Electrophysiology Laboratory

Definitive diagnoses and treatments of all types of heart rhythm disorders (heart rate disorder, arrhythmia) are conducted at Electrophysiology Laboratory of Pediatric Cardiology Subdivision of Hacettepe University Faculty of Medicine.

Normal heart conduction system and normal cardiac rhythm Arrhythmias (abnormal rhythms)
Electrophysiology Laboratory- Tests used in diagnosis of Arrhythmia (rhythm disorder)
Electrocardiogram (ECG)
Heart rate variability (HRV)
Ambulatory ECG (Holter monitoring)
Event recorder
Transesophageal electrophysiological study
Tilt testing
Intracardiac electrophysiological study
Arrhythmia treatment
Pacemaker
Implantable cardiac defibrillator
Radiofrequency Catheter Ablation (RFA), Cold Ablation

Normal heart conduction system and normal cardiac rhythm

A normal heart is a strong pump composed of four heart chambers; two atria (right and left atrium) and two ventricles (right and left ventricle). The upper two atria collect blood from the body and lungs and pump it to the ventricles below. Ventricles pump the blood back to the lungs and the body. The blood flows in one direction due to the opening and closing movements of several valves within the heart

Each heart beat begins with a small electrical impulse produced by a special tissue (sinus node) at the right atrium. This impulse spreads to muscle tissue composing the atria after coming outside of the sinus node, and causes atrial contraction. Then, the same electrical impulse reaches another special tissue (atrioventricular node, AV node) which is located between the atria and ventricles. AV node takes the electrical impulse coming from the atria and keeps it for a while, and then transmits it to the ventricular muscles through special ways and ventricles contract rapidly. The waiting period in AV node, allows the ventricles to be filled with blood. If the heart is working normally, these specialized cells make impulses about 70-110 times in older children. This rate increases as the age decreases.

Arrhythmias

An arrhythmia is an abnormal heart rhythm. These can be either irregular heartbeats or faster (tachycardia) and slower (bradycardia) heart rhythms.

What are the reasons of arrhythmia?

A large part of arrhythmias occur in children who have healthy hearts. However, it is known that arrhythmias in children are related with heart abnormalities. Therefore, children with arrhythmia complaint should be examined in terms of heart abnormality. Furthermore, medication use, excessive caffeine intake, smoking and stress factors that can lead to arrhythmias must be questioned.

Do arrhythmias have familial (genetic) types?

Some certain types of arrhythmias and heart diseases may be hereditary and may occur in the same family more frequently. In addition, it is known that, certain genetic diseases cause certain arrhythmias and heart diseases. When such diseases occur, the whole family is screened in order to identify the disease and if needed they can be researched by a center performing genetical tests. Long term QT syndrome can be given as an example of such diseases.

What kind of complaints do arrhythmias cause and what are the syptoms?

Arrhythmias may cause fast heartbeats, fluttering in the chest, weakness, dizziness, blackout, fainting or chest pain.

What are the normal and abnormal heart rhythms?

Normal sinus rhythm

It is a impulse-generating heart rhythm coming from the sinoatrial node on the upper part of right atrium. While the node generates 70-110 impulse per minute in older children, the heart rate increases as the age increases.

Sinus arrhythmia

These are the variations in heart rate, caused by respiration. It is observed in younger children more frequent. It is thought to be normal.

Sinus tachycardia

It is the faster heart rate than normal heart rate originating from sinotrical node in comparison with the determined age.
Sinus bradycardia: It is the lower heart rate than normal heart rate originating from sinotrical node in comparison with the determined age.
premature electrical impulse in the heart, generated above the level of theventricle.

Supraventricular extrasystole

These are the premature heart contractions originating from atria. It is frequently seen in healthy children. It rarely shows symptoms.

Supraventricular tachycardia (SVT)

It is the fast heartbeat attack originating from the heart's upper chambers (atria).It can last as short as seconds or it can continue for days. Normally, during this period, the heart rate is over 150 beats/min.

