Vectorcardiographic study of QRS in patients with transvenous pacemakers and myocardial infarction

J. ELECTROCARDIOLOGY, 7 (1) 27-33, 1974

Vectorcardiographic Study of QRS in Patients With Transvenous Pacemakers and Myocardial Infarction BY H.E. KULBERTUS, M.D.* AND F. DE LEVAL-RUTTEN, M.D.**

SUMMARY

have been described by several investigators. 1-~ The overall appearance of the QRS complex looks very similar to t h a t observed in clinical left bundle branch block, with differences, however, in the direction of the initial vectors. The purpose of the present paper is to describe the vectorcardiographic feat ures observed during ri ght apical vent ri cul ar pacing, in patients with myocardial infarction. T he study was u n d e r t a k e n to search for signs perm i t t i ng recognition of myocardial infarction in patients with p e r m a n e n t pacing. It was also hoped t h a t such an investigation m i ght help increase our ability to diagnose myocardial infarction in the presence of left bundle branch block.

The QRS loop, obtained during right vent r i c u l a r apical stimulation, was studied in 27 patients with d o c u m e n t e d myocardial infarction and in 10 controls. In the latter, the loop was c o n s i s t e n t l y t h i n , e l o n g a t e d a nd inscribed in the left superior and posterior octant, close to the sagittal plane. Two types o f deformities were noted in the patients with m yocar di a l infarction: 1~ disp l a c e m e n t o f the initial portion of QRS (17 cases); and 2~ mid-to-late changes of the loop (18 cases). These mid-to-late alterations consisted e i t h e r o f displacement o f the a f f e r e n t limb outside the left superior and posterior octant or of clearcut departures from a s m o o th loop c o n t o u r ("bites o u t " or "pigtail curls"). Altogether, one or both o f these signs were seen in 25 out of the 27 instances. Assuming t h a t the sequence o f v e n t r i c u l a r activation in p a c e m a k e r r h y t h m is grossly similar to t h a t observed in left bundle b r a n c h block, the f o r m e r alterations were t h o u g h t to be related to septal lesions, whereas the latt e r might be acc ount e d for by the presence o f i n f ar cted segments within the left ventricu l ar free wall. The importance o f mid-to-late deformities for the diagnosis of myocardial i n f a r c t i o n in p a c e m a k e r r h y t h m and left bundle b r an ch block was stressed.

MATERIAL A N D METHODS The study group consisted of 37 subjects. Ten of these (7 female, 3 male) ranging in age from 31 to 78 were devoid of acute myocardial infarction. They suffered from angina (3 cases), arterial hypertension (3 cases), peripheral vascular disease (3 cases), or hyperkinetic heart syndrome (1 case). The QRS complex was normal i/~ 7 and showed signs of moderate left ventricular hypertrophy in 3. These 10 individuals served as controls. The remaining 27 patients had unequivocal histories of myocardial infarction with typical electrocardiographic changes and enzymatic elevations. There were 24 male and 3 female ranging in age from 44 to 78. They were studied between the 7th and the 14th day after the acute episode of coronary occlusion. As far as it could be judged from the standard electrocardiogram, none of them had intraventricular conduction disturbances. Informed consent was obtained from all the patients before carrying out the following procedure. A Zucker-Multipurpose bipolar electrodecatheter (7 F,125 cm) was advanced through the brachial vein under fluoroscopy into the apex of the right ventricle where the tip of the catheter was impinged. Correct positioning of the catheter tip was checked by taking antero-posterior and lateral chest x-rays. The catheter was linked to an R-wave coupled pulse generator (Medtronic Model 5837) and electrical stimuli were delivered between 600 and 1000 msec after onset of the preceding QRS. Spatial vectorcardiograms were recorded using the McFee-Parungao axial system by means of a Hewlett Packard 1520 A vectorcardiograph. To avoid all electrical shock hazards, special attention

The vectorcardiographic patterns observed in p a t i e n t s w i t h t r a n s v e n o u s p a c e m a k e r s

