IMPACT
Our Definitions
As part of our commitment to improving pediatric VAD (ventricular assist device) patient care, ACTION has developed harmonized adverse event (AE) definitions. These updates align with the evolving ECMO-CENTRAL pediatric definitions, adult mechanical circulatory support (MCS) standards, and legacy Intermacs/ACTION criteria—while addressing the unique complexities of children with and without congenital heart disease. Informed by adjudicated ACTION data, pediatric device trial experience, and broad stakeholder input across disciplines and institutions, these definitions reflect the most current consensus in the field. They will continue to evolve through periodic updates to ensure relevance and clinical utility.
VAD Adverse Events
These materials and tools are intended for clinical provider use.
Have Questions?
Need help?
Join one of the following office hours:
Clinician Reference Guide
As of August 1, 2025
Hematologic Events
1. Neurological Dysfunction
TIMING
Anytime during VAD support
TYPES
- Ischemic stroke
- Intracerebral hemorrhage (in brain/spinal cord)
- Extra-axial hemorrhage (around brain/spinal cord)
- Undefined type
- Hypoxic ischemic encephalopathy
- Encephalopathy (other)
- Neuropathy
PRESENTATION
- Overt: With neurological symptoms
- Covert: No exam findings; injury detected on imaging
GRADES
2: No change in management
3: Requires any of the following:
- New antiepileptic medication,
- Discontinuation of antithrombotic therapy >24 hrs
- Change in transplant listing
4: Requires neurosurgical or interventional procedure
2. Bleeding
TIMING
- Grade 4: Any time after index procedure
- Grades 2–3: Identified ≥72 hrs after leaving OR/cath lab
Report each event with location and grade
LOCATIONS
- GI
- Nasal/Oral
- Pleural/Mediastinal
- Pericardial
- Pulmonary
- Genitourinary
- Cannula/Driveline/Percutaneous
- Retroperitoneal
- Other
GRADES
2: Local intervention only (packing, superficial cautery, topical hemostatic agent)
3: Any of the following:
- PRBC transfusion due to bleed.
- New surgical/percutaneous drain placement.
- All anticoagulation held >24 hrs (if started).
4: Invasive procedure (e.g., surgical exploration
or embolization)
3. Hemolysis
TIMING
Anytime during VAD support
LAB CRITERIA
Any of the following on 2 separate draws:
- Plasma Free Hgb > 50 mg/dL (clean draw)
- LDH > 3× upper limit of normal (no other cause; provider judgment)
- Moderate or greater hemolyzed cells on smear
GRADES
2: Isolated lab criteria without other clinical findings
3: Lab criteria plus:
- PRBC transfusion (hemolysis main reason), or
- External pump/component exchange (hemolysis main reason)
4: Lab criteria plus:
- Surgical intracorporeal pump exchange, or
- AKI from hemolysis requiring RRT
Device Related Events
1. Pump Thrombosis
TIMING
Anytime during VAD support
TYPES
Note: Applies only if pump is functioning appropriately. If the device is not functioning appropriately, the exchange will qualify as a device malfunction AE.
Paracorporeal/Transcatheter Devices:
- Criteria met if device/component is exchanged
due to thrombus/fibrin - Multiple components exchanged in one procedure due to or related to thrombosis = one AE
Intracorporeal Devices:
- Criteria met if 2 or more of the following are present, attributed to thrombus:
- Abnormal device function or parameter changes
- Inadequate cardiovascular support or embolic event
- Hemolysis
- Confirmed thrombus (on imaging or after explant)
GRADES
2: No embolization; external component replaced
3: Embolization (e.g., stroke); external component replaced
4: Any embolization status; surgical or transcatheter replacement of internal component
Note: Multiple AE definitions may be met; for example, if hemolysis leads to concern for pump thrombosis and pump exchange, the criteria for hemolysis may also apply. Another example: If the patient has a stroke with evidence of pump thrombosis, complete the Neurological Event form as well.
2. Device Malfunction (includes all components)
TIMING
Anytime during VAD support
DEFINITION
Device not functioning per manufacturer specifications (excludes routine maintenance). Report even if due to user error or non-FDA accessories.
