Study Unit 1.3: Cardiovascular System

Cardiovascular System: Key Concepts and Conditions

Definitions

  • Blood pressure: Pressure exerted by blood against large artery walls (Systolic: during contraction; Diastolic: during relaxation).

  • Thrombus: Clot in an undamaged blood vessel.

  • Embolism: Clot moved from origin, causing obstruction.

  • Oedema: Tissue swelling due to increased interstitial fluid.

  • Capillary refill: Time for capillary bed to regain color after blanching.

Factors Influencing Blood Pressure

  • Age: Decreased elasticity, narrowed vessel lumen.

  • Physical Activity: Temporary systolic BP increase.

  • Emotion: Can lower or increase BP.

  • Rest: BP decreases, lowest during deep sleep.

Myocarditis vs. Pericarditis

Myocarditis

  • Definition: Inflammation of the myocardium (heart muscle).

  • Causes: Viruses, autoimmune conditions.

  • Effects: Impaired contractility and electrical impulses, leading to heart failure/dysrhythmias.

  • Management: Symptomatic relief, anticoagulants, rest.

Pericarditis

  • Definition: Inflammation of the pericardium (sac surrounding the heart).

  • Causes: Trauma, inflammatory reaction, high urea, MI; Chronic (TB).

  • Effects: Can cause effusion and scarring.

  • Management: Rest, pain relief, treat underlying causes.

ECG Rhythm and Conduction System

  • ECG: Graphic recording of heart muscle's electrical activity.

  • Indications: Chest pain, changes in vital signs/heart rhythm, routine checks.

  • Conduction System: SA node, AV node, Bundle of His, bundle branches, Purkinje fibres.

  • P Wave: Atrial contraction (SA node firing, HR 60−10060-100 bpm).

  • PR Interval: Conduction time through atria and AV node.

  • QRS Complex: Ventricular depolarisation (contraction).

  • T Wave: Ventricular repolarisation (relaxation).

ECG Dysrhythmias

  • Sinus Bradycardia: SA node fires regularly at < 6060 bpm.

  • Sinus Tachycardia: SA node fires regularly at > 100100 bpm.

  • Atrial Fibrillation: Rate > 100100 bpm, always irregular, no P waves, narrow QRS.

  • Ventricular Tachycardia (VT): Wide, regular QRS, ventricular rate 100−200100-200.

  • Ventricular Fibrillation (VF): Irregular rhythm, no organized electrical activity, no cardiac output.

  • Asystole: Total absence of electrical activity/ventricular contraction.

Peripheral Vascular Disease (PVD)

  • Definition: Obstruction of blood flow in arteries, leading to poor blood supply to organs/tissues.

  • Characteristics: Reduced blood flow due to pump failure, vessel alterations, or circulatory insufficiency.

  • Clinical Manifestations: Intermittent claudication, pain, slow-healing sores, skin changes, diminished pulse, oedema, gangrene.

  • Prevention: Stop smoking, manage hypertension/DM/cholesterol, regular exercise.

Cardiovascular Conditions

Hypertension

  • Definition: Persistent raised blood pressure (SBP > 140mmHg140mmHg, DBP > 90mmHg90mmHg).

  • Causes/Risk Factors: Family history, age, obesity, smoking, salt sensitivity, insulin resistance.

  • Pathophysiology: Vessel scarring/loss of elasticity → increased cardiac workload → heart enlargement → ischemia → ventricular failure and organ damage.

  • Clinical Manifestations: Often asymptomatic early; headache, dizziness, palpitations, blurred vision, angina pectoris.

  • Management: Drug therapy combined with lifestyle modifications.

Deep Vein Thrombosis (DVT)

  • Definition: Clot within deep veins (pelvis or legs) with inflammation.

  • Causes/Risk Factors: Immobility, trauma/surgery, coagulation abnormalities, obesity, pregnancy, malignancies.

  • Pathophysiology: Slowed circulation → blood pooling → clot formation; risk of pulmonary embolism if it breaks off.

  • Clinical Manifestations: Calf pain, swelling, redness (Homen's sign), warmth along affected vessels.

  • Medical Treatment: Pulmonary embolism prevention (bed rest, thrombolytics, anticoagulation, surgical filter).

  • Health Education: Anticoagulant therapy, gentle exercise, avoid prolonged standing/sitting.

Anaemia

  • Definition: Reduced number of functioning RBCs, decreasing oxygen delivery to tissues.

  • Causes: Decreased RBC production, premature destruction, Hb deficiency, excessive loss.

  • Pathophysiology: Decreased RBCs → decreased oxygen-carrying capacity → hypoxia. Compensatory mechanisms include increased HR/CO, blood redirection.

  • Types: Aplastic, Pernicious (B12B12 deficiency), Iron deficiency, Folic acid deficiency, Haemolytic, Sickle cell.

  • Clinical Manifestations: Weakness, pallor, dizziness, dyspnea, cyanosis.

  • Medical Management: Identify/manage underlying causes, oxygen, erythropoietin, iron supplements.

Coronary Artery Disease (CAD)

  • Definition: Impairment of heart function due to imbalance between myocardial oxygen supply and demand.

  • Types of Angina: Stable, Unstable, Nocturnal, Variant.

  • Risk Factors: Age, gender, family history, smoking, poor diet, high stress, obesity, inactivity.

  • Causes: Decreased O2 vs O2 demand (hypertension, valvular disease, fever).

  • Pathophysiology: Atheromatous plaques narrow/obstruct coronary arteries → clot formation → occlusion → myocardial ischemia → angina pectoris and MI.

  • Clinical Manifestations: Chest pain, possibly radiating to jaw, neck, back, shoulder, epigastric area.

  • Management: Control risk factors, diet, nitrates. Pre/post-procedure care for diagnostic tests (e.g., angiogram).