Myocarditis in children : summarized

Myocarditis

Dr Anum Arif

Acute or chronic inflammation of myocardium characterized by inflammatory cell infiltrates, myocyte necrosis or degeneration.

Causes:

i.                    Infections:

Viral infections	Bacterial	Fungal	Protozoal	Parasitic
Adenovirus Parvovirus Ebstein barr virus Parechovirus Influenza virus Cytomegalovirus Hepatitis c virus	Diphtheria Mycoplasma pneumonia Mycobacteria Streptococcus species	Aspergillus Candida Histoplasma	Toxoplasma gondi Trypanosoma cruzi Babesia	Schistosomiasis

ii.                   Immune mediated:

Ø  Churg strauss syndrome

Ø  Ibd

Ø  Sle

Ø  Kawasaki disease

Ø  Takayasu arteritis

Ø  Celiac

iii.                 Drugs:

Ø  Sulphonamides

Ø  Cephalosporin

Ø  Diuretics

Ø  Dobutamine

Ø  Tricyclic antidepressants

iv.                 Toxic:

Ø  Snake bite

Ø  Scorpion bite

Ø  Spider bite

Ø  Ethanol

PATHOPHYSIOLOGY;

Ø  Acute deterioration: myocardial inflammation, injury, necrosis leading to cardiac enlargement systolic dysfunction and ccf ( shock, atrial / ventricular arrhythmia)

Ø  Chronic: myocarditis may become chronic with persistence of viral nucleic acid in myocardium.

CLINICAL FEATUES:
Severe respiratory distress, central/peripheral cyanosis may be there ,
cold peripheries , pallor due to circulatory failure, dehydration due to reduced intake , grunting, head nodding, nasal flaring, suprasternal,intercostal,subcostal,substernal recessions may be there.
Pulses may be good volume but later low volume or absent pulses.
Capillary refill time may be prolonged(>3 Sec)
B.P may be recordable initially but later hypotension or BP not recordable.
Altered Sensorium, or irritability due to decreased cerebral perfusion.

tachypnea,tachycardia, hyperdynamic precordium, muffled heart sounds , gallop rhythm, apical systolic murmur. Hepatomegaly due to congestive cardiac failure, peripheral edema and rales or basal crepitation may occur due to cardiac  failure.

Differential Diagnosis:
Carnitine deficiency
DCM
Hereditary mitochondrial defects
Anomalies of coronary arteries.

Diagnosis:

Ø  Ecg: lOW VOLTAGE ECG  i-e QRS complexes (QRS  amplitude of less then 5 mm in 3 consecutive limb leads and/or less then 10 mm in precordial leads.

Ø  nonspecific st and t wave changes.

Ø  Chest xray: cardiomegaly (ratio of maximum horizontal thoracic diameter and maximum cardiac diameter more then 0.5., pulmonary vascular markings, pleural effusion.

Ø  Cardiac MRI: standard imaging modality.

Treatment:

            Admit the patient.

o   Keep Cleared Airway,

               Prop up to 45 degrees

               Oxygen inhalation via NG in nostril with continuous sp02 monitoring

                Check for adequate/B/L comparable chest rise

o   Maintain I/V line
Monitor :
PR, RR, BP, CRT, Temp, BSL, Urine Output,
Attach spO2 monitor,
Attach Chest electrodes for continuous ECG monitoring.

Restricted maintenance fluids 70%  ( 5%DW + N/2 e 2ccKCl/100ml)
For inotropic support: dobutamine, dopamine, adrenaline infusion or  milrinone(50mcg/kg iv over 10-60 min followed by 0.25-0.75mcg/kg per min iv  can be used) . Consult seniors regarding choice of inotropic support .
Milrinone has the same effects as that of dobutamine , but since it acts through inhibition of Phosphodiesterase, it reduces the myocardial oxygen demand and hence reduces the mortality as compared to dobutamine.

Ø  Diuretics to reduce cardiac pre load.

                Frusemide 1mg per kg per dose X BD (after recording BP)

Ø  Immunomodulation : Intravenous immunoglobins may be given
Inflammatory dose Dexamethasone(steroids) : 1mg/kg/day has a controversial role in acute phase.
Antivirals do not have any proven role.

Ø  If arrhythmias occur, patient may need Pharmacologic or Electric cardioversion.

Ø  Mechanical ventilation may be indicated during the course of disease.