Cardiac Arrhythmia

Cardiac arrhythmia or Cardiac dysrhythmia refers to a disturbance of the heart rhythm. When the regular heart rhythm is disturbed, it can lead to symptoms that can range from mild to life-threatening. The heart may have slower beats or there may be a blockage of the electrical pathway of the heart. One of the most common form of cardiac arrhythmia is atrial fibrillation. This occurs in older persons when the upper atrial chambers of the heart do not pump correctly. This can lead to blood clots. Heart failure or electrolyte imbalance can bring on cardiac arrhythmia.

Tachycardia or Tachydysrhythmia is a condition where there is rapid heartbeat due to inefficiency in the blood circulation. Tachycardia is a condition where the heart rhythm is more than 100 beats/minute. This can happen due to stress, hyperthyroidism or alcohol. On the other hand, Bradycardia or bradyarrhythmia is a condition where the heart rhythm is less than 60 beats/min. A ventricular arrhythmia can be life-threatening. This happens when there is ventricular fibrillation. It is essential to treat this condition and restore the rhythm within minutes to prevent heart damage and death. Allergic reactions can trigger arrhythmia.

Some persons suffering from cardiac arrhythmia notice symptoms such as dizziness, fainting and lightheadedness. There may be a fluttering or pounding sensation in the chest. Anti arrhythmic agents such as amiodarone and sotalol are prescribed to maintain the normal rhythm of the heart. Amiodarone is effective atrial flutter and to establish heart's normal rhythm.

In cases of atrial fibrillation, Warfarin is used to prevent blood clots. Medication for cardiac dysrhythmia includes beta blockers such as metoprolol and atenolol to reduce the heart rhythm. An electronic cardiac pacemaker may be implanted to regulate the heart beat.

Andersen Tawil Syndrome

Andersen Tawil syndrome or ATS is a rare disease characterized by three distinct features that include: periodic paralysis or episodes of muscle weakness, cardiac arrhythmia and distinct facial and skeletal features. However all the three features may not be present in a single patient. Most ATS cases are caused by a mutation in the KCNJ2 gene; other cases result from unknown causes. KCNJ2 gene forms a channel that is responsible for transporting potassium ions into muscle cells. The movement of these ions is essential for maintaining the normal function of muscles. KCNJ2 gene mutations disrupt the structure of the potassium ions and leads to periodic paralysis and irregular heart rhythm.

Periodic paralysis: Anderson Tawil syndrome patients may experience episodes of flaccid paralysis. The lower and the upper limbs normally get affected and the paralysis may remain for short duration or continue for days. The severity and frequency varies from person to person and from episode to episode.

Heart arrhythmia: Anderson Tawil syndrome patients typically present with long QT interval, a disorder of the heart's electrical activity. It can cause sudden, uncontrollable, dangerous arrhythmia in response to exercise or stress.

Distinct Facial or skeletal features: Patients with ATS commonly develop physical abnormalities such as a small lower jaw, dental abnormalities, widely spaced eyes, short stature and curvature of the spine.

Diagnosis and treatment

Examining the clinical features, serum test to assess potassium levels, electrocardiogram to test the heart's electric activity and molecular genetic testing together help in establishing the diagnosis of Anderson Tawil syndrome.

There are no standard protocols laid out for treating ATS because of the rarity of the condition. Treatment of the Anderson Tawil syndrome depends upon the symptoms of the patient. If the patient is suffering from potassium sensitive periodic paralysis, potassium supplements are prescribed to rectify the levels.

However periodic paralysis caused by higher potassium levels resolve on their own in a short while. Of late, drugs known as carbonic anhydrase inhibitors are being used successfully to treat periodic paralysis in individuals with Andersen-Tawil syndrome. Cardiac arrhythmia is normally treated with beta adrenergic blockers and more complicated cases might need pacemakers and implantable defibrillator to prevent sudden cardiac deaths.

Potassium Gluconate

This is a potassium supplement useful in those prone to low blood potassium. Its side effects include numbness and tingling of the extremities, confusion, weakness, arrhythmia, ECG changes, nausea, vomiting, diarrhea, abdominal pain, GI ulcerations, GI bleeding, intestinal obstruction, and intestinal perforation.

Using potassium gluconate

1. Should not be used in cases of severe kidney disease, acute dehydration, or those who are using potassium sparing diuretics (e.g. spironolactone, triamterene).
2. Enteric coated potassium tablets cannot be recommended due to increased risk of GI bleeding and ulceration.
3. Minimize GI symptoms by taking this medication with food.

Adult and adolescent dose: oral, elixir, 10-20 mEq of potassium diluted in one-half glass of cold water or juice, two to four times a day; or 5-10 mEq potassium in tablet form, two to four times a day; dosage adjusted to need (up to 100 mEq potassium per day).