ECG

The SA node, the heart's natural pacemaker, typically fires at a rate of 60-100 beats per minute (bpm). Vagus nerve activity can decrease this rate.

The P wave on an electrocardiogram (ECG) represents atrial depolarization (the atria contracting).

The PR interval on an ECG measures the time it takes for the electrical signal to travel from the atria to the ventricles. Normal ranges are 0.12-0.20 seconds.

The QRS complex on an ECG represents ventricular depolarization - the ventricles contracting.

ECG time is measured in seconds. One small square represents 0.04 seconds, five small squares equal 1 large square, and five large squares equal one second.

A heart condition where the electrical signal is delayed in the right ventricle, causing a wider QRS complex (over 0.12 seconds) and characteristic changes in the ECG.

A rapid heart rhythm originating in the ventricles, characterized by a rate of 100-120 bpm, regular rhythm, wide QRS complexes, and no clear P waves.

A rapid heart rhythm originating in the ventricles, similar to 'Tombstone' VT but with distinct QRS complexes resembling a picket fence pattern.

A life-threatening type of ventricular tachycardia with a characteristic twisting or spinning pattern on the ECG, rate of 200-250 bpm, irregular rhythm, and wide QRS complexes.

A life-threatening condition where the heart's electrical activity is chaotic, leading to ineffective contractions. On the ECG, there are erratic, wide, and indistinguishable QRS complexes.

Similar to coarse VF, but with slightly less chaotic activity, still ineffective heart contractions and wide QRS complexes.

Similar to coarse and medium VF, but with even less chaotic activity, still ineffective heart contractions and wide QRS complexes.

A slow heart rhythm originating in the ventricles, with a rate of 20-40 bpm, regular rhythm, wide QRS complexes, and no clear P waves.

A heart rhythm that originates in the sinoatrial (SA) node and has a rate of 60-100 beats per minute (bpm), regular rhythm, normal P waves, consistent 1:1 P:QRS ratio, normal PR interval, and normal QRS width.

A heart rhythm that originates in the SA node but has a rate greater than 100 bpm, regular rhythm, normal P waves, consistent 1:1 P:QRS ratio, slightly prolonged PR interval, and slightly prolonged QRS width.

A heart rhythm that originates in the SA node but has a rate less than 60 bpm. It maintains a regular rhythm, normal P waves, consistent 1:1 P:QRS ratio, slightly prolonged PR interval, and slightly prolonged QRS width.

A heart rhythm where the SA node temporarily stops firing, resulting in a pause in the electrical activity. The rate is variable, rhythm is irregular, P waves are present except during pauses, 1:1 P:QRS ratio, normal PR interval, and normal QRS width.

A heart rhythm disorder characterized by rapid and irregular atrial contractions. The ventricular rate is variable, the rhythm is irregularly irregular, no discernable P waves, no P:QRS ratio, no measurable PR interval and normal QRS width.

A heart rhythm originating above the ventricles, usually in the atria. The rate is faster than 100 bpm, rhythm is regular, P waves are normal but often obscured by the preceding T wave, 1:1 P:QRS ratio (if P wave is visible), variable PR interval and QRS width.

A heart rhythm where the electrical signal from the atria is delayed before reaching the ventricles. The rate is dependent on the underlying rhythm, the rhythm is regular, normal P waves, 1:1 P:QRS ratio, prolonged PR interval (greater than 0.20 seconds), and normal QRS width.

A heart rhythm where the electrical signal from the atria is progressively delayed until it fails to reach the ventricles. The rate is dependent on the underlying rhythm, irregularly irregular rhythm, normal P waves, variable P:QRS ratio (e.g., 3:2, 4:3, or 5:4), variable PR intervals, and normal QRS width.

A premature ventricular contraction (PVC) originating from a single ectopic focus in the ventricle. All PVCs have the same appearance on the ECG.

A PVC that originates from multiple ectopic foci in the ventricles. The ECG will show different shapes for each PVC.

A PVC pattern where every other heartbeat is a PVC. The ECG will alternate between normal beats and PVCs.

A PVC pattern where every third heartbeat is a PVC.

A PVC pattern where every fourth heartbeat is a PVC.

Two consecutive premature ventricular contractions (PVCs) occurring together.

A downward deflection of the ST segment on the ECG, usually associated with myocardial ischemia (lack of blood flow to the heart muscle).

An upward deflection of the ST segment on the ECG, usually associated with a heart attack (myocardial infarction).

The heart rate of a newborn baby is significantly faster than an adult's due to the smaller heart's reliance on heart rate to maintain blood flow.

As a child grows, their heart rate gradually slows down. This is because their heart gets bigger and stronger, allowing it to pump more blood with each beat.

The QT interval, which measures the time it takes for the ventricles to repolarize, is influenced by heart rate. In children, the faster heart rate leads to a longer QT interval.

The electrical signals recorded on an ECG are generally smaller in newborns due to their smaller heart size.

The PR interval, which measures the time it takes for the electrical signal to travel from the atria to the ventricles, is shorter in newborns and gradually increases as they grow.

The QRS duration, representing ventricular contraction, is shorter in newborns and lengthens as the heart grows larger.

In adults, the left ventricle is larger and dominates the electrical activity. In children, the right ventricle is relatively larger, especially in newborns, and gradually decreases in size as they age.

The appearance of an ECG changes as a child grows due to the increasing size of the heart and changes in electrical activity.