What is Type 2 Long QT Syndrome?
The congenital long QT syndrome occurred due to the mutation in various genes responsible for the regularization of ions in the heart. More specifically, the mutation may be in the ion channels which are responsible for moving the ions in and out of the cell. Type 2 LQTS is the second most common form among various forms of long QT syndrome. It is caused by the mutation in KCNH2 gene, which is also known as hERG. Certain medications are considered for managing this disease however, the fist choice for managing the disease is beta-blockers. The other drugs which can be used for managing the condition is calcium-channel blockers. The variability in the genomic expression may decide the symptoms in such patients. These patients may go on asymptomatic or they may have long QT syndrome without syncope or cardiac arrest.
Symptoms of Long QT Syndrome
The symptoms of the LQTS type 2 depend upon the genetic expression of the mutated gene. There are certain instances when there are no symptoms of long QT syndrome. Sometimes the expression is mild, and the patient may only notice prolonged QT interval. At times there are the symptoms of syncope and cardiac arrest. Thus, the symptoms may include fainting, seizures like condition and cardiac arrest that may be fatal. Further, the patients with LQTS type 2 develop ventricular arrhythmia in response to loud noise and stressful conditions. The symptoms are generally aggravated in women in postpartum period.
Causes of Long QT Syndrome
The LQTS are divided into various typed depending upon the genes that gets mutated. The genetic long QT syndrome is defined as the LQTS developed due to the mutation of those genes, which are responsible for maintaining the proper ion channel across the heart. The proper functioning of the ion channel is essential to allow the heart in proper rhythm. The three most common types of LQTS are type 1, type 2 and type 3. Type 1 is caused due to mutation affecting IKs potassium channel and type 3 is caused due to mutation in gene affecting sodium channel. LQTS type 2 is caused due to the mutation in KCNH2 or hERG gene, which is located on the chromosome 7. KCNH2 encodes the voltage gated potassium channel alpha-subunit Kv11.1. These channels are essential for rhythmic heartbeat. Mutation in the gene causes in loss in function and the loss may be complete or partial depending upon the mutation.
Long QT Syndrome Treatment
The treatment approach in long QT syndrome type 2 is to prevent the patient from sudden cardiac death. Those drugs should be avoided which may trigger the prolonged QT interval. Further, the treatment should also be such that it may prevent fainting, syncope or seizures. The drug which is the first choice in this condition is beta blocker. But sometimes the drug fails to prevent the symptoms. The other drug class which can be used in long QT syndrome type 2 is calcium channel blockers. Further the treatment with psychotropic agents is also considered. The psychotropic drugs which are used may be anti-depressants, antipsychotics, or anxiolytics. In certain severe cases, the ICD are used. ICD is also known as implantable cardiac defibrillator. This device is helpful in correcting the fatal cardiac arrhythmia.
Long QT syndrome type 2 is caused due to the mutation in KCNH2 gene or hERG. The mutation results in the abnormal ion transfer which results in arrhythmia. The symptoms may include syncope and seizures and the condition may worsen in loud noise and conditions involving emotional stress. Further, the condition is aggravated in women in post-partum stage. When the long QT syndrome is genetic, it is very difficult to manage the symptoms due to the reason that it is very difficult to estimate the severity and how much mutation took place. The medications used to manage the long QT syndrome type 2 may include beta blockers and calcium channel blockers.
Further, drugs such as antidepressants and anxiolytics are also used to manage the conditions. In severe cases, the implantable cardia defibrillator is used which corrects arrhythmia.
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