A left posterior fascicular block is an electrophysiologic abnormality that is rarely encountered in clinical practice, but it is well-known for its occurrence in the setting of coronary artery disease (CAD) [1] [2] [3] [4]. Insufficient blood flow to the left posterior fascicle, which is supplied by the right coronary artery and the anterior descending branch of the left coronary artery, causes improper conduction of the electrical signal through the heart [1] [4]. Because of blood vessel occlusion, myocardial infarction may ensue and left posterior fascicular is shown to be present in about 5% of all myocardial infarctions of the inferior wall according to isolated reports [1]. Hence, the clinical presentation of these patients is primarily related to myocardial infarction and CAD. Some reports, however (in which iatrogenic induction of this cardiac abnormality by interleukin-2 was documented) have observed patients in whom the symptoms such as chest pain, syncope, or palpitations weren't present [5]. Atrial flutter and atrial fibrillation, two very important types of arrhythmias, are known to induce the phenomenon of "axis deviation", which may promote the development of left posterior fascicular block [6].

• Asymptomatic

  - Could be myocarditis or some sort nof cardiomyopathy Consequences of Left Posterior Fascicle Block - This is an asymptomatic condition – usually doesn't amount to much. [derangedphysiology.com]

  Atrial fibrillation is associated with an increased risk for mortality and heart failure progression in patients with asymptomatic and symptomatic left ventricular systolic dysfunction: a retrospective analysis of the SOLVD trials. [books.google.com]

  Patients with this type of CHB may remain asymptomatic for appreciable periods of time and are usually haemodynamically stable. [patient.info]

  […] bundle branch block and left posterior fascicular block Although it is a sign of extensive conducting system disease, the risk of progression to complete heart block is relatively low (approximately 1% per year) No treatment is usually required for asymptomatic [medicalexamprep.co.uk]

  Patients with asymptomatic first degree atrioventricular block, asymptomatic second degree Mobitz I with supra-Hisian conduction block or atrioventricular block expected to resolve do not require a pacemaker implantation.[ 9, 23, 34 ] Intraventricular [textbookofcardiology.org]

• Fever

  […] stvincenthospital.com Citation American Heart Hospital Journal 2011;9(2):112-3 DOI https://doi.org/10.15420/ahhj.2011.9.2.112 An electrocardiogram of a 72-year-old man who developed acute respirophasic pain in the left and central anterior chest plus fever [radcliffecardiology.com]

  It may also occur in congestive and hypertrophic cardiomyopathy, myocarditis, acute rheumatic fever, syphilis, cardiac tumours, post-cardiac surgery and in congenital heart disease. [frca.co.uk]

  Inflammatory cardiac disease such as SLE, ankylosing spondylitis, reactive arthritis, dermatomyositis, rheumatoid arthritis, scleroderma, endocarditis, myocarditis, Lyme disease and rheumatic fever. [patient.info]

  Abnormal, non-cardiac causes of sinus tachycardia — fever, hemorrhage, infection, hypoglycemia, anxiety, pain, thyrotoxicosis, shock, hypoxemia, hypovolemia. [nps.freeservers.com]

• Abdominal Mass

  Thicker muscle mass in atria increase distance traveled by the depolarizing impulse and increase current flow in the areas of hypertrophy. [nps.freeservers.com]

• Heart Disease

  Hyperkalemia Myocardial infarction Common Causes Cardiomyopathy Coronary artery disease Hypertensive heart disease Myocardial infarction Causes by Organ System Causes in Alphabetical Order Cor pulmonale Cardiomyopathy Chagas disease Coronary artery disease [wikidoc.org]

  ICD-CODE.org Codes Chapters Blocks Categories Diseases of the circulatory system Other forms of heart disease I44 - Atrioventricular and left bundle-branch block I445 Code I44.5 Code: I445 Description: Left posterior fascicular block Chapter: Diseases [icd-code.org]

  Since it is possible to cover in detail but a few aspects of such a broad subject, the presentation was oriented to stress topics of special value to the physician dealing with patients having heart disease. Footnotes [doi.org]

  If an ischemic heart disease is thought to be present, then the coronary arteries may need to be checked for the presence of blood clots. [justanswer.com]

  Causes of Left Posterior Fascicle Block - The left posterior fascicle has dual blood supply (LAD + AV nodal artery) so if ischaemic heart disease is causing this phenomenon, it is SEVERE indeed. - Could be myocarditis or some sort nof cardiomyopathy Consequences [derangedphysiology.com]

• Tachycardia

  Radiofrequency (RF) ablation was applied during ventricular tachycardia (VT) and termination of the VT or abolishing the inducibility of the tachycardia was used as an endpoint for successful RF. [ncbi.nlm.nih.gov]

