brugada criteria

1649

A New Approach to the DifferentialDiagnosis of a Regular Tachycardia

With a Wide QRS ComplexPedro Brugada, MD; Josep Brugada, MD; Lluis Mont, MD;

Joep Smeets, MD; and Erik W. Andries, MD

Background. In the differential diagnosis of a tachycardia with a wide QRS complex (.0.12second) diagnostic mistakes are frequent. Therefore, we investigated the reasons for failure ofpresently available criteria, and we identified new, simpler criteria and incorporated them in a

stepwise approach that provides better sensitivity and specificity for making a correctdiagnosis.Methods and Results. A prospective analysis revealed that current criteria had a poor

specificity for the differential diagnosis. The value of four new criteria incorporated in a

stepwise approach was prospectively analyzed in a total of 554 tachycardias with a widenedQRS complex (384 ventricular and 170 supraventricular). The sensitivity of the four consecu-

tive steps was 0.987, and the specificity was 0.965.Conclusions. Current criteria for the differential diagnosis between supraventricular tachy-

cardia with aberrant conduction and ventricular tachycardia are frequently absent or suggestthe wrong diagnosis. The absence of an RS complex in all precordial leads is easily recognizableand highly specific for the diagnosis of ventricular tachycardia. When an RS complex is presentin one or more precordial leads, an RS interval of more than 100 msec is highly specificfor ventricular tachycardia. This new stepwise approach may prevent diagnostic mistakes.(Circulation 1991;83:1649-1659)

T he differential diagnosis of tachycardias on the12-lead electrocardiogram is not merely anelectrocardiographic exercise. When the

QRS complex during tachycardia has a normal mor-phology, axis, and duration, the diagnosis of su-praventricular tachycardia is easily made. Fre-quently, however, supraventricular tachycardias mayhave an aberrant intraventricular conduction and awide (>0.12 second) QRS complex. In this case,differentiating between supraventricular tachycardiawith aberrant conduction (SVT) andventricular tachy-cardia (VT) may become difficult.'Even though several criteria have been proposed

to help in the differential diagnosis,2-7 mistakes arenevertheless frequently made.8-10 Not infrequently,these mistakes have led to wrong therapeutic deci-sions with fatal or almost fatal outcomes. Although

From the Cardiovascular Center (P.B., L.M., E.W.A.), Post-graduate School of Cardiology, OLV Hospital, Aalst, Belgium, andthe Departments of Physiology (J.B.) and Cardiology (J.S.), Uni-versity of Limburg, Maastricht, The Netherlands.

Address for correspondence: Pedro Brugada, MD, Professor ofCardiology, Cardiovascular Center, Postgraduate School of Cardi-ology, OLV Hospital, Moorselbaan 164, B-9300, Aalst, Belgium.

Received September 5, 1990; revision accepted January 8, 1991.

the reasons for wrong diagnoses are unclear, lack ofknowledge of current criteria for the differentialdiagnosis does not seem to be one; rather, suchmistakes seem to be the result of the way the criteriaare applied or interpreted.8-10The purpose of this study was twofold. On the

one hand, we sought the reasons for failure ofcurrently available criteria to provide a correctdiagnosis by prospectively analyzing these criteriain a series of tachycardias with a wide QRS com-plex. On the other hand, we sought new and simplercriteria and incorporated them in a stepwise ap-proach to make the differential diagnosis simpler,more decisive, and more accurate.

MethodsIn the first part of the study, presently available

criteria for differentiating between SVT with aber-rant conduction and VT were prospectively analyzedin 236 tachycardias with a wide QRS complex. Therewere 172 VTs and 64 SVTs with aberrant conductionwith electrophysiological proven mechanism. Com-plete 12-lead electrocardiograms were available forall patients who were not receiving antiarrhythmic

1650 Circulation Vol 83, No 5 May 1991

TABLE 1. Morphology Criteria in This Study for Ventricular Tachycardia

Sensitivity Specificity PredictiveSVT VT SN SP +Value -Value

Tachycardia with a right bundle branch block-like QRSLead V,Monophasic R 11/69 39/65 0.60 0.84 0.78 0.69tQR or RS 1/69 20/65 0.30 0.98 0.95 0.60tTriphasic 57/69 6/65 0.82 0.91 0.90 0.834

