Hypertrophic cardiomyopathies

They account for 25 % of the cardiomyopathies in childhood, and 50 % of them are familial. It is essential to distinguish the obstructive forms, where an asymmetric septal hypertrophy creates a pressure gradient in the LV during the systole, from the non-obstructive forms. An useful element for assessing the myocardial function preoperatively is to measure the mass of the LV by ultrasound in 2 dimensions (2DLVmass): it is normally about 60 g / m2 in infants; the risk of rhythm disorders and ischemia is increased if it is greater than 150 g / m2.

Etiopathogeny	concerned pathologies
secondary to chronic systolic overload (concentric hypertrophy)	aortic stenosis, coarctation, high blood pressure, mitral abnormality
transient	newborn of diabetic mother corticosteroids in preterm infants
associated with other localizations of a pathology	Noonan, Friedreich, glycogenosis (Pompe), some mitochondrial cytopathies , disorders of the β-oxidation of the fatty acids, Danon's disease
isolated	familial or idiopathic forms (see this term)

Causes of hypertrophic cardiomyopathy in the child

diastolic function	decreased compliance of the LV diastolic dysfunction of the LV LA dilation increased pressure in the LA
systolic function	normal or increased contractility of the LV (if obstructive) normal RV
pulmonary circulation	increased pressure in the LA leads to increased pulmonary pressure risk of reversible then irreversible increase in pulmonary resistance
preload effect	decrease in ventricular filling poorly tolerated if obstructive avoid hypervolemia as the decrease in compliance of the LV will increase the pressure in the LA
heart rate effect	Bradycardia well tolerated (especially if obstructive) Avoid tachycardia because it decreases the filling of the VG and can produce subendocardial hypoperfusion Rhythm disorders (P wave loss, atrial fibrillation) are very poorly tolerated
post-charge effect	avoid decreased peripheral resistance (especially if obstructive) increased peripheral resistances are well tolerated

Hemodynamic consequences of hypertrophic cardiomyopathies

Non-obstructive hypertrophic cardiomyopathies

They may remain asymptomatic for a long time or present as cardiac failure, syncope, sudden death or signs of myocardial ischemia.

Anestheticimplications:

recent echocardiography; the thick myocardium needs high filling pressures and normal or high systemic resistances (and therefore sysBP and diastBP) to preserve its coronary perfusion. It is therefore useful to use a 5-leads ECG and monitor the changes in the ST segment.

Ketamine and etomidate preserve peripheral resistance and are therefore preferable to propofol, except at very low doses. Sevoflurane can be used with caution because it decreases peripheral resistance and carries a risk of loss of sinus rhythm. Locoregional anesthesia is an alternative to general anesthesia in this context. Risk of associated muscle pathology.

Obstructive hypertrophic cardiomyopathies

Treatment with a β-blocker reduces the contractilityof the LV and therefore the functional obstacle; in case of failure, a surgical septoplasty is performed. Treatment with mavacantem (an allosteric inhibitor of cardiac ß-myosin) p os decreases the intraventricular gradient and avoids septoplasty.

Anestheticimplications:

recent echocardiography; it is important to limit the obstructive component by decreasing myocardial contractility and ensuring adequate ventricular filling while maintaining a sinus rhythm: ketamine is therefore not a good choice and low-dose sevoflurane and an opiate should be preferred.

It is necessary to avoid hypovolemia and vasodilation which will induce reflex tachycardia and decrease the volume of the LV. It is useful to keep esmolol ready at hand to be able to quickly control tachycardia.

References :

- Batisse A, Fermont L, Lévy M
Cardiopathie par dysfonction myocardique.
In Cardiologie pédiatrique pratique, 4ème éd. Doin, 2013, p 187-93.

- Ing RJ, Ames WA, Chambers NA.
Paediatric cardiomyopathy and anaesthesia.
Br J Anaesth 2012 ; 108 : 4-12

- Kipps AK, Ramamoorthy C, Rosenthal DN, Williams GD.
Children with cardiomyopathy: complications after noncardiac procedures with general anesthesia.
Pediatr Anesth 2007; 17:775-81.

- Lynch J, Pehora C, Holtby H, Schwarz SM, Taylor K.
Cardiac arrest upon induction of anesthesia in children with cardiomyopathy : an analysis of incidence and risk factors.
Pediatr Anesth 2011 ; 21 : 951-7

- Williams GD, Hammer GB.
Cardiomyopathy in childhood.
Curr Opin Anaesthesiol 2011 ; 24 : 289-300.

Updated: September 2023