TYPES
- Mechanical failure: e.g., controller overheating
- Structural failure: e.g., membrane/cannula rupture
- Dysfunction: e.g., battery not charging
- None: Device working but replaced due to concern
GRADES
2: Device functioning properly, requires:
- Non-routine Reset/alarm response or power source change (e.g., battery swap), or
- Non-routine replacement/repair of an external paracorporeal pump or component (e.g., sound, abnormal appearance)
3: Device not working, no clinical symptoms, requires:
- Non-routine replacement/repair of paracorporeal/percutaneous component (e.g., tubing tear), or
- Repair of external intracorporeal device’s external component (e.g., driveline repair)
4: Device not working and either:
- Symptoms + vasoactive meds; treatment includes replacement/repair of paracorporeal/intracorporeal component, or
- Surgical replacement of internal component (symptoms may or may not be present)
Infection Events
1. Device-Specific Infections
TIMING
Anytime during VAD support
REPORTING
Each event includes a type and grade
TYPES
- Superficial driveline/cannula/peripheral site infection:
- Negative blood culture and
- At least one of: purulence, pain, erythema, or induration at the site
- Deep percutaneous site infection:
- Meets superficial criteria plus at least two of:
- Fluid collection at site
- Imaging consistent with deep infection
- Fever, leukocytosis, tachycardia, or systemic inflammatory response
- Meets superficial criteria plus at least two of:
- Device-specific bloodstream infection:
- Positive blood culture plus one of:
- Deep site infection
- Culture from device circuit
- Persistent culture with same organism >72 hrs apart
- Imaging evidence of vegetation/thrombus
- Positive blood culture plus one of:
- Sternal wound infection with mediastinal extension:
- Involves external device components and
- Positive culture from surrounding tissue/fluid
- Systemic signs of infection (e.g. fever, leukocytosis)
GRADES
1: Superficial infection managed with:
- Dressing changes
- Topical antimicrobials or
- < 24 hrs systemic antimicrobials
2: Superficial infection, no systemic signs, treated with >72 hrs of enteral antimicrobials
3: Either:
- Superficial infection with systemic signs, treated with >72 hrs of IV/IM antimicrobials
- Superficial infection (± systemic signs) requiring:
- External component exchange
- I&D at site
- Long-term (>4 weeks) oral or IV therapy
4: Deep infection with any of:
- Internal device component exchange
- Surgical/invasive procedure (e.g. chest tube, washout)
- ≥3 positive cultures with same organism over ≥7 days, requiring long-term IV therapy
2. Non-Device Related Infections
TIMING
Anytime during VAD support
REPORTING
Each event includes a type and grade
TYPES
- Viral upper/lower respiratory infection
- Viral gastroenteritis
- Sternal wound infection (no mediastinal extension)
- Pneumonia (with radiographic + clinical findings)
- UTI (clinical + positive culture)
- Other
GRADES
1: Observation or antimicrobials <72 hrs
2: Admission or oral antibiotics ≥72 hrs
3: IV/IM antibiotics >72 hrs or fluids <40 mL/kg
4: IV/IM antibiotics + ≥40 mL/kg fluids, vasoactives, or surgery
End-Organ Failure Events
1. Right Heart Failure (Biventricular Circulation Only)
TIMING
- Additional of RVAD or transition to ECMO anytime post VAD placement
- Medical management for right heart dysfunction >10 days post-op
DIAGNOSTIC CRITERIA
- Requires a functioning LVAD and one finding from both categories, ≥10 days post-index operation:
HEMODYNAMICS (one of) - Right-sided/systemic venous pressure >14 mmHg
- Clinical signs of elevated CVP (e.g., effusions, ascites, hepatomegaly) with inadequate LVAD preload (CO <50% expected and not responsive to pump changes)
IMAGING (one of) - Moderate/severe tricuspid regurgitation
- Moderate/severe RV systolic dysfunction (documented)
OR, AT ANY TIME POST-OP - Transition to ECMO (for RV failure)
- RVAD implantation
GRADES
3: Medical management requiring vasoactives, invasive drainage, or prolonged drain use due to RV failure
4: ECMO or RVAD placement for RV failure
2. Renal Dysfunction
TIMING
Anytime during VAD support
DIAGNOSTIC CRITERIA
Requires abnormal creatinine or eGFR (via Cystatin C, modified Schwartz, or CKiD) on 2 consecutive lab draws
GRADES
2: Creatinine 2–3× baseline* or eGFR 35–60 ml/min/1.73 m²
3: Creatinine ≥3× baseline* or eGFR <35 ml/min/1.73 m²
4: New need for renal replacement therapy (RRT)
*Baseline = last lab draw before VAD placement
3. Hepatic Dysfunction
TIMING
Anytime during VAD support
DIAGNOSIS
Requires ≥2 of the following, confirmed on two consecutive labs:
