Cardiology Part 2 Flashcards
What are the 4 cardiac arrest rhythms?
- Ventricular fibrillation
- Ventricular tachycardia (pulseless)
- PEA
- Asystole
Explain what a sinus arrhythmia is? Is it normal?
- Normal sinus arrhythmia – slight variations in heart rate due to reflex changes in vagal tone during the respiratory cycle
Describe sinus bradycardia?
- Sinus bradycardia – heart rate less than 60bpm, can be physiological, caused by drugs or ischaemia, if acute it can be treated with atropine, if chronic and causing haemodynamic compromise will need pacing
Describe sinus tachycardia?
- Sinus tachycardia – heart rate more than 100bpm, could be due to anxiety, fever, hypotension, anaemia or drugs, should treat underlying cause and if persistent use beta blockers
Explain what atrial flutter is?
- This is a re-entrant rhythm where electrical signal re-circulates itself stimulating atrial contraction at 300bpm, usually every second beat is passed to the ventricles so most often there is a ventricular rate of 150 bpm
Sawtooth appearance on ECG with P wave after p wave
Atrial flutter
Conditions associated with atrial flutter?
- It is associated with hypertension, ischaemic heart disease, cardiomyopathy and hyperthyroidism
Management of atrial flutter?
- Management is similar to AF but can also do radiofrequency ablation of the re-entrant rhythm
Explain what is meant by a SVT?
- Technically encompasses any arrhythmia originating above the ventricles but generally atrial fibrillation and atrial flutter are considered as separate
- SVTs usually occur due to there being some form of perpetuating electrical signal loop with no end point
What happens with AVRNT?
Atrioventricular Nodal re-entrant tachycardia (AVNRT)
* This happens when there are 2 pathways in the AV node- a slow and fast pathway
Explain what happens with AVRT?
- This is due to accessory pathways between the atria and the ventricles
- It is most often caused by a condition called Wolf Parkinson White Syndrome, and in this syndrome the patient has an extra pathway called “The Bundle of Kent”
- WPW can be asymptomatic and the person may not experience tachycardia
Characteristic WPW ECG pattern?
- Characteristic ECG patter of WPW is slurred part of the QRS called a delta wave
Management of a SVT (AVRT and AVNRT)
- First vagal manoeuvres
- Next adenosine (depresses SA and AV node)
- If these not worked, try verapamil or a beta blocker
- Last resort would be synchronised DC cardioversion
Explain what vagal manoeuvres are and describe some examples?
Vagal manoeuvres stimulate the vagus nerve increasing parasympathetic activity which can slow conduction of electrical activity in the heart potentially terminating a SVT
3 examples are:
1. Valsava manoeuvres – these increase intrathoracic pressure e.g. blowing into 10ml syringe for 10-15 seconds, other versions involves popping ears, holding breath and bearing down (appears to be several versions)
2. Carotid sinus massage – attempt to stimulate baroreceptors in the carotid sinus by massaging that area on one side of the neck at a time (avoid in patients with carotid artery stenosis, carotid bruits or previous stroke/ TIA)
3. Diving reflex involves submerging that patient’s face in cold water
What is torsades de pointes?
- Torsades de Pointes is a form of polymorphic VT that occurs in patients with a long QT interval
- Normal VT is monomorphic – all the waves look the same
Define the QT interval?
- QT interval = start of QRS complex to the end of the T wave
When is QT interval prolonged?
- QT interval is prolonged if it is more than 440 ms (11 boxes) in men or 460 ms in women (11.5 boxes)
Causes of long QT interval?
- Causes of prolonged QT include inherited long QT syndrome, medications such as antipsychotics, citalopram, flecanide, sotalol, amiodarone and macrolide antibiotics and electrolyte imbalances such as hypokalaemia, hypomagnesaemia and hypocalcaemia
Management of long QT?
- Management of long QT involves stopping/ avoiding medications that prolong QT interval, correcting any electrolyte abnormalities, beta blockers and potentially pacemakers or implantable cardioverter defibs
- If you have long QT syndrome generally advised to avoid strenuous exercise, swimming should be avoided, stressful situations, startling noises e.g. alarm clocks
Management of torsades de pointes?
