C4

Infective Endocarditis

• Definition & Pathophysiology:

  • Infective endocarditis is an infection of the endocardium, most commonly caused by bacterial organisms.

  • Infectious organisms attach to damaged heart valves, leading to the formation of vegetations.

  • Vegetations consist of bacteria enclosed within a protective matrix of platelets and fibrin.

  • The fibrin and platelet casing protects the enclosed bacteria from circulating immune responses and antibiotic penetration.

  • These vegetations cause structural damage to heart valves and can break off into the circulation as arterial or venous emboli.

• High-Risk Populations & Etiology:

  • History of mitral valve prolapse.

  • History of rheumatic heart disease.

  • Congenital heart defects.

  • Presence of prosthetic heart valves.

  • History of intravenous (IV) drug use.

  • Poor oral hygiene, specifically severe gingivitis.

• Clinical Manifestations & Physical Findings:

  • Systemic signs: Fever, fatigue, dyspnea, cough, and peripheral edema.

  • Valvular dysfunction: Incomplete valve closure due to vegetative growth (most frequently affecting the mitral valve on the left side of the heart).

  • Cardiac auscultation: Presence of a new or changing cardiac murmur caused by damaged valve mechanics.

  • Pathognomonic cutaneous and ocular lesions:

  • Splinter Hemorrhages: Dark red linear streaks underneath the fingernails that resemble tiny splinters.

  • Petechiae: Small, pinpoint hemorrhagic lesions on the skin or mucous membranes.

  • Janeway Lesions: Painless erythematous macules located on the palms of the hands and soles of the feet.

  • Osler Nodes: Painful subcutaneous nodules found on the pads of the fingers and toes.

  • Roth Spots: Hemorrhagic retinal lesions with pale centers visualised during ophthalmoscopic examination.

• Organ-Specific Embolic Complications:

  • Brain: Embolization leads to cerebrovascular accidents (strokes), stroke-like symptoms, and altered level of consciousness (LOC).

  • Kidneys: Embolization causes flank pain and hematuria.

  • Lungs: Embolization leads to acute dyspnea and chest pain.

  • Spleen: Embolization produces severe abdominal pain.

  • The brain and lungs represent the most common primary target sites for critical embolic damage, leading to organ tissue ischemia or failure.

• Diagnostic Evaluation:

  • Positive blood cultures to identify the specific pathogen.

  • Echocardiogram (TTE or TEE) to directly visualize valvular vegetations and measure valvular damage.

  • Initial acute presentation workup (for dyspnea or chest pain): Electrocardiogram (EKG/ECG) and Chest X-ray.

  • Secondary imaging: Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) as clinically indicated.

  • Outpatient or inpatient cardiology consultation for advanced diagnostic evaluation.

• Medical & Nursing Management:

  • Mandatory hospital admission for long-term intravenous (IV) antibiotic administration.

  • Combination antibiotic therapy is often necessary to penetrate the protective platelet-fibrin shield surrounding the bacteria.

  • Conservative care: Bed rest, supportive care, and antipyretics for fever control.

  • Medical management of concurrent heart failure symptoms as indicated.

  • Transition to outpatient IV antibiotic therapy once clinical stability is achieved.

• Vascular Access & Discharge Education:

  • Patients require central vascular access, such as a Peripherally Inserted Central Catheter (PICC line), due to prolonged antibiotic regimens and the frequency of IV site rotations required with standard peripheral IVs.

  • Patient education regarding central line maintenance begins during inpatient hospitalization and continues under home health nursing:

  • Maintaining strict line cleanliness and keeping the insertion site dry.

  • Instructions on emergency protocols if the catheter becomes dislodged or compromised.

  • Case management nursing coordinates post-discharge home health services, verifies insurance coverage, and secures required equipment.

• Surgical Options & Prevention:

  • Surgical valve repair or valve replacement is indicated for severe structural valve failure or unmanageable infection.

  • Rigorous daily oral hygiene and professional dental care are required to eliminate portal-of-entry risk factors.

  • Prophylactic antibiotic administration prior to invasive dental or medical procedures is required for high-risk patients:

  • Patients with prosthetic heart valves.

  • Patients with a documented history of infective endocarditis.

  • Patients with specific high-risk congenital heart defects.

Myocarditis

• Definition & Overview:

  • Myocarditis is an inflammatory disorder of the myocardium (heart muscle) that causes structural damage to cardiac muscle fibers and secondary cardiomegaly.

