1. Hypertension
Hypertension, commonly known as high blood pressure, is a chronic medical disorder characterized by persistently elevated arterial pressure in the systemic circulation. Clinically, it is defined as a sustained systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg measured on multiple occasions under standardized conditions.
Elaboration:
Hypertension is often asymptomatic in its early stages, earning the moniker “silent killer,” yet it imposes substantial strain on the heart, blood vessels, kidneys, and brain over time. It is classified as:
- Primary (Essential) Hypertension: A multifactorial disorder with no identifiable single cause, influenced by genetics, environmental factors, dietary habits (high salt intake), obesity, physical inactivity, and stress.
- Secondary Hypertension: Caused by identifiable conditions such as chronic kidney disease, endocrine disorders (e.g., hyperthyroidism, Cushing’s syndrome), vascular abnormalities, or medications (steroids, NSAIDs, oral contraceptives).
Pathophysiology:
Sustained high blood pressure leads to increased shear stress on arterial walls, resulting in vascular remodeling, endothelial dysfunction, and accelerated atherosclerosis. The heart responds with left ventricular hypertrophy to overcome increased afterload, eventually leading to heart failure if untreated.
Complications:
Hypertension increases the risk of myocardial infarction, stroke, heart failure, chronic kidney disease, and retinal damage. Management includes lifestyle interventions (weight control, reduced salt intake, exercise), and pharmacological therapy using ACE inhibitors, beta-blockers, diuretics, or calcium channel blockers.
2. Hypotension
Hypotension refers to an abnormally low blood pressure, usually defined as systolic pressure <90 mmHg or diastolic pressure <60 mmHg. It can be transient or chronic and may result in insufficient perfusion of vital organs.
Elaboration:
Unlike hypertension, hypotension is less prevalent but can be acutely life-threatening. It results when the circulatory system fails to maintain adequate arterial pressure to ensure tissue perfusion. The condition is categorized as:
- Orthostatic (Postural) Hypotension: A sudden drop in blood pressure upon standing, often due to autonomic dysfunction, dehydration, or prolonged bed rest.
- Acute Hypotension: Often caused by severe blood loss (hemorrhage), sepsis, anaphylaxis, or cardiac dysfunction.
- Chronic Hypotension: May occur in healthy individuals without symptoms or secondary to endocrine or cardiac disorders.
Pathophysiology:
Low arterial pressure reduces perfusion of the brain, heart, and kidneys, which may trigger compensatory tachycardia. Severe or prolonged hypotension can lead to organ ischemia, shock, and multiorgan failure.
Clinical Features:
Patients may experience dizziness, syncope (fainting), blurred vision, fatigue, and cold extremities. Management depends on the underlying cause, including fluid resuscitation, medications to raise blood pressure, and lifestyle adjustments.
3. Arteriosclerosis
Arteriosclerosis is a broad term describing the thickening, stiffening, and loss of elasticity of the arterial walls. It primarily affects medium and large arteries and is commonly associated with aging.
Elaboration:
Arteriosclerosis results in decreased compliance of arteries, impairing their ability to accommodate the pulsatile flow of blood from the heart. This contributes to increased systolic blood pressure and afterload on the heart.
Pathophysiology:
Structural changes in arteriosclerosis include fibrosis of the arterial media, calcium deposition (medial calcification), and hypertrophy of the vascular smooth muscle. These alterations compromise vascular elasticity, making arteries rigid and prone to injury.
Clinical Relevance:
Arteriosclerosis predisposes individuals to cardiovascular events, including stroke, coronary artery disease, and peripheral arterial disease. It often coexists with other conditions like hypertension and diabetes, which accelerate vascular damage.
4. Atherosclerosis
Atherosclerosis is a chronic, progressive disease characterized by the accumulation of lipid-laden plaques, cholesterol, calcium, and cellular debris within the intimal layer of arteries, leading to arterial narrowing and stiffening.
Elaboration:
Atherosclerosis is a major underlying cause of coronary artery disease, cerebrovascular disease, and peripheral arterial disease. It begins early in life and progresses silently over decades. Risk factors include hyperlipidemia, hypertension, smoking, diabetes mellitus, obesity, sedentary lifestyle, and genetic predisposition.
Pathophysiology:
The process involves endothelial dysfunction, lipid deposition, inflammatory cell infiltration, smooth muscle proliferation, and fibrous cap formation. Plaque rupture can trigger thrombosis, leading to acute vascular events such as myocardial infarction or ischemic stroke.
