Intraventricular conduction time (H-V interval) during antegrade conduction in patients with heart block

Intraventricular Conduction Time (H-V Interval) During Antegrade Conduction in Patients with Heart Block PREM K. GUPTA, MD, FRCP (C) EDGAR LICHSTEIN, MD KUL D. CHADDA, MD Elmhurst, New York

Intraventricular conduction time ( H - V interval) was recorded during antegrade conduction in 16 patients with various intraventricular conduction abnormalities who showed second degree or complete heart block. In 9 patients the block was localized distal to the His bundle potential (H) by His bundle electrography. The remaining 7 patients had shown block before the study. The H - V interval during antegrade conduction was prolonged in 15. Atrial pacing was performed in 6 patients during 1:1 A - V conduction. In 3 patients second degree atrioventricular ( A - V ) block developed distal to the H potential. In 2 o! these patients, complete heart block had been noted earlier, and in 1 it developed 3 months after the study. The remaining 3 patients showed 1:1 A - V conduction during atrial pacing, even though each had earlier shown complete heart block. We conclude that the majority of patients with bundle branch block who experience heart block have a prolonged H - V interval during antegrade conduction. Atrial pacing performed during 1:1 A - V conduction may or may not produce block distal to the H potential.

Clinical and electrocardiographic studies have shown t h a t the majority of p a t i e n t s d e m o n s t r a t e some form of bundle b r a n c h block before the onset of high grade or c o m p l e t e heart block. 1-6 Diffuse fibrosis of the bundle b r a n c h e s has been noted on pathologic e x a m i n a t i o n of the conduction s y s t e m in such patients, v-l° Recent studies utilizing His bundle e l e c t r o g r a p h y have shown t h a t in m o s t p a t i e n t s with chronic c o m p l e t e h e a r t block the block is distal to the His bundle potential; t h a t is, in the bundle b r a n c h e s or, rarely, in the His bundle. 11-13 At present there is no way to predict in which p a t i e n t with bundle b r a n c h block c o m p l e t e heart block will develop.14 Although a prolonged i n t r a v e n t r i c u l a r conduction t i m e ( H - V interval) is t h o u g h t to indicate delay in the functioning bundle, an increased risk of heart block has not been d e m o n s t r a t e d in such cases. Sixteen p a t i e n t s with various i n t r a v e n t r i c u l a r conduction abnormalities and s p o n t a n e o u s second degree or c o m p l e t e h e a r t block are described (Table I). T h e H - V interval recorded during s u p r a v e n tricular conduction was prolonged in 15 patients. Atrial pacing at various rates was p e r f o r m e d in several cases. T h e prognostic value of the H - V interval a n d the role of atrial pacing are discussed. From the Department of Medicine, Division of Cardiology, Mount Sinai Hospital Services, City Hospital Center at Elmhurst, Mount Sinai School of Medicine, of the City University of New York, Elmhurst, N.Y. Manuscript accepted January 24, 1973. Address for reprints: Prem K. Gupta, MD, Division of Cardiology, Mount Sinai Hospital Services, City Hospital Center at Elmhurst, 79-01 Broadway, Elmhurst, N.Y. 11373.

Methods His bundle electrograms were recorded by the method described by Scherlag et al. 15 A no. 6 bipolar electrode catheter with an interelectrode distance of 1 cm was passed percutaneously by way of a femoral vein and advanced until the tip was across the tricuspid valve. His bundle electrograms were recorded on an Electronics for Medicine multichannel recorder at a frequency response of 40 to 500 Hz and at paper speeds of 75 and 150 mm/sec. One or more leads of the peripheral electrocardiogram were recorded simultaneously. Atrial pacing was performed with a second catheter

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H-V INTERVAL IN HEART BLOCK--GUPTA ET AL.

TABLE I Summary of 16 Cases Interval Case Age (yr) no. & Sex

QRS Configuration

A-H H-V P-R(sec) (msec) (msec)

Effect of Atrial Pacing

1

76F

RBBB, LAH

0.24-0.28

140

80-120

2

82M

RBBB, LAH

0.22

90

100

AP 130/min; 2:1 block distal to H

3

90F

RBBB

0.17-0.20

100

60-90

...

4

78M

RBBB, LAH

0.18

100

60

5

81M

RBBB, LAH

0.16

80

75

AP 100/min; Mobitz type II block distal to H ...

6

65M

RBBB, LAH

0.22

60

125

7

98F

LBBB RBBB, LPH

0.17

70

70

AP l l 8 / m i n ; 2:1 A-V block distal to H ...

8

55F

RBBB, LAH

0.20-0.28

90

110-190

...

9

54F

RBBB, LAH

0.23

150

60

...

10

88M

RBBB

0.22

140

65

...