  • Clinical course ranges from mild, self-limiting inflammation to severe, life-threatening myocardial dysfunction, heart failure, or sudden cardiac death.

• Disease Progression & Manifestations:

  • Early Manifestations (Systemic/Infectious Phase):

  • Fatigue.

  • Fever and malaise.

  • Pharyngitis.

  • Myalgias (muscle aches).

  • Gastrointestinal discomfort.

  • Lymphadenopathy.

  • Late Manifestations (Approximately $2\,\text{weeks}$ post-onset if uncorrected):

  • Severe chest pain.

  • Exertional dyspnea.

  • Cardiac palpitations.

  • Tachycardia.

  • Severe End-Stage Complications: Ventricular dysrhythmias and sudden cardiac death, typically resulting from cardiogenic shock.

• Hemodynamic Changes & Physical Findings:

  • Signs of initial left-sided heart failure.

  • Blood Pressure: Hypotension (low blood pressure).

  • Heart Rate: Tachycardia initially; eventual bradycardia or arrest as the myocardium decompensates.

  • Peripheral Pulses: Weak and thready (tachycardia limits diastolic filling time, reducing stroke volume and pulse pressure).

  • Auscultation & Oxygenation: Pulmonary crackles present; systemic oxygenation is reduced.

• Diagnostic Workup:

  • Initial assessment for acute chest pain/dyspnea: Electrocardiogram (EKG/ECG).

  • Imaging: Echocardiogram, Chest X-ray (evaluates anatomical anomalies and cardiomegaly), and Cardiac MRI.

  • Laboratory Testing: Complete Blood Count (CBC), viral antibody panels, and cardiac enzymes.

  • Troponin: Specific cardiac biomarker indicating active myocardial injury.

  • Invasive testing: Cardiac catheterization and endomyocardial biopsy.

• Therapeutic Interventions:

  • Direct management of the underlying inflammatory or infectious cause.

  • Complete bed rest and strict physical activity restriction to minimize cardiac workload, contractility, and oxygen consumption.

  • Strict avoidance of cardiac stimulants, including alcohol, tobacco, and physical exercise.

  • Pharmacotherapy: ACE inhibitors, beta-blockers, diuretics, and positive inotropic agents.

  • Mechanical Circulatory Support: Intra-Aortic Balloon Pump (IABP) placement (balloon inflates and deflates within the aorta in synchrony with the cardiac cycle to reduce afterload and augment coronary perfusion).

  • Refractory cases: Heart transplantation for end-stage myocardial destruction.

Pericarditis

• Definition & Pathophysiology:

  • Pericarditis is inflammation of the pericardium, the fibroserous sac surrounding the heart.

  • Pericardial inflammation and swelling restrict ventricular expansion during diastole, decreasing ventricular filling, stroke volume, and overall cardiac output, resulting in systemic hypotension.

  • Acute Pericarditis: Resolves within $6\,\text{weeks}$; carries a high risk of recurrence.

  • Chronic Pericarditis: Causes fibrotic scarring and pericardial thickening, producing a rigid pericardial sac that causes permanent filling impairment and chronic heart failure.

• Etiology:

  • Infectious processes (viral, bacterial, fungal).

  • Post-myocardial infarction (Dressler syndrome).

  • Open heart surgery or invasive cardiac procedures.

  • End-stage renal disease / Uremia.

  • Autoimmune disorders.

  • Thoracic trauma or invasive medical procedures.

  • Adverse pharmacological reactions and metastatic malignancies.

• Clinical Manifestations:

  • Substernal Chest Pain: Sharp, intense pain that worsens with deep inspiration, coughing, or lying flat (supine position).

  • Positional Relief: Pain is distinctly relieved when the patient sits upright and leans forward.

  • Pain Radiation: Pain frequently radiates to the neck, clavicle, or left scapula (mimicking acute myocardial infarction).

  • Associated symptoms: Orthopnea, fatigue, low-grade fever, non-productive cough, and peripheral edema.

  • Pericardial Friction Rub: A high-pitched, scratchy, or grating sound best heard over the lower left sternal border during cardiac auscultation.

• Medical & Surgical Management:

  • Mandatory physical rest and activity restriction (athletes must refrain from sports participation until cleared).

  • Treatment aimed at resolving the underlying etiology.

  • Anti-inflammatory Pharmacotherapy: Nonsteroidal Anti-inflammatory Drugs (NSAIDs) and systemic corticosteroids.

  • Pericardiocentesis: Invasive procedure to aspirate excess fluid from the pericardial sac using a needle under sterile conditions; drained fluid is sent for laboratory analysis.