*Agr~g~ de FacultY, Division of Cardiology, Department of Medical Clinics and Semiology, University of Liege School of Medicine, Liege. **Sp~cialiste Adjoint des HSpitaux,. Division of Cardiology, Department of Medical Clinics and Semiology, University of Liege School of Medicine, Liege. This work was supported by the Belgian National Foundation for Scientific Research (F.N.R.S) of which Dr. Kulbertus was a "Chercheur Qualifid". Reprint requests to: H.E. Kulbertus, M.D., Division of Cardiology, Department of Medical Clinics and Semiology, University of Liege, Liege, Belgium. 27

28

KULBERTUS AND DE LEVAL-RUTTEN

~:

iI

L.S,

L_ i FRON

HORIZONTAL

TAL

-90 o

-90 o

0~

.90 ~

_0 o

.180

,90 ~

Fig. 1. U p p e r P a r t : drawing of the QRS contour observed, during right ventricular apical pacing in a patient with hyperkinetic heart syndrome. The extremities of the arrows are 10 msec apart. Lower Part: scattergram of the angular direction of the 20 msec and maximal vectors observed during right ventricular apical pacing, in 10 control subjects (frontal and horizontal projections).

was given to checking regularly the equipment grounding. The X, Y and Z scalar leads were recorded on a magnetic tape (Hewlett Packard Instrumentation Recorder, 3960 A). Together with the three planar loops, they were reproduced on an oscilloscope and photographed by means of a polaroid camera. The overall frequency response of the recording system was set at 200 cycles/sec. The photographs were later enlarged 4 times to ensure easier amplitude measurements. All curves herein illustrated are exact drawings of the actual vectorcardiographic loops. It should be noted that no autopsy data were available in this series and that the location of the infarcted segment could only be assessed from the standard electrocardiogram.

RESULTS A. Vectorcardiographic patterns during right ventricular pacing in patients without myocardial infarction (Fig. 1). In p a t i e n t s w i t h o u t m y o c a r d i a l infarction, the v e c t o r c a r d i o g r a m obtained d u r i n g r i g h t v e n t r i c u l a r apical s t i m u l a t i o n showed a QRS loop w h i c h was a l w a y s thin, e l o n g a t e d and inscribed in the left s u p e r i o r and posterior ocrant, v e r y close to t h e sagittal plane. In the f r o n t a l projection, t h e loop t u r n e d clockwise in 2 cases and showed a figure-of-eight conf i g u r a t i o n in t h e r e m a i n i n g 8. In the horizontal plane, t h e loop was inscribed clockwise J. ELECTROCARDIOLOGY, VOL. 7, NO. 1, 1974

PACEMAKER-VCG IN MYOCARDIAL INFARCTION

F

H

?

29

L.5

/%

o

~

r/

Fig. 2. Examples of the QRS loops obtained during right ventricular apical stimulation in patients with myocardial infarction. Calibration: 0.1 inV. The points on the loops are 10 msec apart. 1. Case no. 2 (extensive anterior infarction): To be noted the rightward shift of the initial portion of QRS and the attraction of the afferent limb into the right posterior and superior octant. 2. Case no. 6 (extensive anterior infarction): Rightward displacement of the initial portion of the loop with, on the afferent limb, a %ite out" bowing rightward, posteriorly and superiorly. 3. Case no. 10 (antero-septal infarction.): The alterations are much more discrete and consist of a small rightward displacement of the initial vectors. 4. Case no. 12 (diaphragmatic infarction): Anterior displacement of the initial forces together with a marked deformity of the afferent limb, bowing anteriorly. 5. Case no. 22 (diaphragmatic and antero-septal infarction): Conspicuous deformity of the mid portion of QRS with convexity pointing anteriorly. To be noted the pigtail curl on the sagittal projection. 6. Case no. 24 (true posterior necrosis): Marked anterior displacement of the initial portion of QRS with slurred conduction. J. ELECTROCARDIOLOGY, VOL. 7, NO. 1, 1974

30

KULBERTUS AND DE LEVAL-RUTTEN

in 3 subjects, counterclockwise in 4 and as a figure-of-eight in three. The three basic types of rotation were also seen in the left sagittal loop (clockwise: 3, figure-of-eight: 4, counterclockwise: 3). The scattergram of the angular direction of the initial 20 msec vector and of the maximal vector in the frontal and horizontal projections is shown in Fig. 1.

