Cardiovascular System Notes

Key Concepts

  • Self-management

  • Fluid and electrolytes

  • Nutrition

  • Perfusion

  • Inflammation

  • Tissue integrity

  • Fatigue

  • Stress

Overview of Anatomy and Physiology

  • Heart Structures and Functions:

    • Epicardium: Outer layer of heart tissue.

    • Myocardium: Middle layer of muscle fibers that contract.

    • Endocardium: Lining of inner surface of heart chambers.

    • Pericardium: Double-layered sac that:

      • Provides a barrier to infection.

      • Prevents displacement of the heart.

      • Elicits changes in heart rate/blood pressure.

    • Right side of the heart:

      • Low-pressure pump.

      • Receives deoxygenated blood and pumps it to the lungs.

    • Left side of the heart:

      • High-pressure pump.

      • Receives oxygenated blood and pumps it to the body.

    • Cardiac valves direct blood flow through heart chambers.

    • Pulmonary artery carries deoxygenated blood away from the heart.

    • Pulmonary veins carry oxygenated blood toward the heart.

  • Contraction of the Heart:

    • Spontaneous electrical activity by pacemaker cells and conduction fibers causes muscle contractions resulting in a heartbeat.

    • Sinoatrial (SA) node:

      • Located in the right atrium.

      • "Pacemaker" of the heart because it initiates electrical impulses.

    • AV node relays impulse from SA node to Bundle of His and ventricles via Purkinje fibers.

    • Heart rate and rhythm are influenced by the autonomic nervous system, which can speed up or slow down.

  • Cardiac Cycle:

    • Systole: Contraction of muscle.

    • Diastole: Relaxation of muscle.

    • Heart pumps out 5 L of blood/minute.

    • Stroke volume: Amount of blood ejected by the ventricle in one contraction.

    • Cardiac output: Stroke volume multiplied by heart rate. Cardiac Output = Stroke Volume \times Heart Rate

    • Ejection fraction:

      • Percentage of blood ejected from the left ventricle during systole.

      • Normal is 50% to 70%.

      • Decreases with heart failure, diminishes tissue perfusion, blood backs up into pulmonary vessels, and can cause pulmonary edema.

  • Blood Flow:

    • Arteries carry oxygenated blood away from the heart, and veins carry oxygen-depleted blood back to the heart (except for pulmonary artery and veins).

    • Venules and arterioles in capillaries participate in the exchange of oxygen and wastes.

    • Aorta is the largest artery in the body.

    • Inferior and superior vena cava are the largest veins in the body.

    • Valves in veins keep blood flowing toward the heart against gravity.

  • Blood Pressure:

    • Systole: Ventricular contraction when blood is ejected into the aorta (highest pressure).

    • Diastole: When ventricles are in the relaxation phase.

    • Pulse pressure: Difference between systolic and diastolic pressures. Pulse Pressure = Systolic Pressure - Diastolic Pressure

    • Atherosclerosis: Fatty deposits/plaques narrow blood vessels, causing increased blood pressure.

    • Increased vessel diameter leads to decreased blood pressure.

    • Sympathetic nervous system regulates vessel diameter.

    • Increased viscosity of the blood increases blood pressure.

  • Cardiovascular System Changes Related to Aging:

    • Aging heart becomes stiffer and less able to contract, so stroke volume decreases.

    • Coronary arteries dilate and have areas of calcification.

    • Cardiac valves become thickened; systolic murmur is common over age 80.

    • SA node loses pacemaker cells, making older adults more prone to dysrhythmias.

    • The aorta becomes stiffer, causing an increase in systolic pressure (hypertension is NOT a normal part of aging).

    • Veins lose elasticity, and valve function decreases, causing varicose veins.

    • Platelet aggregation and potential for increased coagulation lead to a greater risk of thrombus formation.

Cardiovascular Disease

  • Includes congenital heart disease (CHD), heart failure, stroke, hypertension.

  • Affects about 50% of the population in the US. If hypertension is removed, about 10% of people have CVD.

