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Arrhythmias Notes

Medicine Notes > Clinical Cardiology Notes

This is an extract of our Arrhythmias document, which we sell as part of our Clinical Cardiology Notes collection written by the top tier of Bristol University students.

The following is a more accessble plain text extract of the PDF sample above, taken from our Clinical Cardiology Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Arrythmias Normal Conduction in heart
? SA node o 'Cardiac pacemaker' o Posterior wall of atrium
? AV node o postero-inferior atrial spetum o Slow conduction velocity (0.05 m/s) to ensure atrial contraction preceeds ventricular
? Bundle branches and purkinje
? Subendocardium, fast conducting, produce rapid (narrow complex) synchronous systole
? Normally o SAN stimulates impulses o Spreads over atria in co-ordinated fashion to cause atrial contraction o Stimulation of the AVN o Conduction down the bundle of His to the bundle branches following a delay to ensure synchronous contraction o Subsequent conduction in the Purkinje system is rapid to ensure a narrow complex o Rapid ventricular systole
? Arrhythmias occurs when this process is disrupted. Heart Block
? Total heart block=block in the conducting system between the atria and ventricles
? P-waves don't correspond to QRS
? Block in the bundle branches then QRS complexes must be generated in the ventricles independently from the atria o Due to left or right bundle branch block or the presence of ventricular arrhythmias=QRS complexes will be broad (as the bundle/Purkinje system is that which ensures narrow complexes) Ventricular tachycardia (broad complex)
? Def= Tachycardia arising in the ventricles due usually with re-entry
? Causes o CAD o MI o Hypokalaemia
? Features: o Asymptomatic o Palpitations o Syncope o Cardiogenic shock
? Pathophysiology o Increased rate reduces diastolic filling time o Leads to reduced cardiac function o Cardiogenic shock (reduced BP, raised JVP) o Very serious, high mortality!
? ECG o Broad complex (>3sq) - pacemaking occurring in ventricles without conduction through AVN/Purkinje which acts to narrow QRS o Regular o Assume any broad complex tachycardia is VT until proven otherwise

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