B. Vectorcardiographic patterns during right ventricular apical pacing in patients with myocardial infarction (Fig. 2). Out of the 27 studied cases, only 2 showed a QRS loop induced by right apical stimulation which was similar to that seen in patients without myocardial infarction. In the remaining i n s t a n c e s , s i g n i f i c a n t m o r p h o l o g i c a l alterations of the loop could be depicted. Two main types of deformities were encountered: 1~ displacements of the initial or early forces of QRS; and 2 ~ mid-to-late changes of the loop. The mid-to-late alterations consisted either of displacements of the afferent limb outside the left superior or posterior octant, or of clearcut departures from a smooth loop contour which m a y be described as ~bites out", "scallopings" or ~pigtail curls". The latter deformities were only taken into account when they were seen simultaneously in two planes at least, lasted for more than 20 msec and had an amplitude of 0.1 mV or more. The table summarizes the various anomalies which were depicted in the 27 patients and which will be described below in relation to the location of the infarction.

1. Extensive anterior myocardial infarction. Seven patients with extensive anterior infarction were studied. In 6 cases, the QRS loop showed characteristic changes (Fig. 2; 1 and 2) particularly in the horizontal projection where the loop was ballooned and entirely clockwise rotated. There was a consistent rightward displacement of the initial forces of QRS which lasted from 45 to 75 msec. In two cases, the very initial portion of the loop was shifted not only to the right, but also slightly inferiorly. Definite mid-to-late changes were also seen in five of these 6 patients. They consisted of a distinct indentation bowing to the right. The afferent limb even passed into the right posterior quadrant in two instances. The seventh case of this group showed no displacement of the initial forces, b u t displayed the same deformity of the afferent limb as the others. 2. Anteroseptal myocardial infarction. F o u r p a t i e n t s w i t h this diagnosis were studied. It is in this subgroup that the alterations of the p a c e - m a k e r vectorcardiogram were the least noticeable. The initial portion

of the loop was slightly displaced to the right (for about 40 msec) in only one patient (Fig. 2; 3). In the remaining three, the initial forces were directed as in the controls with, however, initial slowing in two cases. A minor deformity of the afferent limb was observed in two out of the four instances. 3. Diaphragmatic myocardial infarction. Seven patients with this diagnosis were studied. In one case, the vectorcardiographic configuration obtained during right ventricular stimulation was similar to that seen in the controls. The initial vectors were unaltered in 2 further instances, whereas in the others, they were displaced to the right (1 case), anteriorly (2 cases), or anteriorly and inferiorly (1 case). Abnormalities of the mid-to-late portion were seen in six instances and consisted of deformities pointing anteriorly in 2 cases and superiorly in 4 (Fig. 2; 4).

4. Anteroseptal and diaphragmatic infarction. Four patients of this series presented with a s s o c i a t e d signs of a n t e r o s e p t a l and diaphragmatic infarction. During right ventricular apical stimulation, their tracings showed initial forces either directed, as in the controls, posteriorly to the left (1 case), or displaced r i g h t w a r d (1 case) or anteriorly (2 cases). A definite deformity of the mid-to-late part of the loop, pointing anteriorly and inferiorly was also seen in two instances (Fig. 2;

5). 5. Posterior infarction. In five patients, signs of true posterior necrosis isolated (2 cases) or combined with inferior infarction (3 cases) were found. On stimulation, their QRS loop displayed initial forces either directed posteriorly to the left, or displaced to the right (1 case), inferiorly (1 case) or anteriorly (1 case) (Fig. 2; 6). The mid-tolate portion of the ventricular loop was normal in 3 cases, but showed an inferior or leftward deformity in the remaining 2.

