ECG Case 063
Elderly patient presenting with reduced level of consciousness, hypothermia and hypotension refractory to inotropes. Describe and interpret his ECG
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
Overview
The most striking abnormality on this ECG is extremely low QRS voltage, in this case due to severe myxoedema.
Definition
The QRS is said to be low voltage when:
- The amplitudes of all the QRS complexes in the limb leads are < 5 mm; OR
- The amplitudes of all the QRS complexes in the precordial leads are < 10 mm
Mechanisms
Low voltage is produced by…
- The “damping” effect of increased layers of fluid, fat or air between the heart and the recording electrode.
- Loss of viable myocardium.
- Diffuse infiltration or myxoedematous involvement of the heart.
Causes
Specific causes of low voltage include:
- Fluid: Pericardial effusion; Pleural effusion
- Fat: Obesity
- Air: Emphysema; Pneumothorax
- Infiltrative / Connective Tissue Disorders: Myxoedema; infiltrative myocardial diseases — i.e. restrictive cardiomyopathy due to amyloidosis, sarcoidosis, haemochromatosis; constrictive pericarditis; and scleroderma.
- Loss of viable myocardium: Previous massive MI; end-stage dilated cardiomyopathy
Most important cause:
Massive pericardial effusion with triad of:
- Low voltage
- Tachycardia
- Electrical alternans
Patients with this triad need to be immediately assessed for clinical or echocardiographic evidence of tamponade.
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Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |