Free exam prep

PNCB CPNP-AC Acute Care Certified Pediatric Nurse Practitioner

Practice Questions200 questions Study Guide72 topics

4.3 Acute Heart Failure, Pediatric Myocarditis & Vasoactive Pharmacotherapy

Q: A 4-year-old with myocarditis has cool extremities, oliguria, depressed left ventricular systolic function, and elevated systemic vascular resistance. The cardiac team confirms that arterial pressure can tolerate afterload reduction. Which infusion provides inotropy, lusitropy, and vasodilation?

Milrinone. Milrinone inhibits PDE-3, increasing cyclic AMP to support contractility and relaxation in cardiac muscle and reduce vascular tone. Its effects fit a low-output, high-resistance state when pressure can tolerate vasodilation. Monitor perfusion, pressure, and rhythm, and adjust for renal dysfunction when needed. Phenylephrine increases vascular tone. Dopamine and epinephrine have dose-dependent adrenergic effects and do not provide the specified PDE-3 inodilator profile.

Q: A 12-year-old with septic shock and secondary myocardial dysfunction remains hypotensive on an epinephrine infusion after initial resuscitation. A multimodal hemodynamic assessment supports low systemic vascular tone, and the team chooses to add an agent with predominantly alpha-adrenergic vasoconstrictor activity. Which drug matches that goal?

Norepinephrine. Norepinephrine provides systemic vasoconstriction with some beta-1 activity. It is a reasonable choice for the specified hemodynamic goal. The 2026 pediatric SSC does not give it a universal first-line preference over epinephrine. Nitroprusside lowers systemic vascular resistance, low-dose dopamine has predominantly dopaminergic effects, and inhaled nitric oxide acts principally on the pulmonary circulation.

Key Takeaways

Suspect myocarditis with otherwise unexplained ventricular dysfunction, conduction disease or arrhythmia. A preceding illness, troponin and natriuretic peptides can support suspicion alongside ECG and echocardiography.
In a stable child, MRI can provide evidence of inflammation. Combining T2 evidence of edema and T1 evidence of injury increases specificity. Biopsy may identify a cause that changes treatment in selected high-risk patients.
Impaired ejection and impaired filling can coexist. In a simplified spherical model, wall stress rises in proportion to pressure and radius at a fixed wall thickness.
Match an infusion to ventricular performance, arterial pressure, rhythm and vascular tone. Milrinone can support contractility and relaxation when blood pressure tolerates vasodilation.
Seek early mechanical-support assessment in refractory shock. During VA-ECMO, monitor for left ventricular distension and evaluate the need for unloading.

Last updated: November 2026

Acute Heart Failure, Pediatric Myocarditis & Vasoactive Pharmacotherapy: Pathophysiology, Inotropes, and Mechanical Circulatory Support

Quick Answer: Suspect acute myocarditis in a child with unexplained myocardial dysfunction or arrhythmia, including after a viral illness. In cardiogenic shock, address impaired perfusion and congestion, select vasoactive support by the physiology, and involve the cardiac team early. Deteriorating perfusion despite initial support warrants assessment for mechanical circulatory support.

Myocarditis, cardiomyopathy and postoperative myocardial stunning can cause acute heart failure. Initial decisions depend on the adequacy of perfusion and the presence of congestion.

Acute Pediatric Myocarditis

Myocarditis is inflammation of the myocardium. Causes include infections and immune-mediated disorders, including autoimmune disease and drug hypersensitivity. A viral syndrome can precede cardiac symptoms, but the timing varies and some children have no clear prodrome. Isolated anthracycline toxicity can cause ventricular dysfunction through a different mechanism.

Presentation and bedside decisions

Infants may have poor feeding, sweating with feeds, tachypnea or irritability. Older children may present with exercise intolerance, chest or abdominal pain, palpitations or syncope. Tachycardia out of proportion to fever, an $S_3$ gallop, hepatomegaly, cool extremities or weak pulses raise concern for heart failure or low output. Arrhythmia, conduction block and rapidly progressive cardiogenic shock are possible. Stabilize oxygenation and circulation, obtain rhythm monitoring, and involve pediatric cardiology early when dysfunction or an important arrhythmia is suspected.

