Overview of the Cardiovascular System

Structure and Function

The cardiovascular system is responsible for the circulation of blood throughout the body, delivering oxygen and nutrients while removing waste products. It consists of the heart, blood vessels, and blood.

• Layers of the Heart Wall:

  • Pericardium: The outer protective sac surrounding the heart.

  • Myocardium: The thick, muscular middle layer responsible for heart contractions.

  • Endocardium: The inner lining of the heart chambers and valves.

• Heart Chambers:

  • Four chambers: two atria (upper) and two ventricles (lower).

  • Valves separate chambers to prevent backflow of blood.

• Great Vessels: Major arteries and veins connected to the heart, including the ascending aorta, superior and inferior vena cava, and pulmonary veins.

• Circulatory Loops:

  • Pulmonary circulation: Blood flow between the heart and lungs.

  • Systemic circulation: Blood flow between the heart and the rest of the body.

Cardiovascular System – Additional Terminology

Key Hemodynamic Concepts

• Cardiac Output (CO): The volume of blood the heart pumps per minute. In a resting adult, this is typically 4–6 L/min.

  • Formula:

  • HR: Heart rate (beats per minute)

  • SV: Stroke volume (volume of blood ejected per beat)

• Preload: The degree of stretch of the heart muscle at the end of diastole, related to venous return.

  • According to the Frank-Starling law, increased stretch leads to stronger contraction and increased stroke volume.

• Afterload: The resistance the left ventricle must overcome to circulate blood, primarily determined by aortic pressure.

Example: During exercise, increased venous return (preload) and sympathetic stimulation increase cardiac output to meet metabolic demands.

Anatomical and Pathophysiological Considerations

Infants and Children

• At birth, oxygenation shifts from the placenta to the lungs.

• By 1 year, the left ventricle's mass reaches the adult ratio of 2:1 compared to the right ventricle.

• Heart murmurs are common in childhood (approx. 30%) and are often benign.

Older Adults – Hemodynamic Changes

• Aging is associated with lifestyle factors and underlying disease.

• Increased systolic blood pressure (BP): Due to thickening and stiffening of large arteries (arteriosclerosis).

• Increased left ventricular wall thickness.

• Diastolic BP may decrease after age 60.

• Reduced ability to augment cardiac output with exercise.

• No significant change in resting heart rate or cardiac output with age.

• Increased risk of dysrhythmias and bundle branch block; ectopic beats are common but usually asymptomatic.

Cardiovascular Conditions – Older Adult

Common Disorders and Risk Factors

• Cardiovascular Disease (CVD): Includes coronary heart disease, stroke, and heart failure.

  • Incidence increases sharply with age; accounts for ~89% of deaths in adults aged 65+.

  • Underlying cause of 25% of all deaths in Australia (2021 data).

• Hypertension: BP ≥ 140/90 mmHg; incidence increases with age. Chronic hypertension damages the heart and other organs.

• Congestive Cardiac Failure: Adults 75+ have a tenfold higher risk than younger adults.

• Peripheral Arterial Disease (PAD): Risk increases with comorbidities such as diabetes.

• Atrial Fibrillation (AF): A common arrhythmia; risk increases with age.

• Physical activity reduces risk of cardiovascular and respiratory diseases in older adults.

Risk Factors for CVD

Cardiovascular Assessment

Subjective Data Collection

Subjective data involves information reported by the patient regarding symptoms and history.

• Chest pain

• Dyspnoea (shortness of breath)

• Orthopnoea (difficulty breathing when lying flat)

• Cough

• Fatigue

• Cyanosis or pallor

• Oedema (swelling)

• Nocturia (nighttime urination)

• Personal and family cardiac history

• Patient-centered care (identification of cardiac risk factors)

Additional History: Infants, Children, and Older Adults

Preparation and Equipment for Cardiovascular Assessment

Preparation

• To evaluate carotid arteries: patient may be sitting.

• To assess jugular veins and precordium: patient should be supine with head and chest slightly elevated.

• Ensure privacy, especially for female patients.

Equipment

• Marking pen

• Small centimeter ruler

• Stethoscope (diaphragm and bell)

• Alcohol wipe for cleaning

• Perform hand hygiene before and after assessment

Cardiovascular Assessment – Objective Data

Inspection, Palpation, and Auscultation

• Inspection: Observe jugular venous pulse and anterior chest for pulsations.

• Palpation:

  • Palpate one carotid artery at a time to avoid compromising cerebral blood flow.

  • Palpate apical pulse (note location, size, amplitude, duration).

  • Palpate across precordium for abnormal pulsations.

• Auscultation:

  • Auscultate apical pulse at the 5th intercostal space, midclavicular line.

  • Use both diaphragm and bell of stethoscope.

  • Compare apical and radial pulse rates.

Application of Anti-Embolic Stockings

Purpose and Procedure

Anti-embolic stockings are used to prevent venous thromboembolism by promoting venous return in the lower limbs.

• Assess limb size and skin integrity before application.

• Ensure correct sizing and fit to avoid constriction or skin damage.

• Monitor for contraindications such as peripheral arterial disease, recent skin grafts, or fragile skin.

Contraindications

• Peripheral arterial disease

• Cardiac/heart failure

• Recent skin grafts or fragile skin

Example: Anti-embolic stockings are commonly used post-operatively to reduce the risk of deep vein thrombosis (DVT).

Additional info: The above notes are expanded with standard academic context for clarity and completeness, suitable for college-level Anatomy & Physiology students.