Aortic stenosis is a progressive narrowing of the aortic valve that obstructs blood flow from the left ventricle into the aorta and creates chronic pressure overload on the heart. Understanding aortic stenosis is important because sustained outflow obstruction leads to ventricular hypertrophy, impaired filling, reduced cardiac output and the development of classic late symptoms that signal advanced, high-risk disease.

Aortic regurgitation is a valvular disorder in which the aortic valve fails to close during diastole, allowing blood to flow back into the left ventricle and creating chronic volume overload. Understanding aortic regurgitation is important because progressive ventricular dilation and wall stress can silently impair cardiac function and, in acute cases, lead rapidly to pulmonary oedema and cardiovascular collapse.

Atherosclerosis is a chronic inflammatory disease of medium and large arteries that leads to plaque formation and, when it affects the coronary arteries, causes coronary artery disease. Understanding atherosclerosis is important because plaque behaviour and instability—not just arterial narrowing—determine the risk of myocardial ischaemia, angina and acute coronary events.

Myocardial infarction occurs when acute obstruction of a coronary artery causes myocardial ischaemia and irreversible cardiac muscle necrosis, presenting as STEMI or NSTEMI depending on the extent of occlusion and tissue injury. Understanding the pathophysiology of MI is essential for recognising time-critical presentations, interpreting ECG changes, and appreciating why rapid reperfusion dramatically improves survival and myocardial salvage.

Left-sided heart failure occurs when the left ventricle cannot pump blood effectively into the systemic circulation, leading to reduced cardiac output and backward pressure into the pulmonary circulation. Understanding its pathophysiology is essential for explaining symptoms such as dyspnoea and pulmonary oedema, recognising disease progression, and interpreting how left ventricular dysfunction drives clinical deterioration.