Your heart rate increases when you breathe in and slows down when you breathe out. The site of VT origin: free wall sites of origin result in wider QRS complexes due to sequential activation (in series) of the two ventricles, as compared to septal sites, which result in simultaneous activation (in parallel). For example, VTs that arise within scar tissue located in the crest of the interventricular septum may break into (engage) the His bundle or proximal bundle branches early, and subsequent spread of electrical activation occurs via the His-Purkinje network, resulting in relatively narrower QRS complexes. Respiratory sinus arrhythmia doesnt cause chest pain. Vereckei A, Duray G, Szenasi G, et al., New algorithm using only lead aVR for differential diagnosis of wide QRS tachycardias, Heart Rhythm, 2008;5(1):8998. Application of irrigated radiofrequency current to a site 8 mm below the apex of Koch's triangle was terminated . Zareba W, Cygankiewicz I, Long QT syndrome and short QT syndrome, Prog Cardiovasc Dis, 2008;51(3):26478. Take an ECG with the ECG app on Apple Watch - Apple Support EKG rhythms Flashcards | Quizlet Griffith MJ, Garratt CJ, Mounsey P, Camm AJ, Ventricular tachycardia as default diagnosis in broad complex tachycardia, Lancet, 1994;343(8894):3868. There are errant pacing spikes (epicardial wires that were undersensing). An inverted P wave may be seen following the QRS due to retrograde conduction. Figure 3. Aberrancy, ventricular tachycardia, supraventricular tachycardia, right-bundle branch block (RBBB), left-bundle branch block (LBBB), intraventricular conduction delay (IVCD), pre-excited tachycardia. 2 years ago. Wide Complex Tachycardia: Definition of Wide and Narrow. Brugada, P, Brugada, J, Mont, L. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. A change in the QRS complex morphology or axis by more than 40, as well as a QRS axis of 90 to 180 suggests a ventricular origin of the arrhythmia.17,18 An entirely positive QRS complex in lead augmented ventor left (aVR) also supports the diagnosis of VT.17 When the sinus rhythm with wide QRS becomes narrow with a tachycardia, this indicates VT.19 The morphology of a tachycardia similar to that of premature ventricular contractions seen on prior ECGs increases the probability of a ventricular origin of the arrhythmia. The risk of developing it increases . Comparison with the baseline ECG is an important part of the process. High Grade Second Degree AV Block, All of the following are generally associated with a wide QRS complex EXCEPT: Select one: a. Jastrzebski, M, Kukla, P, Czarnecka, D, Kawecka-Jaszcz, K.. Comparison of five electrocardiographic methods for differentiation of wide QRS-complex tachycardias. QRS Width. Figure 1. Sometimes . A PVC that falls on the downslope of the T wave is referred to as _____ & is considered very dangerous. R-R interval is regular (constant) b. Sinus Bradycardia (normal slow) i. It affects the heart's natural pacemaker (sinus node), which controls the heartbeat. QRS duration 0.06. A widened QRS interval. You cant prevent respiratory sinus arrhythmia. Broad complex tachycardia Part I, BMJ, 2002;324:71922. B. This happens when the upper and lower chambers of the heart are beating in sync. An abnormally slow heart rate can cause symptoms, especially with exercise. Sinus Tachycardia. 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. English KM, Gibbs JL,. The term narrow QRS tachycardia indicates individuals with a QRS duration 120 ms, while wide QRS tachycardia refers to tachycardia with a QRS duration >120 ms. 1 Narrow QRS complexes are due to rapid activation of the ventricles via the His-Purkinje system, suggesting that the origin of the arrhythmia is above or within the His bundle. Clin Cardiol. 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 the QRS duration is normal (<0.12 seconds), the arrhythmia is said to be a narrow complex tachycardia (NCT). 2. nd. Some leads may display all waves, whereas others might only display one of the waves. 