Wolff–Parkinson–White syndrome (WPW): It is the most common reason of STVs in children. It occurs due to the presence of additional electrical conduction pathway,accessory pathway, between the atria and ventricles. Accessory pathway can be detected by ECG. While it can disappear by itself during infancy, after this period it can rarely recover by itself.

AV nodal reentrant tachycardia

It occurs in adults more commonly. It is seen in infants rarely. It occurs due to the presence of an extra pathway in AV node. It occurs and terminates suddenly.

Atrial flutter

It rarely occurs in children. It is caused by an abnormal electrical circulation in atria. It generally occurs in patients at increased ages, who had surgeries due to complex cardiac anomalies.

Atrial fibrillation

It rarely occurs in children. It is the irregular SVT due to multiple irregular electrical impulses origining from atria. It is rarely familial. I may also occur after the cardiac surgeries.

Ventricular extrasystole (VES, premature heartbeats due to ventricles): While it occurs in children with healthy heart, it may be an indication of an abnormality, thus it should be examined.

Ventricular tachycardia

These are the regular and fast heartbeats caused by ventricles. While it can last for minutes- hours (long duration), it may also take less than 30 seconds. Generally, it may occur along with an underlying heart disease.

Ventricular fibrillation

It is the irregular and critically too fast heart rhythm originating from ventricles. In this case, as the heart does not contract sufficiently, it cannot pump blood.

Heart block

The electrical impulse which begins from the upper chamber of heart (right atrium), passes through certain pathways until arriving in lower ventricles. The electrical impulse coming from the upper part cannot be conducted to lower ventricles, due to the blockage in any of those pathways. Therefore, the concordance between atria and ventricles is corrupted. In this case, lower ventricles contracts in lower rates than upper atria.

Sick sinus syndrome

It is the occurrence of excessive deceleration and pause of electrical impulse origining from sinoatrial node due to the damage in sinoatrial node because of a certain heart disease or a surgery. It may cause abnormal low heart rates.

Tests used in electrophysiology

Electrocardiogram (ECG)
It is a procedure of recording the electrical activities of heart on a paper by affixing electrodes to certain parts of the body. Patients do not feel anything during recording. If it is requested by the physician, ECG can be recorded and evaluated within the same day.

Heart rate variability (HRV)

It is obtained with examining the short-term (5 min.) or long-term (24 hours) ECG records. It gives information on autonomic control of heart by the examination of variations (oscillations) in heart rate.

Ambulatory electrocardiogram (Holter monitoring)

Similar to ECG, it is a procedure of recording heart’s electrical activities on a tape or on a disk for 24-48 hours with electrodes connected to body and a small device, then examining the records with a computer. The patient is allowed to go home after the device is affixed to the body of the patient between 09:00-11:00 in the morning , then is told to come back for the device to be removed 24-48 hours later, at 09:00 at the latest. So, the changes on ECG that may indicate ischemia can be detected in addition to the abnormal rhythms and extra heart beats, and the effectiveness of the treatment can be defined.

Holter appointment

At most 5 appointments can be scheduled per day, as there are 5 recording devices in the department. The appointments are scheduled at Holter room in Pediatric Cardiology Subdivision by telephone or by applying in person within working hours.

When are Holter results submitted?

The results are given to patients in the afternoon of the same daythat devices are delivered back.

What are the considerations before Holter test?

You should bring 2 ‘’DURACELL’’ alkaline batteries of 1.5 volts with you. You can get them from the canteen by the entrance of gate 7. As the devices will be affixed to other patients after you it is necessary to deliver the devices on time.

Event recorder

It is a beeper-sized device that enables defining the arrhythmias which could not be defined with Holter test and it remains on patients for 15 days. Thus, the appointments are scheduled for every 15 days. There are 2 event recorder devices in the department. When the patient has discomfort she/he presses the button on the device, then the device begins recording and it records during the time it is programmed. Afterwards, the records are examined on computer.

How is an event recorder appointment scheduled?

It can be scheduled at the same place of Holter appointment by phone or by applying in person.

