ECG Rhythms
Normal Sinus Rhythm
Looking at the ECG you'll see that:
- Rhythm - Regular
- Rate - (60-99 bpm)
- QRS Duration - Normal
- P Wave - Visible before each QRS complex
- P-R Interval - Normal (<5 small Squares. Anything above and this would be 1st degree block)
^ What you want your patient ECG to look like
Sinus Bradycardia
A heart rate less than 60 beats per minute (BPM). This in a healthy athletic person may be 'normal', but other causes may be due to increased vagal tone from drug abuse, hypoglycaemia and brain injury with increase intracranial pressure (ICP) as examples
Looking at the ECG you'll see that:
Sinus Tachycardia
An excessive heart rate above 100 beats per minute (BPM) which originates from the SA node. Causes include stress, fright, illness and exercise. Not usually a surprise if it is triggered in response to regulatory changes e.g. shock. But if their is no apparent trigger then medications may be required to suppress the rhythm
Looking at the ECG you'll see that:
Supraventricular Tachycardia (SVT) Abnormal
A narrow complex tachycardia or atrial tachycardia which originates in the 'atria' but is not under direct control from the SA node. SVT can occur in all age groups
Looking at the ECG you'll see that:
Atrial Fibrillation
Many sites within the atria are generating their own electrical impulses, leading to irregular conduction of impulses to the ventricles that generate the heartbeat. This irregular rhythm can be felt when palpating a pulse
It may cause no symptoms, but it is often associated with palpitations, fainting, chest pain, or congestive heart failure.
Looking at the ECG you'll see that:
Atrial Flutter
Looking at the ECG you'll see that:
1st Degree AV Block
1st Degree AV block is caused by a conduction delay through the AV node but all electrical signals reach the ventricles. This rarely causes any problems by itself and often trained athletes can be seen to have it. The normal P-R interval is between 0.12s to 0.20s in length, or 3-5 small squares on the ECG.
Looking at the ECG you'll see that:
2nd Degree Block Type 1 (Wenckebach)
Another condition whereby a conduction block of some, but not all atrial beats getting through to the ventricles. There is progressive lengthening of the PR interval and then failure of conduction of an atrial beat, this is seen by a dropped QRS complex.
Looking at the ECG you'll see that:
2nd Degree Block Type 2
When electrical excitation sometimes fails to pass through the A-V node or bundle of His, this intermittent occurance is said to be called second degree heart block. Electrical conduction usually has a constant P-R interval, in the case of type 2 block atrial contractions are not regularly followed by ventricular contraction
Looking at the ECG you'll see that:
3rd Degree Block
3rd degree block or complete heart block occurs when atrial contractions are 'normal' but no electrical conduction is conveyed to the ventricles. The ventricles then generate their own signal through an 'escape mechanism' from a focus somewhere within the ventricle. The ventricular escape beats are usually 'slow'
Looking at the ECG you'll see that:
Bundle Branch Block
Abnormal conduction through the bundle branches will cause a depolarization delay through the ventricular muscle, this delay shows as a widening of the QRS complex. Right Bundle Branch Block (RBBB) indicates problems in the right side of the heart. Whereas Left Bundle Branch Block (LBBB) is an indication of heart disease. If LBBB is present then further interpretation of the ECG cannot be carried out.
Looking at the ECG you'll see that:
Premature Ventricular Complexes
Due to a part of the heart depolarizing earlier than it should
Looking at the ECG you'll see that:
Junctional Rhythms
In junctional rhythm the sinoatrial node does not control the heart's rhythm - this can happen in the case of a block in conduction somewhere along the pathway. When this happens, the heart's atrioventricular node takes over as the pacemaker.
Looking at the ECG you'll see that:
Below - Accelerated Junctional Rhythm
Ventricular Tachycardia (VT) Abnormal
Looking at the ECG you'll see that:
Ventricular Fibrillation (VF) Abnormal
Disorganised electrical signals cause the ventricles to quiver instead of contract in a rhythmic fashion. A patient will be unconscious as blood is not pumped to the brain. Immediate treatment by defibrillation is indicated. This condition may occur during or after a myocardial infarct.
Looking at the ECG you'll see that:
Asystole - Abnormal
A state of no cardiac electrical activity, as such no contractions of the myocardium and no cardiac output or blood flow are present.
Looking at the ECG you'll see that:
Myocardial Infarct (MI)
Looking at the ECG you'll see that: