3.3 Inflammatory Disease, Hypertensive Crisis & Vascular Occlusions

Inflammatory Myocardial and Endocardial Disease

Myocarditis

Myocarditis is myocardial inflammation, most often viral (enterovirus, adenovirus, parvovirus B19, influenza, SARS-CoV-2, and others) or immune-mediated. Children may present days after a viral illness with tachycardia out of proportion to fever, new gallop, chest pain, vomiting (hepatic congestion), syncope, ventricular ectopy, or frank cardiogenic shock. ECG may show low voltages, ST-T changes, or ectopy; troponin and BNP/NT-proBNP rise; echo shows systolic dysfunction ± dilation; MRI supports diagnosis when the child is stable enough.

PICU priorities: continuous arrhythmia monitoring (VT/VF and high-grade block can appear abruptly), supportive heart-failure therapy, avoidance of unnecessary athletic stimulation historically emphasized in ambulatory care, and early discussion of VA-ECMO for fulminant collapse. Immunomodulatory therapies (IVIG, steroids, other agents) are etiology- and center-dependent — know your protocol, but never delay hemodynamic rescue for diagnostic perfection. Nursing actions include quiet clustered care, electrolyte optimization, readiness for cardioversion/defibrillation, and family support through a rapidly changing trajectory that can swing from "mild troponin leak" to ECMO within hours.

Infective Endocarditis

Infective endocarditis (IE) is infection of endocardium/valves, more common in children with congenital heart disease, prosthetic material, or chronic central lines. Pathogens include staphylococci, streptococci, and organisms associated with healthcare exposure. Hallmarks: prolonged or recurrent fever, new or changing regurgitant murmur, splenomegaly, petechiae, and embolic phenomena (stroke, splenic/renal infarcts, pulmonary emboli with right-sided disease). Blood cultures before antibiotics when possible, echocardiography (including TEE when indicated), and prolonged IV bactericidal therapy are standards. Surgery enters for refractory heart failure, uncontrolled infection, or large mobile vegetations with embolization.

Nursing focus: meticulous line care, culture timing, antibiotic trough/peak adherence when ordered, neurologic checks for embolic stroke, and monitoring for acute valve failure (flash pulmonary edema, cardiogenic shock). Teach families that dental and procedural antibiotic prophylaxis follows cardiology guidance for the highest-risk lesions.

Kawasaki Disease Sequelae

Acute Kawasaki disease is a medium-vessel vasculitis of childhood; the CCRN-Pediatric cardiovascular focus is often the sequelae: coronary artery dilation/aneurysms, myocardial ischemia/infarction from thrombosis or stenosis, and valvular regurgitation. Children with giant aneurysms may require antiplatelet therapy plus anticoagulation. PICU presentations include chest pain or irritability with ischemic ECG changes, ventricular dysfunction, and arrhythmia. Nursing priorities: medication adherence teaching (aspirin/warfarin/DOAC per plan), prompt evaluation of ischemic symptoms, and blood-pressure control to protect coronary perfusion without excessive afterload.

Hypertensive Crisis in Children

Hypertensive crisis means severe blood-pressure elevation with evidence of end-organ injury (hypertensive emergency) — encephalopathy (seizure, visual change, severe headache), pulmonary edema, acute kidney injury, or myocardial ischemia. Severe elevation without acute organ injury is urgency and still needs controlled reduction, usually with oral/IV meds in a monitored setting.

Pediatric thresholds are age- and height-percentile based; do not apply adult 180/120 cutoffs blindly to toddlers. Common PICU drivers: acute glomerulonephritis, renovascular disease, catecholamine excess, medication nonadherence in chronic hypertension, coarctation-related physiology, and intracranial catastrophe with Cushing response (treat the brain cause, not BP alone).

Management principles:

• Use continuous arterial monitoring when titrating IV antihypertensives.
• Prefer titratable agents such as nicardipine or esmolol (agent choice depends on pathophysiology — for example beta-blockade careful in cocaine/amphetamine exposure until vasodilated; avoid sudden drops).
• Target a controlled reduction (commonly toward ≤25% lowering of the acute severe elevation in the first 8 hours, then gradual normalization) to protect cerebral autoregulation — abrupt normalization can cause ischemic stroke.
• Treat seizures, pulmonary edema, and electrolyte derangements concurrently.
• Investigate secondary causes rather than labeling every child "essential hypertension."

Nursing actions: correct cuff size (bladder width ~40% of mid-arm circumference), confirm readings in more than one site when discrepant, keep neurologic exams frequent during titration, and watch for overshoot hypotension.

Vascular Occlusions and Thrombosis in Children

Critically ill children form clots for different reasons than atherosclerotic adults: central venous catheters, congenital/surgical heart disease with low-flow chambers or Fontan circuits, nephrotic syndrome, infection/inflammation, ECMO/VAD circuits, and inherited thrombophilias.

Venous thrombosis

Presents with limb swelling/pain, superior vena cava syndrome (facial plethora, upper-body edema) from upper-body lines, or respiratory compromise from pulmonary embolism (less classic than in adults but real in adolescents and complex cardiac patients). Ultrasound is first-line for limbs; CT/MR angiography used selectively.

Arterial thrombosis / occlusion

Cool, pale, pulseless extremity after arterial line, cardiac catheterization, ECMO arterial cannula, or embolization from endocarditis/aneurysm. This is a limb- and organ-threatening emergency: notify the team immediately, keep the limb warm and dependent as directed, do not heat-burn the skin, maintain anticoagulation/thrombolysis plans per vascular/hematology guidance, and prepare for surgical or interventional thrombectomy when indicated.

Coronary and cerebral arterial events

Kawasaki aneurysms, emboli from IE or cardiomyopathy thrombus, and hypercoagulable states can cause myocardial infarction or stroke. Pediatric stroke protocols emphasize time to imaging and specialty activation even though adult tPA pathways differ by age and etiology.

Prevention is nursing-owned: daily line necessity review, aseptic technique, early mobilization when safe, sequential compression in appropriate adolescents, and protocolized anticoagulation for mechanical support. When heparin or direct thrombin inhibitors run, know the monitoring assay (ACT, aPTT, anti-Xa) used in your unit and the bleeding signs that trump the number on the pump.

On exam items, link fever + CHD + emboli → endocarditis, viral prodrome + shock/arrhythmia → myocarditis, severe BP + seizure/visual change → emergency with controlled IV reduction, and pulseless cool limb after arterial instrumentation → immediate vascular emergency, not watchful waiting.