectively and, for the effective refractory periods of the ventricular myocardium, they were 227 +/- 17, 206 +/- 15 and 215 +/- 18 ms, respectively. The retrograde effective refractory period of the HPS could be measured in only five patients at the three cycles (600, 400 and 400 to 600 ms) and the mean values were 265 +/- 57, 225 +/- 14 and 305 +/- 27 ms, respectively. With Method III, AP and ventricular myocardium responded in a cumulative manner while HPS demonstrated paradoxical effect. Compared to Method I, changes with Methods II and III were statistically significant for all variables measured. During all three cycles, the retrograde effective refractory period of the HPS exceeded the effective refractory period of the AP; and the HPS demonstrated progressive conduction delay while the AP responded to no or minimal delays when the V1V2 intervals were similar. An abrupt cycle length change of the short-to-long type facilitated the induction of orthodromic tachycardia during ventricular pacing.(ABSTRACT TRUNCATED AT 400 WORDS)

Wolff-Parkinson-White syndrome: illustrative case and brief review

The Wolff-Parkinson-White syndrome (WPWS) is a pre-excitation syndrome manifested on the 12-lead ECG by a short PR interval (less than .12 sec), a prolonged QRS interval (greater than .10 sec), and an initial slurring of the QRS complex called a delta wave. The anatomical etiology is the presence of accessory atrioventricular conduction fibers called the Kent bundle. Patients with the WPWS may present to the emergency department with a wide spectrum of symptoms, ranging from mild palpitations, to unstable tachydysrhythmias and sudden cardiac death. WPWS should be suspected in any patient presenting with a tachydysrhythmia with a rate exceeding 200/minute. Cardioversion is indicated in the unstable patient. It is impossible to predict the effect of any particular drug without prior electrophysiologic studies in a patient with WPWS. Procainamide is the safest drug for the stable WPWS patient with a tachydysrhythmia, including wide-complex and irregular rhythms. Verapamil is a useful drug in narrow-complex, regular rhythms, although complications have been reported. Atrial fibrillation may be difficult to diagnose in a very rapid tachycardia, and the use of verapamil in WPWS with atrial fibrillation is contraindicated. Electrophysiologic studies are indicated in the WPWS patient to maximize prophylactic therapy. An illustrative case as well as pathophysiology and management of WPWS are discussed.