Electrolyte disorders (such as severe hyperkalemia) and drug toxicity (such as poisoning with antiarrhythmic drugs) can widen the QRS complex. This happens when the upper and lower chambers of the heart are beating in sync. , Had an ECG taken and slightly worried. If a patient meets a criteria at any step then the diagnosis of VT is made, otherwise one proceeds to the next step. There is sinus rhythm at approximately 75 bpm with prolonged PR interval. The risk of developing it increases . In 2007, Vereckei et al. Europace.. vol. Jastrzebski, M, Kukla, P, Czarnecka, D, Kawecka-Jaszcz, K.. Comparison of five electrocardiographic methods for differentiation of wide QRS-complex tachycardias. Fairley S, Sands A, Wilson C, Uncorrected tetralogy of Fallot: Adult presentation in the 61st year of life, Int J Cardiol, 2008;128(1);e9e11. - Case Studies Wide complex tachycardia due to bundle branch reentry. . , In most people, theres a slight variation of less than 0.16 seconds. Brugada P, Brugada J, Mont L, et al., A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex, Circulation, 1991;83(5):164959. VA dissociation is best seen in rhythm leads II and V1. Because of this reason, many patients have only ECG telemetry (rhythm) strips available for analysis; however, there is often sufficient information within telemetry strips to make an accurate conclusion about the nature of WCT. Occasional APBs and one ventricular run. Comments where: sinus rhythm with episodes of sinus tachycardia. The timing of engagement of the His-Purkinje network: at some point during propagation of the VT wave front, the His-Purkinje network is engaged, resulting in faster propagation; the earlier this occurs, the narrower the QRS complex. Heart, 2001;86;57985. ECG results: 79 pbm, Pr interval 152 ms, Qrs duration 100 ms,QT/QTc 352/403 ms, p r t axes 21 20 17. In the hemodynamically stable patient, obtaining an ECG with specially located surface ECG electrodes can be helpful in recognizing dissociated P waves. There is grouped beating and 3:2 atrioventricular (AV) block in the pattern of a sinus beat conducting with a narrow QRS complex, followed by a sinus beat conducting with a wide QRS complex, and culminating with a nonconducted sinus beat ().The wide complex QRS beats are in a left bundle-branch block morphology. Wide complex tachycardia related to preexcitation. Toxicity with flecainide, a class Ic antiarrhythmic drug with potent sodium channel blocking capabilities, is a well-known cause of bizarrely wide QRS complexes and low amplitude P waves. It is atrial flutter with grouped beating. 18. Measurement of the two flutter cycle lengths () exactly equals the rate of the WCT in Figure 8. Normal sinus rhythm is defined as the rhythm of a healthy heart. However, when in doubt, treat the arrhythmia as if it was VT, as approximately 80 % of wide QRS complex tachycardias are of ventricular origin.30,31, Antonia Sambola 28. However, it may also be observed in atrioventricular junctional tachycardia in the absence of retrograde conduction.16 Even though capture and fusion beats are not frequently observed, their presence suggests VT. All rights reserved. , Get useful, helpful and relevant health + wellness information. The QRS complex in rhythm strip V1 shows an RR configuration, but with the second rabbit ear taller than the first; this favors SVT with aberrancy. The following observations can be made from the first ECG: The emergency medical services were summoned and IV amiodarone was administered. The differentiation of wide QRS complex tachycardias remains a diagnostic challenge (see Table 2). , When it happens for no clear reason . This collection of propagating structures is referred to as the His-Purkinje network.. Will it go away? Published content on this site is for information purposes and is not a substitute for professional medical advice. 15. These categories allow the selection of three groups of patients with clearly delineated QRS width: narrow (<90 ms), wide (>120 ms), and intermediate (90-119 ms). Dual-chamber pacemakers may show rapid ventricular pacing as a result of tracking at the upper rate limit, or as a result of pacemaker-mediated tachycardia. In general, the presence of scar can be inferred from QRS complex fractionation or splintering or notching.. All QRS complexes are irregularly irregular. In cases of respiratory sinus arrhythmia, the P-P interval will often be longer than 0.16 seconds when the person breathes out. Respiratory sinus arrhythmia is usually normal and doesnt have symptoms, but the conditions below arent normal and do have symptoms. A complete QRS complex consists of a Q-, R- and S-wave. Pacing results in a wide QRS complex since the