Cardiology Flashcards
Which coronary artery supplies the anterior septum and anterior left ventricular wall?
Left anterior descending
Which coronary artery supplies the marginal branches of the left atrium and ventricle?
Left circumflex artery
Which coronary artery supplies the right atrium and ventricle?
Right coronary artery
Which coronary artery supplies the posterior septum and the posterior right ventricular wall?
Right posterior descending
Which coronary artery supplies the sinus and AV nodes?
Usually a branch of the RCA but can be left too
How should CHD be investigated?
- Exercise tolerance test
- Metabolic perfusion scan
- Stress echo
- PET
- Echogardiogram (USS)
- Cardiac CT
- Angiography (used to determine management)
- Nuclear imaging
How is stable angina managed?
Antiplatelets - 75mg aspirin daily
Nitrates - GTN spray PRN (can become tolerant)
Either:
- Beta-blockers - atenolol, bisoprolol
- Calcium channel blockers - nifedipine, viramipril (unless used in combo with b-blocker, then give amlodipine or MR nifedipine
Lipid lowering - statins
ACE inhibitors - ramipril
What is ACS?
- Unstable angina
- STEMI
- NSTEMI
All 3 involve chest pain at rest or pain not going away - due to atherosclerosis and stenosis of the coronary arteries
Describe how investigations differ in different subtypes of ACS
Unstable angina - ECG changes, normal troponin
NSTEMI - ST depression, T wave inversion, raised troponin
STEMI - ST elevation, new LBBB, raised troponin
How should ACS be managed?
Morphine ONLY if severe pain (+ antiemetic)
Oxygen (maintain >94%)
Nitrates (GTN spray or IV)
Aspirin (300mg)
Ticagrelor (clopidogrel if high bleed risk or prasugrel if for PCI)
+ Fondaparinux if not having PCI
FOR STEMI or high risk NSTEMI:
- If within 12 hours of symptom onset and PCI can be delivered within 2 hours > PCI (+ prasugrel or clopi if on anticoag).
Give unfractionated heparin with GPI during PCI
Can also consider if after 12h with ongoing ischaemia on ECG
- If within 12 hours of symptom onset and PCI CANNOT be delivered within 2 hours > fibrinolysis with alteplase (+ ticagrelor). If ECG 90 minutes post fibrinolysis does not show resolution, should be transferred to cardiac centre for PCI
What does PCI involve?
Catheter in radial artery is used to place a stent in the coronary arteries in order to open them up.
Uses x-ray to visualise stent.
What is the long term medication for a patient who has had an MI?
5 drugs unless contraindicated:
1. Statin
2. ACE inhibitor (BP)
3. B-blocker (cardioprotective)
4. Aspirin (for life!)
5. Ticagrelor/prasugrel/clopidogrel (12 months)
Those with acute MI + LVSF should also start an aldosterone antagonist eg. eplrenone within 3-14 days post MI
Also recommend healthy diet, light exercise
Can have sex 4/52 after uncomplicated MI (no sildenafil until 6 months)
What is the treatment for a patient who has angina which doesn’t respond to treatment, and is not suitable for angioplasty?
Coronary artery bypass graft - usually reserved for 3 vessels or more
Uses saphenous and mammary veins.
Less used now as longer recovery time, increased stroke risk despite decreased anginal symptoms
How is a STEMI diagnosed?
ECG changes in 2 contiguous leads:
- 2mm ST elevation in chest leads (1.5mm in women)
- 1mm ST elevation in limb leads
- new LBBB
Which leads represent the LAD?
V1-4 (chest)
Which leads represent the RCA (inferior MI)
II, III, aVf
Which leads represent the LCA (lateral)
I, aVL, V5, V6
What can cause ST elevation?
LBBB, MI, pericarditis, coronary spasm
What can cause ST depression?
Digoxin, myocardial ischaemia, hypokalemia, hypothermia, stroke
Which patients may have an atypical presentation of MI?
- Women
- Diabetics (silent MI)
How is troponin used in MI diagnosis?
Take troponin at admission, 6 hours and 24 hours (peak). Levels vary between trusts but are generally above the 99th gentile (>30ng)
Levels decrease to baseline over 5-14 days.
What are the three types of troponin?
Troponin C - skeletal muscle
Troponin I - cardiac muscle
Troponin T - cardiac muscle (most sensitive, used in UK)
What can cause a raised troponin?
