Cardiovascular Disorders: Heart Failure, Coronary Artery Disease, and Aortic Aneurysms

Heart Physiology and Pathophysiology

Sequential Path of Blood Flow Through the Heart
- Deoxygenated blood returns from the Body into the (1) Superior Vena Cava and (2) Inferior Vena Cava.
- Blood enters the (3) Right Atrium.
- Flows through the (4) Tricuspid Valve into the (5) Right Ventricle.
- Passes through the (6) Pulmonary Valve into the (7) Pulmonary Arteries.
- Blood enters the Lungs (Right lung and Left lung) for gas exchange and oxygenation.
- Oxygenated blood returns from the lungs via the (8) Pulmonary Veins.
- Blood enters the (9) Left Atrium.
- Flows through the (10) Mitral Valve into the (11) Left Ventricle.
- Passes through the (12) Aortic Valve into the (13) Aorta.
- Blood is distributed to the remainder of the Body.
Cardiac Output (CO) Dynamics
- Definition: Cardiac output is the amount of blood pumped by the heart per minute.
- Determinants of CO:
  - (1) Preload: The volume of blood in the ventricles at the end of diastole before the next contraction.
  - (2) Afterload: The peripheral resistance against which the left ventricle must pump.
  - (3) Myocardial Contractility: The intrinsic strength and ability of the ventricular muscle to contract.
  - (4) Heart Rate (HR): The number of ventricular contractions per minute.
- Stroke Volume (SV): The amount of blood pumped out of the heart per heartbeat.
- Formula: $CO = SV \times HR$
- Normal Cardiac Output: $4-8\,L/min$

Heart Failure Overview and Categorization

General Pathophysiology and Definition
- Heart Failure (HF): The inability of the heart to provide sufficient blood to meet the oxygen needs of the body's tissues and organs.
- Etiology: Develops as a consequence of myocardial insult.
- Systemic Impacts: Decreased cardiac output ( $CO$ ) causes decreased tissue perfusion, impaired gas exchange, fluid volume imbalance, and decreased functional ability.
- Epidemiology: HF is the most common reason for hospital admission in adults over the age of $65\text{ years}$ .
- Risk Factors:
  - Most Common Primary Causes: Hypertension (HTN) and Coronary Artery Disease (CAD).
  - Structural & Mechanical: Congenital abnormalities, dysrhythmias.
  - Inflammatory/Toxic: Infections, inflammation, toxins.
  - Comorbidities: Coexisting conditions significantly increase overall risk.
Ejection Fraction (EF) and Left-Sided Heart Failure
- Left-Sided Heart Failure: The most common type of heart failure.
- Ejection Fraction (EF) Definition: The percentage of total blood volume in the left ventricle (LV) at the end of diastole that is pumped out of the LV during the subsequent systole.
- Heart Failure with Reduced Ejection Fraction (HFrEF / Systolic Heart Failure):
  - Defect: Defect in ventricular systolic function / LV contraction.
  - Ejection Fraction Values: Normal LVEF is $55\%-65\%$ . In HFrEF, LVEF is generally $< 40\%$ .
  - Pathophysiology: The LV cannot generate enough pressure to eject blood forward through the aorta. As a result, blood backs up into the left atrium and pulmonary circulation.
  - Hemodynamic Result: Increased pulmonary hydrostatic pressure leads to fluid accumulation, causing pulmonary congestion and alveolar edema.
  - Etiology: Ventricular inability to pump effectively, increased afterload, cardiomyopathy, and mechanical cardiovascular problems.
- Heart Failure with Preserved Ejection Fraction (HFpEF / Diastolic Heart Failure):
  - Defect: Defect in ventricular diastolic function / filling.
  - Pathophysiology: Results from the inability of the ventricles to relax and fill during diastole. The LV is characterized as stiff and noncompliant.
  - Hemodynamic Result: Reduced $CO$ with associated fluid congestion.
  - Diagnostic Criteria: Presence of clinical signs and symptoms of HF, normal LVEF ( $55\%-65\%$ ), and objective evidence of diastolic dysfunction identified via echocardiogram or cardiac catheterization.
Right-Sided Heart Failure
- Pathophysiology: The right ventricle (RV) fails to pump effectively, causing blood and fluid to back up into the systemic venous circulation.
- Clinical Manifestations: Peripheral edema, abdominal ascites, hepatomegaly, and jugular venous distention (JVD).
- Etiology:
  - Primary Cause: Left-sided heart failure (leading to increased RV workload).
  - Other Causes: RV infarction, pulmonary embolism (PE), and cor pulmonale.
Compensatory Mechanisms
- Neurohormonal Response:
  - Renin-Angiotensin-Aldosterone System (RAAS) activation.
  - Sympathetic Nervous System (SNS) stimulation.
  - Release of Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP).
- Ventricular Adaptations:
  - Dilation: Enlargement of the heart chambers when blood volumes are elevated.
  - Hypertrophy: Increase in muscle mass and cardiac wall thickness in response to overwork.
  - Remodeling: Changes in the size, shape, structure, and function of the heart.
Heart Failure Complications
- Pleural effusion
- Dysrhythmias and dyssynchronous contraction
- Hepatomegaly
- Cardiorenal syndrome
- Anemia
Diagnostic Evaluation
- History and Physical (H&P) examination
- B-type Natriuretic Peptide (BNP) blood levels
- Echocardiogram
- Electrocardiogram (EKG) and Holter monitoring
- Chest X-ray
- Cardiac Catheterization
- Magnetic Resonance Imaging (MRI)
- $6\text{-minute}$ walk test
- Stress testing