wave front of depolarization starts in the myocardium at the ventricular lead location, and then propagates by muscle-to-muscle spread. But respiratory sinus arrhythmia is not a cause for worry. If the sinus node fails to initiate the impulse, an atrial focus will take over as the pacemaker, which is usually slower than the NSR. 2016 Apr. Once again, the clinical scenario in which such a patient is encountered (such as history of antiarrhythmic drug use), along with other ECG findings (such as tall peaked T waves in hyperkalemia) will help make the correct diagnosis. Clin Cardiol. Interestingly enough, no statistically significant difference in sensitivity and specificity was found between the Brugada, Griffith and Bayesian algorithm approaches.25. Study with Quizlet and memorize flashcards containing terms like b. 1. The dysrhythmias in this category occur as a result of influences on the Sinoatrial (SA) node. 2 years ago. Ahmed Farah The copyright in this work belongs to Radcliffe Medical Media. Sinus Tachycardia. The QRS complex in lead V1 shows an rS pattern, with a broad initial R wave, favoring VT (Table V). In other words, the VT morphology shows the infarct location because VT most often arises from the infarct scar location. The wide QRS complexes follow some of the pacing spikes, and show varying degrees of QRS widening due to intramyocardial aberrancy. Explanation. Past medical history was significant for type II diabetes, hypertension, hyperlipidemia, and chronic kidney disease (CKD). It should be noted that hemodynamic stability is not always helpful in deciding about the probable etiology of WCT. The rapidity of the S wave down stroke and the exact halving of the ventricular rate after IV amiodarone made the diagnosis of VT suspect, and eventually led to the correct diagnosis of atrial flutter with aberrancy. It means the electrical impulse from your sinus node is being properly transmitted. et al, Sang Hong Baek, Bernard Man Yung Cheung, Krzysztof Filipiak, Ganchimeg Ulziisaikhan. Wide QRS represents slow activation of the ventricles that does not use the rapid His-Purkinje system of the heart. The QRS complex down stroke is slurred in aVR, favoring VT. Kardia Advanced Determination "Sinus Rhythm with Wide QRS" indicates sinus rhythm with a QRS, or portion of your ECG, that is longer than expected. Depending on your pre disposing factors for coronary artery disease, and your symptoms, if any. This is also indicative of VT (ventricular oscillations precede and predict atrial oscillations). In Camm AJ, Lscher TF, Serruys PW, editors. The rhythm strip shows sinus tachycardia at the beginning and at the end; each sinus P wave is marked. Conclusion: SVT (AVRT utilizing a left-sided accessory pathway) with LBBB aberrancy. The 12-lead rhythm strips shown in Figure 13 were recorded during transition from a WCT to a narrow complex tachycardia. The frontal axis is pointing to the right shoulder, and favors VT. QRS complex: 0.06 to 0.08 second (basic rhythm and PJC) Comment: ST segment depression is present. Its usually a sign that your heart is healthy. The hallmark of VT is ventriculoatrial (VA) dissociation (the ventricular rate being faster than the atrial rate), the following examination findings (Table II), when clearly present, clinch the diagnosis of VT. Its main differential diagnosis includes slow ventricular tachycardia, complete heart block, junctional rhythm with aberrancy, supraventricular tachycardia with aberrancy, and slow antidromic atrioventricular reentry tachycardia. . B. Table III shows general ECG findings that help distinguish SVT with aberrancy from VT. Its normal to have respiratory sinus arrhythmia simply because youre breathing. , There are impressively tall, peaked T waves, best seen in lead V3, as expected in hyperkalemia. Several arrhythmias can manifest as WCTs (Table 21-1); the most common is ventricular tachycardia (VT), which accounts for 80% of all cases of WCT. Pill-in-the-pocket Oral Anticoagulation in AF Patients, Antithrombotic Therapy in AF-PCI Patients, Angiographic Characteristics in Older NSTEACS Patients, TMVR via MitraClip in Patients Aged <65 Years: Multicentre 2-year Outcomes, Approach to the Differentiation of Wide QRS Complex Tachycardias, Content for healthcare professionals only, Persistent Atrial Fibrillation Using Arctic Front Cardiac Cryoablation System, American Heart Hospital Journal 2011;9(1):33-6, https://doi.org/10.15420/ahhj.2011.9.1.33. Of the conditions that cause slowing of action potential speed and wide QRS complexes, there is one condition that is more common, more dangerous, more recognizable, more rapidly life threatening, and more readily . This causes a wide S-wave in V1V2 and broad and clumsy R-wave in V5V6. Atrial paced rhythm with Wenckebach conduction: There are regular atrial pacing spikes at 90 bpm; each one is followed by a small P wave indicating 100% atrial capture. Chen PS, Priori SG, The Brugada Syndrome, JACC, 2008;51(12):117680. - Drug Monographs When you take a breath, your heart rate goes up. In EKG results, nonrespiratory sinus arrhythmia can look like respiratory sinus arrhythmia. 