  • Pericardial Window: Surgical procedure creating a opening in the pericardium, allowing continuous fluid drainage into the pleural or peritoneal cavity to relieve cardiac compression.

  • Pericardiectomy: Surgical resection of the entire rigid pericardium to allow unrestricted ventricular expansion.

Cardiac Tamponade

• Pathophysiology & Urgency:

  • Cardiac tamponade is a life-threatening medical emergency caused by rapid or large-volume fluid collection within the pericardial space.

  • High intrapericardial pressure compresses the heart, preventing diastolic filling of the left ventricle, causing a severe collapse in cardiac output.

• Clinical Manifestations & Physical Assessment:

  • Hypotension with narrowing pulse pressure.

  • Tachycardia and tachypnea.

  • Restlessness, anxiety, and mental confusion secondary to cerebral hypoperfusion.

  • Jugular Vein Distension (JVD) due to elevated systemic venous pressure.

  • Distant, muffled, or soft heart sounds upon cardiac auscultation.

  • Clinical signs of systemic hypoperfusion / low cardiac output state.

• Emergency Treatment & Procedural Complications:

  • Immediate bedside pericardiocentesis utilizing a large-gauge needle attached to a high-capacity syringe (such as a $60\,\text{cc}$ syringe) to drain fluid and relieve mechanical compression.

  • Potential procedure complications include:

  • Accidental myocardial wall puncture or injury.

  • Coronary artery laceration.

  • Pneumothorax (collapsed lung from accidental pulmonary puncture).

  • Laceration-induced hemorrhage.

  • Localized or systemic infection.

Cardiomyopathy

• Definition & General Disease Principles:

  • Cardiomyopathy represents a diverse group of progressive heart muscle disorders causing structural enlargement or electrical/mechanical dysfunction of the myocardium.

  • Results in impaired cardiac output, secondary heart failure, myocardial ischemia, or acute myocardial infarction.

  • Disease is incurable; primary therapeutic goal is symptom management and slowing functional decline.

  • Three primary morphological classifications: Dilated, Hypertrophic, and Restrictive.

• Dilated Cardiomyopathy:

  • Pathophysiology: The most common form of cardiomyopathy. Characterized by severe ventricular chamber dilation paired with thin, weak muscular walls, causing marked systolic dysfunction and low cardiac output.

  • High risk for intraventricular thrombus formation due to blood stasis.

  • Primary Anatomical Location: Principally impacts the left ventricle.

  • Etiology: Genetics, myocarditis, hypertension, end-stage valvular heart disease, myocardial infarction, HIV infection, cardiotoxic chemotherapy agents, heavy alcohol abuse, cocaine use, and environmental toxins.

  • Specific Valvular Etiology: Chronic disease or failure of the aortic valve (stenosis or regurgitation) or mitral valve causes massive blood backflow into the left ventricle, resulting in severe volume overload and secondary chamber dilation.

  • Clinical Manifestations: Severe fatigue, peripheral edema (secondary to right-sided heart failure backing up from left-sided failure), orthopnea, atrial fibrillation, and systemic thromboembolism.

• Hypertrophic Cardiomyopathy:

  • Pathophysiology: Excessive ventricular wall thickening (hypertrophy) that creates a thick, rigid, non-compliant myocardium.

  • Results in severe diastolic filling impairment and potential obstruction of the left ventricular outflow tract (LVOT).

  • High-Risk Clinical Outcome: Primary cause of sudden cardiac death in young people and competitive athletes.

  • Clinical Manifestations: Syncope (especially during or immediately following physical exertion), chest pain, sudden dizziness, and palpitations.

• Restrictive Cardiomyopathy:

  • Pathophysiology: Characterized by an abnormally rigid, stiff myocardium that severely impairs ventricular diastolic filling.

  • Systolic contractile function typically remains normal.

  • Clinical Manifestations: Fatigue, exertional dyspnea, and classic right-sided heart failure manifestations, including dependent peripheral edema and ascites.

• Structural Pathology Summary:

  • Normal Heart: Standard myocardial wall thickness and proportional chamber volume.

  • Dilated Cardiomyopathy: Markedly enlarged chamber dimensions with thinned, stretched, and weakened muscle walls.

  • Hypertrophic Cardiomyopathy: Massively thickened, hyperthrophied muscle walls with severely reduced internal chamber volume.

  • Restrictive Cardiomyopathy: Near-normal muscle wall thickness with extremely rigid, non-compliant muscle tissue that cannot expand during diastole.