Venous thromboembolism (VTE) describes pathological clot formation in the venous system, encompassing both deep vein thrombosis and pulmonary embolism as different outcomes of the same process. Understanding VTE is essential for recognising risk factors, preventing life-threatening embolic events, and identifying early signs of venous clot formation before catastrophic deterioration occurs.

Infective endocarditis is a microbial infection of the endocardium, most commonly affecting the heart valves. Understanding this condition is essential for recognising early clinical features, identifying complications such as embolisation and valve dysfunction, and initiating timely treatment to prevent serious outcomes.

Shock is a state of acute circulatory failure in which tissue perfusion and oxygen delivery are insufficient to meet cellular metabolic demands. Understanding the pathophysiology of shock is essential for early recognition, targeted intervention, and preventing rapid progression to organ failure and death.

Hypovolaemic shock is a form of circulatory failure caused by a critical loss of intravascular volume, leading to reduced venous return, decreased cardiac output and impaired tissue perfusion. Understanding its pathophysiology is essential for recognising early deterioration, prioritising rapid volume replacement, and preventing progression to irreversible cellular hypoxia and organ failure.

Cardiogenic shock is a form of circulatory failure caused by the heart’s inability to pump enough blood to meet tissue oxygen demands despite adequate intravascular volume. Understanding its pathophysiology is essential for recognising that treatment must focus on improving cardiac function rather than fluid replacement, as delayed or inappropriate management rapidly leads to severe hypoxia and organ failure.

Distributive shock is a form of circulatory failure caused by loss of systemic vascular tone, leading to widespread vasodilation and ineffective distribution of blood flow despite normal or increased circulating volume. Understanding this mechanism is essential for recognising why hypotension and tissue hypoperfusion occur without true volume loss and why management must target vascular tone, not fluids alone.

The stages of shock describe the progressive physiological deterioration that occurs as circulatory failure impairs oxygen delivery and cellular metabolism over time. Understanding these stages is essential for recognising early, reversible shock and appreciating why delayed intervention leads to organ failure and reduced treatment responsiveness.

Disseminated intravascular coagulation (DIC) is a systemic coagulation disorder in which widespread activation of clotting occurs throughout the circulation rather than at sites of injury. Understanding DIC is essential because it explains how patients can develop simultaneous thrombosis and life-threatening bleeding as a consequence of severe underlying illness.

Cardiomyopathies are primary disorders of the heart muscle characterised by abnormal myocardial structure and function that impair contraction, relaxation, or chamber geometry. Understanding cardiomyopathies is important because these structural changes directly reduce cardiac output and can lead to heart failure, arrhythmias, and sudden cardiac death even in the absence of coronary or valvular disease.

Aortic dissection is a life-threatening condition in which a tear in the aortic intima allows blood to split the layers of the aortic wall, creating a false lumen. Understanding aortic dissection is critical because rapid progression can compromise organ perfusion or cause rupture, leading to sudden death without prompt recognition and intervention.

Mitral stenosis is a valvular heart disease in which narrowing of the mitral valve obstructs blood flow from the left atrium to the left ventricle during diastole. Understanding mitral stenosis is important because progressive obstruction raises left atrial and pulmonary pressures, leading to breathlessness, atrial fibrillation, pulmonary hypertension, and heart failure.

Mitral regurgitation is a valvular disorder in which incomplete closure of the mitral valve during systole allows blood to flow backward from the left ventricle into the left atrium. Understanding mitral regurgitation is important because chronic volume overload leads to atrial and ventricular remodelling, heart failure and arrhythmias, while acute regurgitation can cause sudden pulmonary oedema and haemodynamic instability.

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Pericarditis is an inflammatory condition affecting the pericardial layers that surround the heart, disrupting their normal frictionless function. Understanding pericarditis is important because inflammation and fluid accumulation can impair cardiac filling, cause acute chest pain, and in severe cases progress to life-threatening complications such as cardiac tamponade or constrictive pericarditis.

Cardiac arrhythmias are disorders of heart rhythm that occur when the electrical impulses controlling the heartbeat are generated or conducted abnormally. Understanding arrhythmias is important because they can reduce cardiac output, cause symptoms such as syncope or palpitations, and in some cases lead to stroke, heart failure, or sudden cardiac death.

Cardiac tamponade is a life-threatening condition in which rapid accumulation of fluid in the pericardial sac compresses the heart and impairs ventricular filling. Understanding tamponade is critical because it causes a rapid fall in cardiac output and can quickly progress to obstructive shock and death without urgent intervention.

Right-sided heart failure occurs when the right ventricle cannot effectively pump blood into the pulmonary circulation, leading to systemic venous congestion. Understanding this condition is important because it explains clinical features such as peripheral oedema, ascites and jugular venous distension, and helps differentiate systemic congestion from pulmonary causes of heart failure.

Biventricular heart failure occurs when both the left and right ventricles are unable to pump effectively, resulting in combined impairment of systemic perfusion and venous return. Understanding this condition is important because it explains the simultaneous presence of pulmonary congestion and systemic oedema, and reflects advanced cardiac disease with high clinical complexity.

Hypertension is characterised by persistently elevated arterial blood pressure due to primary (essential) mechanisms or identifiable secondary causes. Understanding how different mechanisms raise blood pressure is important because long-term hypertension drives progressive cardiovascular, renal and vascular damage even in the absence of early symptoms.

Pulmonary hypertension is a condition characterised by abnormally elevated pressure within the pulmonary arterial circulation, a system normally designed to operate at low resistance and low pressure. Understanding pulmonary hypertension is important because sustained pressure overload places progressive strain on the right ventricle, ultimately leading to right-sided heart failure and significant morbidity.