Inherited & sudden cardiac death syndromes flashcards
22 high-yield MRCP Part 1 cards from the Intellect Medicos Cardiology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
Study these 22 cards Save progress — free account
-
Which long QT syndrome subtype is classically triggered by exercise, especially swimming, and which gene is affected?
Show answer
LQT1, due to a KCNQ1 mutation.
Why? KCNQ1 encodes the slow delayed rectifier potassium channel (IKs), which shortens repolarisation when the heart rate rises with sympathetic drive. Without it, exercise prolongs the QT dangerously.
-
Which long QT subtype is triggered by a sudden loud noise (such as an alarm clock) or the postpartum period, and which gene is affected?
Show answer
LQT2, due to a KCNH2 (hERG) mutation.
Why? KCNH2 encodes the rapid delayed rectifier potassium channel (IKr). It is also the channel blocked by most QT-prolonging drugs.
-
Which long QT subtype causes events at rest or during sleep, and which gene is affected?
Show answer
LQT3, due to an SCN5A (cardiac sodium channel) mutation.
Why? A persistent late sodium current prolongs repolarisation, most dangerously at slow heart rates. Mexiletine (a sodium channel blocker) is the specific add-on for LQT3 in the notes.
-
Congenital long QT with sensorineural deafness: name the syndrome and its inheritance.
Show answer
Jervell and Lange-Nielsen syndrome — autosomal recessive.
Why? Both copies of a potassium channel gene (KCNQ1 or KCNE1) are affected. The same channel is needed in the inner ear for endolymph production, explaining the deafness.
-
Which beta-blocker should NOT be used to treat congenital long QT syndrome?
Show answer
Sotalol.
Why? Sotalol has class III (potassium channel blocking) activity that prolongs the QT interval further. Non-QT-prolonging beta-blockers such as propranolol or nadolol are used instead.
-
List four drug groups that cause acquired QT prolongation.
Show answer
Any four of: class Ia/III antiarrhythmics (quinidine, sotalol, amiodarone), tricyclic antidepressants, antipsychotics (haloperidol), macrolides (erythromycin), quinolones (ciprofloxacin), methadone.
Why? Most of these block the hERG (IKr) potassium channel, delaying repolarisation and predisposing to torsades de pointes.
-
What is the inheritance of hypertrophic obstructive cardiomyopathy, and which proteins are typically mutated?
Show answer
Autosomal dominant. Sarcomere proteins, most often β-myosin heavy chain (MYH7) or myosin-binding protein C.
Why? Abnormal sarcomere proteins lead to disorganised, hypertrophied myocytes (myocyte disarray), especially in the septum.
-
The three classic echo findings in HOCM are ______, ______ and ______.
Show answer
mitral regurgitation; systolic anterior motion of the mitral valve; asymmetric septal hypertrophy
Why? During systole, the anterior mitral leaflet is pulled towards the thickened septum (SAM). This both obstructs the outflow tract and makes the mitral valve leak.
-
Which drug classes should be avoided in HOCM? (Mnemonic: DANI)
Show answer
Dihydropyridine CCBs and Digoxin, Diuretics; ACE inhibitors and ARBs; Nitrates; Inotropes.
Why? Anything that reduces preload or afterload, or increases contractility, shrinks the left ventricular cavity and worsens outflow tract obstruction.
-
What is the mechanism of action of mavacamten in obstructive HCM?
Show answer
It is a selective cardiac myosin inhibitor: it reduces actin–myosin cross-bridge formation, lowering hypercontractility and the outflow gradient.
Why? HOCM is driven by excess sarcomere contraction, so directly damping myosin activity treats the mechanism rather than just the rate.
-
A 24-year-old cyclist collapses during a race. ECG: T-wave inversion in V1–V3 and small notches just after the QRS in V1–V3. Echo: dilated right ventricle with a thin free wall. What is the diagnosis, and what are the notches called?
Show answer
Arrhythmogenic right ventricular cardiomyopathy (ARVC). The notches are epsilon waves.