Lead V6R to S ratio <1 4/69 27/65 0.41 0.94 0.87 0.63tQS or QR 0/69 19/65 0.29 1.0 1.0 0.60tMonophasic R 0/69 1/65 0.01 1.0 1.0 0.52tTriphasic 44/69 3/65 0.64 0.95 0.93 0.714R to S ratio >1 21/69 15/65 0.30 0.76 0.58 0.514

Tachycardia with a left bundle branch block-like QRSLead V, or V2Any of following:*R >30 msec,>60 msec to nadir S, notched S 3/24 91/91 1.0 0.89 0.96*

Lead V6QR or QS 0/31 6/35 0.17 1.0 1.0 0.52*Monophasic R 31/31 29/35 1.0 0.17 0.51 1.0t

Data obtained from References 5 and 6.*Including any Q wave in lead V6.tValues for the diagnosis of VT.*Values for the diagnosis of SVT with aberrant conductiorSVT, supraventricular tachycardia; VT, ventricular tach

predictive negative value; R to S ratio, ratio of R wave to S v

drugs. Electrocardiograms were analyzed at a paperspeed of 25 mm/sec as usual in clinical practice.

Current criteria analyzed included 1) a left axis ofthe QRS complex in the frontal plane, which favorsthe diagnosis of VT,4.5 2) the presence of atrioven-tricular dissociation, which favors the diagnosis ofVT,2-7 3) a QRS complex longer than 0.14 second,

+Value, predictive positive value; -Value,

which favors the diagnosis of VT,45 and 4) morphol-ogy criteria favoring the diagnosis of VT when theQRS complex had a right2-5,7 or a left bundle branchblock-like6 morphology.

Particularly important during the first part of thestudy were the recent observations by Kindwall et al.6These investigators reported that an interval between

TABLE 2. Presence of Atrioventricular Dissociation, Left Axis, and Duration of the QRS Complex in 236 ProspectivelyAnalyzed Tachyeardias With a Widened QRS Complex

AV dissociation Left axis QRS> 140 msec

n n ' n1 n %SVT-RB 43 0 0 3 10 7 17SVT-LB 21 0 0 12 57 8 38All SVT 64 0 0 15 23 15 23VT-RB 97 18 19 63 65 73 75VT-LB 75 19 25 57 76 63 84All VT 172 37 21 120 70 136 79

Diagnosis of VTSN 0.21 0.70 0.79SP 1.0 0.76 0.72Predictive + value 1.0 0.89 0.90Predictive - value 0.32 0.48 0.52

QRS complex >0.12 second.AV, atrioventricular; SVT-RB, supraventricular tachycardia with right bundle branch block aberrant conduction;

SVT-LB, supraventricular tachycardia with left bundle branch block aberrant conduction; VT-RB, ventriculartachycardia with a right bundle branch block-like QRS complex; VT-LB, ventricular tachycardia with a left bundlebranch block-like QRS complex; + value, predictive positive value; - value, predictive negative value.

Brugada et al Differential Diagnosis of Tachycardias 1651

ABSENCE OF AN RS COMPLEX IN ALL PRECORDIAL LEADS?

YES 0o

/T NEXT QUESTION

R TO S WTERVAL >100 MS IN ONE PRECORDIAL LEAD?

YES NO

VYT XT QUESTION

ATRVENTRICULAR DISSOCIATION?

YES No

VT NXT CKESTION

MORHLG CRITERIA FOR VT PRESENT BOTH IN PRECORDIAL LEADS Vl-2 AND VS?

VT SVT WITH AIBERRANT CONDUCTIO

FIGURE 1. Algorithm for diagnosis of a tachycardia with a

widened QRS complex. When an RS complex cannot beidentified in any precordial lead, the diagnosis of ventriculartachycardia (VT) is made. Ifan RS complex is present in one

or more precordial leads, the longest RS interval is measured.If the RS interval is longer than 100 msec, the diagnosis ofVTis made. If shorter than 100 msec, the next step of thealgorithm is considered: whether atrioventricular dissociationis present. Ifpresent, the diagnosis of VT is made. If absent,the morphology criteria for VT are analyzed in leads V, andV6. If both leads fulfill the criteria for VT, the diagnosis of VTis made. If not, the diagnosis of supraventricular tachycardia(SVT) with aberrant conduction is made by exclusion of VT.

the onset of the R wave to the deepest part of the Swave in lead V, or V2 of more than 60 msec in a leftbundle branch block-like wide QRS complex tachy-cardia suggested the diagnosis of VT. We hypothe-sized that measurement of the intrinsic deflection inany unipolar precordial lead with a clear RS complexshould be helpful in differentiating between VT andSVT with aberrant conduction irrespective of themorphology of the arrhythmia. Therefore, data wereprospectively collected on two aspects of the arrhyth-mia during the first part of the study: 1) whether anRS complex was present in at least one precordiallead, and 2) the length of the longest interval in anyprecordial lead from the beginning of the R wave tothe deepest part of the S wave when an RS complexwas present in one or more precordial leads.