~~~
Cardiac (MI, heart failure)
Trauma
Renal failure
Surgery
Inflammatory states
PE
Sepsis
Burns
Rhadbomyolysis
Drug toxicity
Can also use CK, myoglobin if troponin not helpful
What is prinzmetal angina?
Chest pain due to coronary artery spasm, can occur in absence of atherosclerosis.Precipitated by emotional states, cold, drugs, smoking
Pain at rest, shows ST elevation
Give CCBs and GTN (aspirin can aggravate!!)
Which ECG changes occur in acute MI?
ST elevation, tall T waves, LBBB
Which ECG changes occur a few days after MI?
T wave inversion
Pathological Q wave (think longer and over 25% size of the R wave)
What is a GRACE score?
A score system to risk stratify patients with diagnosed ACS to estimate in-hospital admission and 6 month to 3 year mortality - it is also used to decide whether to undergo PCI vs conservative
Looks at:
- age
- HR/BP
- cardiac and renal function
- cardiac arrest on presentation
- ECG findings
- troponin levels
If risk >3% (intermediate), consider PCI within 72h
What are the complications of MI?
- Cardiac arrest
- Unstable angina
- Bradycardias/heart block
- Tachyarrhytmias
- Heart failure
- Pericarditis
- DVT/PE
- Cardiac tamponade
- Mitral regurgitation
- Dresslers syndrome
How do arrhythmias usually present?
Palpitation, chest pain, syncope, hypotension, pulmonary oedema
May be asymptomatic
What is long QT syndrome?
An inherited condition associated with delayed repolarization of the ventricles which can lead to VT/torsade de pointes. There are 3 types:
LQT1 - associated with exertional syncope eg. swimming
LQT2 - associated with stress related syncope
LQT3 - events occur at night or rest
What causes long QT (>430 in males, >450 in females)?
Congenital:
- Jervell-Lange-Nielsen syndrome (includes deafness, due to abnormal K channel)
- Romano-Ward syndrome (no deafness)
Drugs (the usual mechanism of this is by blocking potassium channels):
- Amiodarone, sotalol, class 1a antiarrhythmic drugs
- Antidepressants (TCAs, SSRIs esp citalopram)
- Methadone
- Chloroquine
- Erythromycin
- Haloperidol
- Ondansetron
- Terfenadine (non sedating antihistamine)
Other:
- Electrolytes ( LOW K, Ca, Mg)
- Acute MI
- Myocarditis
- Hypothermia
- SAH
What causes a shortPR?
WPW syndrome
What causes U waves?
Hypokalemia
Small deflection immediately following the t wave, usually in the same direction
Describe the electrical conduction of the heart
- Sinoatrial node initiates an electrical impulse causing atrial contraction
- Atrial depolarisation (P wave)
- Impulse reaches AV node
- AV node generates a slow action potential
- Activation of the bundle of His and generation of a fast action potential (PR interval)
- Impulse conducted to right and left bundle branches
- Impulse travels through purkinje fibres causing depolarisation in the ventricles (QRS complex)
- Ventricles repolarise and myocardium relaxes (T wave)
NB - atrial repolarisation hidden in QRS complex on ECG
What is heart block?
Cardiac electrical disorder defined as impaired conduction from the atria to the ventricles, shown as PR abnormalities and bradycardia on ECG
The severity is described in degrees.
What causes heart block?
- Levs disease (fibrosis/calcification of conduction system)
- Ischaemic heart disease
- Cardiomyopathy
- Myocarditis
- His Purkinje disease
- Use of AV nodal blocking agents
What is 1st degree heart block?
Electrical impulse moves more slowly through AV node. Common in athletes (increased vagal tone) and caused by certain drugs.
Generally asymptomatic without significant complications.
ECG shows increased PR interval >0.2s
What is 2nd degree heart block - Mobitz I?
aka Wenckebachs
PR interval gradually increases until a QRS complex is lost
Due to reversible conduction block at the AV node (athletes, drugs, inferior MI, myocarditis)
Asymptomatic patients dont require treatment - give atropine if symptomatic and stop AV node blocking drugs (ABCD - adensine, beta blockers, CCBs, digoxin)
What is 2nd degree heart block - Mobitz II?
Some P waves do not have QRS complexes following them (intermittent non-conducted P waves) without progressive PR prolongation
Due to failure of conductive at the His-Purkinje system (below the AV node), due to drugs, ischaemia, structural damage, hyperkalemia, inflammation
May be symptomatic. More likely to be associated with haemodynamic instability and asystole so need active management with digoxin/pacemaker
What is 3rd degree heart block?
