# What are normal ECG intervals?

## What are normal ECG intervals?

PR interval: 120-200 milliseconds. PR segment: 50-120 milliseconds. QRS complex: 80-100 milliseconds. ST segment: 80-120 milliseconds.

### What are the normal ECG deflection waves and intervals?

Normal range is 120 – 200 ms (3 to 5 1-mm-divisions) and no longer. The QT interval is measured from the beginning of the QRS to the end of the T wave. It represents the time in which the ventricles depolarize and repolarize and is a measure of ventricular action potential (AP) duration.

#### What are ECG waveforms?

Waveforms. These are representations of electrical activity created by depolarization and repolarization of the atria and ventricles. If the electrical current is flowing towards the lead then a positive deflection will be seen. If flowing away from lead then a negative deflection will be seen.

What does QT interval represent?

The Q-T interval is the section on the electrocardiogram (ECG) – that represents the time it takes for the electrical system to fire an impulse through the ventricles and then recharge. It is translated to the time it takes for the heart muscle to contract and then recover.

What are the positive waveforms in a standard ECG?

T and U waves The T wave represents ventricular repolarization. Generally, the T wave exhibits a positive deflection. The reason for this is that the last cells to depolarize in the ventricles are the first to repolarize.

## What is the normal waveform for the subclavian artery?

The usual average PSV values in the adult subclavian artery, axillary artery, and brachial artery are 105 cm/sec, 80 cm/sec, and 60 cm/sec, respectively (,10). In our experience, lower velocities are seen in children.

### What is multiphasic waveform?

Multiphasic waveforms cross the zero-flow baseline and contain both forward and reverse velocity components. Monophasic waveforms do not cross the zero-flow baseline and reflect blood which flows in a single direction for the duration of the cardiac cycle.

#### What does a normal ECG indicate?

Summary An electrocardiogram (ECG) is a medical test that detects heart problems by measuring the electrical activity generated by the heart as it contracts. ECGs from healthy hearts have a characteristic shape. If the ECG shows a different shape it could suggest a heart problem.

What is the normal speed of an ECG?

The ECG paper speed is ordinarily 25 mm/sec. As a result, each 1 mm (small) horizontal box corresponds to 0.04 second (40 ms), with heavier lines forming larger boxes that include five small boxes and hence represent 0.20 sec (200 ms) intervals. On occasion, the paper speed is increased to 50 mm/sec to better define waveforms.

What does a normal ECG look like?

An ECG detects your heart’s electrical rhythm and produces what’s known as a tracing, which looks like squiggly lines. This tracing consists of representations of several waves that recur with each heartbeat, about 60 to 100 times per minute. The wave pattern should have a consistent shape.

## What are normal variants on an ECG?

Reading a Young Person’s ECG – Top 5 Tips. This is a common normal variant on the resting ECG of young people, Also, in the young, T waves are normally inverted in V1 and V2 (the ‘juvenile T wave pattern’). Complete RBBB (qrs duration > 0.12s) is also common in the young in the absence of heart disease.