11

75M

RBBB, LPH

0.20

100

85

AP 150/min; 1:1 A-V conduction

12 13

71F 75M

RBBB RBBB, LAH

0.20 0.21

90 85

70 85

... ...

14

48M

RBBB, LAH

0.21

90

100

...

15

86F

RBBB, LPH RBBB

0.18 0.16

85 100

80 50

AP 150/min; 1:1 A-V conduction ...

16

75F

RBBB, LAH

0.16

80

75

AP 150/min; 1:1 A-V conduction

Type and Site of Block High grade and complete heart block before and during study. Block localized distal to H CHB 3 months after initial study. Block localized distal to H Wenckebach block during study. Block localized distal to H Transient complete heart block before study Mobitz type II second degree block before study Transient CHB before study 2:1 and high grade block during study. Block localized distal to H Wenckebach and high grade block during study. Block localized distal to H Transient high grade and CHB before study Mobitz type II block during study, block localized distal to H Transient CHB before study (during prostate surgery) Transient CHB before study 2:1 A-V block during study. Block localized distal to H Transient high grade and complete A-V block during study. Block localized distal to H 2:1 A-V block during study. Block localized at A-V node and distal to H Transient CHB before study

AP = atrial pacing; A-V = atrioventricular; CHB = complete heart block; H = His potential; LAH = left anterior hemiblock; LBBB = left bundle branch block; LPH = left posterior hemiblock; RBBB = right bundle branch block.

positioned against the lateral wall of the right atrium. His bundle pacing was attempted in several patients. M e a s u r e m e n t s : The following intervals were measured: The A - H interval, which includes intranodal conduction time, was measured from the onset of the atrial depolarization (A) to the onset of the His bundle depolarization (H). The H-V interval, which includes conduction time through the His bundle and the bundle branches, was measured from the onset of the His bundle deflection (H) to the onset of the ventricular depolarization either on the intracardiac electrogram or on the peripheral electrocardiogram, whichever came earlier. The normal range of the A-H and H-V intervals in our laboratory was determined from 12 patients with a normal P - R interval and QRS configuration who were receiving no medication. In these patients the A - H interval ranged from 70 to 140 msec and

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the H-V interval from 35 to 55 msec. These values are similar to those reported by othersJ 6,z~ P a t i e n t m a t e r i a l : The 16 patients described here are among the 170 patients with various conduction abnormalities studied in our laboratory during the past 18 months. Fifteen patients were hospitalized because of syncope. Their ages ranged from 48 to 98 years. Eight patients were male and 8 female. None had acute myocardial infarction. Nine patients had right bundle branch block and left anterior hemiblock. Four patients had only right bundle branch block. One had right bundle branch block and left posterior hemiblock. One had left bundle branch block alternating with right bundle branch block and left posterior hemiblock, and another had right bundle branch block with alternating left anterior and posterior hemiblock. Atrial pacing at various rates was per-

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F I G U R E 1. C a s e 14. T h e 12 l e a d e l e c t r o c a r d i o g r a m ( t o p ) has a p a t t e r n of right b u n d l e b r a n c h b l o c k and left a n t e r i o r h e m i b l o c k . T h e r h y t h m strip s h o w s c o m p l e t e A - V b l o c k w i t h an i d i o v e n t r i c u l a r r a t e of a b o u t 3 6 / m i n . His b u n d l e e l e c t r o g r a m s in the upper panel s h o w sinus r h y t h m w i t h 1:1 A - V c o n d u c t i o n . High g r a d e b l o c k is p r e s e n t in the lower panel. B l o c k o c c u r s distal to the H p o t e n t i a l . The last QRS c o m p l e x in the l o w e r p a n e l is a v e n t r i c u l a r e s c a p e beat. P a p e r s p e e d 150 m m / s e c ; t i m e lines 1 s e c o n d .

formed in 6 patients during supraventricular conduction. His bundle pacing attempted in several patients invariably resulted in depolarization of the adjacent myocardium. Five patients were studied more than once. Results

The H - V interval was recorded in all 16 patients during supraventricular conduction and ranged from 50 to 190 msec. In 15 patients it was prolonged and ranged from 60 to 190 msec. In the remaining patient it measured 50 msec. Two patients (Cases 3 and 8) showed W e n c k e b a c h type of second degree A-V block, and in each instance the delay occurred distal to the His bundle potential. In 9 patients (Cases 1 to 3, 7, 8, 10 and 13 to 15) the block (second degree, high grade or complete) was localized distal to the His bundle potential by His bundle electrography. The remaining 7 patients showed Mobitz type II or complete heart block on the electrocardiogram only; 1:1 A-V conduction had r e t u r n e d in each of these 7 patients at the time of His bundle recordings. However, the configuration of the idioventricular complexes suggested t h a t the site of the block was distal to the main His bundle. Atrial pacing produced Mobitz type II block distal to the H potential in 3 patients (Cases 2, 4 and 6).