Based on the results of the first part of the study,the second part was undertaken prospectively. Twoindependent observers unaware of the diagnosis an-

alyzed 554 wide QRS complex tachycardias. In allcases, the diagnosis of these tachycardias was provenelectrophysiologically. The observers were givencomplete 12-lead electrocardiograms during tachy-cardia recorded at a paper speed of 25 mm/sec. Noendocavitary or esophageal electrograms or other

TABLE 3. Classic Morphology Criteria in 236 Prospectively Ana-lyzed Tachycardias With a Widened QRS Complex

Morphology criteria present in leads

V1,2 andV1,2 V6 V6 None

n n % n % n % n %

SVT-RB 43 35 81 35 81 28 65 1 2SVT-LB 21 18 86 13 62 12 57 2 10All SVT 64 53 83 48 75 40 62 3 4VT-RB 97 81 83 75 77 64 66 5 5VT-LB 75 63 84 47 62 41 55 6 8All VT 172 144 84 122 71 105 61 11 6

QRS complex .0.12 second.SVT-RB, supraventricular tachycardia with right bundle branch

block aberrant conduction; SVT-LB, supraventricular tachycardiawith left bundle branch block aberrant conduction; VT-RB, ven-tricular tachycardia with a right bundle branch block-like QRScomplex; VT-LB, ventricular tachycardia with a left bundle branchblock-like QRS complex.

recordings, such as aortic pressure, were available tothem. The two observers were not asked to give adiagnosis but were asked 1) to determine whether anRS complex was present in at least one precordiallead, 2) to measure the longest RS interval in anyprecordial lead with an RS complex, 3) to determinewhether atrioventricular dissociation was present,and 4) to decide whether both leads V1 and V6fulfilled classic criteria for ventricular tachycardia.The observers were not aware of the diagnosis, andthe four steps were used in the following way: 1) Ifthe RS complex was not present in at least oneprecordial lead, the diagnosis of VT was noted, andfurther analysis was stopped. 2) If an RS complex waspresent with an RS interval of more than 100 msec,the diagnosis of VT was noted, and analysis wasstopped. 3) If atrioventricular dissociation was diag-nosed, the diagnosis of VT was made, and analysiswas stopped. 4) If the tachycardia fulfilled the mor-phology criteria for VT in leads V1 and V6, thediagnosis of VT was made. Table 1 summarizes themorphology criteria used. This analysis by the twoobservers was, therefore, a stepwise approach. Whena positive diagnosis of VT was made at any step, theobserver was asked to stop analysis. When all foursteps had been undertaken and had been answerednegatively, the diagnosis of SVT with aberrant con-duction was made by exclusion of VT.

Figure 1 summarizes the steps in the diagnosis.Observer 1 analyzed 329 tachycardias with a wideQRS complex (232 VTs and 97 SVTs with aberrantconduction). Observer 2 analyzed 225 tachycardiaswith a wide QRS complex (152 VTs and 73 SVTswith aberrant conduction). Because the tachycardiasanalyzed were not the same, no consideration wasmade of possible interobserver variability in thediagnosis. As will be described, 11 of 554 tachycar-dias (2%) were misclassified. Further analysis ofthese 11 tachycardias was undertaken later to assessreasons and possible corrections of misdiagnosis.

1652 Circulation Vol 83, No S May 1991

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FIGURE 3. Panel A: Twelve-lead electrocardiograms showa ventricular tachycardia (VT) with morphology criteriasuggesting supraventricular tachycardia (SVT) with aberrantconduction. Note the triphasic QRS complex in lead V, andthe R to S wave ratio of more than 1 in lead V6. Right axisof the QRS complex is in the frontal plane (not helpful in thedifferential diagnosis), and atnioventricular dissociation isabsent. Only the duration of the QRS complex can suggestthe diagnosis of VT, but most criteria suggest SVT withaberrant conduction. Panel B: Twelve-lead electrocardio-grams show another VT with a triphasic QRS complex in

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QRS duration of 120 msec. Atrioventricular dissociation isonly recognizable to the expert eye in lead avr. Paper speedwas 25 mm/sec.