DISCUSSION With the exception of the initial forces, the overall morphology of the QRS loop induced by right ventricular apical pacing is generally agreed to be similar to that seen in clinical left b u n d l e b r a n c h block w i t h left axis deviation. 1-5 In a study of the genesis of QRS in left bundle branch block, Walston et al ~ correlated the vectorcardiographic features with the sequence of ventricular activation studied by m u l t i p l e epicardial and i n t r a m u r a l elecJ. ELECTROCARDIOLOGY, VOL. 7, NO. 1, 1974

PACEMAKER-VCG IN MYOCARDIAL INFARCTION

31

TABLE 1 QRS abnormalities observed during right ventricular apical pacing in 27 patients with myocardial infarction.

Site of infarction as determined from standard ECG

Displacement of initial forces Direction Timin 9 (msec) Amplitude (mV)

Mid-to-late deformity Direction Timin 9 (msec) Amplitude (mV)

A. Extensive Anterior

B. Antero-septal 8

R R R+I R

0- 65 0-75 0-55 0- 45

R+I R

0-55 0- 65

Marked slurring

0- 30

0.10 0.50 0.29 0.26

(F, (F, (F, (F, 0.37 (F, 0.18 (F,

H) H) H) H) H) H)

R R R R R + P+S R

8 0 -1 4 0 100-170 90-110 100-150 9 0 -1 4 0 120-170

R+S

70-110

90 -130

10 11

R Marked slurring

Diaphragmatic 12 13

0-40 20-70

0.08 (F, H)

0- 35 0-25

0.26 (S) 0.10 (F, H)

14

15 16

A+I

17

A+S S+R

6 0 -1 3 0 60-120

S+R

70-100

0-25

0.17 (H)

60- 80

O- 35

0.13 (H, S)

8 0 -1 0 0

18

D. Antero septal and diaphragmatic 19 2O 21 22

8 0 -1 0 0

R A A (slurring)

0- 45 0- 40 0-70

0.05 (F, H) O.O5 (H, S) 0.05 (H)

24

0-75

0.30 (F,H,S)

0-70

0.10 (F, H)

0 -40

0.11 (F,S)

0.50 (H, S) 0.40 (F, S) with pigtail curl (F) 0.10 (F) with pigtail cuff (F) 0.10 (F, S) with pigtail curl (F,S) 0.10 (H,S) with pigtail curl (H) 0.30 (F, S) with pigtail curl (F)

70 - 120

0.30 (S)

A+I

50- 100

0.48 (H)

30-

A (slurring)

0.17 (F) with pigtailcurl (H) 0.14 (H) with pigtailcurl (H)

A+I

E. True posterior 23

Posterior and diaphragmatic 25 26 27

0.15 (H) 0.41 (F) 0.17 (H) 0.40 (F) 0.28 (F) 0.21 (H)

I

50

90- 140

0.10 (F) with pigtail curl (S)

0.37 (F, S)

R = right; L = left; S = superior; I = inferior; A = anterior; P = posterior. The dane (F = frontal; H = horizontal; S = left sagittal) where the deformity displayed the greatest magnitude is indicated between brackets. J. E L E C T R O C A R D I O L O G Y ,

