Paper I — 2021 February (Supplementary) (2010 Scheme) — Q2
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Paper I
2021 February (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
A 50 years old male patient came to hospital with a complaint of breathlessness,
Orthopnoea and swelling of both feet since 10 days. He is a known ischemic heart
disease patient, using aspirin only and not taking the other drugs as prescribed. His
heart rate is 128/mt and his blood pressure is 160/100 mm of Hg. Echocardiogram
shows dilated cardiac chambers.
(a) Classify drugs used in congestive heart failure 2 mark(s)
(b) Explain the mechanism and pharmacological action of digoxin 2 mark(s)
(c) Describe the adverse effects of beta blockers 2 mark(s)
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Answer
This clinical picture (breathlessness, orthopnoea, bilateral pedal oedema, tachycardia, dilated cardiac chambers on echo in a known IHD patient) is consistent with congestive cardiac failure (dilated cardiomyopathy pattern).
(a) Classification of drugs used in CCF
Diuretics: Furosemide, Spironolactone
ACE inhibitors/ARBs: Enalapril, Losartan
Beta blockers: Carvedilol, Bisoprolol, Metoprolol
Positive inotropes: Digoxin, Dobutamine
Vasodilators: Hydralazine, Isosorbide dinitrate
(b) Mechanism and pharmacological action of digoxin
Inhibits the Na⁺-K⁺-ATPase pump in cardiac myocytes, leading to increased intracellular Na⁺, which reduces the activity of the Na⁺-Ca²⁺ exchanger, causing increased intracellular Ca²⁺
Also increases vagal tone, slowing AV conduction (useful for rate control in atrial fibrillation) and reducing heart rate (negative chronotropic effect)
(c) Adverse effects of beta blockers
Bradycardia, heart block
Bronchospasm (especially non-selective agents — caution in this patient if there is coexisting airway disease)
Fatigue, cold extremities
Masking of hypoglycaemia symptoms in diabetics
Worsening of acute decompensated heart failure if not carefully titrated (started at low dose and up-titrated slowly in CCF)
Rebound hypertension/tachycardia with abrupt withdrawal
