Cardiology Notes 3

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  ARRHYTHMIAS

ECG for all very important

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  Differentiating SVT from VT

Features that favour VT are: QRS of > 140ms, cannon a waves on JVP fusion and/or capture beats dissociated p waves, history of ischaemic heart disease, right bundle branch block with left axis deviation, concordance of the QRS complexes in the chest leads HR >170 beats per minute.

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  ttt of arrhythmias: Following basic ABC assessment, patients are classified as being stable or unstable according to the presence of any Adverse signs:

•systolic BP < 90 mmHg •reduced conscious level •chest pain •heart failure

If any of the above adverse signs are present then synchronized DC shocks should be given

Treatment following this is given according to whether the QRS complex is narrow or broad and whether the rhythm is regular or irregular.

Broad-complex tachycardia

Regular

•assume ventricular tachycardia (unless previously confirmed SVT with bundle branch block): loading dose of amiodarone followed by 24 hour infusion

Irregular

1. AF with bundle branch block - treat as for narrow complex tachycardia

2. Polymorphic VT (e.g. torsade de pointes) - IV magnesium

3- pre-excited AF give amiodarone

Narrow-complex tachycardia

Regular

•vagal maneuvers followed by IV adenosine 6mg then 12 then 12mg

•if above unsuccessful consider diagnosis of atrial flutter and control rate (e.g. beta-blockers)

Irregular

•probable atrial fibrillation

If onset < 48 hr consider electrical or chemical cardioversion

If >48 rate control (e.g. beta-blocker or digoxin) and anticoagulation

If need urgent electrical cardioversion >> Do TOE 1st to exclude thrombus

INR= 2-3 >>3 week before elective cardioversion and 4 week after elective or urgent one

Chronic ttt of AF: IF age >65 and with Ht failure rate control (BB, Digoxin,verapamil)+/- anticoagulation therapy. Other try rhythm control >> use Class Ic in normal structure HT and Class III for abnormal one