Results

Analysis of Current Criteria

Tables 2 and 3 summarize findings in the 236 tachy-cardias with a wide ORS complex that were analyzed.A left axis of the ORS complex in the frontal planefrequently occurred in SVTs with left bundle branchblock aberrant conduction and less frequently in SVTs

with right bundle branch block aberrant conduction.Similar findings were also reported by Kindwall et a16 intachycardias with a left bundle branch blocklike QRScomplex. When the complete 12-lead electrocardio-gram was analyzed, a duration of the QRS complex ofmore than 0.14 second was far from a rarity in SVTswith aberrant conduction. Similar observations werepreviously reported by Akhtar et al. These two criteriawould have favored the diagnosis of VT. Atrioventric-ular dissociation was not present in any SVT, however;although 100% specific for the diagnosis of VT, it wasseen in only 21% of the VTs. This incidence of atriov-entricular dissociation is similar to the incidence re-ported in other studies.45,7 The morphology criteria forthe corresponding tachycardia (SVT or VT) were fre-quently present in lead V, or V6. However, 4% of theSVTs and 6% of the VTs did not fulfill the criteria fortheir diagnosis in any lead (Figures 2 and 3). Moreimportant, more than one third of the SVTs and VTsdid not fulfill the morphology criteria in lead V1 andlead V6. That is, although one lead suggested thediagnosis of VT, the other lead suggested the diagnosisof SVT, or vice versa (Figure 4). Akhtar et a17 alsopreviously discussed these points. Thus, discordance inmorphology criteria occurred frequently, and criteriasuggesting VT, such as a left axis of the QRS complexin the frontal plane or a duration of the QRS complexof 0.14 second or more, were frequently present in SVTwith aberrant conduction.

RS Complex and Interval in the Precordial Leads

During this first part of the study, an RS complexwas present in at least one precordial lead in all SVTswith aberrant conduction. However, 45 of 172 (26%)VTs did not have an RS complex in any precordiallead (Figure 5).The interval from the onset of the R wave to the

deepest part of the S wave was measured, irrespec-tive of the morphology of the tachycardia, in alltachycardias showing an RS complex in at least oneprecordial lead. When an RS complex was present inmore than one precordial lead, the longest RS inter-val in any precordial lead was measured. Figure 6illustrates the measurement of this interval, andTable 4 lists the distribution of this interval in thedifferent tachycardias. As shown, an RS intervallonger than 100 msec was not observed in any SVTwith aberrant conduction. About half of the VTshaving an RS complex in at least one precordial leadhad an RS interval of 100 msec or less (61 of 127,48%), and the other half (52%) of the VTs had an RSinterval of more than 100 msec. From these observa-tions, we concluded that the absence of an RScomplex in all precordial leads or an RS interval ofmore than 100 msec in any precordial lead when anRS complex was present were each 100% specific forthe diagnosis of VT. From the first part of the study,we also concluded that atrioventricular dissociationwas 100% specific for the diagnosis of VT.


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finding is 100% specific for the diagnosis of ventricular tachycardia. Only QS, QR, or monophasic R complexes are observed.

TABLE 4. Distribution and Means for RS Intervals in the Precordial Lead With the Longest RS Interval, LongestDuration of the QRS Complex in That Lead, and Longest Duration of the QRS Complex in Any Lead in 236Tachycardias With a Widened QRS Complex

RS interval (msec)

n <40 <60 <80 <100 <120 <140 <160 <180 <200

SVT-RB 43 7 14 14 8 0 0 0 0 0SVT-LB 21 2 9 8 2 0 0 0 0 0

All SVT 64 9 23 22 10 0 0 0 0 0VT-RB 66 2 2 12 13 23 5 8 1 0

VT-LB 61 0 0 11 21 14 10 3 2 0All VT 127* 2 2 23 34 37 15 11 3 0

RS interval (msec)< 100 msec > 100 msec

n %

All SVT 64/64 100 0/64 0

All VT 61/127 52 66/127 48

Mean Mean L QRS (msec)RS QRS Mean Range

SVT-RB 66 126 136 120-200

SVT-LB 65 132 143 120-160VT-RB 110 165 170 120-300

VT-LB i11 168 180 120-260

QRS complex >0.12 second.SVT-RB, supraventricular tachycardia with right bundle branch block aberrant conduction; SVT-LB, supraventric-

ular tachycardia with left bundle branch block aberrant conduction; VT-RB, ventricular tachycardia with a right bundlebranch block like QRS complex. VT-LB, ventricular tachycardia with a left bundle branch block like QRS complex;mean QRS, mean duration of the QRS complex in the lead in which the RS interval was measured; mean L QRS, meanduration of the longest QRS complex measured at any lead.

