2026%20circulaation

Circulation

Definitions

  • Circulation: The blood flow throughout the heart and the blood vessels. This process is essential for transporting nutrients and oxygen to tissues while removing carbon dioxide and waste.

  • Perfusion: The process of delivering oxygenated blood to the body's tissues and organs, ensuring that they receive the necessary substances to function properly.

  • Deoxygenated Blood: Blood that returns from the body to the right atrium via the superior vena cava after delivering its oxygen and nutrients.

  • Oxygenated Blood: Blood that has been enriched with oxygen from the lungs and enters the left ventricle, eventually being pumped throughout the body via the aorta.

Structures of the Heart

The heart consists of several essential structures:

  • Right Atrium: Receives deoxygenated blood from the body.

  • Tricuspid Valve: Prevents backflow of blood from the right ventricle to the right atrium.

  • Right Ventricle: Pumps deoxygenated blood to the lungs.

  • Pulmonic Valve: Guards the opening between the right ventricle and the pulmonary arteries.

  • Pulmonary Arteries: Carry deoxygenated blood from the right ventricle to the lungs.

  • Pulmonary Veins: Return oxygenated blood from the lungs back to the left atrium.

  • Left Atrium: Receives oxygenated blood from the lungs.

  • Mitral Valve: Prevents backflow of blood from the left ventricle to the left atrium.

  • Aortic Valve: Regulates blood flow from the left ventricle into the aorta.

  • Aorta: The main artery carrying oxygenated blood from the heart to the rest of the body.

Blood Flow through the Heart

The pathway of blood flow through the heart involves a systematic route that includes:

  1. Deoxygenated Blood Flow: Enters through the superior and inferior vena cavae into the right atrium.

  2. Passes through the Tricuspid Valve into the right ventricle.

  3. From the right ventricle, blood is pumped through the pulmonic valve into the pulmonary arteries leading to the lungs for oxygenation.

  4. After oxygenation, blood returns via the pulmonary veins into the left atrium.

  5. It flows through the mitral valve into the left ventricle.

  6. Blood is then pumped through the aortic valve into the aorta, distributing oxygenated blood to the body.

Layers of the Heart

  • The heart is comprised of three layers:

    • Epicardium: The outermost layer, which provides a protective layer.

    • Myocardium: The middle layer, consisting of cardiac muscle responsible for the heart's contraction.

    • Endocardium: The innermost layer that lines the chambers and valves of the heart.

Electrophysiology

Understanding the heart's electrical system involves several key components:

  • Sino-atrial Node (SA Node): The primary pacemaker of the heart, located in the right atrium.

  • Bachman's Bundle: A tract that conducts impulses from the SA node to the left atrium.

  • Intranodal Pathways: Pathways that conduct impulses from the SA node to the AV node.

  • Atrioventricular Node (AV Node): Acts as a relay station that slows impulses before they enter the ventricles.

  • Bundle of His: A pathway that conducts impulses from the AV node into the ventricles.

  • Right and Left Bundle Branches: Conduct impulses along the left and right sides of the interventricular septum to the ventricles.

  • Purkinje Fibers: Terminal fibers that distribute impulses throughout the ventricular muscle, facilitating contraction.

How Oxygen (O2) and Carbon Dioxide (CO2) are Transported

Hemoglobin

  • Oxygen Transport:

    • 97% of oxygen is bound to hemoglobin.

    • Oxygen leaves hemoglobin, dissolves in blood, and passes through capillary membranes into tissues.

Carbon Dioxide Transport

  • Carbon Dioxide: A waste product of aerobic metabolism.

    • 7% is dissolved in plasma.

    • 23% attaches to hemoglobin.

    • 70% is converted to bicarbonate ions, which are converted back to CO2 and exhaled.

Brainstem Centers

  • Baroreceptors: Located in the walls of the heart, aortic arch, and carotid artery.

    • Respond to drops in blood pressure by increasing heart rate and causing vasoconstriction.

  • Chemoreceptors: Found in the aortic arch and carotid artery.

    • React to changes in pH, O2, and CO2 levels.

Cardiac Output

  • Cardiac Output (CO): The amount of blood that comes out of the heart in 1 minute.

  • Stroke Volume (SV): The amount of blood ejected from the heart with each contraction.

  • Heart Rate (HR): The number of beats per minute.

CO Calculation

The relation is given by the formula:
CO=SVimesHRCO = SV imes HR

  • Normal Range: 4-6 liters/minute.

Factors That Influence Cardiac Function

Developmental Stages

  • Infants:

    • Transition to life outside the uterus.

    • Watch for congenital heart anomalies.

  • Preschool/School-age:

    • Growth and dietary changes may impact cardiac health.

    • Development of obesity as a risk factor.

  • Adolescents:

    • Substance use and abuse, diet, obesity remain significant.

  • Adults:

    • Affected by lifestyle changes, stress, heredity, diet, and exercise.

  • Older Adults:

    • Changes include thicker, more rigid valves, decreased myocardial strength, lower exercise tolerance, and other health issues.

Environmental Factors

  • Stress:

    • Influence of environmental factors such as air quality and weather conditions.

  • Medications:

    • CV depressants: Slow heart rate or reduce myocardial contraction force.

    • Beta Blockers: Specify medications like metoprolol tartrate (Lopressor) and bisoprolol fumarate (Zebeta).

