Domain 2.3Anatomy and Physiology

Cardiovascular System And Common Diseases

Last updated June 16, 2026

Overview

Welcome to your study guide for the Cardiovascular System! As a Medical Assistant, this is perhaps the most critical system you will interact with daily. From taking blood pressure and performing EKGs to recognizing the signs of a heart attack in the waiting room, your knowledge here directly impacts patient survival.

Why This Matters:

  • Emergency Response: You are often the first to interact with a patient. Recognizing chest pain or stroke symptoms immediately can save a life.
  • Procedural Skills: You will likely perform EKGs (Electrocardiograms) and apply Holter monitors. Understanding the anatomy helps you place leads correctly.
  • Vital Signs: You must understand what blood pressure actually measures (peripheral resistance) to interpret accurate readings.
  • Patient Education: You will reinforce provider instructions regarding diet, exercise, and medication compliance for chronic conditions like hypertension.

1. Anatomy and Physiology

To understand heart disease, you must first master the normal structure and function of the heart and vessels.

The Heart: Structure and Conduction

The heart is a hollow, muscular pump located in the thoracic cavity.

  • Layers of the Heart:
    • Pericardium: The sac surrounding the heart.
    • Myocardium: The thick muscle layer responsible for the contraction.
    • Endocardium: The smooth inner lining.
  • The Chambers:
    • Atria (Right and Left): The top chambers that receive blood.
    • Ventricles (Right and Left): The bottom chambers that pump blood out. The Left Ventricle is the thickest and strongest chamber because it pumps blood to the entire body.
  • The Valves:
    • Tricuspid Valve: Between Right Atrium and Right Ventricle.
    • Bicuspid (Mitral) Valve: Between Left Atrium and Left Ventricle.
  • The Conduction System (Electrical):
    • Sinoatrial (SA) Node: The natural pacemaker of the heart. It initiates the electrical impulse.
    • Atrioventricular (AV) Node: The "gatekeeper" that briefly delays the signal to allow ventricles to fill.
    • Bundle of His & Purkinje Fibers: Distribute the impulse to the ventricles, causing contraction.

Exam Tip (Blood Flow Order): You MUST memorize the path of blood through the heart. Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonic Valve → Pulmonary Artery (to lungs) → Pulmonary Veins (from lungs) → Left Atrium → Mitral Valve → Left Ventricle → Aortic Valve → Aorta → Body.

Mnemonic: Tissue Paper My Assets (Tricuspid, Pulmonic, Mitral, Aortic).

Blood Vessels

The "plumbing" of the body.

Vessel Type Function Characteristics
Arteries Carry blood Away from the heart. Thick, muscular walls to withstand high pressure. Palpable pulse. Carry oxygenated blood (except the Pulmonary Artery).
Veins Carry blood Toward the heart. Thinner walls. Contain valves to prevent backflow. Carry deoxygenated blood (except Pulmonary Veins).
Capillaries Connect arterioles to venules. One cell thick. The site of gas and nutrient exchange between blood and cells.

Blood Components

  • Erythrocytes (RBCs): Contain hemoglobin to carry oxygen.
  • Leukocytes (WBCs): Fight infection.
  • Thrombocytes (Platelets): Essential for clotting (hemostasis).
  • Plasma: The liquid portion of the blood.

2. Common Cardiovascular Diseases and Conditions

Hypertension (HTN)

Definition: Often called the "Silent Killer," this is a chronic elevation of blood pressure in the arteries. It puts strain on the heart and damages blood vessels over time.

  • Signs & Symptoms: Usually asymptomatic (no symptoms) until severe. In crisis: headache, blurred vision, nosebleeds (epistaxis), dizziness.
  • Risk Factors: High sodium intake, obesity, smoking, stress, African American heritage, family history.
  • Diagnostic Findings (AHA Guidelines):
    • Normal: < 120 / < 80
    • Elevated: 120–129 / < 80
    • Stage 1: 130–139 / 80–89
    • Stage 2: ≥ 140 / ≥ 90
    • Hypertensive Crisis: > 180 / > 120 (Medical Emergency)
  • Treatment Highlights:
    • Lifestyle: Low sodium diet (DASH diet), weight loss, exercise.
    • Meds: Diuretics ("water pills"), Beta-blockers, ACE inhibitors.

Coronary Artery Disease (CAD)

Definition: The narrowing or blockage of the coronary arteries (the vessels that supply blood to the heart muscle itself). This is usually caused by Atherosclerosis (plaque buildup of fat/cholesterol).

  • Signs & Symptoms: Angina Pectoris (chest pain), shortness of breath (dyspnea).
  • Risk Factors: High cholesterol (High LDL), smoking, diabetes, hypertension, physical inactivity.
  • Diagnostic Findings: High lipid profile (Cholesterol > 200), abnormal stress test, blockage visible on Angiogram.
  • Treatment Highlights:
    • Statins: Medications to lower cholesterol.
    • Angioplasty: Surgical repair of a vessel using a balloon and stent.

Myocardial Infarction (MI)

Definition: Commonly known as a Heart Attack. Occurs when blood flow to a part of the heart is completely blocked for a long enough time that part of the heart muscle dies (necrosis).