*Forty~five VT did not have an RS complex in any precordial lead.

1656 Circulation Vol 83, No S May 1991

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FIGURE 6. Tracings from the 12-lead electrocardiogramillustrating the measurement of the RS intervaL A ventriculartachycardia with a right bundle branch blocklike QRScomplex is shown. An RS complex is observed in theprecordial leads V4 to V6. S wave is, however, not sharpenough in lead V? to measure confidently an RS interval. RSinterval (enlarged in the right panel) measures 160 msec in

lead V, and 70 msec in lead V6. Thus, the longest RS intervalis more than 100 msec and diagnostic of ventricular tachy-cardia. Paper speed was 25 mm/sec.

The duration of the RS interval was not dependenton the duration of the QRS complex in the same leadand was independent of the morphology of the tachy-cardia. The correlation coefficient between duration ofthe RS interval and duration of the ORS complex inthe lead where the QRS complex was measured was

0.0764 for SVT and 0.52 for VT (p=NS).

Prospective Analysis of the New CriteriaFigure 7 illustrates how the diagnosis of the tachy-

cardias (of which the observers were unaware) was

made using the four new criteria. Of the 384 VTs, 379(98.7%) were correctly classified. Of the 170 SVTswith aberrant conduction, 164 (96.5%) were correctlyclassified. Therefore, the sensitivity of the four step-wise criteria for the diagnosis of VT was 0.987, andthe specificity was 0.965.

Together, the two observers misclassified 111 tachy-cardias: five VTs and six SVTs with aberrant conduc-

ABSENCE OF AN RS COLEX IN ALL PRECORDIAL LEADS?

83 YES 471 NO

R TO S INTERAL >100 MS INOEPEOIA LEA?

175 YES 296 NO

172 VT, 3 SVT SN=.6 W=.9oa

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/\YES 237

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MORPHOLOGY CRITERIA FOR VT PRESENT BOTH PRECORDIAL LEADS VI-2 AND VS?

/ \68 YES 169 NO

65 VT, 3 SVT

SN=.987 SP=.965

164 SVT, S VT

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FIGURE 7. Algorithm of the diagnosis made by two observersin 554 tachycardias with a widened QRS complex. Number oftachycardias classified at each step is given. Sensitivities (SN)and specificities (SP) for the diagnosis of ventricular tachyvcar-dia (VT) are also shown at each step and also for thediagnosis ofsupraventricular tachycardia (SVT) with aberrantconduction at the last step. Note that the four consecutivecriteria reached a sensitivity of 0.987 and a specificity of 0. 965for the diagnosis of VT and of 0.965 and 0.987 for thediagnosis of SVT with aberrant conduction.

tion. Three of the six SVTs were considered to havean RS interval in at least one precordial lead that waslonger than 100 msec. Two of the three were misclas-sified by observer 1 and one by observer 2. The threeother SVTs were misclassified as VTs, one by ob-server 1 and two by observer 2 because these were

believed to fulfill the morphology criteria for VT inleads V, and V6. Three VTs were misclassified as

SVTs with aberrant conduction by observer 1 andtwo by observer 2 because after the first three steps ofthe analysis were answered negatively, the observersconsidered that these tachycardias did not fulfill themorphology criteria for VT in the precordial leads V,and V6. Thus, the absence of an RS complex in theprecordial leads had a specificity of 1.00 and a

sensitivity of 0.21 in diagnosing VT. When the secondcriterion (RS interval, >100 msec) was applied next,the sensitivity increased to 0.66, and specificity in-creased to 0.98. When the criterion of atrioventricu-lar dissociation was included, the sensitivity in-creased to 0.82, and specificity increased to 0.98. Thelast step increased sensitivity to 0.987 and decreasedspecificity to 0.965.

