ECG interpretation and Cardiac Arrhythmias Flashcards
p wave
atrial depolarisation (contraction)
QRS complex
ventricular depolarisation, atrial repolarisation
T wave
ventricular repolarisation (resting phase)
U wave
usually not visible, may indicate hypokalaemia
when is bradycardia normal?
in athletes
during sleep
in response to a vagal manoeuvre
name some causes of brady
Hypoglycaemia Hypothyroidism Previous cardiac history Medications Toxic exposure MI – inferior wall involving right coronary artery
signs and symptoms of brady
Syncope Dizziness Chest pain SoB Exercise intolerance Cool, clammy skin
risk of brady
reduced CO
treatment of Brady
if patient is symptomatic - atropine
if patient is haemodynamically compromised - pacing
causes of tachy
Damage to heart tissues Hypertension Fever Stress Excess alcohol, caffeine, nicotine or recreational drugs such as cocaine Side effect of medications Response to pain Imbalance of electrolytes Hyperthyroidism
signs and symptoms of tachy
Dizziness SoB Light headedness Rapid pulse rate Heart palpitations Chest pain Syncope
risks of tachy
CO may fall due to inadequate ventricular filling time
Myocardial oxygen demand increases
Can cause myocardial ischaemia or infarct
treatment of tachy
aimed at finding cause and treating
what is sinus arrest or pause?
Transient absence of sinus P waves that lasts from 2 seconds to several mins
causes of sinus arrest or pause
May occur in individuals with healthy hearts during sleep Myocarditis Cardiomyopathy MI digoxin toxicity Elderly Vagal stimulation
signs and symptoms of sinus arrest or pause
Syncope
Dizziness
LOC
Bradycardia
risks of sinus arrest or pause
Sudden cardiac death Syncope Fall Thromboembolic events inc stroke CHF Atrial tachyarrhythmias such as atrial flutter or fibrillation
treatment of symptomatic sinus arrest or pause
atropine
pacemaker
causes of atrial flutter
>60 years old Mitral valve disorder Thickening of the heart muscle Ischaemia Cardiomyopathy COPD
signs and symptoms of atrial flutter
Palpitations SOB Anxiety Weakness Angina Syncope
risks of atrial flutter
Clot formation in atria as atria not completely emptying -> stroke, PE
Dramatic drop in cardiac output
treatment of atrial flutter
Cardioversion
Antiarrhythmics such as procainamide
Slow ventricular rate using diltiazem, verapamil, digitalis or B blocker
Heparin to reduce incidene of thrombus formation
causes of atrial fibrillation
Hypoxia Hypertension Congestive heart failure Coronary artery disease Dysfunction of the sinus node Mitral valve disorders Rheumatic heart disease Pericarditis Hyperthyroidism Excessive alcohol or caffeine consumption
signs and symptoms of atrial fibrillation
Heart palpitations Irregular pulse which feels too rapid or too slow, racing, pounding or fluttering Dizziness or light-headedness Fainting Confusion Fatigue Trouble breathing Difficulty breathing when lying down Sensation of tightness in the chest
risks of atrial fibrillation
Clot formation in atria (atria not completely emptying) -> Stroke or PE
Dramatic drop in cardiac output
treatment of atrial fibrillation
Rate control using digoxin, beta-adrenergic blockers, calcium channel blockers
Anti-thrombotic therapy
Chemical or electrical cardioversion
describe ventricular tachy
- All fast arrhythmias in which the HR is greater than 150 bpm
- Usually not a discernible P wave
causes of ventricular tachy
- Stimulants
- Hypoxia
- Stress or over exertion
- Hypokalaemia
- Atherosclerotic disease
signs and symptoms of ventricular tachy
- Palpitations
- Chest discomfort
- Light-headedness or dizziness
- Syncope
- SoB
- Pounding pulse
- Sweating
- Tightness or fullness in the throat
- Tiredness
- Excessive urine production
risk of ventricular tachy
heart failure
treatment of ventricular tachy
- Stable patients = vagal manoeuvres
- Adenosine
- Cardioversion if unstable
what are premature atrial contractions?
- Ectopic beat that originates from the atria
causes of PACs
- Occurs in healthy patients
- Stress
- Stimulants
- Hypertension
- Valvular condition
- Infectious disease
- Hypoxia
signs and symptoms of PACs
palpitations
skipped beat
risks of PACs
- Benign
* May be a sign of underlying heart condition
treatment of PACs
if symptomatic, treat the cause
BBs or CCBs
describe premature ventricular contractions
- Ectopic beat that arises from an irritable site in the ventricles
- Always wide and bizarre compared to a normal beat
causes of PVCs
- Exercise
- Stress
- Caffeine
- Heart disease
- Electrolyte imbalances
- Hypoxia
- Tricyclic antidepressants
- Digitalis toxicity
signs and symptoms of PVCs
- Palpitations
- Weakness
- Dizziness
- Hypotension
risks of PVCs
- Reduced CO
- HF
- May convert to V tach or V fib
treatment of PVCs
- Oxygen
- Treat the cause
- Lidocaine
describe idioventricular rhythm
- Ventricular escape rhythm
- Last attempt by ventricles to prevent cardiac standstill
- Rhythm is slow, no P wave, wide and bizarre QRS
causes of idioventricular rhythm
- Drugs – digitalis
- MI
- Metabolic imbalances
- Hyperkalaemia
- Cardiomyopathy
signs and symptoms of idioventricular rhythm
- Pale
- Cool with mottled skin
- Weakness
- Dizziness
- Hypotension
- Alteration in mental status
risks of idioventircular rhythm
- Usually a terminal event occurring before ventricular standstill
- Death – cardiac arrest
treatment of idioventricular rhythm
- Atropine
- Pacing
- Dopamine when hypotensive
- CPR
what is accelerated idioventricular rhythm?
exactly the same except the rate is 41-100bpm
describe agonal rhythm
- Idioventricular rhythm is 20 beats or less per minute
- Last ordered semblance of a heart rhythm when resus efforts are unsuccessful
- no P waves
causes of an agonal rhythm
- Trauma
- Acute MI
- Natural progression to death
describe ventricular fibrillation
- Coarse and fine
- No coordinated atrial or ventricular contraction
why does ventricular fibrillation occur?
can be deterioration from ventricular tachy
as a result of multiple weak ectopic foci in the ventricles
causes of ventricular fibrillation
- AMI
- Untreated VT
- Electrolyte imbalance
- Hypothermia
- Myocardial ischaemia
- Drug toxicity or overdose
- Trauma
signs and symptoms of ventricular tachy
- Loss of consciousness
* Absent pulse
causes of torsades de pointes
- Assoc with prolonged QT interval
- Often caused by drugs recommended for VT
- Phenothiazine or tricyclic antidepressant overdose
- Electrolyte disturbances, especially hypokalaemia and hypomagnesemia
signs and symptoms of torsades de pointes
- Chest pain
- Loss of consciousness
- Dizziness
- Nausea
- SoB
treatment of torsades de pointes
- CPR
- Eliminate predisposing factors
- Magnesium sulfate bolus
- Synchronised cardioversion when the patient is unstable if possible or defibrillate
causes of asystole
- Extensive myocardial damage, secondary to MI
- Failure of pacemakers
- Cardiac tamponade
- Prolonged V fib
- PE
signs and symptoms of asystole
- No palpable pulse
- No measurable BP
- Loss of consciousness
causes of pulseless electrical activity
Hs and Ts
signs and symptoms of PEA
- Pulselessness
- Loss of consciousness
- No palpable BP