  • Signs & Symptoms:
    • Crushing chest pain/pressure (often radiating to the left arm, jaw, or back).
    • Diaphoresis (heavy sweating).
    • Nausea/Vomiting.
    • Note: Women often present differently (fatigue, jaw pain, indigestion) than men.
  • Risk Factors: CAD, previous heart attack, smoking.
  • Diagnostic Findings:
    • EKG: ST-segment elevation ("STEMI").
    • Labs: Elevated Troponin levels (cardiac enzyme released when heart muscle is damaged).
  • Treatment Highlights:
    • Immediate: MONA (Morphine, Oxygen, Nitroglycerin, Aspirin).
    • Time is Muscle: Rapid transport to a cath lab is critical.

Clinical Application: If a patient complains of chest pain in the office, stop what you are doing. Sit them down, notify the provider immediately, and be prepared to perform an EKG and obtain vital signs.

Congestive Heart Failure (CHF)

Definition: A chronic condition where the heart muscle is too weak to pump blood effectively to meet the body's needs. Fluid backs up (congests) in the body.

  • Signs & Symptoms:
    • Left-Sided Failure: Fluid backs up into the Lungs. Symptoms: Shortness of breath (dyspnea), crackles/rales on auscultation, orthopnea (cannot breathe while lying flat).
    • Right-Sided Failure: Fluid backs up into the Body. Symptoms: Peripheral edema (swollen legs/feet), distended neck veins (JVD), ascites.
  • Risk Factors: Long-term hypertension, previous MI, valve disorders.
  • Diagnostic Findings: Elevated BNP (B-type Natriuretic Peptide) lab test; Echocardiogram showing low ejection fraction.
  • Treatment Highlights:
    • Diuretics (e.g., Lasix/Furosemide): To help the kidneys remove excess fluid.
    • Daily Weight: Patients must weigh themselves daily to monitor fluid retention.

Exam Tip: Remember Left = Lungs (respiratory symptoms). Right = Rest of body (swelling/edema).

Atrial Fibrillation (A-Fib)

Definition: An irregular, rapid heart rate that causes poor blood flow. The atria "quiver" instead of beating effectively.

  • Signs & Symptoms: Palpitations ("fluttering" in chest), fatigue, shortness of breath, dizziness.
  • Risk Factors: Age, heart disease, alcohol use.
  • Diagnostic Findings:
    • EKG: "Irregularly irregular" rhythm. No distinct P-waves are visible (replaced by wavy lines).
  • Treatment Highlights:
    • Anticoagulants (Blood Thinners): The biggest risk of A-Fib is blood pooling in the atria, forming a clot, and causing a Stroke. Patients are placed on Warfarin or newer thinners.

Aneurysms

Definition: A ballooning and weakened area in an artery. The most common location is the Abdominal Aortic Aneurysm (AAA).

  • Signs & Symptoms: Often asymptomatic. May cause a pulsating mass in the abdomen or deep back pain.
  • Risk Factors: Atherosclerosis, smoking, hypertension.
  • Diagnostic Findings: Ultrasound or CT scan showing the bulge.
  • Treatment Highlights:
    • Monitoring size.
    • Surgical repair if the risk of rupture is high.
    • Emergency: A ruptured aneurysm causes rapid internal bleeding and hypovolemic shock.

3. Diagnostic Tests and Procedures

As an MA, you will perform or prepare patients for these specific cardiac tests.

Test Description MA Role/Key Info
Electrocardiogram (EKG/ECG) Records the electrical activity of the heart. V1-V6 are the chest (precordial) leads. Skin must be dry and free of hair/oil for electrodes to stick.
Holter Monitor A portable EKG worn for 24-48 hours. Instruct patient: Do not shower/bathe with it on. Keep a diary of symptoms and activities.
Echocardiogram Ultrasound of the heart. Uses sound waves to visualize valves and wall motion. Non-invasive.
Stress Test EKG performed while patient exercises (treadmill). Used to detect coronary artery blockages that only appear under stress.
Angiography (Cardiac Cath) Invasive procedure using contrast dye to see blockages. Dye is injected via femoral or radial artery. Check for Shellfish/Iodine allergy before the test.
Lipid Panel Blood test for cholesterol. Patient should be fasting (usually 8-12 hours).

4. Final Key Takeaways

  • Blood Flow Path: Memorize the path from Right Atrium to Aorta. Remember: Arteries = Away, Veins = Toward.
  • Electrical Path: SA Node (Pacemaker) → AV Node → Bundle of His → Purkinje Fibers.
  • Hypertension: Know the cutoff for Stage 1 (130/80) and Stage 2 (140/90).
  • MI vs. Angina: Angina is temporary pain relieved by rest/nitro; MI is tissue death with persistent pain.
  • Left vs. Right Heart Failure: Left = Lungs (shortness of breath). Right = Edema (swelling legs).
  • Cholesterol: HDL is Healthy (want it High). LDL is Lousy (want it Low).
  • A-Fib Danger: The primary complication of Atrial Fibrillation is a Stroke caused by a blood clot.
  • Patient Safety: Before an MRI, ensure the patient has no pacemaker. Before a CT with contrast, check for iodine allergies and kidney function (Creatinine).