6
Definitions and Classifications
Table 5. Physiological Variables as Used in ACHD AP
Classification
Variable Description
Arrhythmia Arrhythmias are very common in patients with ACHD and
may be both the cause and the consequence of deteriorating
hemodynamics, valvular dysfunction, or ventricular dysfunction.
Given that arrhythmias are associated with symptoms, outcomes,
and prognosis, they are categorized based on their presence and
their response to treatment.
• No sustained arrhythmia: No documented clinically relevant
atrial or ventricular tachyarrhythmias
• Arrhythmia not requiring new treatment or a change in therapy
in the past 12 months: Bradyarrhythmia, atrial or ventricular
tachyarrhythmia not requiring new antiarrhythmic therapy,
cardioversion, ablation, or pacemaker/ICD placement
• Recurrent arrhythmias that are hemodynamically significant
and/or refractory to treatment
Concomitant
valvular heart
disease (VHD)
Severity defined according to the 2020 VHD guideline.
• Mild VHD
• Moderate VHD
• Severe VHD
Exercise capacity Patients with ACHD are oen asymptomatic despite exercise
limitations that manifest as diminished exercise capacity upon
objective evaluation; accordingly, assessing both subjective and
objective exercise capacity is important (see NYHA classification
system below). Exercise capacity is associated with prognosis.
• Abnormal objective cardiac limitation to exercise is defined as
an exercise maximum ventilatory equivalent of oxygen below
the range expected for the specific congenital heart disease
anatomic diagnosis.
Hypoxemia/
hypoxia/cyanosis
See Section 3.5 for a detailed definition of cyanosis.
• Hypoxemia is defined as baseline oxygen saturation measured
by pulse oximetry at rest ≤92%.
• Severe hypoxemia is defined as oxygen saturation at rest ≤85%.
• Hypoxia refers to inadequate tissue oxygenation that may or
may not be present in the setting of chronic hypoxemia.
• Cyanosis is blue or purple discoloration of the skin, lips, and
nailbeds caused by levels ≥5 g/dL of desaturated hemoglobin; it
is visible in patients with chronic hypoxemia and normal or high
hemoglobin levels but may be absent in patients with anemia.