Management of Acute Decompensated Heart Failure (ADHF)

Clinical Manifestations
- Definition: A sudden increase in HF symptoms accompanied by a decline in functional status, frequently necessitating acute therapeutic escalation and inpatient hospital admission.
- Primary Drivers: Symptoms and clinical signs directly stem from pulmonary congestion and systemic volume overload.
- Progression of Pulmonary Fluid Accumulation:
  1. Interstitial edema
  2. Alveolar edema
  3. Pulmonary edema

Clinical manifestations of heart failure

Acute Nursing Interventions
- Continuous monitoring of vital signs and $O_2$ saturation.
- Strict tracking of daily weight and fluid intake and output (I/O).
- Assessment of mental status / mentation.
- Continuous or serial ECG monitoring.
- Positioning: Place the patient in High Fowler's position with legs horizontal or dangling. This depresses the diaphragm, relaxes abdominal respiratory muscles, improves breathing, and reduces venous return (preload).

High Fowler's positioning for breathing optimization

Pharmacotherapy for ADHF
- Diuretics: Administered to reduce volume overload and pulmonary congestion.
- Vasodilators: Reduce preload and afterload to improve myocardial performance.
- Morphine: Decreases anxiety, reduces preload and afterload, and lowers respiratory rate/work of breathing.
- Positive Inotropes: Increase myocardial contractility in acute cardiogenic states.

Management of Chronic Heart Failure

Clinical Manifestations
- Systemic & Respiratory: Fatigue, dyspnea, cough, tachycardia, palpitations, chest pain.
- Fluid & Renal: Edema, weight changes, changes in urine output (UOP).
- Dermatological: Skin changes (stasis dermatitis, pallor, cyanosis).
- Neurological & Behavioral: Neurologic changes, behavioral alterations, sleep perturbations.
Interprofessional Care and Lifestyle Interventions
- Dietary Modifications: Sodium restriction and fluid restriction.
- Monitoring: Routine daily weights (reporting sudden weight gains).
- Oxygenation & Mobility: Supplemental $O_2$ therapy, continuous pulse oximetry monitoring, and structured cardiac rehabilitation.
Pharmacotherapy for Chronic Heart Failure
- Angiotensin-Converting Enzyme (ACE) Inhibitors
- Angiotensin II Receptor Blockers (ARBs)
- Diuretics
- Aldosterone Antagonists
- Beta Blockers
- Digitalis
Health Promotion and Interventional Therapies
- Coronary revascularization procedures.
- Surgical valve repair or replacement as indicated.
- Device therapy: Pacemaker implantation, Implantable Cardioverter-Defibrillator (ICD).
- Weight management, dietary adherence, physical exercise, and annual immunizations.
End-Stage Heart Failure Interventions
- Continuous intravenous inotrope therapy.
- Mechanical Circulatory Support (MCS) devices, such as Left Ventricular Assist Devices (LVAD).
- Heart transplantation evaluation.
- Palliative care and hospice consultation.

