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Bradycardia: Difference between revisions
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=Introduction= | =Introduction= | ||
Bradycardias are defined as symptomatic heart rhythm disorders resulting in a inappropriately low heart rhythm during during physiologic conditions. Generally this results in a cut-off value of <60 beats per minute, however variation of | Bradycardias are defined as symptomatic heart rhythm disorders resulting in a inappropriately low heart rhythm during during physiologic conditions. Generally this results in a cut-off value of <60 beats per minute, however variation of heart rate exists. For instance, during sleep and in athletes the heart rate can be as low as 40 beats per minute. | ||
Bradycardia can be caused by a variety of intrinsic and extrinsic causes. | Bradycardia can be caused by a variety of intrinsic and extrinsic causes. | ||
Fortunately the human heart has a couple of backup mechanisms that can | Fortunately the human heart has a couple of backup mechanisms that can sustain a heart rate in case of severe bradycardia. These escape mechanisms can occur in every part of the heart (i.e. atrium, AV, node, ventricle). In general, the rate of the escape mechanism is faster when the escape rhythm is located higher in the conduction system. | ||
To understand the pathophysiologic basis of most conduction disorders or disorders of impulse formation it is important to understand the physiology of cardiac conduction and mechanisms of arrhythmia as detailed in the general cardiac arrhythmia section [Link]. | To understand the pathophysiologic basis of most conduction disorders or disorders of impulse formation it is important to understand the physiology of cardiac conduction and mechanisms of arrhythmia as detailed in the general cardiac arrhythmia section [Link]. | ||
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==Ventricular Conduction Block== | ==Ventricular Conduction Block== | ||
===RBBB=== | ===RBBB=== | ||
The right bundle branch is composed of one fascicle. Right bundle branch block is a unifascicular block of the right bundle and can be found in xx% of normal people. However a new RBBB in a patient with a history of normal ventricular conduction warrens further cardiological investigation. | |||
===LAFB=== | ===LAFB=== | ||
The left bundle branch is composed of two fascicles. One of the fascicle has an anterior location and activates the interventricular septum and the anterior of the ventricle. | |||
===LPFB=== | ===LPFB=== | ||
=== | The second fascicle of the left bundle branch is the posterior fascicle. This fascicle has a posterior location and activates the posterior and lateral part of the ventricle. | ||
===LBBB=== | |||
If the two fascicles of the left bundle branch there is a left bundle branch block, this bifascicular block is uncommon in healthy patients and further cardiologic investigations need to be performed to screen for underlying disease. | |||