What are the considerations before the event recorder appointment?

You should bring an alkaline battery with you.

When are the results submitted? After patient’s records are delivered to the department, the results are submitted on the very same day.

Transesophageal electrophysiologic study (TEEPS)

It is a semi-invasive method and can be used to determine the causes of fast heart beats (tachycardia) or to treat (transforming fast heart beats to normal sinus rhythm) it. TEEPS is used in order to record the electrical activity in atria, to impulse atria temporarily, to evaluate function of conduction, to clarify the mechanism of arrhythmia and to terminate tachycardia. It can be performed for all age groups and it takes approximately 15-30 minutes.

How is TEEPS performed?

In this method, a catheter (a thin, soft and flexible plastic tube) with a metal tail end is placed on the back part of atria from nostril through alimentary canal (esophagus) by establishing vascular access in electrophysiology laboratory after 3 hours of fasting and giving a sedative medication to the patient. Since the alimentary canal is just near the atria, the ECG records acquired from there provide more precise information than the surface ECG. Tachycardia is tried to be stimulated by giving electric current to the catheter inserted to the alimentary canal of the child through nose and by transfusing medications, for a certain time and in a certain intensity which is, then the type of stimulated tachycardia is defined and necessary treatment is decided.

TEEPS method is used for stimulating tachycardia, determining the mechanism of tachycardia, identifying the patient in risk of Wolff–Parkinson–White syndrome, specifying the effectiveness of medication treatment used, terminating tachycardia and in controlling the patients who are subjected to tachycardia treatments with ablation methods. This method is insufficient in detecting ventricular tachycardia.

It is also safe for infants. Although it is a low-risk method, it may cause resistant arrhythmia and tachycardia and also slight scratchiness in alimentary canal. Therefore, t is good for the patients to take liquid foods which are not very hot or cold, for 12 hours after the procedure.

When is the result submitted?

The test is evaluated and submitted to the family immediately after the procedure.

When is the patient allowed to leave after the procedure?

Hospitalizing the patient after the procedure is not necessary. The patient is observed for 1 hour following the procedure and allowed to go home after recovering oneself.

Tilt testing (Tilt table test)

The procedure is performed by monitoring (tracing the heart beats on the display) the patient and establishing the vascular access in an environment where all kinds of interventions can be practiced in case of emergency. The patient is laid down on a moving table. Patient is tied to the table with special belts to prevent falling in case of fainting during the test. Table is tilted 60-80 degrees and the patient is observed approximately for 45 minutes, tension and pulse are controlled in every 5 minutes. In case of severe decreases of blood pressure and slow down of pulsation, or fainting, the test is immediately terminated. It is used to determine the cause and definitive diagnosis of the fainting. Since the test takes more than 1 hour with the preparation and resting periods, tilt testing is performed to one patient per day. Tests are performed after 15:00 on appointment date. Patients can go home after the test.

What are the considerations before the test?

Unless indicated otherwise by your physician, you should fast for 2-3 hours before the test.

Intracardiac (through the heart) electrophysiological study (IEPS)

Intracardiac electrophysiological study may be necessary to determine the features of electric conduction system of heart, to define and treat the causes of abnormal rapid heartbeats (tachycardia). In this procedure, a catheter (a thin, soft and flexible plastic tube) which has one or more metal tile ends, is moved from inguinal to heart through large vessels and placed in certain regions within heart. The recorded electric signals in the heart , provide more certain information than surface ECG. During the test, heart can be stimulated to beat fastly or irregularly. The response of heart against this impulse enables the cardiologist to identify the features of rhythm disorders better and to detect the pathway of the activity during tachycardia. Therapeutic interventional method can only be performed in older children. Test is performed in Electrophysiology Laboratory, located in Cardiac Catheterization room of Pediatric Cardiology, and it takes approximately 2-4 hours. After the patients are taken to the laboratory, vascular access is established and a blood pressure measuring device is inserted in order to measure the blood pressure automatically at certain intervals. Electrodes are connected to the body for following the heart rhythm (ECG) on the display. Test can be performed on easy going older children by giving only sedative medication (midazolam). To perform the test, general anesthesia (e.g. intravascular ketamine) may be required in naughty and restless children.. Patient is suggested not to eat or drink for 4 hours after the test. The patients are discharged from the hospital after being followed up for a night. It is suggested to keep away from movements that may damage inguinal region for a week after the test.

