Cardiovascular disease and common treatments explained
Organisation • Animal tissues, organs and systems
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Key concepts
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Coronary heart disease (CHD): cause and effect
Atherosclerosis is the process in which fatty material (plaque) accumulates on artery walls. Plaque reduces the diameter of coronary arteries and decreases blood flow to cardiac muscle. Cause → effect: high blood cholesterol, high blood pressure, smoking and poor diet promote plaque formation; plaque narrows arteries → less oxygen and glucose reach heart cells → cells become damaged or die, producing chest pain (angina) or a heart attack. Limiting factors include the extent and location of artery narrowing and the presence of collateral circulation. Small or slowly forming plaques can allow partial compensation, whereas sudden blockage from a ruptured plaque causes rapid tissue death.
Stents: function, procedure and limits
A stent is a small mesh tube inserted into a narrowed coronary artery and expanded (often with a balloon) to hold the artery open. Cause → effect: inserting and expanding the stent compresses plaque against the artery wall → artery diameter increases → blood flow improves and oxygen delivery to the heart muscle rises. Advantages include being less invasive than bypass surgery and faster recovery. Risks and limits include possible blood clot formation around the stent, restenosis (re-narrowing), and the need for antiplatelet drugs after the procedure. Patient suitability depends on plaque location, artery size and overall health.
Statins: how they work and considerations
Statins are drugs that reduce blood cholesterol by inhibiting enzymes involved in cholesterol production in the liver. Cause → effect: lowering blood cholesterol reduces the amount of lipid available to form plaques → slower progression of atherosclerosis and reduced risk of coronary events. Benefits include reduced risk of heart attack and stroke when combined with lifestyle changes. Disadvantages include daily, long-term use, possible side effects (muscle pain, liver enzyme changes) and delayed onset of benefit. Statins suit patients with high cholesterol or existing cardiovascular risk.
Mechanical devices and transplant options
Artificial hearts and ventricular assist devices (VADs) offer mechanical support when the heart cannot pump effectively. Use cases include bridging a patient to transplant or allowing the native heart to rest and recover. Cause → effect: a mechanical pump takes over or supports cardiac output → tissues receive needed oxygen and nutrients → patient survival is prolonged while definitive treatment is arranged. Donor heart or heart-and-lung transplants replace the failed organ(s) with matched donor tissue. Transplants restore normal circulation when other treatments fail but require donor matching, major surgery and lifelong immunosuppression to prevent rejection. Waiting lists and suitability limit availability.
Faulty heart valves and replacements
Heart valves that fail to open or close properly allow backflow or obstruct forward flow. Cause → effect: valve leakage or stenosis reduces cardiac efficiency → reduced tissue perfusion causes breathlessness, fatigue and dizziness. Severe valve disease requires surgical replacement. Replacement options include biological valves (donor or animal tissue) and mechanical valves (metal or synthetic). Biological valves reduce the need for lifelong blood-thinning drugs but can degenerate over time; mechanical valves last longer but require permanent anticoagulation to prevent clots.
Evaluation: drugs versus devices versus transplants
Drugs (statins, antiplatelet agents) often act systemically and reduce risk or manage symptoms with low invasiveness. Mechanical devices (stents, VADs) act locally or mechanically to restore flow or pump function and provide immediate effect but carry procedural risks and device-related complications. Transplants offer definitive organ replacement but are invasive, limited by donor supply and require lifelong immunosuppression. Treatment choice depends on severity, patient age, comorbidities and risk tolerance. Less invasive options suit many patients; surgery or transplant suits severe or unresponsive cases. Ethical and practical limits include donor availability, rejection risk and long-term side effects.
Risk factors for cardiovascular disease
Major modifiable risk factors include poor diet (high saturated fat and cholesterol), smoking, physical inactivity, obesity and excessive alcohol. Non-modifiable factors include age, sex and genetic predisposition. Cause → effect: risk factors increase blood pressure or blood lipid levels or damage vessel linings → atherosclerosis accelerates → coronary arteries narrow more quickly. Risk reduction strategies include dietary changes, smoking cessation, regular exercise and medical management of blood pressure and cholesterol.
Key notes
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