Paradoxical Motion of InterventricularSeptum in Left Bundle Branch Block

By ABDUL S. ABBASI, M.B., M.R.C.P., LESLIE M. EBER, M.D.,

REx N. MACALPIN, M.D., AND ALBERT A. KATTUS, M.D.

SUMMARYAbnormal interventricular septal motion, with pre-ejection posterior motion and anterior mo-

tion away from the posterior left ventricular wall during ejection, was demonstrated by echocar-diography in 14 out of 17 cases with complete left bundle branch block (LBBB). Two of 14cases had intermittent LBBB and showed abnormal septal motion only during LBBB. Of the con-

trol group of 49 patients without LBBB but with cardiac disorders similar to the cases with LBBB,only two showed abnormal septal motion. However, pre-ejection motion was not seen in these twocases. During right ventricular pacing abnormal septal motion was observed in three out of tencases. It is suggested that conduction abnormalities are responsible for abnormal septal motionin LBBB; normal septal motion in most cases with right ventricular pacing may be due to dif-ferent c3nduction pathways not affecting the septum.

Additional Indexing Words:Noninvasive techniqueRight ventricular volume overload

CardiomyopathyUltrasound

Right ventricular pacing

LEFT VENTRICULAR WALL MOTIONhas been found to be normal in angio-

cardiographic studies of patients with completeleft bundle branch block (LBBB) and no othercardiac abnormalities.' However, motion ofthe in,terventricular septum in LBBB has not beeninvestigated angiographically because of the diffi-culty in visualizing the septum without simulta-neous opacification of both ventricular cavities.2Echocardiography is a convenient method for

recording motion of the ventricular septum.3-6 Thisstudy was carried out to evaluate septal andposterior left ventricular wall motion using echo-cardiography in patients with LBBB.

MethodsEchocardiograms were analyzed in four groups of

patients: group 1 consisted of 17 patients with LBBB;group II consisted of 49 patients without LBBB butwith cardiac diseases similar to those present in groupI; group III consisted of 30 healthy volunteers; groupIV consisted of ten patients whose hearts were beingpaced electrically from the region of the apex of the

From the Department of Medicine, University ofCalifornia School of Medicine, Los Angeles, California.

Address for reprints: A. S. Abbasi, M.D., UCLA MedicalCenter, Los Angeles, California 90024.

Received August 29, 1973; revision accepted forpublication November 19, 1973.

Circulation, Volume XLIX, March 1974

right ventricle with an electrode catheter, and whosepaced beats resembled LBBB.

Patients with suspected or proven coronary arterydisease were excluded from groups I, II, and III.Diagnoses were confirmed by cardiac catheterizationand coronary arteriography in all cases in group I, andall but eight cases of uncomplicated hypertension ingroup II.The criteria for LBBB were those of the New York

Heart Association: QRS _I~ 0.12 see; notching or slur-ring of the QRS which shows an initial R wave in I,aVL and left precordial leads; in these leads the peak ofthe R wave or one of its prominent notches occurs rela-tively late in the QRS interval; displacement of the S-Tsegment and usually the T wave in a direction oppositethat of the principal QRS deflection.7

Echocardiograms were performed with commerciallyavailable equipment using a 2.25 MHz, 0.5 cmdiameter transducer with a focus at 10 cm and arepetition rate of 1000 impulses per second. With theconventional technique described previously,8 thetransducer was placed in the fourth or fifth intercostalspace close to the left sternal border, and was directedantero-posteriorly and slightly medially to identify themitral valve. The transducer was then pointed laterallyand inferiorly, to obtain echoes simultaneously from theventricular septum and posterior left ventricular walljust below the mitral valve. Care was taken to point thetransducer inferiorly and not superiorlv in order toavoid recording from the aortic root and membranouspart of the interventricular septum. Records showingonly a small part of the mitral valve were included. Ifthe entire anterior mitral valve leaflet was seen in therecord, the tracing was not included in the present

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ABBASI4, EBER, MACALPIN, KATTUS

study because this inidicated that the transducer waspointed medially and the beam may have been close tothe root of the aorta. In this positiorn, abnormal septalmotion has beeni seen by us and others5' even in normalindividuals. Occasioially with a dilated left ventricle itwas not possible to obtain an adequate record of theposterior wall without recording the mitral valve.However in such cases the transducer was directedenough laterally to avoid the aortic root. With adjust-ment of the gain controls it was possible to recordendocardium of the posterior left ventricular wallin all buit fotur cases. In these the epicardial-pericardialechoes were anialyzed.