Beta Blockers' Mechanism

  • Beta Blockers: Affect receptors in the heart and blood vessels, thereby reducing the impact of adrenaline and noradrenaline, leading to:

    • Slowed heart rate (SA-node is affected).

    • Reduction in workload of the heart by dilating arteries and lowering blood pressure.

Cardiovascular Disease and Risk Factors

Modifiable Risk Factors

  • High Blood Pressure: Aim to maintain below 130/80 mm Hg.

  • Tobacco Use: Behavioral interventions and pharmacotherapy recommended for cessation.

  • Physical Activity: Recommended to perform at least 150 minutes/week of moderate or 75 minutes/week of vigorous activity.

  • Diet: Focus on consuming vegetables, fruits, nuts, legumes, fish, and whole grains.

  • Type II Diabetes: Managed through diet and exercise, with metformin as the primary therapy.

Non-Modifiable Risk Factors

  • Age: Older age increases risk.

  • Family History: Genetic predisposition plays a role.

  • Sex: Certain conditions may have different prevalence based on sex.

  • Race: Some ethnicities are at higher risk for certain conditions.

Types of Heart Disease

  1. Rheumatic Heart Disease: An autoimmune reaction to a strep infection, often causing valve inflammation, primarily in children.

  2. Cardiomyopathy: Enlargement and impairment in cardiac contraction.

  3. Heart Failure: Ineffective pumping action of the heart.

  4. Myocardial Ischemia: Reduced blood flow to the heart, unmet oxygen requirements may lead to myocardial infarction (MI).

  5. Carditis: Inflammation of heart layers, including endocarditis, myocarditis, and pericarditis.

  6. Coronary Artery Disease: Plaque buildup in coronary arteries, leading to blood flow obstruction.

  7. Thrombus: A blood clot that can obstruct blood vessels.

  8. Cardiac Dysrhythmias: Alterations in the heart's rhythm can compromise cardiac output and oxygenation.

  9. Valvular Heart Disease: Includes conditions like valve insufficiency and stenosis.

  10. Aortic Aneurysm: A weakness in the aorta's wall that poses a rupture risk.

Cardiovascular Assessment

Risk Factor Assessment

  • Assess modifiable risk factors: High blood pressure, tobacco use, obesity, sedentary lifestyle.

  • Identify non-modifiable factors: Age, family history, sex, race.

Physical Exam Focus Areas

  • Assess for pain, fatigue, dyspnea, dependent edema, diaphoresis, cardiac arrhythmia, and vital signs.

Diagnostic Measures

  • 12 Lead EKG: Used to monitor heart activity.

  • Cardiac Monitoring: Continuous assessment of heart rhythm.

  • Blood Work: Tests for troponin, B-type natriuretic peptide (BNP), and lipid profile.

  • Exercise Stress Test: Evaluates heart function under stress.

Electrocardiogram (ECG)

  • An electrocardiogram is a record of the electrical activity of the heart.

  • It involves 3 to 5 electrodes placed on the chest to display waveform data, used for various diagnostic purposes:

    • Establishing a baseline rhythm and rate.

    • Recognizing significant changes and lethal dysrhythmias.

    • Monitoring treatment effectiveness.

Deep Vein Thrombosis

  • A blood clot that typically occurs in the veins due to immobility and venostasis.

Symptoms:

  • Swelling

  • Pain

  • Redness

Assessment:

  • Measure calf circumference.

Treatment:

  • Use of venidyne boots and anticoagulants.

Cardiovascular Nursing Diagnosis

  • Activity Intolerance: Related to the imbalance between oxygen supply and demand.

  • Risk for Excess Fluid Volume: Related to impaired cardiac function or fluid retention.

  • Ineffective Tissue Perfusion: Associated with decreased cardiac output or impaired circulation.

  • Acute Pain: Secondary to myocardial ischemia.

  • Ineffective Coping: Related to hospitalization for oxygenation impairment.

Cardiovascular Nursing Planning and Interventions

Goals:

  • Manage anxiety, promote circulatory function, and prevent clot formation.

Medication Administration:

  • Vasodilators: These medications help to ease the heart's workload, dilate arterioles (decreasing afterload), and decrease venous return to the heart.

    • Common types: ACE inhibitors, ARBs, nitrates; monitor for hypotension.

  • Beta-adrenergic blocking agents: Used in various cardiac conditions to decrease heart rate and myocardial oxygen demand.

  • Diuretics: Increase urine output by removing excess sodium and water, beneficial in managing congestive heart failure (CHF).

  • Positive Inotropes: Improve heart contractility without increasing myocardial oxygen demand; include cardiac glycosides and phosphodiesterase inhibitors.

  • Anticholesterol Medications (Statins): Lower triglyceride levels and LDL cholesterol, particularly important for patients at high risk for cardiovascular disease.

Cardiopulmonary Resuscitation (CPR)

Basic Life Support (BLS)

  • Signs of Cardiac Arrest: Unresponsiveness, apnea, and absence of pulse. Quick action is crucial, with only 4-6 minutes to avoid brain damage from hypoxia.

CPR Process:

  • Focus on effective chest compressions (minimum of 100 compressions per minute).

  • Ratio: 30 compressions to 2 breaths.

  • Be prompt and efficient without interruption.

In-Hospital Protocol:

  • Activate