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. Normal Sinus Rhythm vs. Atrial Fibrillation Irregularities - WebMD To reinforce the material we would like to offer of this protocol are 96.5 and 95.7 %, respectively, which is similar to the previous alghorithm published by this group.29 To reinforce the material we would like to offer two ECGs for review (see Figures 1 and 2). The four criteria are: This algorithm has a better sensitivity and specificity than the Brugada criteria being 95.7 and 95.7 %, respectively.26 More recently, a new protocol using only lead aVR to differentiate wide QRS complex tachycardias was introduced by Vereckei et al.29 It consists of four steps: Similar to the previous algorithm, only one of the four criteria needs to be present. Name: Ventricular Fibrillation- Lethal Rate: N/A Rhythm: chaotic baseline activity which may be coarse or fine P-Waves: none PR-Interval: N/A QRS Complex: none. Leads V2 and V3, however, show swift down strokes (onset to nadir <70 ms), favoring SVT with LBBB aberrancy. The QRS complex: ECG features of the Q-wave, R-wave, S - ECG & ECHO Morady F, Baerman JM, DiCarlo LA Jr, et al., A prevalent misconception regarding wide-complex tachycardias, JAMA, 1985;254(19):27902. This material may not be published, broadcast, rewritten or redistributed in any form without prior authorization. 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. Sinus tachycardia is when your body sends out electrical signals to make your heart beat faster. EKG Interpretation - Nurses Learning Wide QRS Duration | American Journal of Critical Care | American 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. An abnormally slow heartbeat is called bradycardia, while an abnormally fast heartbeat is called tachycardia. The QRS duration is very broad, approaching 200 ms; the rate is 125 bpm. 2. The following observations can be made from the second ECG, obtained after amiodarone: Conclusion: Atrial flutter with LBBB aberrancy with unusual frontal axis and precordial progression. Supraventricular tachycardia (SVT) with aberrancy accounts for . I strongly suspect that the Kardia device will be reporting correctly. Articles marked Open Access but not marked CC BY-NC are made freely accessible at the time of publication but are subject to standard copyright law regarding reproduction and distribution. This is called a normal sinus rhythm. is wide QRS tachycardia dangerous? - Heart Rhythm - MedHelp The QRS complex (ventricular complex): normal and abnormal configurations and intervals. The latest information about heart & vascular disorders, treatments, tests and prevention from the No. The presence of antiarrhythmic drugs (especially class Ic or class III antiarrhythmic drugs) or electrolyte abnormalities (such as hyperkalemia) can slow intra-myocardial conduction velocity and widen the QRS complex. When you take a breath, your heart rate goes up. I gave a Kardia and last night I upgraded the Kardia and my first reading was - Answered by a verified Doctor . Your heart rate increases when you breathe in and slows down when you breathe out. Normal sinus rhythm is defined as the rhythm of a . He proceeded to have an episode of WCT while in bed with dizziness and drop in blood pressure, which self-terminated. . What causes a junctional rhythm in the sinus? Permission is required for reuse of this content. 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. If the QRS duration is prolonged (0.12 seconds), the arrhythmia is a wide complex tachycardia (WCT). This is where the experienced electrocardiographer must weigh the conflicting indicators and reach a clinical decision. Study with Quizlet and memorize flashcards containing terms like Normal Sinus Rhythm, Sinus Arrest, Sinus arrhythmia and more. 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. , Wide Complex Tachycardia - Rush Emergency Medicine Sinus bradycardia occurs when your sinus rhythm is below 60 bpm. The normal PR interval is 0.12-0.20 seconds, or 3-5 small boxes on the ECG graph paper. QRS duration 0,12 seconds. While it is common to have sinus tachycardia as a compensatory response to exercise or stress, it becomes concerning when it occurs at rest. Occasional APBs and one ventricular run. The narrow QRS tachycardia shows the typical features of atrial fibrillation (AF). When it's not, you could have an irregular heartbeat called AFib . , The QRS complex is wide, about 150 ms; the rate is about 190 bpm. There are two main types of bradycardiasinus bradycardia and heart block. Electrocardiogram characteristics of AIVR include a regular rhythm, 3 or more ventricular complexes with QRS complex > 120 milliseconds, a ventricular rate between 50 beats/min and 110 beats/min, and occasional fusion or capture beats. It means the electrical impulse from your sinus node is being properly transmitted. 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. Huemer, M, Meloh, H, Attanasio, P, Wutzler, A. However, careful observation shows VA dissociation (best seen in lead V1) with slower P waves. 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. 