Coronary Artery Disease (CAD)

Overview and Epidemiology
- Epidemiology: CAD is the leading cause of death in the United States.
- Definition: A focal or diffuse blood vessel disorder categorized under the umbrella of atherosclerosis.
- Clinical Spectrum: May remain asymptomatic for extended periods or progress to chronic stable angina or Acute Coronary Syndrome (ACS).
Pathophysiology of Atherosclerosis
1. Chronic Endothelial Injury: Induced by risk factors such as hypertension, tobacco use, hyperlipidemia, hyperhomocysteinemia, diabetes, systemic infections, or circulating toxins.
2. Fatty Streak: Lipids accumulate within the damaged intima and migrate into vascular smooth muscle cells.
3. Fibrous Plaque: Collagen covers the accumulated fatty streak; the vessel lumen progressively narrows, blood flow is impaired, and arterial fissures can develop.
4. Complicated Lesion: High-risk stage characterized by plaque rupture, localized thrombus formation, further lumen compromise, or complete vascular occlusion.

Pathophysiology of CAD atherosclerosis stages

Collateral Circulation
- Mechanism: Arterial anastomoses or secondary blood supply channels that develop and enlarge over time in response to chronic myocardial ischemia.
- Significance: Provides alternative pathways for perfusion around chronically occluded major coronary vessels.

Collateral circulation development in coronary arteries

Risk Factor Profile
- Non-Modifiable Risk Factors:
  - Age
  - Gender
  - Ethnicity
  - Genetics / Family History
- Modifiable Risk Factors:
  - Elevated serum lipid levels
  - Hypertension (HTN)
  - Tobacco use
  - Metabolic syndrome and Diabetes mellitus
  - Obesity
  - Physical inactivity
Therapeutic Risk Reduction Strategies
- Lifestyle & Diet: Adoption of low-saturated-fat diets, structured physical exercise, weight reduction for obesity, and stress reduction strategies.
- Substance Modifications: Smoking cessation and elimination/reduction of alcohol and illicit drug intake.
- Medical & Lipid Optimization: Strict adherence to prescribed regimens for underlying hypertension and diabetes; targeted lowering of Low-Density Lipoprotein (LDL) cholesterol using statin therapy.
- Antiplatelet Considerations: Routine low-dose aspirin therapy remains controversial and requires patient-specific risk-benefit evaluation.
Disease Progression Pathways
- CAD may progress sequentially or acutely into:
  - Chronic stable angina
  - Unstable angina
  - Non-ST-Segment Elevation Myocardial Infarction (NSTEMI)
  - ST-Segment Elevation Myocardial Infarction (STEMI)

Aortic Aneurysm

Definition and Etiology
- Definition: A permanent, localized outpouching or dilation of the arterial wall.
- Pathophysiologic Causes: Degenerative changes, congenital structural defects, infectious mechanisms, mechanical vascular injury (penetrating or blunt trauma), or inflammatory vessel conditions (aortitis).
- Modifiable Risk Factors: Hypertension, coronary artery disease, tobacco use, peripheral artery disease (PAD), hypercholesterolemia, and obesity.
- Non-Modifiable Risk Factors: Advanced age, male gender, and family history / genetic predisposition.
- Prognostic Correlation: The physical size of the aneurysm directly correlates with the risk of catastrophic rupture (larger size = higher rupture risk).