ResultsPatient PopulationThe types of cases in groups I and II are shown in

table 1. One patient in group I and two patients ingroup II with aortic stenosis had an aortic pros-thetic valve, implanted at least one year prior tothe study. Patients with hypertension had diastolicpressures of over 100 mm Hg. None of the patientswith mitral insufficiency had associated tricuspid in-sufficiency. Congestive cardiomyopathy was diag-nosed on the basis of cardiomegaly and episodesof clinical failure in the absence of valvular, athero-sclerotic, or hypertensive heart disease. Echocardio-grams were available with and without LBBB inone patient who had congestive cardiomyopathyand one normal person with intermittent LBBB.The ten patients in group IV were those requiring

a temporary or permanent right ventricular pace-maker because of heart block or the sick sinus nodesyndrome. Four of these had clinical evidence ofischemic heart disease.The mean age of groups I and II was comparable

(49 years, with range of 28-72 for group I, and 45years, with range of 25-68 for group II). The meanage of the healthy volunteers was younger (30years, with a range of 22 to 45). The group IV pa-tients were sliqhtly older (mean age of 52 years,with a range of 40-80).

Table 1

Types of Patients in Groups 1 and II

Group I (with LBIB) Group II (without LBBB)

Aortie stetiosisHypertensionMitral insufficieneyCa,rdiomvoptath-Normal

Total

23

217

S10)1516

49

Normal Poradoxics Interrnediae

V Septurn , 5-'

ECG

PostLV

Figure 1

Diagrammatic echocardiographic patterns of interventricularseptuim (IV septum) and posterior left ventricular wall(Post. LV) in normal and in LBBB. The echocardiogranswere recorded at different scales; thus the amplitudes ofwall motion are not directly comparable. The time markingsin each record are 1.0 sec apart.

ElectrocardiogramsThe duration of QRS in group I was between

0.12 and 0.14 in seven cases, between 0.15 and 0.17in eight cases, and 0.18 in two cases. The meanfrontal plane QRS axis was normal in seven casesand leftward (superior to -300) in ten cases.

EchocardiogramsRepresentative echocardiograms from the various

groups are presented in figures 1 to 4 and show leftventricular wall and ventricular septal motion.The letters used to represent different intervals

in this study were those introduced by Edler andGustafson to describe the timing of mitral valvemotion'0 and by Kraunz and Kennedy for left ven-tricular wall motion.'1

Normally, following the P wave of the electro-cardiogram, the posterior left ventricular wall andventricular septum move away from each other as

Figure 2

Normal echocardiograms showing interventricular septal andposterior left ventricular tcall m.otion. EGG Electrocardio-gram; Phono = Phonocardiogram; Chordae Chordae ten-dineae.

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SEPTAL MOTION IN LBBB

RV

}.V Septum

-ECG

Post LV

Figure 3

Echocardiogram showing paradoxical ventricuilar septal mo-tion in left BBB.

the left ventricular cavity is distended by the atrialcontraction; this phase is represenited by AB (figs. 1anid 2). During isovolumetric contraction (BC) theseptum moves slightly anteriorly away from theposterior left ventricular wall; this phase in the pos-terior ventricular wall is usually associated withposterior motion;" however, it may not be separate-ly identified. During ejection (CD) the posteriorleft ventricular wall and ventricular septum ap-proximate each other. During the last part of ejec-tion, both the posterior wall and the septum moveparallel to each other.6 Following this phase, theposterior wall and the septum move away fromeach other in opposite directions, as the ventriclefills with blood during ventricular relaxation (EF).

-I V Septum

-ECG

At the beginning of ventricular diastole a notch inthe septal motion is comtmoinly sent This generalpattern of the posterior left ventricular wall andthe septal motion was seen in all the normal sub-jects in group III, and all but two cardiac casesof group II. These two cases had congestive cardio-myopathy without LBBB, and had abnormal septalmotion similar to that seen in group I except forone important difference described below.The patients with LBBB (group I) showed three

patterns of ventricular septal motion: 1) normalmotion in three cases; 2) paradoxical septal motionin ten cases; 3) intermediate septal motion in fourcases. There was no relationship between the typeof cardiac disease and the type of septal motion(table 2).The analysis of paradoxical septal motion in