V O L . 7, NO. 1, 1 9 7 4

32

KULBERTUS AND DE LEVAL-RUTTEN

trodes. With a fair approximation, their results m a y be summarized as follows. In left bundle branch block, the first half of QRS is related to right-to-left septal activation a n d , to a lesser extent, to depolarization of the thinner right ventricular free wall. The second half of QRS corresponds to depolarization of the left ventricular free wall with a wavefront moving from right to left across most of the myocardial wall rather than, as usual, in an endocardial to epicardial direction. The vectorcardiographic manifestations of myocardial infarction are related to loss of forces normally generated towards the i n farcted segment and, consequently, consist of deformities of the loop pointing away from the infarcted zone. The time of the QRS complex where t h e deformity begins and the spatial direction of the deformity are determined by the location of the infarcted zone in relation to the activation fronts. ~ Therefore, in view of Waltson's results, v it seems that if one wishes to investigate the vectorcardiographic manifestations of infarction in p a t i e n t s w i t h t r a n s v e n o u s pacemakers, it m a y be useful to consider the two halves of QRS separately. Lesions involving the septal masses might indeed be expected to produce alterations of the first half of depolarization, whereas necrotic areas located within the left ventricular free wall would probably result in deformities of the mid-tolate portion of the loop. Thus, in extensive damage of the interventricular septum, loss of electromotive vectors normally generated by septal depolarization m a y be expected to leave unopposed forces resulting from right ventricular wall activation and, therefore, to displace to the right the initial and early portion of QRS. Septal lesions having a predominant inferior, superior or posterior location would similarly account for superior, inferior or anterior displacement of the initial vectors. Applying a similar reasoning to lesions lying within the ventricular free wall, one can predict that they m a y be attended by mid-to-late deformities pointing away from the site of infarction. Confirming t h e s e predictions, the pacem a k e r VCG of our patients with documented myocardial infarction showed an abnormal direction of the initial forces in 17 out of 27 instances. Deformities of the afferent limb were also seen in 18 patients. Altogether, one or both of these signs, which were not encountered in controls, could be depicted in 25 out of the 27 cases who were studied during the subacute stage of a coronary occlusion. Without the help of anatomic documentation, it was t h o u g h t hazardous to try and localize the infarcted area from the vectorcardiographic abnormalities. Nonetheless, it is

pertinent to stress the particular aspect of the VCG observed during pacing in patients with extensive anterior infarction. In six out of the 7 cases with this diagnosis, the horizontal plane loop a p p e a r e d v e r y wide open and showed a rightward displacement of both the initial and afferent limb of QRS. This vectorcardiographic pattern was so characteristic as to be almost pathognomonic. Similarly, although the corresponding anomalies were less conspicuous, it is also worth noting that anterior and inferior displacements of the initial forces could only be seen in cases where the standard ECG suggested lesions of the diaphragmatic or postero-basal aspects of the heart respectively: In the authors' experience, the study of the rotation of the loops as well as the search for localized slowings of conduction failed to yield further reliable information regarding the e'xistence of necrotic areas within the myocardium. Altogether, these results are in accord with previous reports on the effects of myocardial infarction on the VCG recorded during right ventricular pacing. In a study of 15 such patients, Zoneraich and Zoneraich 9 observed a 20 msec vector displaced to the right in anterior infarction and anteriorly in posterior infarction. Similar observations were made by Rothfeld et al 1~ in an experimental study of the electrical diagnosis of myocardial infarction in the paced dog heart. Such a l t e r a t i o n s closely resemble those seen in clinical left bundle branch block complicated by myocardial infarction. De Pasquale and Burch 11 investigated 15 patients with left bundle branch block and autopsy d o c u m e n t e d infarction, w h e r e a s W a l s h 12 evaluated 32 patients with the same conduction disturbance and clinical evidence of infarction. In general, the QRS loop showed abnormal direction of the initial forces pointing away from the infarcted zone. Experimental documentation of this phenomenon was provided by Bisteni et al ~3 in their experimental study on dogs. Although these findings are in good agreement with the present results, it should be stressed that their authors mainly focused their attention towards the initial portion of QRS. The data presented in this paper emphasize the diagnostic importance of mid-tolate deformities. This feature predicted by Selvester et al, s was already pointed out by Walsh 12 who noted, for example, that the afferent limb of the loop may be displaced to the right and posteriorly in the presence of left bundle branch block with infarction of the left ventricular free wall. It is the authors' belief that in the presence of a pacemaker rhythm or left bundle branch block, careful examinaJ. ELECTROCARDIOLOGY, VOL 7, NO. 1, 1974

