The conduction system of the heart
- Sinoatrial node
- SA node, sinus node
- The “pacemaker”
- Located in the right atrium
- Specialized cells that generate the electrical impulse which travels through the heart causing it to beat.
- The normal rate at which the SA node will fire is between 60 and 100 times per minute.
- Normal sinus rhythm is between 60 and 100 bpm
- Atrioventricular node
- AV node
- Electrically connects the atria with the ventricles.
- The AV node will fire 40–60 times per minute if not acted upon by an external stimulant.
- Ventricular rhythm is between 40 and 60 bpm
- Abnormal heart rhythm
- Often the result of an abnormal impulse or impulses
- Theses abnormal impulses may be generated anywhere in the heart
- Poor conduction of normal impulses through the heart may also cause an arrhythmia
- MI is a major cause of arrhythmias. Electricity is conducted through the path of least resistance. If heart tissue is damaged the conductive activity of that tissue changes.
- The impulse originates above the AV node.
- The QRS complex will be narrow.
- Brady = slow
- Less than 60 beats per minute
- Normal P waves
- Narrow QRS
- Tachy = fast
- Greater than 100 bpm
- Normal p waves
- Narrow QRS
Paroxysmal supraventricular tachycardia (PSVT)
- Above the ventricles = Narrow QRS
- Above 100 bpm, usually 150–250
- Like a spams or seizure
- A spasm of supraventricular tachycardia
- Quick onset and may stop abruptly on its own.
- Can be a short circuit in the near the AV node that causes the electrical impulse to go through a reentrant loop and propagate itself.
- Palpitations - Dizzyness - Chest discomfort
- Narrow QRS with a rate between 150-250 and the p waves usually get lost in the fast QRS - P wave may be abnormal but are usually buried in the QRS complex
- Vagal nerve stimulation
- The vagus nerve signals the SA node to slow down
- The vagus nerve slows conduction through the AV node
- Carotid massage
- Patient lying down
- Right side first
- Listen for bruits first
- Gentle pressure of over the carotid artery at the angle of the jaw for 10–15 seconds
Getting a job in surgery with no experience.