Patients 4 and 6 had earlier shown transient complete heart block, whereas P a t i e n t 2 had complete heart block 3 m o n t h s after the study. In 3 other patients (Cases 11, 14 and 16), atrial pacing failed to produce block distal to the His bundle, although all 3 patients had previously shown complete heart block. One patient with a normal H - V interval had block at the A-V node and distal to the His bundle potential on different occasions. The only patient who w a s a s y m p t o m a t i c (Case 11) showed transient complete heart block during prostate surgery. Illustrative case descriptions: Figure 1 is from Patient 14, who was admitted because of an episode of syncope while watching television at home. The 12 lead electrocardiogram recorded in the emergency room shows a pattern of right bundle branch block and left anterior hemiblock. The rhythm strip recorded soon after admission shows complete A-V block. His bundle electrograms recorded during pacemaker insertion show many nonconducted beats. The block is distal to the His bundle potential. Two days after admission 1:1 A-V conduction returned. However, the QRS configuration had changed to right bundle branch block with left posterior hemiblock. Atrial pacing at a rate of 150/min at this time failed to produce block distal to the His bundle. Figure 2 is from Patient 8, who was admitted because of multiple syncopal episodes. The admission electrocardio-

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H-V INTERVAL IN HEART BLOCK--GUPTA ET AL.

~ '-' s-.-

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FIGURE 2. Case 8. The electrocardiogram (top) shows a )attern of right bundle branch block and left anterior hemiblock. The rhythm strip shows a Wenckebach type of second degree A - V block. In the His bundle electrogram the A-H interval remains constant, but the H-V interval varies and the block occurs distal to the H potential. Paper speed 75 m m / s e c ; time lines 1 second.

gram shows a pattern of right bundle branch block with left anterior hemiblock. The A-V conduction pattern shows block of the Wenckebach type. His bundle electrograms obtained at the time of admission show a progressive increase in the H-V interval prior to dropped beats• The A-H interval remains unchanged. This kind of block has previously been noted by othersJ s,19 Intravenous administration of atropine decreased the A-H interval, but the Wenckebach type of block distal to the H potential persisted. Discussion

Progression of bifascicular block to complete heart block has been well established by several electrocardiographic and clinical studies. 1-6 The reported incidence of high grade or complete heart block in patients with right bundle branch block and left anterior hemiblock ranges from 6 to 13 percent, whereas heart block may develop in 62 percent of patients with right bundle branch block and left posterior hemiblock.2,3,5 It is presently not possible to predict in which patient with bundle branch block heart block will develop. 14 A prolonged H-V interval in a patient with bundle branch block indicates delay in the functioning bundle and has been found in 72 percent of patients with right bundle branch block and left anterior hemiblock, 100 percent of patients with right bundle branch block and left posterior hemiblock and 50 to 100 percent of patients with complete left bundle branch block. 2o-23 Although a prolonged H-V interval is consistent with trifascicular disease, a direct correlation with the risk of heart block is not presently available. In the present series second degree block developed distal to the H potential during atrial pacing in

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3 patients. All had prolonged H-V intervals. In 2, transient complete heart block had occurred earlier, and in the third, complete heart block developed subsequently. Three additional patients who had shown complete heart block earlier did not have block during atrial pacing. In the series of Narula and Samet, 2o 4 patients had block distal to the H potential during pacing, and all had a prolonged H-V interval. Rosen et al. 17 described 3 patients with left bundle branch block who had block distal to the H potential during atrial pacing. The H-V interval was prolonged in all. None of the 24 patients described by Haft et al. 21 had block distal to the H potential during pacing. We have not seen any patient with a normal H-V interval who had block distal to the H potential during atrial pacing. In patients with a prolonged H-V interval, block distal to the H potential may occasionally develop during pacing. The role of atrial pacing as a stress test to the conduction system in patients with a normal H -V interval seems to be of little or no value at present. The finding of a prolonged H-V interval in 15 of 16 patients in our series is in agreement with the results of Narula and Samet 2° and Ranganathan et al. 19 Among 123 patients with various intraventricular conduction abnormalities described by Narula and Samet, 2° 19 had shown spontaneous Mobitz type II or complete A-V block, and all 19 had a prolonged H-V interval. In a relatively small series of 4 patients with Mobitz type II block distal to the His bundle potential, Ranganathan et al. 19 found a prolonged H-V interval in all. Rosen et al. 22 described a patient with left bundle branch block who had complete heart block 1 to 1~/2 years after the initial

H-V INTERVAL IN HEART BLOCK--GUPTA ET AL.

study. The H-V interval was prolonged in this patient also. In contrast, Kranz and Haft 24 found a prolonged H-V interval in only 1 of the 5 patients who showed Mobitz type II or complete heart block. Clinical implications: The results of our studies and those of others 19,2° suggest that the majority of patients with bundle branch block in whom heart block develops have a prolonged H-V interval during antegrade conduction. However, this does not mean that all patients with a prolonged H-V interval will have heart block or that patients with a normal H-V

interval are excluded from the risk of complete heart block. In a patient with a normal H-V interval, a prolonged H-V interval may gradually develop after months or years because of the progression of fibrosis in the functioning conduction system. Serial electrophysiologic studies of the conduction system would be necessary to prove this hypothesis. We believe that patients with a prolonged H-V interval have a higher risk of experiencing heart block. A long-term follow-up study of such patients is necessary to confirm this assumption.

References 1. Lepeschkin E: Electrocardiographic diagnosis of bilateral bundle branch block in relation to heart block. Progr Cardiovasc Dis 6:445-471, 1964 2. Lasser RP, Haft JI, Friedberg CK: Relationship of right bundle branch block and marked left axis deviation (with left parietal or peri-infarction block) to complete heart block and syncope. Circulation 37:429-437, 1968. 3. Scanlon PJ, Pryor R, Blount SG: Right bundle branch block associated with left superior or inferior intraventricular block: clinical setting, prognosis and relation to complete heai't block. Circulation 42:1123-1133, 1970 4. Rosenbaum MR, Elizari MV, Lazzarl JO, et al: Intraventricular trifascicular blocks. Review of the literature and classifications. Amer Heart J 78:450-459, 1969 5. Rosenbaum MB, Elizari MF, Lazzari JO: The Hemiblocks. Tampa Tracings, Oldsmar, Fla, 1970, p 130, 146 6. Kulbertus M, Collignon P: Association of right bundle branch block with left superior or inferior intraventricular block. Its relation to complete heart block and Adams-Stokes syndrome. Brit Heart J 31:435-440, 1969 7. Yater WM, Cornell VH, Clayton T: Auriculo-ventricular heart block due to bilateral bundle branch lesions. Arch Intern Med (Chicago) 57:132-173, 1936 8. Lenegre JF: Etiology and pathology of bilateral bundle branch block in relation to complete heart block. Progr Cardiovasc Dis 6:409-444, 1964 9. Davies M, Harris A: Pathological basis of primary heart block. Brit Heart J 31:219-226, 1969 10. Harris A, Davies M, Redwood D, et al: Etiology of chronic heart block. A clinico-pathological correlation in 65 cases. Brit Heart J 31:206-218, 1969 11. Narula OS, Scherlag BJ, Javier RB, et al: Analysis of the A-V conduction defect in complete heart block utilizing His bundle recordings. Circulation 41:437-448, 1970 12. Steiner C, Lau SH, Stein E, et al: Electrophysiologic documentation of trifascioular block as the common cause of complete heart block. Amer J Cardiol 28:436-441, 1971

13. Ehsani A, Rosen KM, Dingra R, et al: Sites of chronic heart block in adults--clinical and electrocardiographic correlations (abstr). Circulation 46: suppl I1: 91, 1972 14. Haft JI, Lasser RP: ECG patterns useful in the diagnosis of intermittent heart block. JAMA 222:184-188, 1972 15. Scherlag BJ, Lau SH, Helfant RH, et al: Catheter technique for recording His bundle activity in man. CirCUlation ~}9:1318, 1969 16. Damato AN, Lau SH, Helfant RH, et al: Study of atrioventricular conduction in man using electrode catheter recording of His bundle activity. Circulation 39:287-295, 1969 17. Rosen KM, Rahimtoola SH, Chuquimia R, et al: Electrophysiological significance of first degree atrioventricular block with intraventricular conduction disturbance. ,Circulation 43:491-502, 1971 18. Narula OS, Samet P: Wenckebach and Mobitz type II A-V block due to block within the His bundle and bundle branches. Circulation 41:947-965, 1970 19. Ranganathan N, Dhurandhar R, Phillips JH, et al: His bundle electrograms in bundle branch block. Circulation 45: 282-294, 1972 20. Narula DS, Samet P: Right bundle branch block with norL mal, left or right axis deviation. Analysis by His bundle recordings. Amer J Med 51:432-455, 1971 21. Haft Jl, Weinstock M, DeGuia R, et al: Assessment of atrioventricular conduction in left and right bundle branch block using His bundle electrograms and atrial pacing. Amer J Cardiol 27:474-480, 1971 22. Rosen KM, Ehsani A, Rahimtoola SH: H-V intervals in left bundle branch block. Circulation 46:717-723, 1972 23. Cannom DS, Goldreyer BN, Damato AN: Atrioventricular conduction system in left bundle branch block with normal QRS axis. Circulation 46:129-137, 1972 24. Kranz PD, Haft JL: Intraventricular conduction (H-Q) intervals during orthograde conduction in patients with complete heart block (abstr). Circulation 46: suppl II: 90, 1972

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