Electrocardiography ECG pattern in<unk> . According to consensus guidelines, Type 1 ST segment elevation, either spontaneously present or induced with the sodium channel-blocker challenge test, is considered diagnostic. Type 2 and 3 may lead to suspicion, but provocation testing is required for diagnosis. The ECGs in the right and left panels are from the same patient before (right panel, type 3) and after (left panel, type 1) administration of Ajmaline.<unk>  is diagnosed by identifying characteristic patterns on an electrocardiogram. The pattern seen on the ECG includes ST elevation in leads V1-V3 with a right bundle branch block (RBBB) appearance. There may be evidence of a slowing of electrical conduction within the heart, as shown by a prolonged PR interval. These patterns may be present all the time, but may appear only in response to particular drugs (see below), when the person has a fever, during exercise, or as a result of other triggers. The ECG pattern may become more obvious by performing an ECG in which some of the electrodes are placed in different positions from usual, specifically by placing leads V1 and V2 higher up the chest wall in the 1st or 2nd intercostal spaces. Three forms of the<unk>  ECG pattern have historically been described, although the Type 3 pattern is frequently merged with the Type 2 pattern in contemporary practice. * Type 1 has a coved type ST elevation with at least 2 mm (0.2 mV) J-point elevation and a gradually descending ST segment followed by a negative T-wave. * Type 2 has a saddle-back pattern with at least 2 mm J-point elevation and at least 0.5 mm elevation of the terminal ST segment with a positive or biphasic T-wave. A type 2 pattern can occasionally be seen in healthy subjects. * Type 3 has a saddle-back (type 2 like) pattern, with at least 2 mm J-point elevation but less than 1 mm elevation of the terminal ST segment. According to current recommendations, only a Type 1 ECG pattern, occurring either spontaneously or in response to medication, can be used to confirm the diagnosis of<unk>  as Type 2 and 3 patterns are not infrequently seen in persons without the disease. Provocation testing Some medications, particularly antiarrhythmic drugs that block the cardiac sodium current INa, can reveal a Type 1<unk>  pattern in susceptible people. These drugs can be used to help make a diagnosis in those suspected of having<unk>  (e.g. survivors of an unexplained cardiac arrest, family members of a person with<unk>  but in whom a diagnostic ECG pattern has not been seen. In these cases, sodium current blocking medications can be given in a controlled environment. The most commonly used drugs for this purpose are ajmaline, flecainide, and procainamide, with some suggestions indicating that ajmaline may be the most effective. Precaution must be taken in giving these medications as there is a small risk of causing abnormal heart rhythms. Genetic testing Genetic testing can be helpful to identify patients with<unk> , most commonly in family members of a person with<unk> , but sometimes performed in a person who has died suddenly and unexpectedly. However, interpretation of the results of genetic testing is challenging. In family members who all carry a particular genetic variant associated with<unk> , some family members may show evidence of<unk>  on their ECGs while others may not. This means that carrying a genetic mutation associated with<unk>  does not necessarily imply that a person is truly affected by the condition. To further complicate matters, many frequently occurring variations in the SCN5A gene do not cause any problems, and therefore genetic variants are sometimes identified in persons with<unk>  that are not truly causing the disease. Other investigations Invasive electrophysiological studies, in which wires are passed through a vein to stimulate and record electrical signals from the heart, can sometimes be used to assess the risk of a person with<unk>  experiencing dangerous abnormal heart rhythms. Risk stratification is also sometimes performed using a signal averaged ECG. Ambulatory ECG monitoring, including implantation of a loop recorder, is sometimes used to assess whether dizziness or faints in a person with<unk>  are due to abnormal heart rhythms or other causes such as vasovagal syncope. File:Brugada syndrome type1 example1 (CardioNetworks ECGpedia).Type 1<unk>  ECG pattern (note non-standard lead position, V5 is placed one intercostal space above V1 and V6 is placed one intercostal space above V2).. File:Brugada syndrome type2 example1 (CardioNetworks ECGpedia).Type 2<unk>  ECG pattern
Brugada syndrome
Arrhythmogenic cardiomyopathy
Pacak–Zhuang syndrome
Duchenne muscular dystrophy
Woodhouse–Sakati syndrome
Romano–Ward syndrome
Pascual-Castroviejo syndrome type 1
Catecholaminergic polymorphic ventricular tachycardia