  (PSVT) (Medical Encyclopedia) Ventricular tachycardia (Medical Encyclopedia) Wolff-Parkinson-White syndrome (Medical Encyclopedia) [ Read More ] [icdlist.com]

  Idiopathic ventricular tachycardia (IVT) is a term that has been used for ventricular tachycardia (VT) in the absence of clinically apparent structural heart disease (1). [escardio.org]

  Left ventricular tachycardia is often considered a life-threatening arrhythmia. Idiopathic fascicular left ventricular tachycardia (ILVT) accounts for 10–15% of all left ventricular tachycardias. [innovationsincrm.com]

• Flushing

  Mousa of New York Hospital Queens in Flushing. The presence or absence of right bundle branch block in patients with LAFB on their resting ECG did not affect the diagnostic accuracy of their ECG exercise stress test. Dr. [mdedge.com]

The diagnostic workup of patients with a left posterior fascicular block starts with a thorough clinical assessment. A detailed patient history is necessary in order to reveal possible risk factors, mainly CAD. If the abrupt clinical presentation of sudden chest pain and other typical signs seen in a myocardial infarction are noted, immediate employment of electrocardiography (ECG) is of great importance. Left posterior fascicular block can appear in association with a right bundle branch block (RBBB) or as an isolated entity, and recently proposed criteria for this abnormality state the following findings are necessary to make the diagnosis [1] [2] [5] [7]:

• Right axis deviation - A shift of the frontal plane to 90°-180° in adults is one of the crucial findings in a left posterior fascicular block.
• Duration of the QRS complex of < 120 milliseconds
• A QR pattern in leads aVF and III
• An RS pattern (a small R wave with a deep S wave) in leads aVL and I

As soon as these criteria are met, it is recommended to perform coronary angiography (and left ventricular angiography if possible), mainly because CAD in the case of left posterior fascicular block frequently affects up to 3 coronary vessels [1].

• Right Axis Deviation

  The left posterior fascicular block is diagnosed by right axis deviation and by ruling out other causes of right axis deviation. In RAD, Lead III will have a taller positive ( R ) wave than Lead II, and a negative Lead I. [ecgguru.com]

  Electrocardiography is the single most important study for revealing a left posterior fascicular block, showing either intermediate (90° to 120°) or marked (120° and 180°) right axis deviation, alongside several other findings involving the QRS complex [symptoma.com]

  Do not be tempted to diagnose LPFB until you have ruled out more significant causes of right axis deviation : Example: acute pulmonary embolus ; tricyclic overdose ; lateral STEMI ; and right ventricular hypertrophy. [lifeinthefastlane.com]

  Therefore, the latter portion of the QRS depolarizes toward the inferior myocardium, manifesting as strong right axis deviation. 2. [studymedicalphotos.blogspot.com]

  Dr, Burns walks us through some of expected ECG findings and also reminds that you should not dx LPFB without first considering more worrisome causes of right axis deviation : PE, TCA overdose, lateral MI, or RVH. Check out his post on LITFL. [maricopaemergencymedicine.com]

• Left Axis Deviation

  Wide complex tachycardia with RBBB morphology in lead V1 and left axis deviation. [ecgmedicaltraining.com]

  If left axis deviation is present, think about left anterior fascicular block, and if right axis deviation is present, think about left posterior fascicular block in addition to the RBBB. [frca.co.uk]

  Verapamil-sensitive, idiopathic left ventricular tachycardia (ILVT) with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated [ncbi.nlm.nih.gov]

  Abstract Verapamil-sensitive, idiopathic left ventricular tachycardia (ILVT) with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated [doi.org]

  This concurrence of RBBB with either LAFB (producing left axis deviation) or LPFB (producing right axis deviation) is termed bifascicular block, as described below. [angelfire.com]

• Right Bundle Branch Block

  Using these criteria, 18 cases were selected from a group of 4600 patients and 340 healthy subjects; isolated left posterior fascicular block was seen in 10 cases, and was associated with right bundle-branch block in 8 cases. [ncbi.nlm.nih.gov]

  Right Bundle Branch Block With Left Posterior Fascicular Block This is a good clear example of right bundle branch block with left posterior fascicular block. [ecgguru.com]

  block 426.2 Left bundle branch hemiblock 426.3 Other left bundle branch block 426.4 Right bundle branch block 426.50 Bundle branch block, unspecified 426.52 Right bundle branch block and left anterior fascicular block 426.53 Other bilateral bundle branch [healthprovidersdata.com]

• Left Anterior Fascicular Block

  Left posterior fascicular block was associated with right bundle branch block in nine cases and alternated with left anterior fascicular block in three. [ncbi.nlm.nih.gov]

  Left anterior fascicular block (hemiblock) and left posterior fascicular block (hemiblock). [ecgwaves.com]