Study	What it adds
Troponin and BNP or NT-proBNP	Troponin supports myocardial injury. A normal result cannot exclude myocarditis and an elevated result cannot establish the cause. Natriuretic peptides reflect myocardial wall stress and may support assessment of heart failure in context.
ECG and telemetry	Look for ST–T changes, ectopy, tachyarrhythmia or AV block. Monitor for evolving rhythm disturbance.
Chest radiograph	Cardiomegaly or pulmonary congestion can support heart failure. A normal film does not exclude early disease.
Echocardiogram	Assess ventricular function and size, wall thickness, regurgitation, effusion and coronary origins when visible. Dysfunction can be regional or global and varies in severity. Consider structural disease, including an anomalous coronary origin, when the presentation warrants it.
Cardiac magnetic resonance (CMR)	Once stable for imaging, assess for edema and injury. Updated Lake Louise criteria use a T2 marker such as increased myocardial T2 and a T1 marker such as elevated native T1, increased extracellular volume or nonischemic late gadolinium enhancement. Evidence from both categories increases specificity. One category can support possible myocarditis in an appropriate clinical setting with lower specificity.
Endomyocardial biopsy (EMB)	Discuss with pediatric cardiology for high-risk presentations or selected cases when identifying the cause may change treatment, such as suspected giant-cell or eosinophilic myocarditis. Histology, immunohistochemistry and, when indicated, molecular testing can inform the diagnosis. Patchy disease can be missed and the procedure carries risk.

AHA pediatric myocarditis statement · Updated Lake Louise criteria · 2025 ESC myocarditis guideline

Acute management and escalation

Support perfusion while assessing congestion. With poor perfusion and suspected myocardial dysfunction, use serial examination, blood pressure, rhythm, lactate and echocardiography to guide support. Pulmonary congestion and high filling pressures favor avoiding large boluses. When inadequate preload is plausible, give cautious, reassessed fluid. Involve cardiac critical care early if perfusion deteriorates. AHA pediatric cardiogenic shock statement
Consider etiology when selecting immune therapy. Evidence for routine IVIG or corticosteroids in acute pediatric myocarditis is uncertain. Use a specialist-directed plan when a specific immune-mediated cause is suspected or identified. Multisystem inflammatory syndrome in children (MIS-C) has a separate treatment pathway.
Escalate for persistent low output, end-organ dysfunction or unstable arrhythmias despite initial support. VA-ECMO can support circulation and gas exchange. Retrograde arterial flow with peripheral VA-ECMO can raise left ventricular afterload. Low arterial pulsatility, failure of the aortic valve to open, ventricular distension, intracardiac stasis or increasing pulmonary edema warrant prompt reassessment with the support team. Individualize flow and afterload management and consider ventricular unloading if clinically significant distension or stasis persists. A ventricular assist device can provide longer support in selected patients. AHA pediatric acute decompensated heart failure statement

Pediatric Acute Heart Failure Pathophysiology

Systolic dysfunction reduces the ability to eject blood. Diastolic dysfunction impairs relaxation or increases stiffness, so a ventricle may require a higher filling pressure for a given volume. Ejection fraction can remain preserved in impaired filling, and both forms of dysfunction can coexist. A child with edema or pulmonary congestion may still have low forward flow.

Neurohormonal response and wall stress

Low effective arterial perfusion increases sympathetic drive. Increased heart rate, contractility and vascular tone can initially support pressure. Persistent tachycardia can impair filling, and increased vascular resistance can impede forward ejection. Reduced renal perfusion and sympathetic stimulation also activate the renin–angiotensin–aldosterone system. Renin generates angiotensin I from angiotensinogen. Angiotensin-converting enzyme produces angiotensin II, which promotes vasoconstriction and aldosterone release. Sodium and water retention can contribute to congestion.

For a simplified thin-walled spherical ventricle, average wall stress follows:

$\sigma \approx \frac{P r}{2h}$

Here $P$ is transmural pressure, $r$ is chamber radius and $h$ is wall thickness. At the same pressure and thickness, a modeled radius increase from 2 to 3 cm raises estimated stress by a factor of $3/2$ , or 50%. This model illustrates why dilation can increase the load on the myocardium even at the same pressure. Actual ventricular wall stress also depends on chamber geometry and wall structure. Ventricular wall stress modeling study

Critical Care Vasoactive Pharmacotherapy

Vasoactive infusions must be selected based on receptor pharmacology and individual hemodynamic targets.