Further Analysis of the 11 Misclassified TachycardiasThe 11 misclassified tachycardias were reanalyzed

by three observers fully aware of currently used

A N=554 (384 VT, 170 SVT WITH ABERRANCY)


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FIGURE 8. Twelve-lead electrocardiograms showing one of the 11 tachycardias with a widened QRS compleV misclassified usingclassic and new criteria. This is a ventricular tachycardia with a left bundle branch block-like QRS complex in which axis durationofthe QRS complex, and morphology criteria all suggest the wrong diagnosis ofsupraventricular tachycardia with left bundle branchblock aberrant conduction. New criteria also incorrectly classified this ventricular tachycardia. After reconsideration, the observersdiscussed whether lead V3 showed an RS complex. If lead V, was considered to have a QS complex, the correct diagnosis ofventricular tachycardia had been made in the first step using the new criteria. Note that lead V4 shows an RSR complex, not an RScomplex. Because the observers could not agree whether lead V3 had a QS or RS complex, limitations of old and new criteria wereaccepted in this case. Paper speed was 25 mm/sec.

criteria and of the new criteria. Each observer wasasked to reconsider the diagnosis on the basis of bothcriteria. No tachycardia could be classified correctly.An example is shown in Figure 8.

DiscussionSeveral investigators previously discussed the

limitations of currently available criteria in thedifferential diagnosis of a tachycardia with a wid-ened QRS complex.6-10 To the experienced rhyth-mologist, the diagnosis may seem obvious evenwhen criteria show discordance or suggest differentdiagnoses. However, mistakes in the diagnosis aremade frequently, and therapeutic decisions basedon a wrong diagnosis may have fatal or almost fatalconsequences.8 10

This study shows that currently used criteriafavoring the diagnosis of VT are frequently found inSVTs with aberrant conduction when a complete12-lead electrocardiogram is analyzed. The sensi-tivity and specificity of the old criteria are notoptimal. The major problem seems, however, thatleads V, and V6 frequently show discordant mor-

phology patterns that suggest a different diagnosis.It is understandable that morphology discordancemay confuse the physician confronted with a tachy-cardia having wide QRS complex and may lead toan incorrect diagnosis.Another major limitation of the currently used

criteria is that they do not include a stepwise.decision tree-like approach. When all criteria arenot in agreement with a diagnosis, the physiciandoes not have any further steps to help in decisionmaking. An algorithm with simple criteria, withsteps that render clear decisions, and with knownsensitivity and specificity for each step seems highlydesirable.The new criteria we developed were based on

these concepts and on the observations made byKindwall et a16 in tachycardias with a left bundlebranch block-like QRS complex. We hypothesizedthat the intrinsic deflection, measured from the onsetof the R wave to the deepest part of the S wave,should be longer in VT than in SVT in any unipolarprecordial lead having an RS morphology, irrespec-tive of the morphology of the tachycardia (right or

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SAtVA-t,NV%sZWtk_ FIGURE 9. Twelve-lead elec-trocardiograms illustrating thevalue of the new criteria com-pared with old criteria in differ-ential diagnosis. Panel A: ven-tricular tachycardia (VT) in apatient with surgically correctedtetralogy of Fallot. RS complexoccurs in leads V2 to V,6. 1RSinterval is clearly longer than 100msec and is diagnostic for VT.Panel B: Supraventriculartachy-cardia (SVT) with right bundlebranch block aberrant conduc-tion from the same patient QRScomplex is longer than 200 msec.Atrioventricular dissociation isnot visible, and axis of the QRScomplex in the frontal plane is ofno help in the differential diag-nosis. QRS complex is triphasicin lead V,, but the R to S waveratio is less than 1 in lead V6.Thus, old critera favor the diag-nosis of VTin this case. With thenew criteria, the correct diagno-sis of SVT with right bundlebranch block aberrant conduc-tion was made as follows. 1)Absence of an RS complex inprecordial leads: An RS complexis in lead V6. 2) RS intervalgreater than 100 msec in oneprecordial lead: RS interval isless than 100 msec. 3) Atrioven-tricular dissociation: Not recog-nizable. 4) Morphology criteriafor VTpresent in both precordialleads V, and V,: No, becauselead V1 had a tnphasic complex.Thus, by excluding VT with thefour steps, the correct diagnosisof SVT was made.