  What is a left anterior fascicular block? A left anterior fascicular block is known as a cardiac condition that may often be determined by a left bundle branch block. [justanswer.com]

  […] parts of the left ventricle, and; The septal fascicle, which supplies the septal wall Left Anterior Fascicular Block In left anterior fascicular block (LAFB) the anterior portion of the left bundle branch is defective. [medicalexamprep.co.uk]

  I44.69 Other fascicular block Approximate Synonyms Left anterior fascicular hemiblock Left anterior fascicular hemiblock (heart rhythm) Left anterior hemiblock Left posterial fascicular hemiblock Left posterial fascicular hemiblock (heart rhythm) Left [icd9data.com]

Advanced level treatment material, such as complete thrombus formation, treatment and management offers critical information for both the hospital setting and the EMS setting. [books.google.com]

Similar electrocardiogram changes were noticed during 2 subsequent cycles of high-dose IL-2 treatment, both of which resolved spontaneously. [ncbi.nlm.nih.gov]

No specific treatment is indicated. Click here for Patient Education [merckmanuals.com]

What treatment is needed for a left anterior fascicular block and a right bundle branch block? A right bundle branch block and left anterior fascicular block may often be referred to as a bi-*fascicular block. Often, no treatment may be needed. [justanswer.com]

The development of RBBB + LPFB during acute myocardial infarction is a sign of poor prognosis. RBBB + LPFB has a high probability to turn into complete AV block. References Circulation 2009;119:e235-e240 Circulation 2007;115:1154-1163 ECG 1. [metealpaslan.com]

For the same reason, left posterior hemiblock carries a poorer prognosis. [cardiophile.org]

Prognosis of left anterior fascicular block (LAFB) Isolated LAFB is considered a benign conduction defect. [ecgwaves.com]

Questions regarding left anterior fascicular block may be very common regarding what left anterior fascicular block is, the causes, prognosis, symptoms, as well as treatments. [justanswer.com]

RAD — Etiology • May occur normally in slender person and in infants. [nps.freeservers.com]

Co-authors include Mala Mandyam of the UCSF Division of Cardiology, Electrophysiology Section; Eric Vittinghoff, PhD, of the UCSF Department of Epidemiology and Biostatistics; Elsayed Z. [ucsf.edu]

Canis ISSN: 2398-2942 Synonym(s): Left axis shift Contributor(s): Dan Ohad, Mark Oyama Pathophysiology The bundle branches of the cardiac conduction system arise from the bundle of His as it exits the atrioventricular node. [vetstream.com]

Knowledge of the anatomy and electrophysiology of the cardiac conduction system from the atrioventricular (AV) junction to the distal Purkinje fibers is essential to understanding the pathophysiology of left bundle branch (LBB) block (LBBB). [emedicine.medscape.com]

With the current knowledge concerning the pathophysiology of the tachycardia and modern ablation techniques, ILVT now has an excellent prognosis. References Lerman BB, Stein KM, Markowitz SM. Mechanisms of idiopathic left ventricular tachycardia. [innovationsincrm.com]

This type of occlusion is often called the "Widow Maker", and requires very rapid intervention to restore blood flow and prevent complicatons. [ecgguru.com]

Definition (MSH) A form of heart block in which the electrical stimulation of HEART VENTRICLES is interrupted at either one of the branches of BUNDLE OF HIS thus preventing the simultaneous depolarization of the two ventricles. [fpnotebook.com]

In addition, it prevents sudden death for patients that experience atrial fibrillation. When the atria are fibrillating, what’s to stop the ventricles from fibrillating? The AV node! [ems12lead.com]

Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). [escardio.org]

1. Godat FJ, Gertsch M. Isolated left posterior fascicular block: a reliable marker for inferior myocardial infarction and associated severe coronary artery disease. Clin Cardiol. 1993 Mar;16(3):220-6.
2. Surawicz B, Childers R, Deal BJ, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology. J Am Coll Cardiol. 2009 Mar 17;53(11):976-81.
3. Patanè S, Marte F, Mancuso A, Di Bella G. Transient right axis deviation with left posterior hemiblock and junctional rhythm during acute myocardial infarction. Int J Cardiol. 2009;135(3):e69-72.
4. Rokey R, Chahine RA. Isolated left posterior fascicular block associated with acquired ventricular septal defect. Clin Cardiol. 1984;7(6):364-369.
5. Singla A, Denmeade SR. Left posterior fascicular block due to high-dose interleukin-2. Ann Pharmacother. 2008;42(9):1340-1343.
6. Patanè S, Marte F, Sturiale M. Right bundle branch block with revelation of changing axis deviation at the end of atrial fibrillation. Int J Cardiol. 2009;137(3):e54-56.
7. Ashley EA, Niebauer J. Cardiology Explained. London: Remedica; 2004. Chapter 8, Arrhythmia.