Cardiology Flashcards
Which ECG leads refer to a Lateral MI?
I, aVL, V5, V6
Which ECG leads refer to an Anterior MI?
V3, V4
Which ECG leads refer to a septal MI?
V1, V2
Which ECG leads refer to an inferior MI?
II, III, aVF
Which coronary arteries supply the anterior, lateral, septal and inferior parts of the heart?
Anterior: LAD
Lateral: Circumflex
Septal: LAD anterior 2/3 , RCA posterior 1/3
Inferior: RCA
Troponin results are used to diagnose an?
NSTEMI
Is Troponin needed to diagnose a STEMI?
No, based on presentation and ECG
GRACE score?
GRACE score gives a 6-month probability of death after having an NSTEMI.
3% or less is considered low risk
Above 3% is considered medium to high risk
Patients at medium or high risk are considered for early angiography with PCI (within 72 hours).
What is Dressler’s syndrome?
Dressler’s syndrome is also called post-myocardial infarction syndrome. It usually occurs around 2 – 3 weeks after an acute myocardial infarction. It is caused by a localised immune response that results in inflammation of the pericardium.
It presents with pleuritic chest pain, and a pericardial rub on auscultation.
Management is with NSAIDs (e.g., aspirin or ibuprofen) and, in more severe cases, steroids (e.g., prednisolone).
Diagnosis of Dressler’s syndrome
A diagnosis can be made with an ECG (global ST elevation and T wave inversion), echocardiogram (pericardial effusion) and raised inflammatory markers (CRP and ESR).
Four main differentials of a narrow complex tachycardia
Sinus tachycardia (treatment focuses on the underlying cause)
Supraventricular tachycardia SVT (treated with vagal manoeuvres and adenosine)
Atrial fibrillation (treated with rate control or rhythm control)
Atrial flutter (treated with rate control or rhythm control, similar to atrial fibrillation)
The resuscitation guidelines break down broad complex tachycardia into
Ventricular tachycardia or unclear cause (treated with IV amiodarone)
Polymorphic ventricular tachycardia, such as torsades de pointes (treated with IV magnesium)
Atrial fibrillation with bundle branch block (treated as AF)
Supraventricular tachycardia with bundle branch block (treated as SVT)
Narrow complex tachycardia vs broad complex tachycardia
QRS>3 small squares = broad <3 small squares = narrow
What is atrial flutter?
Atrial flutter is caused by a re-entrant rhythm in either atrium.
The electrical signal re-circulates in a self-perpetuating loop due to an extra electrical pathway in the atria.
The signal goes round and round the atrium without interruption. The atrial rate is usually around 300 beats per minute.
What is atrial flutter?
Atrial flutter is caused by a re-entrant rhythm in either atrium.
The electrical signal re-circulates in a self-perpetuating loop due to an extra electrical pathway in the atria.
The signal goes round and round the atrium without interruption. The atrial rate is usually around 300 beats per minute.
Relative ventricular rates in atrial flutter
The signal does not usually enter the ventricles on every lap due to the long refractory period of the atrioventricular node.
This often results in two atrial contractions for every one ventricular contraction (2:1 conduction), giving a ventricular rate of 150 beats per minute.
There may be 3:1, 4:1 or variable conduction ratios.
Atrial flutter ECG appearance
Atrial flutter gives a sawtooth appearance on the ECG, with repeated P wave occurring at around 300 per minute, with a narrow complex tachycardia.
Prolonged QT leads to an ECG showing
Torsades De Pointes
Afterdepolarisations spread throughout the ventricles, causing a contraction before proper repolarisation.
Causes of prolonged QT
Long QT syndrome (an inherited condition)
Medications, such as antipsychotics, citalopram, flecainide, sotalol, amiodarone and macrolide antibiotics
Electrolyte imbalances, such as hypokalaemia, hypomagnesaemia and hypocalcaemia
On an ECG, first-degree heart block presents as
A PR interval greater than 0.2 seconds (5 small or 1 big square).
Mobitz type 1 (Wenckebach phenomenon)
Is where the conduction through the atrioventricular node takes progressively longer until it finally fails, after which it resets, and the cycle restarts.
On an ECG, there is an increasing PR interval until a P wave is not followed by a QRS complex. The PR interval then returns to normal, and the cycle repeats itself.
Mobitz type 2
Intermittent failure of conduction through the atrioventricular node, with an absence of QRS complexes following P waves. There is usually a set ratio of P waves to QRS complexes, for example, three P waves for each QRS complex (3:1 block). The PR interval remains normal. There is a risk of asystole with Mobitz type 2.
RBBB +left anterior or posterior hemiblock (left axis deviation) + 1st-degree heart block =
Trifasicular block
Hypertrophic cardiomyopathy is inherited in a ___ fashion
AD