1-ranked heart program in the United States. A short PR interval and delta wave are present, confirming ventricular pre-excitation and excluding aberrant conduction (excludes answer A). Is sinus rhythm with wide QRS dangerous. I gave a Kardia and If you have respiratory sinus arrhythmia, your outlook is good. Sinus rythm with mark. There is sinus rhythm at approximately 75 bpm with prolonged PR interval. ECG- Final Flashcards | Quizlet A 56-year-old woman with end-stage renal disease presented with dizziness and altered mental status. The correct diagnosis is essential since it has significant prognostic and treatment implications. Is It Dangerous? The exact same pattern of LBBB aberrancy was reproduced during rapid atrial pacing at the time of the electrophysiology study. Am J Cardiol. 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. 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. The width of the QRS complex, both with aberrancy and during VT, can vary from patient to patient. PACs are extra heartbeats that originate in the top of the heart and usually beat . She has missed her last two hemodialysis appointments. Interpretation = Ventricular Escape Rhythms. Figure 2. Careful observation of QRS morphology during the WCT shows a qR pattern, also favoring VT. [1] The normal resting heart rate for adults is between 60 and 100, which varies based on the level of fitness or the . In most people, theres a slight variation of less than 0.16 seconds. The interval from the pacing spike to the captured QRS complex progressively gets longer, before a pacing spike fails to capture altogether; this is consistent with Pacemaker Exit Wenckebach. Normal sinus rhythm in a patient at rest is under the control of the sinus node, which fires at a rate of 60-100 bpm. 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). 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. 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 . Ahmed Farah However, early activation of the His bundle can also . Twelve-lead ECG after electrical cardioversion of the tachycardia. It is generally a benign arrhythmia and in the absence of structural heart disease and symptoms, generally no treatment is required. , by Mohammad Saeed, MD. Only articles clearly marked with the CC BY-NC logo are published with the Creative Commons by Attribution Licence. 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. Each EKG rhythm has "rules" that differentiate one rhythm from another. European Heart J. vol. You have a healthy heart. Long QT syndrome - Symptoms and causes - Mayo Clinic 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. The QRS complexes may look alike in shape and form or they may be multiform (markedly different from beat to beat). Sick sinus syndrome causes slow heartbeats, pauses (long periods between heartbeats) or irregular heartbeats (arrhythmias). A narrow QRS complex (<120 milliseconds) reflects rapid activation of the ventricles via the normal His-Purkinje system, which in turn suggests that the arrhythmia originates above or within the atrioventricular (AV) node (ie, a . A normal sinus rhythm means your heart rate is within a normal range. The QRS complex in lead V1 shows an rS pattern, with a broad initial R wave, favoring VT (Table V). What is Sinus Rhythm with Supraventricular Ectopy? pp. Respiratory sinus arrhythmia is actually a sign of a healthy heart. Importantly, the EKGs were not available for additional EKG review, which also . Alternating QRS Duration and Abnormal T Waves | Circulation Sinus Tachycardia - an overview | ScienceDirect Topics A change in the QRS complex morphology or axis by more than 40, as well as a QRS axis of 90 to 180 suggests a ventricular origin of the arrhythmia. The baseline ECG ( Figure 2) showed sinus rhythm with a PR interval of 0.20 seconds and QRS duration of 0.085 seconds. ECG results: 79 pbm, Pr interval 152 ms, Qrs duration 100 ms,QT/QTc 352/403 ms, p r t axes 21 20 17. Europace.. vol. Dendi R, Josephson ME, A new algorithm in the differential diagnosis of wide complex tachycardia, Eur Heart J, 2007;28:5256. No protocol is 100 % accurate. Any cause of rapid ventricular pacing will result in result in a WCT. Its usually a sign that your heart is healthy. Wide QRS complex tachycardias: Approach to management But did one tonight and it gave normal sinus rhythm with wide QRS I have clicked on it and it says something . Citation: Had an ECG taken and slightly worried. Copyright 2023 Haymarket Media, Inc. All Rights Reserved. A sinus rhythm result only applies to that particular recording and doesn't mean your heart beats with a consistent pattern all the time. What condition do i have? A complete QRS complex consists of a Q-, R- and S-wave. Sometimes, these electrical impulses are sent out faster than this typical rhythm, causing sinus tachycardia. A Junctional rhythm can happen either due to the sinus node slowing down or the AV node speeding up. Figure 8: WCT tachycardia recorded in a male patient on postoperative day 3 following mitral valve repair. 