- Total bilirubin >3x upper limit of normal or >3x baseline if elevated pre-implant
- INR >3 (not from anticoagulants, dilution, or vitamin K deficiency)
- AST/ALT >3x upper limit of normal or >3x baseline (not due to hemolysis, myositis, rhabdo)
- Hepatic encephalopathy diagnosed by neurology
*Baseline = last lab draw before VAD placement
GRADES
2: Meets lab criteria
3: Labs + hepatic encephalopathy and/or coagulopathy needing FFP, cryo, or clotting factor products
4: Encephalopathy requiring mechanical ventilation or hepatic replacement therapy (MARS)
4. Respiratory Dysfunction
TIMING
Escalation in respiratory support >10 days post VAD placement or transition to ECMO, oxygenator addition, or tracheostomy placement at any time post VAD
DEFINITION
New need for PPV (invasive or non-invasive) or MCS (e.g., ECMO, oxygenator) due to impaired respiratory function unrelated to diagnostic/therapeutic procedures
GRADES
2: New non-invasive PPV (e.g., CPAP, BiPAP) not prescribed pre-VAD
3: >10 days post VAD, requirement of PPV via ETT or tracheostomy for >24 hours (not procedure-related)
4: ECMO, oxygenator addition, or new tracheostomy
5. Vasoplegia
TIMING
Within 72 hours post VAD implant
DEFINITION
- Low SVR with hypotension and normal/elevated device flow (CI >2.4 L/min/m2) with no alternative cause
- End organ hypoperfusion with new kidney/liver dysfunction
GRADES
3: ≥3 vasoconstrictors required
4: >3 vasoconstrictors + one of the following:
- ECMO
- Distal extremity necrosis requiring treatment
Gastrointestinal Events
1. Feeding Intolerance
TIMING
Identified >10 days post VAD implant
DEFINITION
Inability to meet caloric goals enterally. Excludes intolerance due to pre-existing GI abnormalities or other AEs.
GRADES
2: Caloric goal met via enteral + TPN/IL
3: TPN/IL dependent, no enteral intake
4: TPN/IL dependent with TPN cholestasis (conjugated bili >2x upper limit of normal or no route meets caloric needs
2. Chylothorax
TIMING
Anytime during VAD support
DEFINITION
- Effusion (pleural/peritoneal) with:
- Triglycerides >110 mg/dL, or
- Pleural triglyceride > serum triglyceride, or
- >80% lymphocytes in pleural fluid
GRADES
2: NPO >72 hrs for chylothorax
3: NPO + medical therapy (e.g., Octreotide) and/or new chest tube placement to treat chylothorax
4: Requires surgical or transcatheter intervention
3. Necrotizing Enterocolitis (NEC)
- Meets Modified Bell Criteria:
- Imaging: Intestinal dilation, pneumatosis, pneumoperitoneum, or portal gas
- ≥2 clinical signs: Temp instability, apnea/bradycardia, bloody stool, thrombocytopenia/DIC (abdominal), or distension
Inadequate Support
1. Inadequate Hemodynamics After VAD
TIMING
>10 days post-implant or patient death before 10 days
DEFINITION
- Inadequate systemic perfusion or ongoing congestion despite a functioning VAD, evidenced by:
- Continued vasoactive support and lack of improvement in ≥2 end-organ systems (Respiratory, Hepatic, Renal, Feeding intolerance)
GRADES
3: Lab-based organ dysfunction managed with vasoactive drugs
4: Organ replacement therapy (e.g., dialysis, TPN, ventilation) due to inadequate support
2. Fontan Venous Failure after SVAD
TIMING
- Identified anytime post VAD procedure requiring placement of Fontan venous VAD (right-sided VAD) or transition to ECMO
- Worsening clinical evidence of high venous pressure >equal to 10 days post VAD placement
DIAGNOSTIC CRITERIA
- Inadequate SVAD preload (no response to VAD changes):
- Worsening signs of high venous pressure (e.g., effusions, ascites, lymphatic dysfunction) >10 days post op
- Transition to ECMO (for right-sided failure) anytime
- Right-sided VAD (“Fontan” VAD) implantation anytime
GRADES
2: ≥10 days post-op, persistent effusion output <25 mL/kg/day for >3 days
3: ≥10 days post-op, high output effusions >25 mL/kg/day for >3 days
4: ECMO use or Fontan VAD placed as a separate procedure
Inadequate Support
1. Arrhythmia
TIMING
Anytime during VAD support
DEFINITION
Abnormal rhythm resulting in a new IV medical treatment and/or invasive therapy
GRADES
3: Requires IV therapy
4: Requires cardioversion, ICD, permanent pacemaker, or ablation
2. Vascular Access Site Injury
TIMING
Anytime during VAD support
DEFINITION
Injury related to percutaneous cannulation
TYPES
- Perforation
- Pneumothorax
- Pseudoaneurysm
- AV fistula
- Thrombosis
- Dissection
- Stenosis
- Bleeding at cannulation site (may need Bleeding AE if meets criteria)
- Limb hypoperfusion/ischemia
GRADES
3: Injury not requiring surgery/intervention
4: Requires surgery/intervention or results in
loss of limb/digit