  • Nearly a million people die each year.

  • Many conditions can be prevented or controlled.

  • Women and Heart Disease:

    • Incidence between men and women is equal, but more women die.

    • Prevention: Regular physical activity, manage cholesterol, no smoking, maintain healthy weight, no more than one alcoholic drink daily, stress reduction exercises, control blood pressure/blood sugar as indicated.

  • Causes of Cardiovascular Disorders:

    • Congenital: Coarctation (narrowing) of the aorta, holes in the septum, abnormal formation of valve.

    • Acquired:

      • Arteriosclerosis, atherosclerosis, aneurysms, inflammation of valves, hypertrophy, ischemia/infarct, heart failure, disturbances in the heart’s conduction system, infection/inflammation, rheumatic heart disease, injury to artery walls due to hypertension.

      • Caused by substance use, alcoholism, diabetes, smoking, high levels of LDL/low levels of HDL, obesity, emotional stress, hypertension.

  • Prevention of Cardiovascular Disease:

    • CVD accounts for 1 in 3 deaths in the US and accounts for a large percentage of chronic illnesses and disability.

    • Nurses have a responsibility to educate about heart disease/prevention.

    • Nonmodifiable risk factors: Heredity, race, sex (men have more MIs early in life, men and women are equal later in life), age.

    • Modifiable risk factors: Hypertension/diabetes, high cholesterol, smoking, drug use (cocaine, methamphetamine), obesity, sedentary lifestyle, excessive emotional stress, excessive alcohol use.

  • Diagnostic Tests and Procedures:

    • Least invasive first.

    • Cardiac monitoring:

      • Continuous monitoring (telemetry) for patients admitted for cardiac issues, postoperative, or at risk for dysrhythmias.

    • Electrocardiography (ECG/EKG):

      • Determine rate, rhythm, pacemaker, injury at rest.

    • Holter monitor/loop recorder:

      • Portable EKGs record rhythm over hours, days, weeks, or months.

    • Stress test:

      • Exercise (treadmill) or chemical (medications) to determine how the heart reacts to increasing levels of exercise.

      • Chemical stress tests are for patients who cannot tolerate exercise.

    • Echocardiography/stress echocardiogram:

      • Evaluates size, shape, structures, and movement of the heart.

      • Before and after exercise to determine the difference.

    • CT, MRI, PET:

      • Determines size/condition of vessels/cardiac tissue/aneurysms, patency of vessels, myocardial perfusion.

    • Angiogram/arteriogram:

      • Invasive, involves injection of contrast dye to visualize vessel anatomy.

      • A stent may be placed during the procedure to keep the vessel open.

    • Cardiac catheterization:

      • Assesses the size/patency of coronary arteries, pumping action of the left side of the heart, assesses the degree of narrowing and material causing the narrowing.

      • Possible intervention as needed.

    • Right heart hemodynamic monitoring via pulmonary artery (PA) catheter (Swan-Ganz).

    • Laboratory tests:

      • B-type natriuretic peptide (BNP), C-reactive protein (CRP), serum lipids, myoglobin, troponin, creatinine phosphokinase (CPK), CK-MB (creatinine kinase), homocysteine, myeloperoxidase (MPO).

  • Specific Tests for Vascular Disorders:

    • History and physical.

    • CBC, urinalysis, lipid/cholesterol, metabolic panel, kidney/liver function, electrolytes, blood glucose.

    • Doppler to detect venous thrombus.

    • Ankle-brachial index (ABI) to evaluate arterial status in lower extremities.

      • Calculated by dividing systolic ankle pressure by systolic brachial pressure. ABI = \frac{Systolic Ankle Pressure}{Systolic Brachial Pressure}

      • ABI of 1 is normal; less than 0.9 indicates a vascular cause for ischemic pain in the legs.

Nursing Management

  • Assessment/Data Collection:

    • History taking:

      • Determine the presence of risk factors.