cases with LBBB (figs. 1 anid 3) showed an anteriordisplacement of the septum following the P wave,as was seen in normal eases. However, during pre-ejection phase there was a rapid posterior septalmotion, often quite prominent. Following this, therewas a major anterior (paradoxical) septal motionaway from the posterior left ventricular wall duringejection, instead of a normal posterior septal mo-tion; the posterior left veitr-iculor wall moved nor-mally, that is, anteriorly at this time. At the begin-inig of ventricular diastole, following the T wave ofthe electrocardiogram, both the septum and theposterior wall moved posteriorly, as compared tothe normal anterior septal motion during ventric-ular diastole. One healthy adult and one patientwith cardiomyopathy, both with intermittent LBBBshowed abnormal septal motion as described aboveonly during a LBBB pattern. During normal con-duction the septal motion was normal.The intermediate type of septal motion was more

complex (figs. 1 and 4). It had a similar anteriormotion following the P wave, as seen in normalcases or in cases with LBBB. Following the QRSthere was a prominent pre-ejection posterior septalmotion as seen in paradoxical septal motion

Table 2

Interventrictular Motion Patterns in 17 Cases with LBBB

W- Post LV

Figure 4

Echocardiogram showing intermediate type of ventricularseptal motion in LBBB. Endocardium of the posterior leftventricular twall could not be recorded in this case.

Circulasion, Volume XLIX, March 1974

Diagnosis

Aortic steriosisHypert.ernsioniMitral insufficiencyCardiomyopathyNornal

Intersventriciilar septal miotionNormral Paradoxical Intermediate

2 0l L 11 1 11) 1 1

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ABBASI, EBER, MACALPIN, KATTUS

described above. However, the subsequent anterior(paradoxical) septal motion was much reduced inamplitude and was often interrupted by one or twomid- to late systolic posterior motions, toward theposterior left ventricular wall.Although the initial rapid pre-ejection motion

was seen in both the types of abnormal septal mo-tion associated with LBBB, it was absent in twocases of cardiomyopathy that showed abnormalseptal motion without LBBB.A careful analysis of the echocardiogram in three

patients with apparently normal septal motionshowed a delayed posterior left ventricular wallmotion in one. No significant difference in QRSduration or axis deviation was noted in these threepatients as compared to those with LBBB and para-doxical septal motion.

In patients in group IV, only three out of tenshowed paradoxical septal motion.

DiscussionOur study showed abnormal septal motion in 14

out of 17 cases with LBBB. No abnormality wasfound in posterior left ventricular wall motion. Intwo of the cases showing abnormal septal motion,no further abnormality was detected on physicalexamination or at cardiac catheterization. That theabnormal septal motion was secondary to abnormalconduction was further demonstrated by two caseswith intermittent LBBB. In both, abnormal septalmotion occurred only during LBBB. During normalconduction, the ventricular septal motion wasnormal. The relationship of abnormal septal motionto LBBB was further supported by findings in ourcontrol group II without LBBB, all but two ofwhich showed normal septal motion, even thoughcardiac disorders similar to those in group I werepresent. In these two cases abnormal septal motionmay have been related to the intrinsic cardiac dis-ease, which was cardiomyopathy in both. Motionabnormalities of left ventricular wall have beenfound secondary to cardiomyopathy or ischemicheart disease.' Abnormal septal motion has alsobeen reported in ischemic heart disease with orwithout LBBB.12 It is possible that abnormal septalmotion may also occur in cardiomyopathy unasso-ciated with LBBB. Our study did not include caseswith coronary artery disease. The incidence of para-doxical septal motion without LBBB in our series ofcardiomyopathy was low (12.5%); while withLBBB, a significant number of patients withcardiomyopathy (four out of five) had abnormalseptal motion. This suggests that paradoxicial

motion in cardiomyopathy is more often related toLBBB. Moreover, an important difference betweenthe abnormal septal motion associated with LBBBand that occurring with cardiomyopathy, but with-out LBBB, was noted; this was the presence of pre-ejection posterior septal motion with LBBB and itsabsence without LBBB. Thus it appears that thepre-ejection motion of the septum may be the morespecific abnormality associated with LBBB.An abnormal septal motion has been found in

patients with right ventricular volume overloadwhich was not present in any of our cases.4' 5, 13The mechanism of paradoxical septal motion in

LBBB is uncertain. It may be that LBBB results inearly pre-ejection posterior motion of the septumdue to displacement from rising right ventricularisovolumic pressure that exceeds the pressuredeveloped by the delayed left ventricular contrac-tion.14 However, normal septal motion duringapical right ventricular pacing does not favor thishypothesis. A better explanation may be an initialseptal activation on the right side of the septum asoccurs in LBBB5 causing septal contraction firstwhen the rest of the left ventricle is quiescent.When the rest of the left ventricle contracts, theseptum is relaxed and is pushed anteriorly awayfrom the posterior left ventricular wall because ofrising left ventricular pressure.The three patients with LBBB who had apparent-

ly normal septal motion could have a moreperipheral block, as has been suggested to occur insome cases with LBBB.16 Thus the septal activationmay occur normally, and septal motion may remainnormal. A delayed posterior left ventricular wallmotion may be expected in these cases; however, itwas only seen in one of our three cases.

