Waves and Segments ECG practice flashcards

Comprehensive vocabulary-style flashcards covering the physiology, normal ranges, and clinical abnormalities of ECG waves and segments as described in the lecture notes.

P wave Physiology

The phase of the ECG representing atrial depolarisation.

Normal Sinus Rhythm P wave Orientation

P waves are upright in lead 2 and inverted in lead aVR, sharing the same shape.

Right Atrial Enlargement (ECG sign)

Indicated by P waves greater than $2.5\,mm$.

Left Atrial Enlargement (ECG sign)

Indicated when P waves are split into two distinct peaks.

Heart Block (P wave observation)

Occurs when a P wave is not followed by a QRS complex.

Atrial Enlargement

A condition where the left or right upper chamber of the heart grows larger than normal because the heart works too hard to move blood.

PR Interval

The interval from the start of the P wave to the start of the QRS complex, regardless of whether the QRS starts with an R or Q.

PR Interval Physiology

Continuation of atrial depolarisation and contraction; the AV node delays the electrical signal here to allow the atrium to stop contracting before the signal passes to the ventricles.

Normal PR Interval Range

$120-200\text{ miller seconds}$ or $3-5\text{ small squares}$.

AV Heart Block (PR sign)

Indicated by a prolonged PR interval greater than $1\text{ big square}$.

Pre-excitation syndrome (WPW)

A condition indicated by a short PR interval of less than $3\text{ small squares}$, where the AV node does not delay the electrical impulse.

ST Segment

The portion of the ECG from the end of the QRS to the start of the T wave, which normally has no electrical activity.

Normal ST Segment Characteristics

The shape concaves up and is on the same horizontal line as the T-P segment.

Potential Causes of ST Changes

Ischaemia (elevation or depression), Pericarditis, LBBB, or Aneurism.

T Wave Physiology

Represents ventricular repolarisation.

Normal T Wave Orientation

Most are upright; V1 and aVR are usually inverted, while V2 and leads 2, 3, and aVF can sometimes be inverted.

Hyper acute T waves

Tall T waves that can be early signs of MI or indicate Hyperkalaemia.

QT Interval

The interval from the start of the QRS complex to the end of the T wave, representing ventricular depolarisation and repolarisation.

QT Interval Heart Rate Relationship

A faster heart rate resulting in a shorter QT interval, and a slower heart rate resulting in a longer QT interval.

Prolonged QT Interval (Men)

A QT interval duration over $440\text{ miller seconds}$.

Prolonged QT Interval (Women)

A QT interval duration over $460\text{ miller seconds}$.

Torsades de Pointes VT Risk

Associated with a QT interval measurement over $500\text{ miller seconds}$.