      • Develop trusting/therapeutic rapport/relationship to gather details patients may not necessarily want to share ("junk food"/diet, emotional stressors).

      • Sensitive phrasing to elicit honest responses.

      • Effective communication to gain information/plan for teaching.

      • Thorough medication history, including OTC/herbals/supplements.

      • Ask about chest pain/associated symptoms, palpitations, coughing, smoking history, history of chronic illness, family history, stress/coping mechanisms, cultural competence-cultural/religious observances/diet.

    • Physical assessment:

      • Observe for pallor/discoloration of skin, edema.

      • Auscultate heart sounds/apical pulse (listen for a full minute).

        • Use the bell to listen for murmurs.

      • Obtain vital signs.

      • Pulses:

        • Rate, rhythm, character.

        • Compare bilaterally.

      • Bruits:

        • Listen with the bell for whooshing or purring sounds.

      • Blood pressure:

        • Make sure you have the correct cuff size.

        • Ask the patient about anything in the last 30 minutes that could impact blood pressure.

        • Orthostatic/postural hypotension: Drop of 20 mmHg systolic or drop of 10 mmHg diastolic.

      • Skin:

        • Consider the temperature of the environment.

        • Color, temperature, presence of edema.

        • Chronic insufficiency: Shiny, smooth skin with no hair/thick, yellow nails.

  • Problem Statement/Nursing Diagnosis, Planning, and Implementation:

    • Decreased activity tolerance, impaired tissue perfusion, risk for decreased cardiac output.

    • Promote a healthy lifestyle to prevent CVD by addressing childhood obesity and blood pressure/blood sugar control.

    • Plan activities to conserve the patient’s energy.

    • Obtain blood pressure/heart rate before medication administration; follow parameters.

    • Administer medications as ordered, monitor I & O, use TED hose/SCDs as indicated, promote comfort, psychosocial support, and patient education.

  • Collaboration:

    • Open communication:

      • Often involves a dietitian, nursing, physical therapy, primary care provider, respiratory therapy, cardiologist, and home care professionals.

    • Begin discharge planning/referrals early.

  • Evaluation:

    • Monitor for effectiveness of medications, side/adverse effects.

    • Laboratory results.

    • Look at trends of information, serial blood pressure readings.

    • Heavy on subjective information from the patient.

    • Discontinue and revise plan as needed.

Common Problems of Patients with Cardiovascular Disorders

  • Fatigue and Dyspnea:

    • Caused by general hypoxia of tissue due to the inability of coronary arteries to supply oxygen to the heart.

    • Activity restrictions initially; monitor telemetry closely as activity level is increased.

    • Heart rate does not rise more than 20 over baseline, systolic pressure does not drop, no complaints of chest pain/dyspnea/fatigue, no dysrhythmia.

  • Edema:

    • Fluid backs up in vessels and leaks into tissues when the heart does not pump effectively.

    • Daily weight is the best way to assess fluid balance.

      • Use the same scale at the same time every day before breakfast.

  • Pain:

    • Chest pain can be indicative of a life-threatening event.

    • Assess carefully, including associated symptoms (nausea, vomiting, palpitations).

    • Restore oxygen supply to the heart and relieve symptoms.

      • MONA: Morphine, oxygen, nitroglycerin, aspirin.

  • Altered Tissue Perfusion:

    • Avoid extremes of heat and cold.

    • Provide a warm environment to keep vessels relaxed and prevent blood flow from being sluggish.

    • Elevate extremities periodically to encourage venous return to the heart.

    • Exercise, especially walking, to promote blood flow.

  • Impaired Tissue Integrity:

    • Tissues with a poor blood supply are at risk of severe, irreversible damage due to the excessively slow healing.

    • Avoid injury and report even the most minor of injuries.

    • Stasis ulcers are common and chronic.

      • Heal very slowly and may NEVER heal COMPLETELY.

    • Prevention:

      • TED hose/elastic stockings/support hose.

      • Positioning and exercise.

      • Preventing injury.

      • Avoiding extremes of heat and cold.