Paroxysmal supraventricular tachycardia initiated by ventricular couplets in concealed ventricular trigeminy

Journal of Electrocardiology Vol, 28 No. 1 1995

Paroxysmal Supraventricular Tachycardia Initiated by Ventricular Couplets in Concealed Ventricular Trigeminy

Shinji Kinoshita, MD, Go Konishi, PharmB, Masayuki and Shinsaku Ogawa, MD

Sakurai, MD,

Abstract: A case report of a man with ventricular concealed trigeminy in w h o m ventricular couplets initiating paroxysmal supraventricular tachycardia were occasionally seen is reported. This is the first report on concealed trigeminy with couplets. This strengthens the authors' previous suggestion that supernormal conduction may occur in the reentrant pathway of extrasystoles, as a mechanism of ventricular couplets. Key words: paroxysmal supraventricular tachycardia, ventricu/ar couplets, concealed ventricular trigeminy, supemormal conduction, reentry.

In some cases of extrasystoles, ~ 5 the n u m b e r of sinus QRS complexes intervening between two successive manifest extrasystoles is generally 3n - 1 (ie, 2, 5, 8, 1 I, 14, etc.), where n is any positive integer. This p h e n o m e n o n was originally reported in 1960 by us ~ in a case of ventricular extrasystoles, and later it was termed concealed trigeminy by Schamroth and Marriott. 2 This shows that although the mechanism producing the trigeminal r h y t h m continues in effect, it is not always manifested on the electrocardiogram (ECG). In our previously reported cases of concealed trigeminy, 4'5 it was suggested that concealed 3:2 Wenckebach periodicity occurred in the reentrant pathway of extrasystoles in which the effective refractory period was markedly long. In this study, a case of concealed ventricular trigeminy is reported in which ventricular couplets (ie, paired ventricular extrasystoles) initiating paroxysFrom the Health Administration Center and Department of Cardiovascular Medicine, School of Medicine, Hokkaido University and Department of Medicine, Sapporo Hospital, Japan Self-Dejense Force, Sapporo, Japan.

Reprint requests: Shinji Kinoshita, MD, Health Administration Center, Hokkaido University, Sapporo, Japan.

mal supraventricular tachycardia were occasionally seen. This is the first study on concealed trigeminy coexisting with couplets, which strengthens our previous suggestion 6,7 that longitudinal dissociation and supernormal conduction may occur in the reentrant pathway of extrasystoles as a mechanism of ventricular couplets.

Case Report Electrocardiograms were recorded from a 51 -yearold m a n with ventricular extrasystoles. He was apparently healthy and was not receiving antiarrhythmic therapy during the recording. Figure 1 shows part of the Holter monitor ECG. In the figure, coupling intervals of extrasystoles, X, to the preceding sinus QRS complexes, R, are somewhat variable, ranging between 0.52 and 0.57 second. The number of sinus QRS complexes intervening between two successive extrasystoles satisfies the equation S = 3n - 1 (ie, 2, 5, 8, 11, or 14), where S is the n u m b e r

70

Journal of Electrocardiology Vol. 28 No. 1 January 1995

CC51 ::;:

:.)!;;.! ~i

::.

:.i i . ! .

:;;...

R62:X

RI

R2X

2 '

R!!

: ,

s5 2

R5

'R2

C:~: :

:

R 4

55

~:

:

:

. . . .

::;

2

s4 .....

:

.........

. . . . . . . . . . . .

56 Fig. 1. Concealed ventricular trigeminy. All strips are continuous. This tracing was recorded at a speed of 12.5 mm/s. Time intervals are expressed in hundredths of a second. R~, the ith sinus QRS complex after the preceding extrasystole; X, ventricular extrasystole.

NASA

'

i

i

'

i

i

-P

-P

=

i

(V2) R23

~(1

R1

~v5~

R2

i R3

.....................................................................................................

"

R5

X2._......X~ .............R' ......

R'

i-,:I

..................

!, .!

+

Ra

NASA

R,.

F

-

-P

I

.'pRi . . . . .