Clinical Significance:
Patients may remain asymptomatic until arterial narrowing becomes severe. Complications depend on the site of the affected arteries: coronary arteries → angina or MI; cerebral arteries → stroke; peripheral arteries → intermittent claudication. Management involves lifestyle modification, statins, antiplatelet therapy, and surgical interventions such as angioplasty or bypass surgery.
5. Angina (Angina Pectoris)
Angina is a clinical syndrome marked by episodic chest discomfort, pressure, or tightness due to transient myocardial ischemia, without causing irreversible cardiac muscle necrosis.
Elaboration:
Angina arises when oxygen demand by the myocardium exceeds the oxygen supply due to narrowed or spastic coronary arteries. It is a warning sign of underlying coronary artery disease and often precedes myocardial infarction.
Types:
- Stable Angina: Predictable, occurs with exertion or stress, relieved by rest or nitrates.
- Unstable Angina: Unpredictable, may occur at rest, signals imminent myocardial infarction.
- Variant (Prinzmetal) Angina: Caused by coronary artery spasm, often occurs at rest or at night.
Clinical Features:
Retro-sternal pain radiating to the left arm, jaw, or neck; associated with dyspnea, sweating, palpitations, and nausea. Long-term management involves nitrates, beta-blockers, calcium channel blockers, antiplatelet therapy, and revascularization procedures if indicated.
6. Myocardial Infarction (MI)
Myocardial infarction, or heart attack, is the irreversible death of cardiac myocytes due to prolonged ischemia, most often caused by occlusion of a coronary artery following rupture of an atherosclerotic plaque and thrombosis formation.
Elaboration:
MI is a life-threatening emergency that disrupts normal cardiac function and may precipitate arrhythmias, cardiogenic shock, or sudden cardiac death. Risk factors include age, male gender, hypertension, diabetes, dyslipidemia, smoking, obesity, and family history of heart disease.
Pathophysiology:
The ischemic cascade begins with reduced oxygen delivery, leading to metabolic derangements, loss of contractility, and eventual cell death. Necrotic myocardium is replaced with fibrous tissue, which lacks contractile function.
Clinical Features:
Severe, persistent chest pain or pressure, often radiating to the left arm, jaw, or back; dyspnea; nausea; diaphoresis; and anxiety. ECG changes (ST elevation, T wave inversion, Q waves) and elevated cardiac biomarkers (troponins, CK-MB) confirm diagnosis. Rapid reperfusion via thrombolysis or percutaneous coronary intervention is critical to limit myocardial damage.
7. Congestive Heart Failure (CHF)
Congestive heart failure is a chronic, progressive disorder in which the heart is unable to pump blood efficiently, resulting in fluid accumulation (congestion) in the lungs, liver, extremities, and other organs.
Elaboration:
CHF is often the end-stage manifestation of various cardiovascular diseases including myocardial infarction, hypertension, valvular heart disease, and cardiomyopathies. The heart initially compensates through mechanisms like ventricular hypertrophy, increased sympathetic activity, and activation of the renin-angiotensin-aldosterone system, but these eventually exacerbate cardiac dysfunction.
Clinical Features:
Dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, fatigue, jugular venous distension, and hepatomegaly. CHF can be left-sided (pulmonary congestion), right-sided (systemic congestion), or biventricular. Management involves diuretics, ACE inhibitors, beta-blockers, lifestyle modification, and advanced therapies like ventricular assist devices or heart transplantation in refractory cases.
8. Cardiac Arrhythmias
Cardiac arrhythmias are a heterogeneous group of disorders characterized by abnormal rhythm, rate, or conduction of the heart, resulting from disruptions in the electrical impulses that coordinate myocardial contraction.
Elaboration:
Arrhythmias may be benign or life-threatening depending on their origin and hemodynamic impact. They are broadly classified as:
- Tachyarrhythmias: Rapid heart rate (e.g., atrial fibrillation, ventricular tachycardia).
- Bradyarrhythmias: Slow heart rate (e.g., sinus bradycardia, atrioventricular block).
- Irregular rhythms: Uncoordinated electrical activity (e.g., atrial fibrillation, ventricular fibrillation).
Pathophysiology:
Arrhythmias arise from abnormal automaticity, triggered activity, or reentry phenomena within the conduction system. Predisposing factors include ischemic heart disease, electrolyte imbalances, structural heart disease, medications, and systemic conditions.
Clinical Features:
Palpitations, syncope, dizziness, fatigue, chest discomfort, or sudden cardiac arrest in severe cases. Diagnosis relies on electrocardiography, Holter monitoring, and electrophysiological studies. Treatment includes antiarrhythmic drugs, catheter ablation, pacemaker or defibrillator implantation, and correction of underlying causes.