Acute left ventricular failure in children

In children, acute left ventricular failure is most often diagnosed after anatomical correction of simple transposition of the great arteries (by the arterial switch method), as well as after total anomalous drainage of the pulmonary veins. The development of left ventricular failure is associated with relative hypoplasia of the LV or coronary blood flow disorders in the early postoperative period. In the early postoperative period, in such patients, the moderately underdeveloped LV is unable to fully provide blood flow in the systemic circulation. This leads to the formation of pulmonary hypervolemia (and subsequently to pulmonary edema), as well as to the occurrence of systemic hypoperfusion.

Criteria for low cardiac output:

• Peripheral spasm with capillary filling symptom for more than 4 s.
• Tachycardia is usually non-sinus (more than 180 per minute), with normal plasma potassium concentration.
• Heart rhythm disturbances.
• A decrease in the rate of diuresis to less than 1 ml/kg/h).
• Extremely low mean blood pressure (less than 40 mmHg).
• Low pulse pressure (less than 20 mmHg).
• An increase in the filling pressure of the left and right atria to a level exceeding 12-14 mm Hg.
• Metabolic acidosis.
• Venous hypoxemia (Pu02 less than 28 mm Hg, Bu02 less than 40%), serum lactate concentration exceeds 4 mmol/l.
• Hypotension is a late manifestation of low CO in infants. The earliest signs are low pulse pressure (less than 20 mm Hg), decreased diuresis to 1 ml/kg h (or less), tachycardia over 180 beats per minute, and increased left atrial pressure to 12 mm Hg (or more).

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Drug treatment of acute left ventricular failure

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Sedation

To achieve a sedative effect, children are prescribed fentanyl infusions [3-10 mcg/(kg h)], and pipecuronium or pancuronium are administered in age-appropriate doses for the purpose of myoplegia.

Infusion therapy

The volume of fluid administered during the first and second days after surgery is limited to 2 ml/(kg h). From the third day, the volume of fluid is increased to 3 ml/(kg h). Considering the fluid retention during artificial circulation, by the time of sternum reduction and extubation, it is necessary to achieve a negative water balance, provided there is adequate preload (CVP and left atrial pressure - 5-8 mm Hg, satisfactory peripheral blood flow).

Diuretic therapy

To maintain a sufficient diuresis rate [at least 1 ml/(kg x h)], furosemide is administered as a bolus at a dose of 1-4 mg/(gh x day) from the first day after the operation. The development of signs of fluid retention against this background (positive water balance for three hours or more, increased pressure in the left atrium and CVP over 12 mm Hg, increasing peripheral edema, an increase in the liver size) is an indication for the maximum limitation of the volume of administered fluid and the performance of furosemide infusions at a dose of 5-25 mg/(kg x day). With plasma osmolarity over 310 mmol/l, it is recommended to administer mannitol in a single dose of 0.5 g/kg (up to a daily dose of 1 g/kg).

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Hemodynamic support

In case of LV failure, reducing the ventricular afterload while maintaining a minimum of mean arterial pressure sufficient for adequate coronary blood flow and diuresis is the basis of hemodynamic support.

The minimum systolic blood pressure level sufficient for adequate coronary and peripheral perfusion of the newborn is 50 mm Hg, the safe level is 60 mm Hg, the safe level of mean blood pressure is 40-45 mm Hg. The pressure in the left atrium must be maintained at 10-12 mm Hg (but not higher). Its further increase does not lead to an increase in CO and indicates decompensation of LV failure. It is extremely important to exclude systemic hypertension (the systolic blood pressure level in a patient under sedation and analgesia is no more than 80 mm Hg).

Dopamine [at a dose of 2-10 mcg/(kg x min)] in combination with dobutamine [at 2-10 mcg/(kg x min)] are the starting cardiotonic drugs used in acute left ventricular heart failure. All patients are recommended to undergo nitroglycerin infusion at a dose of 0.5-3 mcg/(kg x min) (vasodilator).