2016. pp. Escardt L, Brugada P, Morgan J, Breithardt G, Ventricular tachycardia. The WCT overtakes the sinus P waves starting at the fourth beat, resulting in apparent PR interval shortening. This pattern is pathognomonic of VT, and represents a form of VA dissociation during VT onset. This is achieved by rapid propagation along the common bundle of His, the right and left bundle branches, the fascicles of the left bundle branch, and the Purkinje network. R-R interval is regular (constant) b. Sinus Bradycardia (normal slow) i. The ECG in Figure 4 is representative. Furushima H, Chinushi M, Sugiura H, et al., Ventricular tachyarrhythmia associated with cardiac sarcoidosis: its mechanisms and outcome, Clin Cardiol, 2004;27(4):21722. This rhythm has two postulated, possibly coexisting . Introduction. A normal QRS should be less than 0.12 seconds (120 milliseconds), therefore a wide QRS will be greater than or equal to 0.12 seconds. Twelve-lead ECG after electrical cardioversion of the tachycardia. When the direction is reversed (down the LBB, across the septum, and up the RBB), the QRS complex exactly resembles the QRS complex during SVT with RBBB aberrancy. The electrical signal to make the heartbeat starts . Such VTs may look very similar to SVT with aberrancy. In this article we try to summarize approaches which we consider optimal for the evaluation of patients with wide QRS complex tachycardias. Of course, such careful evaluation of the patient is only possible when the patient is hemodynamically stable during VT; any hemodynamic instability (such as presyncope, syncope, pulmonary edema, angina) should prompt urgent or emergent cardioversion. Kardia showed normal sinus rhythm with wide QRS. (Never blacked out) Rhythm: Sinus rhythm is present, all beats are conducted with a normal PR . Jastrzebski, M, Sasaki, K, Kukla, P, Fijorek, K. The ventricular tachycardia score: a novel approach to electrocardiographic diagnosis of ventricular tachycardia. Such a re-orientation of lead I electrodes so that they straddle the right atrium, often allows more accurate recognition of atrial activity, and if dissociated P waves are seen, the diagnosis of VT is established. Furthermore, there will often be evidence of VA dissociation, with the ventricular rate being faster than the atrial rate, pointing to the correct diagnosis of VT. The ECG shows normal sinus rhythm at 56 bpm with normal atrioventricular and intraventricular conduction and . 1649-59. Scar tissue, as seen in patient with prior myocardial infarctions or with cardiomyopathy, may further slow intramyocardial conduction, resulting in wider QRS complexes in both situations. Brugada, P, Brugada, J, Mont, L. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Using EKG results, your provider will make sure you dont have: Providers see this a lot in healthy children and young adults. QRS complex duration of more than 140 ms; the presence of positive concordance in the precordial leads; the presence of a qR, R or RS complex or an RSR complex where R is taller than R and S passes through the baseline in V. QRS complex duration of more than 160 ms; the presence of negative concordance in the precordial leads; the absence of an RS complex in all precordial leads; an R to S wave interval of more than 100 ms in any of the precordial lead; the presence of atrio-ventricular dissociation; and, the presence of morphologic criteria for VT in leads V. the presence of atrio-ventricular dissociation; the presence of an initial R wave in lead aVR; a QRS morphology that is different from bundle branch block or fascicular block; and. The ECG exhibits several notable features. Study with Quizlet and memorize flashcards containing terms like Normal Sinus Rhythm, Sinus Arrest, Sinus arrhythmia and more. The ECG recorded during sinus rhythm . Sarabanda AV, Sosa E, Simes MV, et al., Ventricular tachycardia in Chagas' disease: a comparison of clinical, angiographic, electrophysiologic and myocardial perfusion disturbances between patients presenting with either sustained or nonsustained forms, Int J Cardiol, 2005;102(1):919. An electrocardiogram (EKG) can tell your provider if you have sinus arrhythmia. QRS complexes are described as "wild-looking" and with great swings and exceed 0.12 