Physiological Tests and Laboratory Data:
Electrical activity of heart is recorded.
Used for detection of cardiac arrhythmias, conduction defects and to help diagnose myocardial hypertrophy, ischaemia and infarction.
Components of EKG wave pattern:
P = atrial depolarisation; QRS = ventricle depolarisation; T = ventricle repolarisation
PR interval – from beginning of P wave to the beginning of QRS complex; if longer than normal heart block; if shorter Wolf-Parkinson-White syndrome
ORS interval – from beginning of Q wave to end of S wave
Q wave – appears or enlarges in myocardial infarction
ST segment – from end of QRS complex and beginning of T wave; increased in myocardial infarction
T wave – if inverted ischaemia; if elevated hyperkalaemia
U wave – occasionally seen following T waves
Noninvasively uses ultrasound to visualise heart, blood flow and movement of valves.
Chest x-ray size of heart, calcification of arteries
Catheter inserted into artery or vein and advanced to heart – used to measure intracardiac pressures, takes samples and inject contrast media.
Indicated for coronary artery disease, valve disease, congenital heart disease, cardiomyopathy, endomyocardial biopsy