Sinus Arrhythmia

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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.

The sinus node rate can change with inspiration/expiration, especially in younger people. The heart rate speeds up with inspiration (since it inhibits your vagal nerve) and decreases with expiration (stimulates your vagal nerve). 

Sinus arrhythmia, if not in a young person and not occurring with repsiration, may be a sign of sick sinus syndrome (SSS). Sick sinus syndrome occurs when over time the sinus node scars and becomes replaced with fibrous tissues. SSS contains a spectrum of arrhythmias including severe sinus bradycardia, tachycardic-bradycardic syndrome (tachy-brady syndrome), or sinus exit block/sinus pauses.

Also known as "tachy-brady syndrome," sick sinus syndrome is a common condition that affects the elderly, accounting for the majority of patients undergoing pacemaker implantation in the U.S.  It is frequently associated with atrial fibrillation or atrial flutter.

In brief, it is due to the inability of the heart to maintain and regulate a steady and normal heartbeat. It either goes too fast (during atrial fibrillation or flutter) or too slow (after conversion to normal rhythm), and rarely just right.  The heart can sudden stop for up to 6 seconds, as in the case below.

What are symptoms of sick sinus syndrome?

Symptoms of SSS are caused by the frequent alternation of rapid and slow heart beat, resulting in palpitation (pounding heart beat), fainting, fatigue, and shortness of breath.

What causes sick sinus syndrome?

Everything that causes atrial fibrillation and atrial flutter can cause sick sinus syndrome. Age is the number one risk factor for developing SSS. It is frequently exacerbated by the use of medications (i.e., digoxin, beta blocker, calcium channel blocker).  The main purpose of these medications is slow down the fast heartbeat in this syndrome, but the often inevitable trade-off is excessive slowing of the heart rate to the point of needing pacemaker.

Consequences of sick sinus syndrome.

The main feature of this syndrome is inability to maintain normal stable heart rate. The resultant symptoms can include palpitation, shortness of breath, easy fatigue, and fainting spells. 

Treatment options.

In patients with predominantly a slow heart rate problem, pacemaker is the treatment option of choice.  There are no reasonable medical alternatives as no medications can speed up the heartbeat effectively and safely on a long term basis.  For those with both fast and slow heart rate problem, medications used to control the rapid heartbeat in this syndrome often slow the heart rate to the point  of requiring a pacemaker.  This is the classic "rock and hard place" scenario where if left untreated, the rapid heart rate can potentially lead to other serious consequences.  Very frequently, patients end up with a combination of medications plus pacemaker.


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.


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.

The term "long QT" refers to an abnormal pattern seen on an EKG (electrocardiogram). An EKG is a test that detects and records the heart's electrical activity. The QT interval, recorded on the EKG, corresponds to the time during which the lower chambers of your heart are triggered to contract and then build the potential to contract again. These chambers are called ventricles.

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.