Aneurysm Classifications
- True Aneurysm: The wall of the artery forms the aneurysm, with at least one vessel layer remaining structurally intact.
  - Fusiform Aneurysm: Circumferential and relatively uniform in shape along the affected arterial segment.
  - Saccular Aneurysm: Outpouching shaped like a sac, featuring a narrow neck connecting the bulge to one side of the arterial wall.
- False Aneurysm (Pseudoaneurysm):
  - Not a dilation of all vessel wall layers; results from a breach in the vessel wall where blood leaks and forms a hematoma contained by outer soft tissues or organized clot.
  - Can involve a torn intima with blood dissecting or pooling outside the true lumen.

Classifications of true and false aortic aneurysms

Clinical Manifestations
- Thoracic Aortic Aneurysm (TAA):
  - Frequently asymptomatic prior to expander expansion or impingement.
  - Deep, diffuse chest pain extending to the interscapular region.
  - Angina, Transient Ischemic Attacks (TIAs).
  - Cough, shortness of air (SOA), hoarseness, dysphagia (from pressure on adjacent thoracic structures).
  - Jugular venous distention (JVD) and facial or upper extremity edema.
- Abdominal Aortic Aneurysm (AAA):
  - Frequently asymptomatic during early growth.
  - Pulsatile mass in the periumbilical abdominal area.
  - Audible abdominal bruit upon auscultation.
  - Persistent back pain, epigastric discomfort, altered bowel elimination habits, and intermittent claudication.
Complications and Emergency Management
- Aortic Rupture:
  - Significantly higher incidence in individuals who smoke tobacco.
  - Clinical Markers: Presence of Grey Turner sign (flank ecchymosis/ecchymotic discoloration) and severe hypovolemic shock.
  - Mortality: Extremely high mortality rate.
  - Immediate Action: Immediate emergency transport to the operating room (OR) accompanied by rapid mass blood product transfusion protocols.

Emergency transport of patient with ruptured aneurysm

Diagnostic Modalities
- Chest and Abdominal X-rays
- Electrocardiogram (EKG)
- Echocardiography
- Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI)

Interprofessional Management Guidelines
- Small Aneurysms ( $< 5.4\,cm$ ):
  - Conservative medical therapy.
  - Aggressive risk factor reduction (tobacco cessation, BP management).
  - Optimization of chronic medical comorbidities.
  - Serial diagnostic imaging surveillance every $6-12\text{ months}$ to track growth rate.
- Large Aneurysms ( $\ge 5.5\,cm$ ):
  - Surgical intervention is strongly recommended.
  - Open Aneurysm Repair (OAR): Direct surgical exposure and synthetic graft insertion.
  - Endovascular Aneurysm Repair (EVAR): Minimally invasive placement of an endovascular stent-graft inside the aneurysm lumen.
  - Surgical Complications:
    - Endoleak: The most common complication following EVAR, where blood continues to leak into the aneurysm sac.
    - Intraabdominal Hypertension (IAH): Can trigger Abdominal Compartment Syndrome, a potentially lethal postoperative complication.
Comprehensive Nursing Care and Postoperative Management
- Preoperative & Surveillance Care:
  - Monitor continuously for early indicators of aneurysm growth or impending rupture.
  - Baseline monitoring of peripheral pulses, neurological status, and renal clearance.
  - Provide preoperative education and robust emotional support.
  - Promote health interventions: complete tobacco cessation and stringent management of comorbidities.
- Postoperative ICU Care ( $24-48\text{ hours}$ ):
  - Graft Patency: Maintain blood pressure within precise limits to ensure graft flow without risking suture line disruption.
  - Cardiovascular & Perfusion: Monitor cardiovascular status, peripheral arterial perfusion, and lower extremity pulse strength.
  - Organ Systems: Monitor renal perfusion (urine output, serum creatinine), neurological function, gastrointestinal function (bowel sound return, ileus prevention), and signs of systemic infection.
- Ambulatory & Discharge Education:
  - Instruct patient to gradually increase daily physical activity levels.
  - Strict prohibition of heavy lifting for $6\text{ weeks}$ post-procedure.
  - Teach techniques to check and monitor the color, warmth, and peripheral pulse quality in lower extremities.
  - Infection & Rupture Warnings: Direct patient to report any incisional redness, localized swelling, escalating pain, wound drainage, or body temperature exceeding $100^\circ F$ ( $> 100^\circ F$ ).