Why? Right ventricular muscle is progressively replaced by fibrofatty tissue, delaying activation of part of the RV (the epsilon wave) and creating a substrate for VT with LBBB morphology.
-
Naxos disease: what is its inheritance and its classic triad?
Show answer
Autosomal recessive. ARVC + palmoplantar keratoderma + woolly hair.
Why? It is caused by a desmosomal protein defect (plakoglobin). Desmosomes hold together both cardiac muscle cells and skin/hair cells, explaining the combination.
-
A 14-year-old faints during an exciting football match. Resting ECG and echo are normal. On exercise testing she develops bidirectional ventricular tachycardia. What is the diagnosis and the commonest gene involved?
Show answer
Catecholaminergic polymorphic VT (CPVT), most often an RyR2 (ryanodine receptor) mutation.
Why? Faulty ryanodine receptors leak calcium from the sarcoplasmic reticulum during adrenergic surges, causing delayed after-depolarisations and triggered arrhythmias.
-
What is the preferred first-line drug in CPVT?
Show answer
A non-selective beta-blocker, preferably nadolol.
Why? Arrhythmias only happen with catecholamine surges, so blocking adrenergic stimulation is lifesaving. Flecainide is added on top if needed, as it reduces the calcium leak.
-
Brugada syndrome: which gene and inheritance pattern?
Show answer
SCN5A (cardiac sodium channel) loss of function, autosomal dominant.
Why? Reduced sodium current in the right ventricular outflow tract produces the right precordial ST elevation and a substrate for VF, typically at rest, during sleep or with fever.
-
The diagnostic (type 1) Brugada pattern is ______ ST elevation of at least 2 mm in a right precordial lead, followed by a negative T wave; it can be unmasked by ajmaline or flecainide.
Show answer
coved
Why? Sodium channel blockers further reduce the already deficient sodium current, exaggerating the pattern. Type 2 and 3 patterns (saddleback) need drug provocation to confirm.
-
The diagnostic (type 1) Brugada pattern is coved ST elevation of at least 2 mm in a right precordial lead, followed by a negative T wave; it can be unmasked by ______.
Show answer
ajmaline or flecainide
Why? Sodium channel blockers further reduce the already deficient sodium current, exaggerating the pattern. Type 2 and 3 patterns (saddleback) need drug provocation to confirm.
-
In obstructive HCM, which class Ia antiarrhythmic is added to a beta-blocker as third-line for refractory symptoms?
Show answer
Disopyramide.
Why? Its strong negative inotropic effect reduces the outflow gradient. Second-line (if beta-blockers fail or are not tolerated) is a non-dihydropyridine CCB such as verapamil or diltiazem.
-
What is the gold-standard septal reduction therapy for drug-refractory obstructive HCM?
Show answer
Surgical septal myectomy (alcohol septal ablation is the less invasive alternative).
Why? It is indicated for NYHA III–IV symptoms with an LVOT gradient of 50 mmHg or more despite optimal drugs. Myectomy is favoured in younger patients.
-
In Brugada syndrome the definitive treatment is an ______; an acute VF storm is treated with IV isoprenaline.
Show answer
implantable cardioverter-defibrillator
Why? Isoprenaline increases inward calcium current, offsetting the deficient sodium current. Quinidine is an oral adjunct that reduces arrhythmias.
-
In Brugada syndrome the definitive treatment is an implantable cardioverter-defibrillator; an acute VF storm is treated with IV ______.
Show answer
isoprenaline
Why? Isoprenaline increases inward calcium current, offsetting the deficient sodium current. Quinidine is an oral adjunct that reduces arrhythmias.
-
ARVC is caused by mutations in which group of proteins, and which gene is most often involved?
Show answer
Desmosomal proteins; plakophilin-2 (PKP2) is the commonest gene.
Why? Faulty desmosomes let myocytes pull apart under stress; they die and are replaced by fibrofatty tissue. Beta-blockers are first-line drugs, with an ICD for high-risk patients.