13,029. This is one VT which meets every QRS morphology criterion for SVT with aberrancy. Figure 2. Is pain in chest , dizziness, headaches and ability to feel heart beat 24/7 normal? When ventricular rhythm takes over . Ventricular rhythm (Fgure 6) Characterized by wide QRS complexes that are not preceded by P waves. A sinus rhythm result means the heart is beating in a uniform pattern between 50 and 100 BPM. What determines the width of the QRS complex? is one of the easiest to use while having a good sensitivity and specificity. What is aivr in cardiology? Explained by Sharing Culture . A history of both short and long QT syndromes makes a ventricular origin of the tachycardia likely as well.1012 However, patients with a short QT syndrome and the Brugada syndrome are more likely to present with ventricular fibrillation rather than VT. Infiltrative diseases of the heart such as cardiac amyloidosis or sarcoidosis may also predispose patients to ventricular arrhythmias.13,14 Interestingly enough, VT is also common in patients with Chagas disease.15. B, Annotated 12-lead electrocardiogram showing wide complex rhythm with flutter waves best seen in lead V 1 (vertical blue arrowheads). Vijay Kunadian Most importantly, the transition to narrow complex tachycardia is accompanied by an acceleration of the heart rate to about 120 bpm. Ventricular fibrillation. If your heart doesnt have sinus arrhythmia, its a reason for concern. Idioventricular Rhythm - StatPearls - NCBI Bookshelf Although initial perusal may suggest runs of nonsustained VT, careful observation reveals that there is a clear pacing spike prior to each wide QR complex (best seen in lead V4), making the diagnosis of a paced rhythm. 9500 Euclid Avenue, Cleveland, Ohio 44195 |, Important Updates + Notice of Vendor Data Event, (https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/other-heart-rhythm-disorders), (https://www.ncbi.nlm.nih.gov/books/NBK537011/), Visitation, mask requirements and COVID-19 information, Heart, Vascular & Thoracic Institute (Miller Family), Bradyarrhythmia, such as some second-degree and third-degree. This is one VT where the QRS complex morphology exactly mimics that of SVT with aberrancy. 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. For management, see "Management of Wide Complex Tachycardia". Bundle Branch Block; Accessory Pathway; Ventricular rhythm Ventricular escape rhythm; AIVR - Accelerated Idioventricular Rhythm; Normal sinus rhythm is defined as the rhythm of a healthy heart. As expected, the P waves are of low amplitude in hyperkalemia. The rhythm broke and the 12-lead ECG shown in Figure 11 was obtained. When you breathe out, it slows down. Idioventricular rhythm is a slow regular ventricular rhythm, typically with a rate of less than 50, absence of P waves, and a prolonged QRS interval. 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. QRS Interval LITFL ECG Library Basics . Milena Leo 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. However, all three waves may not be visible and there is always variation between the leads. Brugada R, Hong K, Cordeiro JM, Dumaine R, Short QT syndrome, CMAJ, 2005;173(11):134954. Furthermore, the P waves are inverted in leads II, III, and aVF, which is not consistent with sinus origin. Edhouse J, Morris F, ABC of clinical electrocardiography. Escardt L, Brugada P, Morgan J, Breithardt G, Ventricular tachycardia. The ECG in Figure 4 is representative. No. We do not endorse non-Cleveland Clinic products or services. The QRS width is useful in determining the origin of each QRS complex (e.g. Claudio Laudani II. The rhythm strip shows sinus tachycardia at the beginning and at the end; each sinus P wave is marked. Interpretation: Normal sinus rhythm with one PJC. I took an ECG and it showed sinus rhythm with wide QRS. - JustAnswer 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. If the ambient sinus rate is rapid, the resulting ECG may show a WCT. 