Cardiology: overview and clinical practice Cardiology is the branch of medicine concerned with the structure, function, and disorders of the heart and circulatory system. This document provides a structured clinical reference covering core cardiac conditions, diagnostic approaches, and management principles. Anatomy and physiology of the heart The heart is a four-chambered muscular organ consisting of the right and left atria and ventricles. It is enclosed within the pericardium and located in the mediastinum. Contraction is governed by the cardiac conduction system: Sinoatrial (SA) node — the primary pacemaker, generating impulses at 60–100 bpm Atrioventricular (AV) node — delays impulse transmission, protecting the ventricles Bundle of His and Purkinje fibres — rapidly distribute impulses through ventricular myocardium Cardiac output (CO) is calculated as: CO = Heart Rate × Stroke Volume. Normal resting CO is approximately 4–8 L/min. Common cardiac conditions Coronary artery disease (CAD) CAD results from atherosclerotic narrowing of the coronary arteries, reducing myocardial perfusion. It is the leading cause of mortality worldwide. Key manifestations include: Stable angina — exertional chest pain relieved by rest or nitrates Unstable angina — rest pain or new-onset severe angina ST-elevation myocardial infarction (STEMI) Non-ST-elevation MI (NSTEMI) Time is muscle. Primary percutaneous coronary intervention (PCI) should be performed within 90 minutes of first medical contact in STEMI. Heart failure Heart failure (HF) is a syndrome in which the heart cannot pump sufficient blood to meet the body's needs. It is classified by ejection fraction: Type EF (%) Mechanism Example HFrEF < 40 Systolic dysfunction Dilated cardiomyopathy HFmrEF 40–49 Mixed Ischaemic cardiomyopathy HFpEF ≥ 50 Diastolic dysfunction Hypertensive heart disease Arrhythmias Cardiac arrhythmias are disturbances in the rate, rhythm, or site of origin of cardiac impulses. Clinically significant arrhythmias include: Atrial fibrillation (AF) — most common sustained arrhythmia; managed with rate/rhythm control and anticoagulation Ventricular tachycardia (VT) — rapid ventricular activation; risk of haemodynamic compromise Complete heart block — failure of AV conduction; requires permanent pacemaker Supraventricular tachycardia (SVT) — managed with vagal manoeuvres or adenosine Diagnostic investigations A structured diagnostic workup for cardiac disease typically includes: ECG — first-line; identifies ischaemia, arrhythmia, hypertrophy, conduction defects Echocardiography — assesses chamber size, wall motion, valvular function, and EF Troponin (I or T) — gold-standard biomarker for myocardial injury BNP / NT-proBNP — elevated in heart failure; useful for diagnosis and prognosis Coronary angiography — definitive assessment of coronary anatomy and stenosis CT coronary angiography (CTCA) — non-invasive; preferred for ruling out CAD in low-to-intermediate risk Cardiac MRI — evaluates myocardial viability, inflammation, and cardiomyopathies Pharmacological management Drug class Example Indication Key note ACE inhibitor Ramipril HFrEF, post-MI, hypertension Monitor renal function and K⁺ Beta-blocker Bisoprolol, Carvedilol HFrEF, AF rate control, post-MI Avoid in acute decompensation Statin Atorvastatin 40–80 mg CAD, primary prevention Target LDL < 1.4 mmol/L in high risk Antiplatelet Aspirin + Clopidogrel ACS, post-PCI (DAPT) Duration guided by stent type and bleeding risk Anticoagulant Apixaban, Rivaroxaban AF (stroke prevention) Use CHA₂DS₂-VASc score to guide initiation Diuretic Furosemide Decongestion in HF Titrate to dry weight; monitor electrolytes SGLT2 inhibitor Dapagliflozin, Empagliflozin HFrEF, HFpEF, DM with CVD Reduce hospitalisation and mortality Cardiac risk stratification Risk scores guide clinical decision-making in cardiology: HEART score — risk stratification in chest pain presentations in the ED GRACE score — predicts in-hospital and 6-month mortality in ACS CHA₂DS₂-VASc — stroke risk in non-valvular AF; anticoagulation if score ≥ 2 (men) or ≥ 3 (women) TIMI score — risk of ischaemic events in NSTEMI/unstable angina Preventive cardiology Cardiovascular prevention is classified as primary (before disease onset) or secondary (after an event). Key strategies include: Smoking cessation — single most impactful modifiable risk factor Blood pressure control — target < 130/80 mmHg in high-risk patients Lipid management — high-intensity statin therapy for established CVD Glycaemic control — HbA1c targets individualised in diabetes Physical activity — ≥ 150 min/week moderate-intensity aerobic exercise Mediterranean-style diet — reduces cardiovascular events