Common Drugs in Paediatric Cardiology

1. Diuretics

A diuretic is a medicine which increases the amount of water that you pass out from your kidneys as urine. A diuretic causes an increase in urine, called a diuresis. So, they are sometimes called 'water tablets'.

In some heart conditions, there may be excess water retained in the body due to ineffective pumping of blood to the kidneys, or excess of water present in the lungs, which may increase the pressure in the lungs. Diuretics help to dry the lungs and remove the excess body water through the urine.

Your child may be given the dose of diuretic medicine as syrup or a tablet. If your child is admitted, they may be given the drug through an intravenous (I.V) route (injecting directly into the veins)

The dosing of diuretic will depend on your child’s weight, heart condition and body water state. Usually a dose of 1 milligram/kg of body weight is given. This may be given twice daily so as to allow adequate passage of urine and removal of excess body water through the day, while allowing the child to be active.

Diuretics must be used with care because removing too much fluid too quickly can lower the blood pressure, cause lightheadedness or fainting, and worsen kidney function. Also, use caution if the child is suffering from diarrhea.

Your child may have to empty their bladder more frequently after taking a diuretic.

Interactions: Not to be given along with Calcium tablets

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2. Anticoagulants

Anticoagulants are medicines that prevent the blood from clotting as quickly or as effectively as normal. Some people call anticoagulants blood thinners. However, the blood is not actually made any thinner - it just does not clot so easily when you take an anticoagulant.

In some heart conditions such as arrhythmias, post-operative cases or after mechanical valve implantation (in a state where the body is in stress and inflammation), there is a high chance of blood flow slowing down and a clot to form in the blood vessels and heart chambers. This clot could increase in time and may eventually lead to complete blockage of the vessel, cutting off nutrition and oxygen supply to tissues.

Therefore, your child may be started on blood thinners which will help improve the blood flow while the body recovers. Sometimes your child may have to be kept on these blood thinners lifelong.

Blood thinners are available as tablets or may be administered through I.V if your child is admitted.The dosing will be variable based on a number of factors. Your doctor will regularly advise you to do a blood test called PT/INR to check the same, and then adjust the anticoagulant dose so as to keep it at an optimum level to minimize side effects. Usually, INR is kept between 2.0-3.0 but will vary based on the underlying condition.

Typical maintenance dose of the commonest oral anticoagulant, warfarin,  ranges between 2 and 10 mg/day.  Initial doses are often higher than maintenance doses.  In selected cases it may be necessary to overlap with injectable heparin for the first few days.

Side effects include increased bleeding tendency- after falls or wounds, gum bleeds, bruising, nose bleeds. Care has to be taken to avoid injuries of any form while on these.

It is important to recognize that there may be considerable day-day variability in the action of oral anticoagulants.  This is because of variations in diet and consumption of other medications.  It is advisable to maintain a reasonably uniform intake of leafy vegetables (spinach, cabbage, fenugreek leaves, lettuce).  However despite best efforts there is variability in the blood coagulation and therefore INR needs to be tested at 2-4 weekly intervals.  In the initial phase of starting the oral anticoagulants, INR needs to be tested more frequently.

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3. Aspirin

Aspirin works by stopping the production of certain natural substances that cause fever, pain, swelling, and blood clots. In heart conditions, doctors use this medication for its ability to reduce the tendency for blood to clot. 

If a clot forms inside one of the arteries that supply the heart muscles with blood (called the coronary arteries), a heart attack can occur. Likewise, if a clot forms inside one of the blood vessels that supply the brain, a stroke can occur. Aspirin can prevent cardiovascular events because it reduces the chances of blood clot formation by inhibiting the clumping of platelets to the vessel wall that happens at the very beginning of clot formation. . 

Aspirin is available as a tablet. Extended and slow-release tablet forms are also available. It should ideally be given with meals.

The commonest side effect is stomach irritation  (gastritis) that results in pain over the upper part of the abdomen. It may also increase the tendency to bruise after minor injuries. Some children may have hypersensitivity to aspirin and some may not respond to it at all.  In these situation an alternative medication (Clopidogrel) may be given)

Key Interactions: May enhance antiplatelet and anticoagulant effects of drugs. May also increase the hypoglycemic (low blood sugar) effect of drugs.

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4. Iron

Iron is one of the main constituents of haemoglobin, the molecule which transports oxygen in our blood.

In children with heart diseases, growth may be affected because of inefficient blood pumping by the heart leading to poor absorption of nutrients and this could lead to a deficiency of haemoglobin called anemia. Supplementing iron allows the body to replenish the stores and improves the oxygen delivery to tissues. This decreases the stress of pumping on the heart.

Iron is available as syrups of varying strengths per ml, tablets and can rarely also be given as IV/IM preparations. 

Excess of iron, or administration of iron in states of fever and infection could lead to its accumulation and deposition in the liver. Iron supplements can also stain the tongue and teeth and some preparations can irritate the stomach and intestines and result in vomiting and loose stools..

Key Interactions: Not to be given during active infections or at least 2 weeks post recovery from surgery. Do not give oral iron with milk, calcium or antacids.

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5. Medications in pulmonary hypertension

Pulmonary hypertension is a condition in which there is abnormal rise of blood pressure in your child’s lungs and its blood vessels. This increases the work done by the right side of the heart and can lead to heart failure.

Multiple drugs may hence be needed to decrease the pressures and improve lung blood flow. Some of these are Sildenafil, Bosentan, Ambrisentan Macetentan, Calcium channel blockers and Riociguat.  Additionally certain medications such as prostaglandins are widely used in the west but unavailable in India.  Diuretics and blood thinners such as Warfarin may also be given along with the above. 

Doses and choice of drug will vary depending on the severity of pulmonary pressures, and the side effect profile of each drug.  These drugs may need to be given for a long time, till the pressures reduce and normalize.

These medications have to be given under the careful supervision of a pediatric cardiologist and need to be taken very regularly.  Blood tests to monitor liver function every month are needed for those who are on Bosentan.

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6. Heart Failure Medications

In heart failure, your doctor’s goal would be to improve the pumping efficacy of the heart, clear the lungs and push the blood towards the organs for their oxygen and nutrition requirements.

Your doctor may use medications such as ACE inhibitors (Enalapril) and ARB (Losartan) to dilate the vessels and decrease the blood pressure against which the heart works. These are available in a tablet form and the dose is adjusted as per the weight of the child.

Your doctor will also prescribe diuretics to help dry out the extra fluid filling up back into your child’s lungs due to pump failure.

In a state of failure, your body is stressed and releases stress hormones such as adrenaline and noradrenaline which increase the heart rate, at the cost of pumping efficiency. Your doctor may then try to slow the effect of these through added beta blockers such as carvedilol.

Medications that increase the force of contractility of the heart such as digoxin may be added, so also vessel dilators such as hydralazine and nitrates in some cases.

If the child is very sick and unstable, he/she will be admitted and given medications through the Intravenous route and may need intensive care.

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7. Beta blockers

The purpose of beta blockers is to slow down the heart rate when it is unduly fast.  The names of  drugs in this category are propranolol (Inderal or Ciplar), metoprolol, Atenolol and Bisoprolol.

Beta blockers are advised in the following circumstances:

• Rhythm disorders with fast heart rates

• Tetralogy of Fallot with episodes of increasing blueness (Tet spells)

• Selected cases of heart failure

• Certain disease like hypertrophic cardiomyopathy with excessive muscle contractility

• Selected children with high blood pressure

Side effects include low blood pressure, undue slowing of heart rate,  triggering of asthma. They may mask the effect of low blood sugar, by preventing tremors and increase in heart rate.