second. Interpretation: Normal sinus rhythm with first-degree atrioventricular block and left bundle branch block (BBB) with notching of the S wave in leads V 3 -V 5, suggesting prior anterior MI. Sinus rhythm refers to the pace of your heartbeat that's set by the sinus node, your body's natural pacemaker. General approach to the ECG showing a WCT. Reising S, Kusumoto F, Goldschlager N, Life-threatening arrhythmias in the Intensive Care Unit, J Intensive Care Med, 2007;22(1):313. This is where the experienced electrocardiographer must weigh the conflicting indicators and reach a clinical decision. . Edhouse J, Morris F, ABC of clinical electrocardiography. Figure 2. What causes a junctional rhythm in the sinus? Evidence of fusion beats or capture beats is evidence for VA dissociation, and clinches the diagnosis of VT. ECG evidence of even a single dissociated P wave at the onset of tachycardia (i.e., AV dissociation at the onset) may be sufficient evidence on a telemetry strip to recognize VT. Griffith MJ, Garratt CJ, Mounsey P, Camm AJ, Ventricular tachycardia as default diagnosis in broad complex tachycardia, Lancet, 1994;343(8894):3868. The burden of intramyocardial scar: as mentioned above, scar within the ventricles will affect the velocity of propagation through the myocardium and influence QRS complex width. In this article we will discuss the factors which support the diagnosis of VT as well as some algorithms useful in the evaluation of regular, wide QRS complex tachycardias. Regularity of the rhythm: If the wide QRS tachycardia is sustained and monomorphic, then the rhythm is usually regular (i.e., RR intervals equal); an irregularly-irregular rhythm suggests atrial fibrillation with aberration or with WPW preexcitation. Sinus rhythm is necessary, but not sufficient, for normal electrical activity within the heart.. If an old EKG is available, the baseline wide QRS will be present. Rhythms in this category will share similarities in a normal appearing P wave, the PR interval will measure in the "normal range" of 0.12 - 0.20 second, and the QRS typically will measure in the "normal range" of 0.06 - 0.10 second. A 20-year-old man with recurrent supraventricular tachycardia ( Figure 1) was referred for catheter ablation. Updated. What Does Wide QRS Indicate? You probably don't think much about your heartbeat because it happens so easily. When sinus rhythm exceeds 100 bpm, it is considered sinus tachycardia. For left bundle branch block morphology the criteria include: for V12: an R wave of more than 30 ms duration, notching of the downstroke of the S wave, or duration from the onset of the QRS to the nadir of S wave of more than 70 ms; for lead V6: the presence of a QR or RS complex. - Full-Length Features Maron BJ, Estes NA 3rd, Maron MS, et al., Primary prevention of sudden death as a novel treatment strategy in hypertrophic cardiomyopathy, Circulation, 2003;107(23):28725. For the most common type of sinus arrhythmia, the time between heartbeats can be slightly shorter or longer depending on whether youre breathing in or out. During VT, the width of the QRS complex is influenced by: As is true of all situations in medicine, the clinical context in which the wide complex tachycardia (WCT) occurs often provides important clues as to whether one is dealing with VT or SVT with aberrancy. 39. Broad complexes (QRS > 100 ms) may be either ventricular . The baseline ECG ( Figure 2) showed sinus rhythm with a PR interval of 0.20 seconds and QRS duration of 0.085 seconds. When VT occurs in patients with prior myocardial infarction, the QRS complex during VT shows pathologic Q waves in the same leads that showed pathologic Q waves in sinus rhythm. But did one tonight and it gave normal sinus rhythm with wide QRS I have clicked on it and it says something . conduction of a supraventricular impulse from atrium to ventricle over an accessory pathway (bypass tract) so called pre-excited tachycardia. Complexes are complete: P wave, QRS complex (narrow), T wave 3. R on T . Drew BJ, Scheinman MM, ECG criteria to distinguish between aberrantly conducted supraventricular tachycardia and ventricular tachycardia: practical aspects for the immediate care setting, PACE, 1995;18:2194208. By Guest, 11 years ago on Heart attacks & diseases. Impossible to say, your EKG must be interpreted by a cardiologist to differ supraventricular tachycardia with wide QRS from ventricular tachycardia. No. 89-98. A special consideration is WCT due to anterograde conduction over an accessory pathway. Sick sinus syndrome causes slow heartbeats, pauses (long periods between heartbeats) or irregular heartbeats (arrhythmias). Comparison of the QRS complex to a prior ECG in sinus rhythm