The persistence or development of clinical signs of decreased cardiac output with high OPSS against the background of infusion of two catecholamines [at an infusion rate of each drug greater than 10 mcg/(kg x min)], with an optimal heart rhythm and adequate preload, indicates an increase in acute left ventricular heart failure. This condition is considered an indication for the start of infusion of inodilators - phosphodiesterase type III inhibitors or levosimendan.

Enoximone (Perfan) administration begins with a saturation dose of 1-2 mg/kg over 10 min, followed by an infusion of 3-15 mcg/(kg x min).

For milrinone (Primacor), the loading dose ranges from 25 to 75 mcg/(kg x min), the maintenance dose does not exceed 0.25-0.8 mcg/(kg x min) [up to 1.0 mcg/(kg x min)].

If clinical symptoms of low cardiac output persist for 5-6 hours during infusion of phosphodiesterase III inhibitors, or if it is needed for two days (or more), the drug is replaced with levosimendan.

Due to the absence of phosphodiesterase III inhibitors in Russia, levosimendan (Simdax) is considered the drug of choice for the treatment of acute left ventricular failure in children; however, experience with the drug in this category of patients is limited. Levosimendan is administered starting with a saturation dose of 12-24 mcg/kg over 10 min, followed by an infusion of 0.1-0.24 mcg/ (kg x min). The maximum effect is observed 6 hours after the initial administration of the drug. If the saturation dose is effective and the maintenance dose is insufficient, the saturation dose may be repeated. The duration of levosimendan infusion is 24-48 hours. The active metabolite OL-1896 has the same properties as levosimendan, ensuring the preservation of the hemodynamic effects of the drug for at least 1-2 weeks after the end of its use.

The only indication for the use of adrenomimetics [adrenaline or noradrenaline at a dose of 0.03-0.2 mcg/(kg x min)] in acute left ventricular heart failure is the need to increase total peripheral vascular resistance to increase blood pressure with adequate cardiac output, including with intravenous administration of phosphodiesterase III inhibitors or levosimendan.

All patients are started to undergo digitalization immediately after surgery (30-40 mcg/kg digitalis in six administrations over two days). Patients with clinical signs of low SV against the background of normal plasma potassium concentration can undergo rapid digitalization (the first 3 doses are administered 3-6 hours before).

All patients with low cardiac output are prescribed creatine phosphate (Neoton) at a dose of 1-2 g/day. After prolonged (more than 180 min) artificial circulation with low cardiac output, as well as against the background of bleeding, it is necessary to infuse aprotinin (trasylol) at a dose of 10,000 U/(kg h), and also administer proton pump inhibitors (for example, losec at 1 mg/kg 2 times a day) for 1-3 days.

To reduce the signs of SIRS and prevent remote restenoses in the area of vascular anastomoses, glucocorticoids are prescribed on the 1st to 3rd day after surgery (2-4 mg/kg prednisolone per day). To restore or increase the sensitivity of adrenoreceptors to catecholamines, thyroxine is used at a dose of 5 mcg/(kg x day) (for three days).

Non-drug treatment of acute left ventricular failure

Renal replacement therapy

Indications for PD include a decrease in the rate of diuresis [less than 1 ml/(kg h) for 6 hours or less than 0.5 ml/(kg h) for 3 hours], persistent signs of fluid retention (despite the above-described dehydration therapy during the previous 24 hours), and hyperkalemia (more than 5 mmol/l). Dialysis is performed when one of the indications or their combinations is detected.

Respiratory support

ALV is performed in the normoventilation mode (pH - 7.4-7.45, paCO2 - 30-45 mm Hg), hyperoxia is excluded (SaO2 - 95-98%, paO2 less than 100 mm Hg) and hyperinflation (DO - 5-9 ml/kg), PEEP is 3-4 mBar. With progression of signs of acute left ventricular heart failure, it is recommended to increase PEEP to 6-8 mBar.