No relation between P waves and QRS complexes
Due to complete loss of conduction between atria and ventricles. Perfusing rhythm maintained by a junction or ventricular escape rhythm.
Will be symptomatic (fainting, dizziness, fatigue, SOB, chest pain)
High risk of sudden cardiac death, need urgent monitoring, digoxin, atropine, temporary/permanent pacing
What is a Stokes-Adams attack?
Syncopal episode due to a cardiac arrhythmia, most commonly bradycardia/complete heart block
What is bradycardia?
Any heart rhythm slower than 60bpm, due to:
- Reduced automaticity (sinus node dysfunction) due to increased vagal tone
- Conduction block
Why do athletes have bradycardia?
Increased vagal tone
How is bradycardia managed?
> 40bpm, asymptomatic - no treatment, treat cause (stop drugs, hypothyroidism, sick sinus syndrome)
<40bpm or symptomatic, give atropine up to 6 times > transcutaneous pacing > transvenous pacing or temporary pacing wire if no response
What is sick sinus syndrome?
Sinus node dysfunction causing bradycardia and arrest, sinoatrial block or SVT.
Often requires a pacemaker!
What is tachycardia?
Any heart rate above 100bpm, due to:
- Increased automaticity (exercise, ectopic firing)
- Triggered activity (abnormal APs triggered by preceding AP)
- Reentry
What causes narrow complex tachycardia (QRS<120)?
Narrow complex means that the signal must pass through the AV node
- Sinus tachycardia
- Supraventricular tachycardia (p wave absent or inverted)
- AF (wandering baseline)
- Atrial flutter (sawtooth)
- Atrial tachycardia
- Junctional tachycardia
How are narrow complex tachycardias managed?
- If patient compromised use DC cardioversion
- If not, identify underlying rhythm and treat accordingly
- Transient AV block through vagal manoeuvres or IV adenosine
How is SVT managed?
- Vagal manoeuvres
- IV adenosine (6m > 12mg > 18mg UNLESS ASTHMATIC)
- IV verapamil (if asthmatic)
- DC cardioversion (if treatment refractory or if haemodyamically unstable)
Prevention of future episodes with beta blockers or radiofrequency ablation
How is atrial tachycardia managed?
- Stop digoxin if this is the cause
2. Maintain potassium levels
What are junctional rhythms?
Junctional rhythms occur when the AV node takes over as the main pacemaker of the heart. BUT, AV node can only conduct 40-60 beats
Regular rate, absent p waves, normal QRS
Types of junctional tachycardia:
1. AV nodal re-entry tachycardia
2. AV re-entry tachycardia
3. His bundle tachycardia
OFTEN REQUIRE PACING
How is junctional tachycardia managed?
- Vagal manoeuvres
- IV adenosine
- If recurrence, beta blocker or amiodarone
- Radiofrequency ablation
What is WPW syndrome (cause, ECG, management?
Congenital accessory conduction pathway between the atria and ventricles.
ECG shows short PR interval, wide QRS complex (due to slurred upstroke/delta wave)
Patients present with SVT, AF or atrial flutter.
Refer to cardiologist for electrophysiology and ablation of accessory pathway
What is holiday heart syndrome?
Acute arhythmmias due to binge drinking, usually causing SVT and AF
What is atrial fibrillation? What does ECG show?
Supraventricular tacchyarrhythmia, characterised by uncoordinated atrial activity. Causes cardiac output to drop as the ventricles aren’t primed reliably by the atria.
ECG shows absent p waves, and irregularly irregular pulse, wandering baseline.
What are the different types of AF?
Paroxysmal - episode of AF that terminates spontaneously or with intervention in less than 7 days
Persistent - each episode lasts for longer than 7 days
Permanent - AF that cannot be controlled by medication
What are the symptoms of AF?
Palpitations, dyspnoea, angina, dizziness, syncope
May present as stroke, HF
How is acute AF managed (<48h)?
Haemodynamically unstable:
- DC cardioversion
Haemodynamically stable:
Offer either rate or rhythm control
RHYTHM
Heparin and either:
- DC cardioversion (this option if haemodynamically unstable)
- Pharmacological cardioversion; IV amiodarone (if structural heart disease) or flecanide
RATE
- Beta blocker/CCB/digoxin
OFFER DOAC IF SINUS RHYTHM NOT ACHIEVED AFTER 48H, HIGH RISK OF RECURRENCE OR HIGH RISK OF STROKE
When should rate control not be offered in non acute AF?
- AF with a reversible causes
- HF thought to be caused by AF
- New onset AF
- Atrial flutter