~

i "

: :'.::i:i

R'

R'

Fig. 2. Paroxysmal supraventricular tachycardia initiated by a ventricular couplet. Intraventricular conduction of sinus impulses leading to the entrance of the reentrant pathway is represented by dashed lines. Functional longitudinal dissociation divides the reentrant pathway into the fast pathway (thin lines) and the slow pathway (thick lines). Shaded bars represent the abnormally long effective refractory period of the slow pathway, which is interrupted by the supernormal period. The last strip shows lead II of the 12-lead ECG, which indicates the presence of negative and retrograde P waves. NASA and CC~, modified leads V2 and Vs, respectively; R and R', sinus and supraventricular QRS complexes (or impulses giving rise to them), respectively; X and (X), manifest and concealed ventricular extrasystoles, respectively; -P, retrograde P wave; A, atria; AV, atrioventricularjunction; V, ventricles; RP, reentrant pathway ofventricular extrasystoles; S, supernormal period.

Ventricular Couplets in Concealed Trigeminy

of intervening sinus QRS complexes. This indicates the presence of concealed ventricular trigeminy. The upper tracing in Figure 2, which was taken 2 minutes after the recording in Figure I, shows that a ventricular couplet, X2X3, is followed by paroxysmal supraventricular tachycardia. The coupling interval of the extrasystole, X2, initiating the couplet (0.58 second) is longer than those in Figure 1. Two minutes later, the retrograde P wave, -P, disappears, and the tachycardia is terminated (the first lower tracing). In the 30-minute recording, including the recording in Figure I, 14I single ventricular extrasystoles and 2 ventricular couplets (including that in Fig. 2) were found. In all but only two instances, the number of sinus QRS complexes intervening between two successive extrasystoles in this recording satisfied the equation S = 3n - 1. None of the single extrasystoles were followed by paroxysmal supraventricular tachycardia. In this and the other ECGs of this case, whenever a ventricular couplet occurred, paroxysmal supraventricular tachycardia was initiated and was sustained for a period of 0.5-2.0 minutes. The coupling interval of the extrasystole initiating the couplet was comparatively long, ranging between 0.58 and 0.63 second. When the coupling interval of an extrasystole was shorter than 0.58 second, the extrasystole always failed to initiate a couplet.

Discussion It has been suggested that in concealed trigeminy, the effective refractory period in the reentrant pathway of extrasystoles is abnormally long, namely nearly equal to 4"5 or longer than ~'5 the sinus cycle length. It seems that in this case, ventricular couplets originate in such a reentrant pathway. This strengthens our previous suggestion6"7 that longitudinal dissociation and supemormal conduction occur in the reentrant pathway. In a previous study by Kinoshita,8 a theoretic model was derived from the concepts of longitudinal dissociation and supernormal conduction in the reentrant pathway of ventricular extrasystoles in which the effective refractory period of the fast pathway was longer than that of the slow pathway. Using this theoretic model, the diagram below the upper tracing in Figure 2 explains a probable mechanism of the arrhythmia in this case. The diagram shows that functional longitudinal dissociation divides the reentrant pathway of ventricular extrasystoles into fast and slow pathways (represented by thin and thick lines, respectively). Shaded bars represent the abnormally long effective refractory period, which is

•

Kinoshita et al.

