Inappropriate Sinus Tachycardia (IST)

Inappropriate sinus tachycardia (IST) is a condition in which the resting heart rate is abnormally high (greater than 100 beats per minute), and increases rapidly with minimal exertion, accompanied by symptoms of palpitations, fatigue, and exercise intolerance.
While IST can occur in anybody, it is most often a disorder of young women. The average IST sufferer is a woman in her late 20s or early 30s who has been having symptoms for months to years. In addition to the most prominent symptoms of palpitations, fatigue and exercise intolerance, IST can also be associated with a host of other symptoms including a drop in blood pressure upon standing, blurred vision, dizziness, tingling, shortness of breath, and sweating.

Treatment for IST is reasonably effective in many patients, but achieving optimal results often requires trial-and-error attempts with several drugs, singly or in combination.

  • Beta blockers block the effect of adrenaline on the sinus node, and since patients with IST have an exaggerated response to adrenaline, using beta blockers is logical. They are reasonably effective in many patients with IST.
  • Calcium blockers can slow the action of the sinus node, but have been only marginally effective in for IST.
  • Recently, the new drug Ivabradine has been used successfully patients with IST.

Sinus Arrhythmia

One of the most common arrhythmias is a sinus arrhythmia. It involves cyclic changes in the heart rate during breathing. It is very common in children and often found in young adults. Patients with sinus arrhythmia do not experience any cardiovascular symptoms.

Premature Atrial Contractions (PACs)

Premature Atrial Contractions (PACs) are amongst the most common forms of arrhythmias.  It is due to the premature discharge of an electrical impulse in the atrium, causing a premature contraction. 

Therefore, it is named "premature atrial contraction," or PAC.  A PAC is premature, because the it occurs earlier than the next regular beat should have occurred.

Atrial Fibrillation

Problems with the heart's electrical system, called arrhythmias, can make it hard for the heart to pump blood efficiently.

Introduction

Atrial fibrillation (AF) is an irregular and often rapid heart rate that commonly causes poor blood flow to your body. Although AF itself usually isn't life-threatening, it is a serious medical condition. 

Inappropriate Sinus Tachycardia (IST)

Inappropriate sinus tachycardia (IST) is a condition in which the resting heart rate is abnormally high (greater than 100 beats per minute), and increases rapidly with minimal exertion, accompanied by symptoms of palpitations, fatigue, and exercise intolerance.

Premature Ventricular Contractions (PVCs)

Palpitations are feelings that your heart is skipping a beat, fluttering, or beating irregularly, too hard or too fast. Some will be diagnosed by your doctor as Premature Ventricular Contractions (PVCs). PVCs are an arrhythmia and relatively common. Some people are very sensitive and feel every abnormal heart beat; others are blissfully unaware of them.

Supraventricular Tachycardia (SVT)

What is a supraventricular tachycardia?

Adams-Stokes Syndrome

In this condition, the normal heartbeat passing from the hearts upper to lower chambers is interrupted. This result in a condition called a “heart block.” When a heart block occurs the heart rate usually slows considerably. This can result in inadequate blood flow to the brain and fainting.Take a look at this animation of your heart's electrical system for a better understanding of what happens normally:

Take a look at this animation of your heart's electrical system for a better understanding :

Orthostatic Hypotension

Orthostatic Hypotension is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint.

Postural orthostatic tachycardia syndrome (POTS)

POTS is a condition in which a change from supine to an upright position causes an abnormally large increase in heart rate, called tachycardia.

Ventricular tachycardia (VT)

Ventricular tachycardia (VT) is a rapid heartbeat that starts in the ventricles of your heart, with a pulse rate of more than 100 beats per minute and at least three irregular heartbeats in a row.

Long QT syndrome (LQTS)

Long QT syndrome (LQTS) is a disorder of the heart's electrical activity. It may cause you to develop a sudden, uncontrollable, and dangerous heart rhythm called an arrhythmia in response to exercise or stress.

Arrhythmias also can develop for no known reason in people who have LQTS. Not everyone who has LQTS develops dangerous heart rhythms. However, if one does occur, it may be fatal.

Ventricular fibrillation (VF)

Ventricular fibrillation (VF) is an uncontrolled twitching or quivering of the muscle fibers of the lower chambers of your heart. During ventricular fibrillation, blood is no longer pumped out of your heart.