It is not clear why only three of ten patients whohad right ventricular pacing and a "LBBB pattern"on the electrocardiogram during pacing showedabnormal septal motion. However, all these patientshad pacing performed from the apex of the rightventricle. It is possible that several conductionpathways exist in different areas of the rightventricle, and paradoxical septal motion may beseen only when an appropriate region of the rightventricle is stimulated.The question may be raised whether LBBB with

abnormal motion of the interventricular septum hasany hemodynamic consequences. A reduction ofcardiac output has been reported during LBBB inpatients with intermittent LBBB.'6 However, wedid not find any hemodynamic abnormality in twoof our cases with permanent LBBB who had no

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SEPTAL MOTION IN LBBB

associated cardiac disease. It may be that duringacute LBBB, as occurs in patients with intermittentLBBB, stroke volume may drop, and in morechronic cases of established LBBB, compensatorymechanisms may normalize the hemodynamics.

Present evidence in the literature suggests thatLBBB which is unassociated with cardiac diseasemay be benign.'7 18 This may be so in otherwisenormal patients, even though the interventricularseptum may be asynergic. Whether or not patientswith LBBB, occurring concurrently with othercardiac pathology, e.g., aortic stenosis or cardiomy-opathy, are at risk because abnormal septal motionhas not yet been determined.

Since completion of this study, a paper byMacDonald, "Echocardiographic demonstration ofabnormal septal motion in left bundle branchblock" has appeared in print.19 Our findings aresimilar to his. After submission of this manuscriptfor publication, Dillon and his associates reportedstudies that showed that the abnormal septalmotion in LBBB can be distinguished from thatseen in right ventricular overload.20

Acknowledgment

We wish to acknowledge the technical assistance of Mrs.Nancy Ellis.

References

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2. DESILETs DT, KADELL BM, RUITENBERG HD,GOLDBERG SJ, MACALPIN RN: Angiographic dem-onstration of the ventricular septum. Radiology 91:329, 1968

3. PoPP RL, WOLFE SB, HIRATA T, FEIGENBAUM H:Estimation of right and left ventricular size byultrasound. A study of echoes from the interventricu-lar septum. Am J Cardiol 24: 523, 1969

4. DIAMOND MA, DILLON JC, HAINE CK, CHANG S,FEIGENBAUM H: Echocardiographic features of atrialseptal defect. Circulation 43: 129, 1971

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9. Popp RL: A standardized method for manualtransducer orientation to obtain left ventriculardimensions. (abstr) Excerpta Medica No 277: 13,1973

10. EDLER I, GUSTAFSON A: Ultrasonic cardiogram in mitralstenosis. Acta Med Scand 159: 85, 1957

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12. FEIGENBAUM H: Echocardiography. Philadelphia, Lea& Febiger, 1972

13. KERBER RE, DIPPEL WF, ABBOUD FM: Abnormalmotion of the interventricular septum in rightventricular volume overload. Circulation 48: 86,1973

14. BEvANS LC, RAPAPORT E: An echocardiographic studyof left ventricular septal and posterior wall motionin left and right bundle branch block. (abstr) ClinRes 21 No. 2: 234, 1973

15. RODRIGUEZ MI, SODI PALLARES D: The mechanism ofcomplete and incomplete bundle branch block. AmHeart J 44: 715, 1952

16. BOURASSA M, BOrIEAU GM, ALLERSTEIN BJ: Hemody-namic studies during intermittent left bundle branchblock. Am J Cardiol 10: 792, 1962

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18. BEACH TB, GRACEY JG, PETER RH, CRUNWALD PW:Benign left bundle branch block. Ann Intern Med70: 269, 1969

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ABDUL S. ABBASI, LESLIE M. EBER, REX N. MACALPIN and ALBERT A. KATTUSParadoxical Motion of Interventricular Septum in Left Bundle Branch Block

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1974 American Heart Association, Inc. All rights reserved.

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