KNOWLEDGE ABOUT ECG

ECG interpretation

Following cardiothoracic surgical procedures patients may display a variety of cardiac rhythms. It is essential that the bedside nurse can identify and distinguish between non-life threatening and life threatening rhythms. Normal sinus rhythm offers distinct clinical advantage and consequently postoperative management includes strategies for maintaining and/or returning patients to sinus rhythm. Normal sinus rhythm contributes to optimal atrial emptying and ventricular filling, enhancing myocardial function. Patients are routinely monitored for the first 48 hours to detect cardiac rhythm abnormalities.

ECG characteristics

· Atrial rhythm : regular

· Ventricular rhythm : regular

· Atrial rate : 60 - 100 beats / minute

· Ventricular rate : 60 - 100 beats / minute

· P wave : precedes each QRS complex

· PR interval : normal - constant at 0.12 to0.2 seconds

· QRS complex : duration and configuration usually normal

Sinus bradycardia

ECG characteristics

· Atrial rhythm : regular

· Ventricular rhythm : regular

· Atrial rate : less than 60 beats / minute

· Ventricular rate : less than 60 beats / minute

· P wave : precedes each QRS complex

· PR interval : normal - constant at 0.12 to0.2 seconds

· QRS complex : duration and configuration usually normal

Possible causes

· Medication -Digoxin, Beta- blockers, Morphine, Anticholinesterase.

· Increased vagal tone caused by ;- Myocardial infarction

Straining on defecation

Vomiting

Intubation, mechanical ventilation

· Hypothyroidism

· Increased intracranial pressure

· Sick sinus syndrome

· Carotid massage

· May be normal in athletes

Treatment

· Possibly nil if asymptomatic.

· Medication (Atropine, Isuprel, Adrenaline)

· Pacemaker

Junctional rhythm

ECG characteristics

· Atrial rhythm : regular

· Ventricular rhythm : regular

· Atrial rate : 40 to 60 beats / minute

· Ventricular rate : 40 to 60 beats / minute

· P wave : usually inverted , may be upright ,

May precede or is hidden in QRS complex -

Possible causes

· Cardiac surgery

· Myocardial ischaemia

· Valvular disease

· Inferior wall infarction / ischaemia

· Drug toxicity - Digoxin, Verapamil, and Anticholinesterase

· Rheumatic heart disease

· Increased vagal tone

· Organic disease of the sinus node - sick sinus syndrome , S.A. node ischaemia

Treatment

· Usually no treatment is required

· Treat cause if required

· If symptomatic - Atropine

Isuprel

Pacemaker - Transthoracic

Transvenous