Murmurs are irregular sounds that doctors detect when listening to the heart with a stethoscope. It is normal for the heart to make noises as the heart valves open and close.
When the semilunar valves open, blood comes through the vessels that lead out of the heart (the aorta and pulmonary artery). This period in the cardiac cycle is called systole. The opening of these semilunar valves coincides with the closing of the intracardiac valves (tricuspid and mitral). Once all the blood has left, there is a relaxation of the heart causing suction of the blood from the veins towards the heart. This part of the cardiac cycle is known as the diastole. During cardiac auscultation, only the valve closures should be heard. If there are cardiac anomalies (such as holes, abnormal valves or abnormal membranes), a sound will be produced by the passage of blood in these abnormal areas. This is known as an abnormal or “organic” murmur (i.e. caused by some alteration).
Children have small vibratory murmurs; so-called innocent or functional murmurs, which are not produced by any alteration of the heart.
It is believed that these heart murmurs can be related to: the elasticity of the heart, the tachycardia naturally inherent in children, and the small distance between the thoracic cavity and the heart, although their origin is not completely clear. The characteristics of innocent heart murmurs are very specific and pediatric cardiologists are well accustomed to recognizing them. Pediatricians can also recognize them, but sometimes when the murmur persists, they might refer a child to cardiologists to rule out any small cardiac anomalies that may have gone unnoticed.
If the murmur persists or increases in intensity, it is recommended that the cardiologist check the child for any alteration using a ECG (electrocardiogram). Once any intracardiac problems are ruled out, a pediatrician can do the follow-up to confirm the absence of alterations.
Heart rate (HR) increases during exercise to send more blood to the lungs and, in turn, carry more oxygen to the tissues requiring more energy. The maximum HR of the heart is calculated as 220 minus the age in years, meaning younger children have a higher maximum HR. The heart of a 5-year-old child can reach up to 215 bpm (220 – 5 = 215 bpm) when running at high intensity.
You should only worry if your child shows chest pain or discomfort when they run. If this happens you should go to your pediatrician who will assess whether a review by a specialized cardiologist is necessary.
There are other things which can make the heart beat more rapidly, such as anemia (where there is less hemoglobin to transport oxygen, making the heart compensate by increasing the heart rate) or hormonal alterations like hyperthyroidism (where elevated levels of the hormone thyroxine make the heart beat faster). Conversely, hypothyroidism causes the heart to go slower.
If there is any doubt in a child with palpitations, a pediatrician should be consulted and blood tests carried out to rule out extracardiac anomalies.
Alterations of the cardiac rhythm are among the most frequent alterations related to sudden death during exercise. Some people may have diseases affecting the transmission of cardiac rhythm due to alterations of myocardial cells (that is, of the channels that transmit the electricity of cardiac rhythm), among them are the following:
- Long QT syndrome: http://cardiopatiasfamiliares.es/qt-largo/ | http://www.sads.org/sads/media/pdf/sads-lqts-broch-spanish-09.pdf
- Brugada syndrome: http://cardiopatiasfamiliares.es/sindrome-de-brugada/
- Some people may present rhythm disturbances due to abnormal conduction pathways that produce tachycardia during exercise, thereby producing ventricular arrhythmias which can cause heart failure or sudden death, such as Wolff-Parkinson-White Syndrome (WPW):http: //www.fundaciondelcorazon .com / information-for-patients / cardiovascular-diseases / arrhythmias / el-sindrome-de-wolff-parkinson-white.html
The most common syncope (a temporary loss of consciousness due to a fall in blood pressure) is the vasovagal, mediated by the vagus nerve, which connects to the heart. Any stimulus which causes a decrease in heart rate then produces a decrease in blood pressure. Due to a decreased blood supply to the brain the person loses consciousness and collapses (there can sometimes be abnormal movements or a very short seizure, which must be differentiated from a seizure due to a neurological problem such as epilepsy).
It is the typical syncope that occurs when seeing blood or feeling a very acute pain. It is usually preceded by dizziness and sometimes related to heat, suffocation or stress. It lasts less than a minute and has a rapid recovery. It must be differentiated from a syncope due to some cardiological issue which are usually caused by abrupt arrhythmias. They are not preceded by dizziness or related to any event. They usually last more than a minute and have a slow recovery.
Alterations of the heart muscle (cardiomyopathy) may also cause problems during exercise. Arrhythmias or cardiac failure may occur while exercising due to alterations generated by a muscle abnormality. Other alterations include congenital malformations of the coronary arteries (the vessels that supply the heart). In these cases, exercising requires the heart to pump more blood to the muscles, but the vessels cannot adequately supply the heart causing ischemic phenomena (or cardiac infarction).
If the child complains their heart is beating very quickly when they are calm, it must be investigated. Cardiological examinations are recommended to rule out abnormal heart accelerations (tachycardia). Abnormal in this sense refers to a high HR which is not in normal response to your energy demands. An ECG must be taken to determine if there is any sign of arrhythmia caused by abnormal electrical pathways. A Holter (24-hour ECG) should also be used to record electrical activity over a longer period, again to verify if there is any alteration. Sometimes the 24-hour Holter does not register any alteration because the subject does not present symptoms on the day they are observed. In those cases, the Holter can be prolonged to several days (using an event monitor) or a special Holter can be implanted that registers electrical activity over a period of months, detecting an arrhythmia by visualizing the data telematically.
Currently, several systems are being developed for the telematic registration of arrhythmias, called wearables (wireless technology incorporated in a device that allows remote monitoring of the patient’s heart).
In the coming years, we will witness a technological revolution in this field, through new applications of smart watches, with increasingly sophisticated apps for the detection of cardiac arrhythmias.
Dizziness can have several causes, usually related to decreases in blood pressure. This is what we usually call presyncope or ‘feeling faint’, and syncope is actually fainting, when there is loss of consciousness.
The most common syncope is the vasovagal, mediated by the vagus nerve, which connects to the heart. Any stimulus which causes a decrease in heart rate then produces a decrease in blood pressure. Due to a decreased blood supply to the brain the person loses consciousness and collapses (there can sometimes be abnormal movements or a very short seizure, which must be differentiated from a seizure due to a neurological problem such as epilepsy).
This typical syncope can occur after ‘seeing blood’ or feeling a very acute pain. It is usually preceded by dizziness and sometimes related to heat, suffocation or stress. It lasts less than a minute and has a rapid recovery. It must be differentiated from a syncope due to some cardiological issue which are usually caused by abrupt arrhythmias. They are not preceded by dizziness or related to any event, usually last more than a minute and have a slow recovery.
In general, issues involving vasovagal syncope improve with age. An increased intake of fluids and salt is recommended – especially during exercise, and measures should be taken to control the previous symptoms of dizziness to avoid injuries caused by sudden falls.
After a syncope if you have doubts about its origin, it is advisable to go to the pediatric emergency department to carry out complementary tests for its diagnosis. Cardiological assessment should be sought if the fainting is frequent and not suggestive of vasovagal type syncope.