💊Pharmacology for Nurses Unit 16 – Cardiovascular System Basics

Anatomy and Physiology Basics

• Cardiovascular system consists of the heart, blood vessels, and blood which work together to deliver oxygen and nutrients to tissues and remove waste products
• Heart is a muscular organ about the size of a fist located in the chest cavity between the lungs
  • Divided into four chambers: right atrium, right ventricle, left atrium, and left ventricle
  • Right side of the heart pumps deoxygenated blood to the lungs (pulmonary circulation)
  • Left side of the heart pumps oxygenated blood to the body (systemic circulation)
• Blood vessels include arteries, capillaries, and veins
  • Arteries carry blood away from the heart and have thick, elastic walls to withstand high pressure
  • Capillaries are tiny, thin-walled vessels that allow exchange of nutrients, oxygen, and waste products between blood and tissues
  • Veins carry blood back to the heart and have thinner walls and valves to prevent backflow
• Cardiac cycle refers to the sequence of events that occur during one heartbeat, including systole (contraction) and diastole (relaxation)
• Cardiovascular system is regulated by the autonomic nervous system, hormones, and local factors to maintain homeostasis

Key Components of the Cardiovascular System

• Myocardium is the muscular layer of the heart wall responsible for contraction and pumping blood
• Endocardium is the inner lining of the heart chambers and valves that prevents blood clotting and provides a smooth surface for blood flow
• Pericardium is a double-layered sac that surrounds and protects the heart, reducing friction during heartbeats
• Coronary arteries supply oxygenated blood to the heart muscle itself
• Heart valves (tricuspid, pulmonary, mitral, and aortic) ensure unidirectional blood flow and prevent backflow
• Sinoatrial (SA) node, located in the right atrium, acts as the heart's natural pacemaker by generating electrical impulses that initiate heartbeats
• Atrioventricular (AV) node, located between the atria and ventricles, delays electrical impulses to allow atrial contraction before ventricular contraction

Blood Flow and Circulation

• Pulmonary circulation carries deoxygenated blood from the right ventricle to the lungs for oxygenation and returns oxygenated blood to the left atrium
• Systemic circulation carries oxygenated blood from the left ventricle to the body's tissues and returns deoxygenated blood to the right atrium
• Coronary circulation supplies oxygenated blood to the heart muscle through the coronary arteries
• Hepatic portal circulation carries nutrient-rich blood from the digestive system to the liver for processing before returning to the systemic circulation
• Cerebral circulation supplies oxygenated blood to the brain through the carotid and vertebral arteries
• Renal circulation supplies the kidneys with blood for filtration and waste removal
• Cardiac output is the volume of blood pumped by the heart per minute, calculated as stroke volume (volume of blood pumped per beat) multiplied by heart rate

Common Cardiovascular Disorders

• Hypertension (high blood pressure) can lead to heart disease, stroke, and kidney damage if left untreated
• Atherosclerosis is the buildup of plaque in the arteries, narrowing the vessels and reducing blood flow
• Coronary artery disease (CAD) occurs when the coronary arteries become narrowed or blocked, reducing blood supply to the heart muscle
• Myocardial infarction (heart attack) happens when a portion of the heart muscle dies due to a lack of blood supply, often caused by a blocked coronary artery
• Heart failure occurs when the heart is unable to pump enough blood to meet the body's needs, leading to fluid buildup and shortness of breath
• Arrhythmias are abnormal heart rhythms that can be too fast (tachycardia), too slow (bradycardia), or irregular
• Valvular heart disease involves damage or defects in the heart valves, affecting blood flow and potentially leading to heart failure

Pharmacological Interventions

• Antihypertensive medications (ACE inhibitors, beta-blockers, calcium channel blockers, diuretics) are used to lower blood pressure and reduce the risk of complications
• Antiplatelet drugs (aspirin, clopidogrel) prevent blood clots from forming and reduce the risk of heart attack and stroke
• Anticoagulants (heparin, warfarin) are used to prevent or treat blood clots, especially in patients with atrial fibrillation or deep vein thrombosis
• Thrombolytics (tissue plasminogen activator) are used to dissolve blood clots in the event of a heart attack or stroke
• Statins (atorvastatin, simvastatin) lower cholesterol levels and reduce the risk of atherosclerosis and heart disease
• Nitrates (nitroglycerin) dilate blood vessels and improve blood flow to the heart, relieving chest pain (angina)
• Inotropic agents (dobutamine, milrinone) increase the force of heart contractions and improve cardiac output in patients with heart failure

Nursing Considerations and Patient Care

• Assess and monitor vital signs, including blood pressure, heart rate, and oxygen saturation, to detect any changes or abnormalities
• Administer medications as prescribed and educate patients on proper use, side effects, and importance of adherence
• Encourage lifestyle modifications, such as maintaining a healthy diet, exercising regularly, quitting smoking, and managing stress
• Provide emotional support and education to patients and their families, addressing concerns and promoting self-care
• Assist with diagnostic tests and procedures, such as electrocardiograms (ECGs), echocardiograms, and stress tests
• Monitor fluid balance and adjust intake and output as needed, especially in patients with heart failure
• Collaborate with the interdisciplinary team to develop and implement individualized care plans based on patient needs and goals

Monitoring and Assessment Techniques

• Electrocardiogram (ECG) records the heart's electrical activity and can detect arrhythmias, ischemia, and other abnormalities
• Echocardiogram uses ultrasound to visualize the heart's structure and function, assessing valve function, chamber size, and ejection fraction
• Cardiac catheterization involves inserting a catheter into the heart to measure pressures, assess coronary artery blockages, and perform interventions (angioplasty, stenting)
• Stress tests evaluate the heart's response to physical exertion or pharmacological stimulation, detecting ischemia and assessing exercise tolerance
• Holter monitoring involves wearing a portable ECG device for 24-48 hours to detect intermittent arrhythmias or ischemia
• Pulse oximetry measures the oxygen saturation of the blood and can indicate the presence of hypoxia or other respiratory issues
• Cardiac biomarkers (troponin, creatine kinase) are blood tests that can detect heart muscle damage and aid in the diagnosis of myocardial infarction

Special Populations and Considerations

• Elderly patients may have a higher risk of cardiovascular disease due to age-related changes and comorbidities, requiring close monitoring and individualized care
• Pregnant women experience physiological changes that can affect cardiovascular function, such as increased blood volume and cardiac output
  • Some medications may be contraindicated during pregnancy due to potential fetal harm
• Pediatric patients have unique anatomical and physiological characteristics that require specialized care and age-appropriate interventions
• Patients with chronic conditions (diabetes, chronic kidney disease) may have an increased risk of cardiovascular complications and require close monitoring and management
• Cultural and linguistic differences may impact patient education, adherence to treatment, and healthcare access, necessitating culturally competent care and the use of interpreters when needed
• Palliative and end-of-life care focuses on symptom management, comfort, and quality of life for patients with advanced or terminal cardiovascular disease
  • Nurses play a crucial role in providing emotional support and facilitating discussions about goals of care and advance directives