In the majority of cases, right bundle branch block produces no symptoms of the heart condition. The more common sign and symptoms encountered in RBBB includes:
Any of the components of the left bundle can be involved, and this complex interventricular conduction abnormality has previously been described in patients with underlying heart disease. [ncbi.nlm.nih.gov]
pulmonary embolism, rheumatic heart disease, myocarditis, cardiomyopathy, or hypertension. [en.wikipedia.org]
The following tests and diagnostic modalities are implored in the diagnosis of right bundle branch blocks:
- Electrocardiography (ECG): This makes use of multiple electrodes place on the chest of the patient to record the cardiac electrical activities. Often times, RBBB is an incidental ECG finding while another cardiac disease is being worked up.
- Echocardiogram: The use of a two dimensional echocardiograph can elucidate a detailed view of the cardiac structures. This can demonstrate the actual movement of the heart wall, muscles and valves. The discovery of an atrial septal defect (ASD) or ventricular septal defect (VSD) can be facilitated by the echocardiogram.
- Holter monitoring: A continuous ambulatory monitoring of the cardiac electrical activity may be indicated in post-operative cases who undergone VSD or tetralogy of Fallot cardiac repair .
Wide QRS Complex
These are the criteria for multifocal atrial tachycardia MAT, also known as chaotic atrial rhythm,1 chaotic atrial tachycardia,2 and chaotic atrial mechanism.3 The wide QRS complexes 0.12 s with broad S waves in leads I, aVL, and the lateral precordial [ncbi.nlm.nih.gov]
Right bundle branch block ECG characteristics of a typical RBBB showing wide QRS complexes with a terminal R wave in lead V1 and a prolonged S wave in lead V6. [en.wikipedia.org]
So we have a supraventricular rhythm with wide QRS complexes. Once you have determined that a supraventricular rhythm is wide you should go to lead V1 and see if you can classify it as a right or left bundle branch block. [ems12lead.com]
Narrow QRS Complex
A Mobitz type I block (Wenckebach phenomenon) with narrow QRS complex is almost always due to a lesion in the AV node. In a type I block with wide QRS complex ( 0.12sec), the block can be in the His-Purkinje system in 60-70% of the cases. [ncbi.nlm.nih.gov]
Initial electrocardiogram (ECG): sinus tachycardia with narrow QRS complex Figure 2. Echocardiogram (subcostal view) with severe pericardial effusion Figure 3. [bjcardio.co.uk]
When the heart rate slows, the narrow QRS complex returns. A rate-dependent RBBB can, at times, be mistaken for ventricular tachycardia. The Brugada Criteria can be helpful in distinguishing these two entities. [healio.com]
Inferior Q Wave
Q-wave MI 1634 1 (year) Age, left ventricular failure and history of MI USA In-hospital Juárez-Herrera, 2010 [ 18 ] Patients with STEMI 4555 35 days Age, sex, diabetes, hypertension, hyperlipidemia, current smoker, previous AMI, AMI location, killip [ncbi.nlm.nih.gov]
T Wave Inversion
Delayed activation of the right ventricle also gives rise to secondary repolarization abnormalities, with ST depression and T wave inversion in the right precordial leads. [litfl.com]
The ECG revealed new findings, including normal sinus rhythm, (RBBB), multiple ST segment abnormalities, S1Q3T3 pattern, and T wave inversion V1-V3. [journals.lww.com]
It was based on scores as in parenthesis: sinus tachycardia (2); incomplete right bundle branch block (2); complete right bundle branch block (3); T-wave inversion, graded by magnitude (V1 [0 to 2], V2 [1 to 3], V3 [1 to 3], V1 through V4 all inverted [medical-dictionary.thefreedictionary.com]
wave inversion in the anterior leads - There may be an extra R wave in the anterior leads ( R'), or there may just be a broad slurred QRS. - The depolarization of the right ventricle is delayed - The left ventricle activates normally: the early part of [derangedphysiology.com]
Patients presenting with asymptomatic heart block or a first degree heart block do not require any treatment. However, in RBBB presenting with an underlying condition, treatment may be necessary to control the disorder.