- Management of torsades de pointes includes correcting any underlying cause e.g. electrolyte disturbance or medications, magnesium infusion (even if serum magnesium is normal), defibrillation
Explain what ventricular ectopics are?
- These are premature ventricular beats caused by random electrical discharges from outside the atria
- Causes complaints of random brief palpitations and feelings of extra, missed or heavy beats
- Common in all ages and can occur in normal healthy individuals
- Can occur however due to a pre-existing heart conditions
What is bigeminy?
- Bigeminy refers to when every other beat is a ventricular ectopic – ECG shows a normal beat (with a P wave, QRS and T wave) followed immediately by an ectopic beat, then a normal beat, then an ectopic and so on
- Can also get trigeminy and quadrigeminy
Management of ventricular ectopics?
- Reassurance an no treatment in otherwise healthy people with infrequent ectopics
- Seeking specialist advice in patients with underlying heart disease, frequent or concerning symptoms (e.g. chest pain or syncope) or a family history of heart disease/ sudden death
- Beta blockers are sometimes used to manage symptoms
First degree heart block define, causes management?
- This occurs when there is delayed conduction through the AV node
- However, every atrial impulse leads to a ventricular contraction
- Can be defined as a PR interval greater than 0.2 seconds (5 small or 1 big square)
- Causes include ageing, damage from MI or surgery, hypothyroidism, electrolyte abnormalities, systemic disease e.g. sarcoidosis
- Generally, doesn’t cause any symptoms and generally does not require any treatment
Second degree heart block, define, causes, management?
- Causes of second degree heart block include coronary heart disease, cardiomyopathy, congenital heart disease, or as a result of ageing, electrolyte imbalances and some medicines
- Mobitz type 1: progressive lengthening of PR interval until a beat is dropped
- Mobitz type 2: PR interval is constant but every nth beat is dropped
- In Mobitz type 1 no treatment is generally needed, body generally copes well and are often asymptomatic
- In Mobitz type 2 this can be symptomatic and it is likely that the patient will need a pacemaker
Mobitz type 1?
- Mobitz type 1: progressive lengthening of PR interval until a beat is dropped
Mobitz type 2?
- Mobitz type 2: PR interval is constant but every nth beat is dropped
Does Mobitz type 1 or type 2 need treatment?
mobitz type 2 needs treatment - usually a pacemaker
mobitz type 1 does not need treatment
Third degree/ complete heart block, define, causes management?
- Causes of complete heart block include coronary heart disease, cardiomyopathy, congenital heart disease, or as a result of ageing, electrolyte imbalances and some medicines
- No action potentials from the SA node get through to the AV node
- There is no observable relationship between p waves and QRS complexes
- There is a significant risk of asystole – need a pacemaker
Explain what endocarditis is?
- Infective Endocarditis is infection of the endocardium (generally the heart valves), it usually arises due to bacteria in the blood stream and abnormal cardiac endothelium that facilitates their adherence and growth
- Bacteria can form vegetations on the valve after initial endothelial damage makes the valves susceptible to bacteria sticking to them
Explain what valves are affected in endocarditis?
- Most endocarditis is left sided due to the relatively higher pressures on the left side of the heart that produces more turbulent flow across the valves predisposing them to this damage
- Tricuspid valve endocarditis is usually due to drug use as the infective organism comes from the skin into the veins which first travel to the right side of the heart (should note that although right sided disease is most commonly due to drug users, it is still more common that drug users will have left sided disease)
Risk factors for endocarditis?
Anything that either predisposes you to more damage or predisposes you to infection essentially:
* Having a prosthetic valve
* Any form of structural heart pathology e.g. valvular heart disease, HOCM, congenital heart disease, implantable devices e.g. pacemaker
* Rheumatic heart disease
* IV drug use
Organisms involved in endocarditis?
- Most common cause is Staph Aureus – particularly common as an acute presentations and in IV drug users (as inject from the skin into the bloodstream)
- Strep viridans is another common cause – it is found in the mouth – endocarditis of this type would usually be related to dental disease or a dental procedure
- Staph epidermis may be the organism involved in prosthetic heart disease
- Enterococcus faecalis or strep gallolyticus – from the gut – can be related to disease, surgical procedure or malignancy (especially SG)
What criteria can be used for diagnosing endocarditis?
modified dukes criteria