Myocarditis may in some cases have a dramatic course and signs of heart failure and life-threatening arrhythmias can appear. During heart failure, the heart function gets worse – heart contractility is worse than normal. The consequence is that a lower amount of blood is pumped into the body and lower amount of oxygen too. In myocarditis, this situation is caused also by decrease of health heart tissue, which does not fulfil its function properly. The heart tries to resolve this problem by strengthening its wall to increase the amount of blood pumped into the body. On the other hand, a lower amount of blood gets into the heart because of this and heart starts to extend (dilate) the diameter of its ventricles and sometimes atrium. The heart function changes are accompanied by other changes – higher blood pressure, and the body starts to retain fluid etc. Physicians try to influence this situation with standard heart failure treatment:

ACE-INHIBITORS

ACE-I (inhibitors of angiotensin converting enzyme) is an abbreviation of a drug group, which disturbs the effect of an enzyme changing nonactive angiotensin I on active angiotensin II. Angiotensin II has a lot of receptors all around body. When angiotensin II interacts with its receptors in vessels which control the blood inflow to the organs, these vessel contract and leading to an increase of blood pressure. It leads also to a retention of fluid and an increase in the of volume of blood. Both processes mean a higher strain on the heart. The heart, which is weakened by inflammation, is strained more than is necessary. ACE-inhibitors reduce the amount of angiotensin II in blood and it leads to the decrease of blood pressure and it influences blood volume.

From a cardiology point of view, these drugs have even other favourable features (it reduces inflammatory changes, it prevents remodelling – change of heart structure and it effects positively even damage of capillaries (very thin vessels) in kidneys, e.g. at diabetes).

Some samples in this group are captopril, enalapril, linosopril, ramipril, perindopril and many others.

The side-effects of these drugs include dry cough and a bigger blood pressure decrease after the first use. It is also important to monitor kidney function. Generally, it is a very effective drug group in the treatment of heart failure and high blood pressure. They also reduce the inflammation and heart structure changes.

Picture 22: Captopril molecule (author: Benjah-bmm27)

SARTANS (BLOCKER OF ANGIOTENSIN II RECEPTORS).

This is a drug group which blocks the connection of angiotensin II with its receptors and, thanks to this, the effect of angiotensin II is decreased. Sartans are used mostly when a patient cannot be treated with ACE inhibitors for some reason, which are used more frequently in the treatment of heart failure than sartans. A reason for the use of sartans is for example intolerance of ACE inhibitors. Sartans have comparable effect with ACE inhibitors in both heart failure treatment, and high blood pressure (according to some researches they can how a lower effect on high blood pressure decrease).

Some samples of sartans are – losartan, telmisartan, valsartan and candesartan.

Medical experts make their decision about the use of sartans or ACE-inhibitors according to the actual patient´s state of health.

BLOCKERS OF BETA RECEPTOR (BETA BLOCKERS)

Beta blockers are drugs which block so called beta adrenergic receptors, so receptors for stressing hormone epinephrine (adrenalin) and norepinephrine (noradrenalin), (group of so called catecholamines). These hormones cause an increase of heart rate, heart contractility, increase of blood pressure, they extend bronchial tubes, increase the release of insulin and a number of other things, which enable higher release of energy during a stress situation.

Since the 1960s´, beta blockers are divided into beta-1 and beta-2 blockers (2 types of beta receptor). It was shown that so called non-selective (“non-choosy,” it means that they block both beta receptors) betablockers had several unfavourable effects mainly on the function of the bronchial tubes. For example, with asthmatics, the blocking of beta-2-receptors worsened the contractility of bronchial tubes and because of that breathing deteriorated. In cardiology, so called selective (“choosy”) betablockers of beta-1 receptors (2^nd generation of betablockers) are used. They block the effect of catecholamines primarily in the heart and vessels. The blockade of these receptors causes the decrease of heart rate and blood pressure. These substances are therefore used in the treatment of high blood pressure, and in small and gradually increasing dosage also during heart failure treatment. They are also used in case of some arrhythmias. During myocarditis, the use of beta-blocker is recommended when a patient is stable – which means mostly not in the acute phase of the disease.

Samples of the selective beta-blockers are for example atenolol, betaxolol, metoprolol, bisoprolol and others.

