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).

  • Chambers are separated by valves 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: Carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.

  • Systemic circulation: Delivers oxygenated blood from the left ventricle to the body and returns deoxygenated blood to the right atrium.

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)

  • The heart can adjust cardiac output to meet the body's metabolic needs.

• 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.

Anatomical and Pathophysiological Considerations

Infants and Children

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

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

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

Older Adults – Haemodynamic Changes

• The aging process is influenced by lifestyle 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 increase cardiac output during 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 aged 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: Increased activity reduces risk of death from CVD and respiratory illnesses.

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

Physical Examination Steps

• Inspection:

  • Inspect 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.

  • Note rate and rhythm; compare with radial pulse.

Application of Anti-Embolic Stockings

Purpose and Indications

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

• Assess limb size, skin integrity, and suitability before application.

• Contraindications include severe peripheral arterial disease, recent skin grafts, and fragile skin.

Application Steps

• Measure the patient's limb to select the correct size.

• Inspect the skin for any lesions or conditions that may contraindicate use.

• Apply stockings smoothly, avoiding wrinkles or folds.

• Monitor for signs of impaired circulation (e.g., discoloration, pain, numbness).

Contraindications

• Severe peripheral arterial disease

• Recent skin grafts

• Fragile or damaged skin

• Cardiac failure (in some cases)

Additional info: Anti-embolic stockings are also known as graduated compression stockings and are commonly used post-operatively or in immobile patients to reduce the risk of deep vein thrombosis (DVT).