is most helpful; a virtually identical (wide) QRS in sinus rhythm favors a supraventricular tachycardia with preexisting aberrancy. The QRS complex is wide, approximately 160ms. Figure 6: A 65-year-old man with severe alcoholism presented with catastrophic syncope while seated at a bar stool resulting in a cervical spine fracture. Recognition of intermittent cannon A waves on the jugular venous waveform (JVP) during ongoing WCT is an important physical examination finding because it implies VA dissociation, and can clinch the diagnosis of VT. . It affects the heart's natural pacemaker (sinus node), which controls the heartbeat. Tachycardias are broadly categorized based upon the width of the QRS complex on the electrocardiogram (ECG). , We recommend using a protocol that one is most familiar and comfortable with and supplementing it with the steps from other protocols to improve the accuracy of the diagnosis. When this occurs, the change in R-R interval precedes and predicts the change in P-P interval; in other words, the R-R change drives the P-P change, confirming that this is VT with 1:1 VA conduction. Therefore, this tracing represents VT with 3:2 VA conduction (VA Wenckebach); this still counts as VA dissociation. She has missed her last two hemodialysis appointments. The presence of atrioventricular dissociation strongly favors the diagnosis of VT. Aberrancy, ventricular tachycardia, supraventricular tachycardia, right-bundle branch block (RBBB), left-bundle branch block (LBBB), intraventricular conduction delay (IVCD), pre-excited tachycardia. Rate: Below 60; Regularity: Yesyour R-to-R intervals all match up; P waves: You betchaevery QRS has a P wave; QRS: Normal width (0.08-0.11) It basically looks like normal sinus rhythm (NSR) only slower. 578-84. Each "lead" takes a different look at the heart. Wide regular rhythms . No. While it may seem odd to call an abnormal heart rhythm a sign of a healthy heart, this is actually the case with sinus arrhythmia. The QRS duration is 170 ms; the rate is 126 bpm. However, it should be noted that the dissociated P waves occur at repeating locations. It is important to note that all the analyses that help the clinician distinguish SVT with aberrancy from VT also help to distinguish single wide complex beats (i.e., APD with aberrant conduction vs. VPD). Carla Rochira In other words, the default diagnosis is VT, unless there is no doubt that the WCT is SVT with aberrancy. 83. European Heart J. vol. Radcliffe Cardiology is part of Radcliffe Medical Media, an independent publisher and the Radcliffe Group Ltd. The normal QRS complex during sinus rhythm is narrow (<120 ms) because of rapid, nearly simultaneous spread of the depolarizing wave front to virtually all parts of the ventricular endocardium, and then radial spread from endocardium to epicardium. This material may not be published, broadcast, rewritten or redistributed in any form without prior authorization. QRS duration 0,12 seconds. When it's not, you could have an irregular heartbeat called AFib . A. One such example would be antidromic atrioventricular reciprocating tachycardia (AVRT), where the impulse travels anterogradely (from the atrium to the ventricle) over an accessory pathway (bypass tract), and then uses the normal His-Purkinje network and AV node for retrograde conduction back up to the atrium. However, there is subtle but discernible cycle length slowing (marked by the *). Normal sinus rhythm is defined as a regular rhythm with an overall rate of 60 to 100 beats/min. Bundle branch reentry (BBR) is a special type of VT wherein the VT circuit is comprised of the right and left bundles and the myocardium of the interventricular septum. In an effort to aid the clinician, scoring systems have been recently proposed, but their clinical performance is only marginally superior to older criteria (see references). If your QRS complex is longer than 0.12 seconds, it is considered wide. 1165-71. 2. nd. The normal PR interval range is ~120 - 200 ms (0.12-0.20s), although it can fluctuate depending on your age and health. Because ventricular activation occurs over the RBB, the QRS complex during this VT exactly resembles the QRS complex during SVT with LBBB aberrancy. Wide complex tachycardia in the setting of metabolic disorders. vol. A history of ischemic heart disease or congestive heart failure is 90 % predictive of a ventricular origin of an arrhythmia.4 Patients with hypertrophic obstructive cardiomyopathy are prone to have VT.5 A known history of arrhythmogenic right ventricular dysplasia or cathecolaminergic polymorphic VT should also point towards a ventricular origin of the tachycardia. His echocardiogram showed a severely dilated