left bundle branch block-like ORS complex). Asshown in part one of this study and also in theindependent analysis by two observers, this hypothe-sis resulted in accurate diagnoses. During the firstpart of this study, we also observed that when atachycardia with a wide QRS complex does not havean RS complex in at least one precordial lead thediagnosis of VT can immediately be made with 100%specificity. These two criteria, combined with thecriterion of atrioventricular dissociation (also highlyspecific for VT) and with the morphology criteria forVT in both leads V1 and V6, had a high sensitivity andspecificity for differentiating between VT and SVTwith aberrant conduction.The advantages of this stepwise approach to diag-

nosis (Figure 1 and Figure 7) are that it is structured

and positively directed to the diagnosis of the type ofarrhythmia. That is, if RS complex is not present inany precordial lead, the diagnosis of VT is made, andfurther analysis is stopped. If an RS complex ispresent, the longest RS interval in the precordialleads is measured. If the RS interval is longer than100 msec, the diagnosis of VT is made, and theremaining two steps are ignored. When the RSinterval is 100 msec or less, the third step must beconsidered, that is, whether atrioventricular dissocia-tion is present. When present, the diagnosis of VT ismade. When absent, the morphology criteria areanalyzed in leads V, and V6. If both leads have amorphology compatible with the diagnosis of VT, thediagnosis of VT is made. Otherwise, the diagnosis of


SVT with aberrant conduction is made by exclusionof VT (Figure 9).

Obviously, the correct diagnosis depends on carefulapplication of the four criteria. Of emphasis, only anRS complex or its absence in all precordial leads isvaluable for the diagnosis. Complexes with QR, QRS,QS, monophasic R, or rSR morphology are not consid-ered RS complexes. Only when an RS interval ismeasurable can the complex be considered an RScomplex.These new criteria incorporated in a stepwise

approach may help prevent the frequent errors madein the differential diagnosis of tachycardias with awide QRS complex.

References

1. Kistin AD: Problems in differentiation of ventricular arrhyth-mias with abnormal QRS. Prog Cardiovasc Dis 1966;9:1-27

2. Sandler A, Marriot HJL: The differential morphology ofanomalous ventricular complexes of RBBB type in leadV,-Ventricular ectopy versus aberration. Circulation 1965;31:551-556

3. Marriott HJL, Sandler IA: Criteria, old and new, for differ-entiating between ectopic ventricular beats and aberrant ven-tricular conduction in the presence of atrial fibrillation. ProgCardiovasc Dis 1966;9:18-28

4. Wellens HJJ, Bar FWHM, Lie KI: The value of the electro-cardiogram in the differential diagnosis of a tachycardia with awidened QRS complex. Am J Med 1978;64:27-33

5. Wellens HJJ, Bar FW, Vanagt EJ, Brugada P, Farr6 J: Thedifferentiation between ventricular tachycardia and supraven-tricular tachycardia with aberrant conduction: The value ofthe 12-lead electrocardiogram, in Wellens HJJ, Kulbertus HE(eds): What's New in Electrocardiography? The Hague, Marti-nus Nijhoff Publishing, 1981; pp 184-199

6. Kindwall KE, Brown J, Josephson ME: Electrocardiographiccriteria for ventricular tachycardia in wide complex left bundlebranch block morphology tachycardias. Am J Cardiol 1988;61:1279-1283

7. Akhtar M, Shenasa M, Tchou PJ, Jazayeri M: Role of elec-trophysiologic studies in supraventricular tachycardia, inBrugada P, Wellens HJJ (eds): Cardiac Arrhythmias: Where toGo From Here? Mount Kisco, NY, Futura Publishing Co, 1987,pp 233-242

8. Morady F, Bareman JM, DiCarlo LA Jr, DeBuitleir M, KrolRB, Wehr DW: A prevalent misconception regarding widecomplex tachycardias. JAMA 1985;254:2790-2792

9. Danney M, Camm AJ, Ward D: Misdiagnosis of chronicrecurrent ventricular tachycardia. Lancet 1985;2:320-323

10. Stewart RB, Baray GH, Greene HL: Wide complex tachycar-dia: Misdiagnosis and outcome after emergent therapy. AnnIntem Med 1986;104:771-776

KEY WORDS * ventricular tachycardia * supraventriculartachycardia * aberrant conduction * electrocardiography

brugada criteria

Education

diagnosis of vt

diagnosis of svt

wrong diagnosis

simpler criteria

correct diagnosis

differential diagnosis

diagnosis of su

value value tachycardia