Arrhythmia treatment

There have been several options in treating rhythm disorders in children.
Common types of arrhythmia such as supraventricular and ventricular extrasystoles are usually not dangerous, thus treatment is not required. Several things without treatment can be done to terminate supraventricular tachycardias (SVT) in older children like like retching, straining. This kind of events are followed up clinically without treating. Treatment is considered if severe symptoms like dizziness, blackout and fainting are observed during fluttering (tachycardia). Treatment differs in accordance with the type of arrhythmia and whether there is an underlying heart disease. Most of the rhythm disorders, especially tachycardia are responsive to medication treatment.

Medication Treatment

Antiarrhythmic medications cannot fully treat the rhythm disorder. However, they may decrease symptoms, prevent it to begin, decrease heart rate and duration of rhythm disorder. Selection of medications may be difficult and sometimes the right medication can be found by trying various medications. All medications have adverse effects, therefore, children may be hospitalized while medication treatment with certain medications is started. During follow-up, the medication level in blood should be measured, blood tests and organ examinations should be performed due to the effects of medication on organs.

What is pacemaker?

Rhythm disorders that cause slow heart rhythm, such as heart blocks, sick sinus syndrome are the most common reasons of pacemaker usage. Apart from that, in the event of tachycardia that cause fast heart rhythms, pacemakers or implantable cardiac defibrillators can be inserted along with medication treatment. It is a small metal battery-powered device weighs 15-30 gr, and is 3.5X3.5 cm in diameter. It is placed under the chest or abdominal walls and the thin electrode is placed into the heart. it sends small electrical impulses to the heart to avoid pain.
The implantation process of pacemaker takes approximately 2 hours. Patients should fast before the operation. Then, they are discharged from the hospital after being followed-up and the chek-up process is done.

What is implantable cardiac defibrillator (ICD)?

It is used to treat fast or irregular heart rhythms and to restore heart's normal rhythm.The appearance of ICD is similar with pacemaker, but it is a little bigger. It has a role of preventing particularly resistant ventricular tachycardia. In addition to this qualification, it has cardioversion and defibrillation performing features. Implantation of the device is similar to pacemaker. Procedure takes approximately 2 hours. Patients should fast before the procedure.

How is monitoring pacemaker or ICD performed?

Patients implanted with pacemakers or ICDs should be examined with particular devices at certain intervals. Generally, batteries can be used for many years; however they should be changed at certain intervals during the lifetime of user. The battery life, electrode resistances, conductance and threshold tests are checked with a particular device placed on the permanent pacemaker or ICD. At first, after pacemaker or ICD is implanted, patients get examined at short intervals, but after 6 months if there is not a problem; patients are followed up once a 6 month. Controls of patients and batteries are performed in our division.

What is Radiofrequency Catheter Ablation (RFA), Cold Ablation?

More permanent treatment methods may require in certain types of tachycardia (fast heart rhythm) that threaten lives or interrupt the daily activities of children. The definitive treatment of tachycardia in older children is provided with RFA method, by destroying the pathways of abnormal electrical activity which generate SVT and VT.

This method may be used in tachycardia treatment if medication treatment is unsuccessful or on children older than 4 years. By means of this, patients get free from lifelong medication use.

RFA or cold ablation is a method practiced by inserting a catheter to heart. The catheter is replaced on the region that causes tachycardia, by using one of heating or cooling methods the region is destroyed and conduction of electrical current is prevented Although it is rare, there is the risk of complete heart block during the operation. Patients should fast before the operation and it may take as long as 4-6 hours. The patient is suggested to take 1 low dose of aspirin per day during 3-4 months to prevent blood clottingin the proceeded region.