Bradycardia Flashcards
what problems do you think about when you see a patient with bradycardia
- sinus bradycardia
- sinoatrial node dysfunction
- atrioventricular block
- junctional and ventricular escape rhythms
- asystole
What are symptoms associated with bradycardia
- Dizziness
- Syncope
- Falls
- Fatigue
- Shortness of breath
- Chest pain
- Palpitations.
if the heart rate is very slo the patients may have signs of..
haemodynamic instability such as:
- low blood pressure
- cold extremities
- peripheral cyanosis
What are the features of sinus bradycardia
- The heart rate is less than 60 beats per minute
- The rhythm is regular
- Each P wave is followed by a QRS complex
- The P wave is positive (upright) in lead II and negative (inverted) in lead aVR
- The PR interval is normal and constant.
what are the physiological causes of sinus bradycardia
- Trained athletes
- During sleep
- With drugs (for example, beta blockers and digoxin)
- During vomiting
What are the pathological causes of sinus bradycardia
- sinoatrial node disease
- ischaemia heart disease and myocardial infarction
- hypoxia
- hypothyroidism
- hypothermia
- electrolyte imbalance
- obstructive jaundice
- uraemia
- raised intracranial pressure
- sick sinus syndrome
define persistent bradycardia
Sinus node disease when symptomatic or not reversible
Acquired atrioventricular block when not reversible, or when third or type II second degree AV block is present, or when type I second degree AV block is present with symptoms
Define intermittent bradycardia
- Sinus node disease with documented symptoms; including tachy-brady form
- Intermittent or paroxysmal atrioventricular block
- Reflex asystolic syncope
- Asymptomatic pauses due to sinus arrest or atrioventricular block.
what is the cause of sinoatrial node dysfunction
- most commonly occurs in older patients and is a form of degernative heart disease
What is the clinical significance of sinoatrial node dysfunction
- Sinus arrest often does not cause symptoms as the lower subsidiary pacemakers take over. This form of sinoatrial disease carries a benign prognosis and no specific treatment is needed.
- You must be careful when treating these patients with drugs that impair cardiac conduction, such as beta blockers. Sub-clinical SA node disease may be diagnosed for the first time when patients are treated with drugs such as beta blockers
- Pacemaker may be indicated
what are the three degrees of severity of atrioventricular block
- First degree atrioventricular block: the PR interval is lengthened
Second degree - some impulses from the atria are no conducted to the ventricles
- type I: the PR interval progressively prolonged until there is a dropped QRS complex
- Type 2: The PR interval is normal and does not progressively lengthen, there is an intermittent loss of the QRS complex after some P waves
Third degree - no impulses at all are conducted from the atria to the ventricles
What are the common causes of atrioventricular block
- age degeneration of the conduction fibres of the heart
what are the causes of type 1 second degree heart block
- occurs at night in people with high vagal tone
- if it occurs during the day it can indicate degenerative disease
What are the causes of second degree type II heart block
- pathological
- most commonly caused by degeneration through ageing
- can occur in an inferior MI
- infiltrative diseases such as sarcoidosis or amyloidosis
- severe calcific aortic stenosis is associated with ectopic calcification within the cardiac septum
What is the cause of third degree heart block
- pathological
- most common caused by degeneration through ageing
- acute inferior MI
- diabetes
- infiltrative diseases such as sarcoidosis or amyloidosis
- severe calcific aortic stenosis is associated with ectopic calcification within the cardiac septum and bundle branch block and heart block