heart with ejection fraction estimated at 10% to 15%. by Mohammad Saeed, MD. QRS Width. Its very common in young, healthy people. Heart Rhythm. Interpretation = Ventricular Escape Rhythms. There are multiple approaches and protocols, each having its own pros and cons. It can be normal and without consequence, or it can be a sign of various heart issues. A wide QRS complex tachycardia in a patient older than 35 years is more likely to be VT.4 A known history of coronary artery disease, previous myocardial infarction or cardiomyopathy makes VT a probable diagnosis. If right axis deviation is a change from previous ECGs, question the patient for symptoms consistent with an . Claudio Laudani The time between each heartbeat is known as the P-P interval. The PR interval is normal unless a co-existing conduction block exists. There is (negative) precordial concordance, favoring VT. clinically detectable variation of the first heart sound and examination of the jugular venous pressure were noted to be useful for the diagnosis of a ventricular origin of the arrhythmia.3. 2008. pp. A-V Dissociation strongly suggests ventricular tachycardia! This can make it easy to determine the rate of an irregular rhythm if it is not given to you (count the complexes and multiply by 10). Such confusion is most often related to the occasional patient where aberrancy results in a particularly bizarre QRS complex morphology, raising the likelihood that the WCT might be VT. . I gave a Kardia and last night I upgraded the Kardia and my first reading was Sinus rhythm with wide QRS and I was concerned because my left side was hurting and I also had a cramp in my back . Description. In its commonest form, the impulse travels down the RBB, across the interventricular septum, and then up one of the fascicles of the left bundle branch. A wide QRS is a delay beyond an internationally agreed time limit between the electrical conduction leaving the atria and that arriving at the ventricle. Relation to age, timing of repair, and haemodynamic status, Br Heart J, 1984;52(1):7781. Normal QRS width is 70-100 ms (a duration of 110 ms is sometimes observed in healthy subjects). This is called a normal sinus rhythm. Conclusion: Atrial flutter with 2:1 AV conduction with preexisting RBBB and LPFB. Wide complex tachycardia related to preexcitation. Furthermore, the P waves are inverted in leads II, III, and aVF, which is not consistent with sinus origin. Once atrial channel was programmed to a more sensitive setting, appropriate mode-switching occurred and inappropriate tracking ceased. Khairy P, Harris L, Landzberg MJ, et al., Implantable cardioverterdefibrillators in tetralogy of Fallot, Circulation, 2008;117:36370. Absence of these findings is not helpful, since VT can show VA association (1:1 VA conduction or VA Wenckebach during VT). Therefore, measurement of vital signs and a thorough but rapid physical examination are vital in deciding on the initial approach to the patient with WCT. ), this will be seen as a wide complex tachycardia. 2007. pp. incomplete right bundle branch block. Medications should be carefully reviewed. Lau EW, Ng GA, Comparison of the performance of three diagnostic algorithms for regular broad complex tachycardia in practical application, Pacing Clin Electrophysiol, 2002;25(5):8227. The frontal axis superiorly directed, but otherwise difficult to pin down. Today we will focus only on lead II. Since respiratory sinus arrhythmia is normal, people without symptoms rarely need treatment. Left Bundle Branch Block b. Tachycardia-Bradycardia Syndrome c. Ventricular Pacing d. Wolff-Parkinson-White syndrome e. Right Bundle Branch Block, e. Atrial fibrillation with a moderate ventricular . Wide complex tachycardias with right bundle branch block morphologies are more likely to be of ventricular origin in the presence of the following criteria: Left bundle branch block morphology tachycardias are more likely to be VT if they have the following features: In addition to these criteria, the presence of an R wave of more than 30 ms duration, notching of the downstroke of the S wave, or duration from the onset of the QRS to the nadir of the S wave in leads V1 or V2 of greater than 60 ms and any Q wave in lead V6 favors the ventricular origin of an arrhythmia.23 A protocol for the differentiation of a regular, wide QRS complex tachycardia was published by Brugada et al.24 It consisted of four diagnostic criteria: The presence of any of these criteria supports the diagnosis of VT. Morphologic criteria for right bundle branch block for lead V1 are: the presence of monophasic R wave, QR or RS morphology; for lead V6: Larger S wave than R wave, or the presence of QS or QR complexes.