71

interrupted by the supernormal period (labeled s). In the fast pathway, the effective refractory period (which is not shown in the diagram) is still longer than that in the slow pathway. The diagram shows that concealed 3:2 Wenckebach periodicity occurs in the reentrant pathway in the same way as in our previously reported cases of concealed trigeminy.4"5 In the diagram of Figure 2, no sinus impulses conducted to the exit (the upper side of the reentrant pathway in the diagram) of the reentrant pathway of ventricular extrasystoles can enter the pathway because of unidirectional block. Intraventricular conduction of sinus impulses leading to the entrance (the lower side) of the reentrant pathway is represented by dashed lines. The first sinus impulse conducted to the ventricles, R~, after extrasystole X1 passes through the reentrant pathway without showing longitudinal dissociation. Sinus impulse R2 falls in the effective refractory period of the fast pathway and passes slowly only through the slow pathway. After that, it becomes concealed extrasystole (X) because of somewhat insufficient conduction delay. Part of the impulse is retrogradely conducted through the fast pathway. Thereafter, it fails to reenter the slow pathway, but prolongs the effective refractory period by electrotonic mediation. 9 Thus, the next sinus impulse, R3, is invariably blocked at the entrance of the dual pathways. Repeated occurrence of such 3:2 Wenckebach periodicity ~° seems to cause the concealed trigeminal rhythm. In the extrasystole X~ and concealed extrasystole (X) of Figure 2, the impulse retrogradely conducted along the fast pathway falls after and before the supemormal period, respectively. On the other hand, the retrograde impulse in extrasystole X2 falls in the supemormal period and reenters the slow pathway, resulting in the appearance of the couplet X2X3. If the abnormally long effective refractory period of the slow pathway was not interrupted by the supernorreal period, such a couplet would not be produced. The extrasystolic impulse X3 in Figure 2 is retrogradely conducted to the atria, -P, and initiates paroxysmal supraventricular tachycardia. There are three possible mechanisms for the tachycardia: (1) uncommon-type of atrioventricular nodal reentrant tachycardia with long RP and short PR' intervals, (2) atrioventricular reciprocating tachycardia due to a slow accessory pathway, and (3) atrial reentrant tachycardia. In the diagram of Figure 2, the mechanism of the tachycardia is explained by uncommontype atrioventricular nodal reentrant tachycardia, although the other mechanisms are not excluded because an electrophysiologic study was not performed in this case. In summary, this is the first report on concealed

72

Journal of Electrocardiology Vol. 28 No. 1 January 1995

ventricular trigeminy coexisting with ventricular couplets. This s t r e n g t h e n s o u r p r e v i o u s s u g g e s t i o n t h a t s u p e r n o r m a l c o n d u c t i o n m a y o c c u r in t h e r e e n t r a n t p a t h w a y of extrasystoles as a m e c h a n i s m of v e n t r i c u l a r couplets.

5.

6. 7.

References

1. Satoh T, Kinoshita S, Tanabe Yet al: Impulse conductivity in the region surrounding the extrasystolic focus: Wenckebach phenomenon of the coupling intervals, and the "rule of multiples." (in Japanese) SaishinIgaku 15:1865, 1960 2. Schamroth L, Marriott HJL: Concealed ventricular extrasystoles. Circulation 27:1043, 1963 3. Levy MN, Kerin N, Rubenfire M: Concealed atrial bigeminy and trigeminy. J Electrocardiol 11:185, 1978 4. Kinoshita S, Konishi G, Kimura K et al: Mechanism

8.

9.

lO.

of concealed atrial trigeminy. Am J Cardiol 62:1147, 1988 Kinoshita S, Okada F, Konishi G e t a]: Mechanism of bradycardia-dependent appearance of manifest extrasystoles in concealed ventricular trigeminy. Chest 106: 289, 1994 Kinoshita S, Fujita K, Kanda K et al: A cause of paired ventricular extrasystoles. Circulation 60:1395, 1979 Kinoshita S, Kato Y, Kawasaki T, Okimori K: Ventricular tachycardia initiated by late-coupled ventricular extrasystoles: the concept of longitudinal dissociation in the microreentry pathway. (editorial) Am Heart J 103:1090, 1982 Kinoshita S: Mechaifisms of ventricular arrhythmias: a theoretical model derived from the concepts of"electrotonic interaction" and "longitudinal dissociation." (editorial) Am J Cardiol 52:1350, 1983 Kinoshita S, Konishi G: Mechanisms of atypical atrioventricular Wenckebach periodicity. J Electrocardiol 22:227, 1989 Kinoshita S, Konishi G: Atrioventricular Wenckebach periodicity in athletes: influence of increased vagal tone on the occurrence of atypical periods. J Electrocardiol 20:272, 1987