Table 1.

ECG features and the normal values for a healthy adult.

Features	Description	Amplitude	Duration	Disease Diagnosis	References
R-R interval	The interval between two successive R-waves of the QRS complex ventricular rate		0.6–1.2 s	Paroxysmal atrial fibrillation Congestive heart failure	[45,46]
P wave	Atrial depolarization	0.25 mV	0.08–0.11 s	Atrial fibrillation Atrial hypertrophy	[47]
P-R interval	The time between the onset of atrial depolarization and the onset of ventricular depolarization		0.12–0.2 s	Stroke	[41]
QRS complex	Ventricular depolarization	1.60 mV for R peak	0.06–0.1 s	Ventricular enlargement Heart failure Tachycardia Acute Coronary Syndrome	[48,49,50]
ST-segment	The interval between ventricular depolarization and repolarization		0.05–0.155 s	Myocardial ischemia or infarction	[51]
T wave	Ventricular repolarization	0.1–0.8 mV	0.05–0.25 s	Myocardial infarction Pulmonary embolism	[46,52,53]
U wave	The last phase of ventricular repolarization	May not be observed because of its small size	Unknown	Unknown	[44]
QT interval	The time is taken for ventricular depolarisation and repolarisation		0.35–0.44 s	Hypokalemia ventricular arrhythmias	[54]