Vasoactive Agent	Primary Receptor / Mechanism	Hemodynamic Effects (CO, HR, SVR, PVR)	Pediatric Dose Range	Key Indications & ACPNP Monitoring Pearls
Epinephrine	Adrenergic agonist with dose-dependent $\beta$ and $\alpha$ effects	Increases contractility and heart rate. Vasoconstriction is more pronounced at higher doses.	Titrate per pediatric protocol	Can support hypotensive cardiogenic shock. Monitor perfusion, rhythm, blood pressure, and lactate in context.
Norepinephrine	Predominantly $\alpha_1$ with $\beta_1$ activity	Raises vascular tone and arterial pressure	Titrate per pediatric protocol	Reasonable when vasodilation contributes to hypotension. In pediatric septic shock, SSC finds insufficient evidence to prefer it or epinephrine universally. Start through suitable peripheral venous access when needed to avoid delay, with close site checks.
Dopamine	Dopaminergic and adrenergic activity	Lower exposure can produce regional vasodilation. Increasing exposure can add inotropy, tachycardia and vasoconstriction.	Titrate per pediatric protocol	Effects overlap and vary by patient. Low-dose dopamine does not prevent or treat acute kidney injury.
Milrinone	Phosphodiesterase-3 inhibitor	Inotropy, lusitropy, and vasodilation	$0.25–0.75\text{ mcg/kg/min}$ is a typical IV range in the 2026 AHA cardiogenic shock statement	Use when arterial pressure can tolerate vasodilation. Monitor for hypotension and arrhythmia, and consider dose adjustment in renal dysfunction.
Vasopressin	Vascular $V_{1a}$ receptor agonist	Raises systemic vascular tone	Titrate per pediatric protocol	For septic shock requiring high-dose catecholamines, SSC conditionally suggests adding vasopressin or further titrating catecholamines. Assess perfusion and adverse effects.
Sodium nitroprusside	Releases nitric oxide	Arterial and venous vasodilation	FDA-labeled starting rate $0.3\text{ mcg/kg/min}$ IV	Consider in selected hypertensive patients or when ventricular ejection is impeded by excessive afterload and pressure permits vasodilation. Monitor arterial pressure continuously, follow formulation-specific light protection instructions, and assess for cyanide and thiocyanate toxicity with increasing exposure. Renal dysfunction increases thiocyanate accumulation. Prescribing information
Nicardipine	Dihydropyridine calcium channel blocker	Arterial vasodilation	$0.5–4\text{ mcg/kg/min}$ IV infusion in the AAP acute severe hypertension guideline	Titrate to the clinical pressure goal and monitor for hypotension and reflex tachycardia. AAP dosing table

Advanced Pharmacological Principles in Pediatric Shock

The Milrinone Advantage: Lusitropy & Inodilation

Phosphodiesterase-3 degrades cyclic AMP (cAMP) in cardiomyocytes and vascular smooth muscle cells. Milrinone inhibits PDE-3, raising intracellular cAMP:

Cardiomyocyte Inotropy: Elevated cAMP activates protein kinase A (PKA). PKA signaling increases L-type calcium current, in part by phosphorylating the channel regulator Rad. This supports systolic calcium entry and contractile force. Mechanistic study
Cardiomyocyte lusitropy: PKA phosphorylates phospholamban and relieves its inhibition of SERCA2a. Faster calcium reuptake into the sarcoplasmic reticulum supports active relaxation. The clinical response depends on filling, perfusion and tolerance of vasodilation. Human myocardial signaling study
Vasodilation: Increased cAMP in vascular smooth muscle promotes relaxation. Lower vascular resistance can improve forward flow, and excessive vasodilation can reduce perfusion pressure.

Vasopressin in vasodilatory shock

Vasopressin raises vascular tone through a nonadrenergic mechanism. In pediatric septic shock requiring high-dose catecholamines, the 2026 SSC gives a conditional option to add vasopressin or titrate the catecholamines further. An isolated pH does not establish an indication or a preferred drug. Pediatric SSC

Loading diagram...

Hemodynamic decisions in acute myocardial dysfunction

Test Your Knowledge

A 6-year-old with vomiting and fever over the previous week presents with tachypnea, cool extremities and a gallop. Initial echocardiography shows diffuse left ventricular hypokinesis, and troponin is elevated. After treatment and monitored stabilization, perfusion is adequate and the child can safely undergo imaging. Which noninvasive test can best characterize myocardial edema and injury when myocarditis is suspected?

Coronary CT angiography

Technetium-99m pyrophosphate scintigraphy

Cardiac magnetic resonance with T1- and T2-based tissue characterization

Repeat 12-lead ECG

Test Your Knowledge

A 4-year-old with myocarditis has cool extremities, oliguria, depressed left ventricular systolic function, and elevated systemic vascular resistance. The cardiac team confirms that arterial pressure can tolerate afterload reduction. Which infusion provides inotropy, lusitropy, and vasodilation?

Phenylephrine

Dopamine

Epinephrine

Milrinone

Test Your Knowledge

A 12-year-old with septic shock and secondary myocardial dysfunction remains hypotensive on an epinephrine infusion after initial resuscitation. A multimodal hemodynamic assessment supports low systemic vascular tone, and the team chooses to add an agent with predominantly alpha-adrenergic vasoconstrictor activity. Which drug matches that goal?

Norepinephrine

Sodium nitroprusside

Low-dose dopamine

Inhaled nitric oxide

Sections you finish are checked off in the contents.

Up Next

5.1 Acute Upper Airway Obstruction: Croup, Epiglottitis, Bacterial Tracheitis & Foreign Body Aspiration

Chapter 5: Acute Airway Emergencies & Severe Pulmonary Infections