PACEMAKER-VCG IN MYOCARDIAL INFARCTION

tion of the i n t e r m e d i a t e and late portions of QRS might in some cases permit identification of myocardial infarcts t h a t would otherwise r e m a i n unsuspected. As a final r em a r k, it should be r e m e m b e r e d t h a t the findings reported herein were all obt a in ed on patients with recent myocardial infarction; the observed vectorcardiographic deformities m i g h t progressively subside in later stages of the disease. On the other hand, the presence of i n t r a v e n t r i c u l a r conduction disturbances or the development of local fibrosis due to long t e r m implantation m a y also result in significant alterations of the QRS p a c e m a k e r pattern. Therefore, if one wishes to use t h e m for the diagnosis of myocardial infarction in patients with long t e r m pacing, the signs which were described in this paper should be f u r t h e r tested for their specificity and sensitivity in more chronic conditions.

REFERENCES 1. PESCADOR, L AND GARCIA-FERNANDEZ, J L: Vektorkardiographische Untersuchung des Herzens bei Implantiertem Schrittmacher (pacemaker). Verh Dtsch Ges KreislForsch 30:239, 1964 2. THURMANN,M: Vectorcardiographic and electrocardiographic findings of hearts with electrical pacemakers. Am J Med Sci 253:578, 1967 3. CASTELLANOS,A, LEMBERG, L, SALHANICK,L, AND BERKOVITS, B: Pacemaker vectorcardiography. Am Heart J 75:6, 1968 4. ZONERAICH,O, ZONERAICH,S, ANDDOUGLAS,A H: The vectorcardiographic findings in patients with artificial pacemakers. Dis Chest 53:436, 1968 5. CASTELLANOS, A, ORTIZ, J, PASTIS, N, AND CASTILLO,C: The vectorcardiogram of different pacemaker sites. Proc XIth International Vectorcardiography Symposium. New York, 1970, edited by HOFFMAN, I. North Holland

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Publ Co, Amsterdam, 1971, p 304 6. SELVESTER, R H, PALMERSHEIM, J, AND PEARSON, R B: VCG inverse model for the prediction of myocardial disease. Proc XIth International Vectorcardiography Symposium. New York, 1970, edited by HOFFMAN, I. North Holland Publ Co, Amsterdam, 1971, p 54 7. WALSTON,A, BOINEAU,J B, SACH,M S, AVERS, C R, AND ESTES, E H: Relationship between ventricular depolarization and QRS in right and left bundle branch block. J Electrocardiol 1:155, 1968 8. SELVESTER,R H, WAGNER,J O, AND RUBIN, H B: Quantitation of myocardial infarction size and location by electrocardiogram and vectorcardiogram, In Quantitation in Cardiology, edited by SNELLEN, H A, HEMKER, H C, HUGENHOLTZ, P G AND VAN BEMMEL, J H. University Press, Leiden, 1972, p 31 9. ZONERAICH,O AND ZONERAICH, S: Pacemaker vectorcardiography in patients with myocardial infarction and intraventricular conduction defects. Proc XIth International Vectorcardiography Symposium. New York, 1970, edited by HOFFMAN, I. North Holland Publ Co, Amsterdam, 1971, p 314 10. ROTHFELD,E L, ZUCKER, I R, AND AHUJA, U: Electrical diagnosis of myocardial infarction in the paced dog heart. J Electrocardiol 6:27, 1973 11. DE PASQUALE,N AND BURCH, G E: The spatial vectorcardiogram in left bundle branch block and myocardial infarction with autopsy studies. Am J Med 29:633, 1970 12. WALSH,R J: The Frank system in left bundle branch block with myocardial infarction. Proc Long Island Jewish Hosp Symposium Vectorcardiography. 1965, edited by HOFFMAN I. North Holland Publ Co, Amsterdam, 1966, p 232 13. BISTENI, A, MEDRANO, G A, DE MICHELI, A, AND SODI-PALLARES,D: Experimental myocardial infarction in the presence of bundle branch block. Proc Long Island Jewish Hosp Symposium Vectorcardiography. 1965, edited by HOFFMAN, I. North Holland Publ Co, Amsterdam, 1966, p 226