Carvedilol is also sometimes used in heart failure treatment; however, it also blocks also so called alfa receptors. Their blockade cause the decrease of blood pressure.

The side-effects of betablockers include unfavourable effect on the function of the bronchial tubes – because of this, beta-blockers are mostly not used in asthmatics. Beta-blockers can also effect the metabolism of “fat” and “sugar” in the body. In addition, betablockers cause contractions of small vessels, for example in the legs. Because of this, they are not used in patients diagnosed with diabetes, lower limb ischemia, functional spasm of peripheral vessels (cold limbs), asthma, AV blockade 2^nd or 3^rd degree, bradycardia (slowdown of the heart rate), metabolic syndrome, disorder of tolerance of glucose. In the case of chronic obstructive pulmonary disease (COPD), betablockers are not usually indicated, depending of course on patient´s general state of health.

Picture 23: Betaxolol molecule (author: MarinaVladivostok)

DIURETICS

Diuretics are drugs that increase the excretion of urine. Diuretics are one of the basic tools during heart failure treatment. Their effect lies in increased excretion of water and minerals through the kidneys. The reduction of the volume of water in the blood and the body leads to the reduction of blood pressure and volume overload of the heart. This effect makes the work for the heart easier. A group of diuretics are for example so called loop diuretics (furosemide etc.).

During treatment with diuretics, the level of minerals in the blood is continuously monitorated. Some minerals (primarily sodium and potassium) are excreted in urine in higher amounts than normal and therefore diuretics are not usually indicated at patients with significant decreased production of urine (anuria).

Antagonists of aldosterone also belong to diuretics. Aldosterone is a mineralocorticoid – a hormone of the adrenal grands. Aldosterone helps to “keep” a right level of sodium in the body and vice versa it supports the excretion of potassium. Simultaneously, it belongs to substances which increase the volume of fluid in the body and participate on the increase of blood pressure. In the case of heart failure, it plays a role in structural changes to the heart. Antagonists of aldosterone block receptors for aldosterone. These antagonists can be used together with loop diuretics. Parallel use of these drugs leads to the decrease of potassium loses and to the reduction of blood volume. Some samples of aldosterone antagonists include spironolactone and eplerenone.

Picture 24: Kidney (author: Piotr Michał Jaworski)

OTHERS

Treatment of heart failure in myocarditis has already been described in previous articles. However, treatment could be refilled even with other drugs according to actual patient´s state of health.

A sample of these “other drugs” is for example ivabradine which separately slows down the formation of heart electrical impulses in sinoatrial node (see this link) and causing the heart rate to decrease. It is indicated when betablockers are not as effective as required or when the patient cannot use them.

Some arrhythmias may occur during myocarditis; however, they mostly disappear by themselves after the calming of the inflammation.

In case of severe arrhythmias, drugs from groups of antiarrhythmic agents are indicated.

In arrhythmias with slow heart rate, physicians may consider a temporary implantation of a pacemaker (it is a device that is placed under the collarbone, transmitting electrical discharges leading to a contraction of the heart muscle). Alternatively, so called electrical cardioversion may be used when the patient´s arrhythmias are “directed” with use of defibrillator discharges.

A strong contradiction during myocarditis is the use of digoxin. Drug that belongs to the group of heart glycoside. These drugs increase heart contractility and indirectly slow down the heart rate. It has an important role in the treatment of heart failure at some patients, however one of the side-effects is an increase of energy consumption for the heart to work. Digoxin may also provoke some arrhythmias and its level in the blood must be controlled to prevent overdose. Its indication is narrowly depending on the physician´s decision according to the actual and overall patient’s state of health.

During the treatment of myocarditis, some drugs that influence blood coagulability (so called anticoagulants) may be indicated. The creation of blood clots (thrombus) can be a complication of myocarditis and heart failure (even as a result of arrhythmias). Some samples of anticoagulants include heparin, Warfarin and a new generation of anticoagulants called NOAC – dabigatran, rivaroxaban, apixaban.

In severe cases of heart failure, when a patient´s state of health is getting worse quickly and there is a need to support and accelerate heart activity, the use of catecholamines is indicated (for example dopamine or epinephrine). In cases of severe heart failure, dopamine and its pharmacological “twin” dobutamine is frequently used. Both of them increase the heart rate and blood pressure.

Author of the opening picture: Benjah-bmm27.