Cardiac Arrythmias

Cardiac arrhythmia

A cardiac arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. Several forms of cardiac arrhythmia are life-threatening and considered medical emergencies.

In order to diagnose the type of arrhythmia present an electrocardiogram (abbreviated ECG or EKG) should be ordered.
Types of arrhythmias
Premature complexes

Premature complexes. Such complexes represent the most common interruption of normal sinus rhythm, most frequently arising from the ventricles and less often from the atria and the AV node.

* Premature atrial complexes (PACs)
* Premature junctional complexes (PJCs)
* Premature ventricular complexes (PVCs)

Bradycardia (brady-arrhythmias)

In bradycardia the heart beat is less than 60 beats/min. Brady-arrhythmias usually do not pose a diagnostic dilemma and there are relatively few treatment options (atropine, pacing).

* Sinus bradycardia
* Heart block

Tachycardia (tachy-arrhythmias)

In tachycardia the heart beat is more than 100 beats/min. Tachy-arrhythmias are usually not life threatening if short in duration.

Though the underlying mechanism of the tachycardia critically determines both prognosis and therapy, initial investigation may allow only for characterization of the tachycardia as either narrow complex (QRS duration <120 ms) or wide complex (QRS duration >120 ms) as read in the EKG.
I. Narrow complex tachycardia (QRS < 120 ms)

Narrow complex tachy-arrhythmias originate from impulses in the atrium and thus do not affect the width of the QRS wave, hence the name narrow (QRS < 120 ms by EKG). It can be further classified according to its rhythm as either regular or irregular.

a. Regular narrow complex tachycardia

* Sinus tachycardia

* Paroxysmal supraventricular tachycardia: These are paroxysmal; i.e., characterized by an abrupt onset and abrupt termination. They are caused by an accessory pathway in the conduction system between atria and ventricles. This maybe dual AV node (AVNRT) which is present in many people or an accessory pathway (AVRT e.g. Wolf-Parkinson-White syndrome).

o AV nodal re-entrant tachycardia (AVNRT): This is initiated by an ectopic atrial impulse that travels down a dual AV node pathway.
o Atrio-ventricular reciprocating tachycardia (AVRT): Here the ectopic impulse bypasses the AV node into the ventricle via an accessory pathway. These may be orthodromic, which are retrograde and present with a paroxysmal "narrow complex" tachycardia. Or they may be antidromic, which are antegrade and present as a "wide complex" tachycardia). Wolf-Parkinson-White syndrome is an example of AVRT.

* Atrial tachycardia: P wave rate < 250/min. Other characteristics include a long RP interval.

* Atrial flutter: Characterized by very rapid P waves known as flutter waves. In the most common form the P waves are twice as fast as the ventricular rate (i.e. only half the impulses from the atrium are being conducted to the ventricle, also known as a 2:1 conduction

b. Irregular narrow complex tachycardia

* Atrial fibrillation (AF)
* Multifocal atrial tachycardia (MAT)
* Atrial flutter with variable heart block
* Frequent premature atrial complexes (PACs)

II. Wide complex tachycardia (QRS > 120 ms)

Wide complex tachy-arrhythmias originate from impulses in the ventricles and hence affect the width of the QRS wave, hence the name wide (QRS > 120 ms by EKG). It can be further classified according to its rhythm as either regular or irregular.

a. Regular wide complex tachycardia

* Ventricular tachycardia (VTAC)

b. Irregular wide complex tachycardia

* Ventricular fibrillation

Later,
Hannah

Medical Funnies!

* A man goes to his doctor and says, "I don't think my wife's hearing isn't as good as it used to be. What should I do?" The doctor replies, "Try this test to find out for sure.

When your wife is in the kitchen doing dishes, stand fifteen feet behind her and ask her a question, if she doesn't respond keep moving closer asking the question until she hears you."

The man goes home and sees his wife preparing dinner. He stands fifteen feet behind her and says, "What's for dinner, honey?" He gets no response, so he moves to ten feet behind her and asks again. Still no response, so he moves to five feet. still no answer. Finally he stands directly behind her and says, "Honey, what's for dinner?" She replies, "For the fourth time, I SAID CHICKEN!"


* "Doctors at a hospital in Brooklyn, New York have gone on strike. Hospital officials say they will find out what the Doctors' demands are as soon as they can get a pharmacist over there to read the picket signs!"



* The difference between a neurotic and a psychotic is that, while a psychotic thinks that 2 + 2 = 5, a neurotic knows the answer is 4, but it worries him.



* Doctor: I have some bad news and some very bad news.
Patient: Well, might as well give me the bad news first.
Doctor: The lab called with your test results. They said you have 24 hours to live.
Patient: 24 HOURS! That's terrible!! WHAT could be WORSE? What's the very bad news?
Doctor: I've been trying to reach you since yesterday.



* A man speaks frantically into the phone, "My wife is pregnant, and her contractions are only two minutes apart!"
"Is this her first child?" the doctor queries.
"No, you idiot!" the man shouts. "This is her husband!"


Later,
Hannah