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. Wide QRS Complex After Catheter Ablation | Circulation And you dont want to, because its a sign of a healthy heart. et al, Andre Briosa e Gala EKG Interpretation - University of Texas Medical Branch , 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. The prognostic value of a wide QRS >120 ms among patients in sinus rhythm is well established. However, the correct interpretation requires recognition that the narrow complexes are too narrow to be QRS complexes, and are actually pacemaker spikes with failure to capture the myocardium. Children with wide QRS complex tachycardia may present with hemodynamic instability, and if not urgently treated, serious morbidity or death may . However, such patients are usually young, do not have associated structural heart disease, and most importantly, show manifest preexcitation (WPW syndrome ECG pattern) during sinus rhythm. The frontal axis is pointing to the right shoulder, and favors VT. Sick sinus syndrome - Symptoms and causes - Mayo Clinic 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. Response to ECG Challenge. A. In adults, normal sinus rhythm usually accompanies a heart rate of 60 to 100 beats per minute. Providers separate different kinds of sinus arrhythmia based on their causes. When a WCT abruptly becomes a narrow QRS rhythm at exactly half the rate of the WCT, atrial flutter with 1:1 AV conduction transitioning to 2:1 AV conduction is very likely (i.e., SVT with aberrancy). Since respiratory sinus arrhythmia is normal, people without symptoms rarely need treatment. Medications should be carefully reviewed. Name: Normal Sinus Rhythm Rate: 60-100 Rhythm: R-R intervals regular P-Waves: Present, all look alike PR-Interval: . If the dangerous rhythm does not correct itself, then a life-threatening arrhythmia called ventricular fibrillation follows. Normal Sinus Rhythm i. 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. The Lewis Lead for Detection of Ventriculoatrial Conduction Type. vol. The following observations can be made from the first ECG: The emergency medical services were summoned and IV amiodarone was administered. incomplete right bundle branch block. From our perspective, the last protocol by Verekei et al. Tachycardias are broadly categorized based upon the width of the QRS complex on the electrocardiogram (ECG). The normal PR interval range is ~120 - 200 ms (0.12-0.20s), although it can fluctuate depending on your age and health. Sinus Rhythm Types. Any WCT should be assumed to be VT until proven otherwise. For the final assessment at least one criterion for both V12 and V6 have to be present to diagnose VT. Figure 13: A 33-year-old man with lifelong paroxysmal rapid heart action underwent a diagnostic electrophysiology study. His ECG showed LBBB during sinus rhythm (left panel in Figure 6). When a sinus rhythm has a QRS complex of 0.12 sec or greater, you know that this is an abnormality & would note that it has: a wide QRS accelerated ventricular conduction Purkinje disease . 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. Heart Rhythm. A WCT that occurs in a patient with a history of prior myocardial infarction can be safely assumed to be VT unless proven otherwise. It must be acknowledged that there are many clinical scenarios where different criteria will provide conflicting indications as to the etiology of a WCT. All QRS complexes are irregularly irregular. A normal heartbeat is referred to as normal sinus rhythm (NSR). Inappropriate Sinus Tachycardia: Symptoms, Causes, Treatment - WebMD The 12-lead rhythm strips shown in Figure 13 were recorded during transition from a WCT to a narrow complex tachycardia. Her serum potassium was 7.1 mEq/dl, and with aggressive treatment of hyperkalemia, her ECG normalized. When a WCT abruptly becomes a narrow complex tachycardia with acceleration of the heart rate, SVT (orthodromic atrioventricular reciprocating tachycardia using an accessory pathway on the same side as the blocked bundle branch) is confirmed (Coumels law). AIVR is a wide QRS ventricular rhythm with rate of 40-120 bpm, often with variability during the episode. Wide complex tachycardia related to rapid ventricular pacing. The electrical signal to make the heartbeat starts . However, not every P wave results in a QRS complex the PR interval progressively lengthens, culminating in failure of AV conduction ("dropped QRS complexes"). Bruno Garca Del Blanco Wide QRS with sinus rhythm : My Kardia 6L - AF Association The result is a wide QRS pattern. (R-RI=irreg) *unsure/no P-wave (non-distinguishable)* - irreg rhythm BUT reg QRS! Apple Watch ECG that captured a Sinus Bradycardia with a normal QRS interval. The WCT shows a QRS complex duration of 180 ms; the rate is 222 bpm. 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. The Licensed Content is the property of and copyrighted by DSM. Sinus Rhythm With Bundle Branch Block - HealthySinus.net You probably don't think much about your heartbeat because it happens so easily. 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