These may require the intake of medications to control hypertension or diabetes as the primary underlying cause. An invasive coronary angioplasty may be done to repair the blocked coronary arteries to relieve the impending RBBB.
In patients presenting with recurrent fainting, the implantation of an internal pacemaker may prevent further fainting spells. The pacemaker will generate regular electric impulses to regulate heart rhythm and ensure an optimal cardiac pumping.
Some forms of naturally occurring right bundle branch block like familial bundle branch block has a good prognostic outcome. Post VSD repair scarring of heart tissues may present eminently of electrophysiologic studies but may prove to be benign in the long run. However, cardiac scarring due to the tetralogy of Fallot repair have increases risk of cardiac arrhythmia and sudden cardiac death.
ECG finding of right bundle branch block associated with the Brugada syndrome , arrhythmogenic right ventricular cardiomyopathy (ARVC) , and Kearne-Sayre syndrome are also at high risk with sudden cardiac death and arrhythmia; thus, carry a grim prognosis in patients .
The following cardiac conditions are common complications associated with the right bundle branch block:
- Symptomatic bradycardia: The right bundle branch block may consequently slow down the rate of conduction and heart rate causing significant symptoms requiring pacemaker installation in most patients.
- Sudden cardiac death occurs when the bundle branch completely fails to transmit electrical impulses and results to cardiac arrest.
- Misdiagnosis of cardiac diseases: The ongoing RBBB may distort or complicate ECG readings of other heart disorders like myocardial infarction causing a delay in management and an increase in the mortality and morbidity rate in patients.
The following medical conditions can directly cause right bundle branch block in patients:
In the United States, the most common cause of right bundle branch block among children is post-surgical repair scarring of ventricular septal defect (VSD). The incidence rate for RBBB in the surgical repair of VSD alone is 25-81% and up to 60-100% after surgical cardiac repair in tetralogy of Fallot.
The long term effect of surgically induced RBBB in VSD repair has no major hemodynamic significance on the patient. However, in patients who underwent repair of the tetralogy of Fallot may consequently have QRS prolongation of up to 180 milliseconds and may carry some risk for arrhythmia and sudden cardiac death.
A number of trained athletes my present with complete and incomplete RBBB by voltage that points to an innocent physiologic cardiac remodeling phenomenon of the right atrium .
The basic pathophysiological defect in right bundle branch block is primarily due to the non-conduction of electrical impulses from the bundle of His to right bundle branch tracks.
In the advent that the left bundle branch conducts normally, right ventricular depolarization becomes significantly discordant with the left ventricle. This ventricular depolarization mismatch gives out the characteristic electrocardiograph (ECG) reading. There are rare cases of exercise induced right bundle branch block which are presenting similarly but are clinically benign .
Not all right bundle branch block conditions are preventable. However, RBBB can effectively be prevented by keeping the heart healthy to avert cardiac conditions that results to RBBB. The following useful tips can reduce the risk for coronary artery disease that can lead to RBBB:
- A regular healthy diet that is low on cholesterols and fats.
- Regular cardio exercise in up to 30 minutes minimum per week.
- Maintaining an ideal body weight.
- Quitting cigarette smoking.
- Control of hypertension with maintenance antihypertensive medications.
- Active control of diabetes.
- Prompt treatment of hypercholesterolemia and triclyceridemia.
- Regular follow-up with cardiologist for post-operative cardiac patients .
Right bundle branch block (RBBB) refers to a clinical condition wherein the transmission of impulses towards the right ventricle is significantly delayed. The blockage of the right sided electrical pathway can make it difficult for the heart to pump efficiently. There are no specific treatment for RBBB and all management is geared towards the resolution of the underlying cardiac disease.
Electrocardiography, echocardiography, and Holter monitoring may be necessary to diagnose the condition.
Treatment and follow-up
Management of underlying cardiac cause and pacemaker installation are common treatment options.
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