Cardiac Arrhythmias Flashcards
What does the P wave represent?
Atrial depolarization
What is the PR interval?
P-R interval: atrio-ventricular conduction time) normal P-R intervals range between 120 and 200 milliseconds, occasionally being shorter in children and slightly longer in the aged. The P-R interval decreases with increased heart rate (due to exercise or fever) and increases at lower heart rates (sleep).
What is the QRS complex?
contraction of the ventricles. Ventricular depolarization. shape of the QRS complex may be modified by a number of physiological factors (e.g. body position and breathing pattern). adults, the duration of the QRS complex varies between 60 and 100 milliseconds; in children it tends to be shorter.
What is the QT interval?
beginning of the QRS complex to the end of the T-wave represents the time between activation of electrical activity in the ventricles and return to the resting state. Ventricles are contracting and emptying. Like the P-R interval, the Q-T interval shortens at increased heart rates and increases at lower rates.
What is the T wave?
when the electrical activity associated with the cells in the cardiac ventricle returns to the resting state after electrical activation. It signals the start of relaxation of the ventricle walls. Repolarization It tends to be longer lasting than QRS because the onset of relaxation across the ventricle is less tightly synchronized than that of contraction.
What is an arrhythmia?
any change from the normal sequence of electrical impulses. The electrical impulses may happen too fast, too slowly, or erratically – causing the heart to beat too fast, too slowly, or erratically
What is the prevalence of arrhythmia?
Adults over 65yrs old have an arrhythmia 12.6% of the time. most common arrhythmia is atrial fibrillation. Arrhythmias can cause death, patient may need pacemaker
What are signs and symptoms of an arrhythmia?
May have no S & S and are diagnosed routinely Noticeable symptoms: heart fluttering, tachycardia, bradycardia, chest pain, shortness of breath, dizziness, sweating, syncope.
What types of dental precautions do you need to take for a patient with a cardiac arrhythmia?
Know type of arrhythmia, signs and symptoms are of their arrythmia, and if they use any blood thinners Obtain medical consult prior to therapy if patient has atrial fibrillation and is being treated with Coumadin Keep patient anxiety and stress to a minimum, and use sedation for stressful procedures Short morning appointments Avoid excessive epinephrine; AVOID vasoconstrictors in patients taking Digoxin Use caution with electrical equipment in patients with pacemakers (electro-surgery, ultrasonic bath or cleaner, and battery operated curing light). ADA states that you should consult the cardiologist before using.
Normal sinus rhythm
Sinus arrhythmia
Heart rate changes with respirations
Common finding in healthy young people
May sound like a fib on monitor
Normal QRS and P wave, just an irregular rhythm
Sinus tachycardia
Electrical impulses originate from SA node at a rate of 101-180 BPM
Etiology: anxiety, fever, pain, acute anemia, hemorrhage, sudden excitement, hyperthyroid, hypoxia, infection
drugs: atropine, nicotine, caffeine, amphetamine
Normal ECG just faster
Can become problematic if patient has poor cardiac output (stroke volume x heart rate)
Dysrhythmia that occurs when all electrical impulses originate from the SA node but at a rate of slower than 60 impulses per minute.
Common in athletes and young adults.
Etiology: vomiting, vasovagal syncope, myxedema, increased intracranial pressure, intracranial tumor, hypothermia, gram-negative sepsis, and/or drugs such as lithium, B-blockers, Ca2+-channel blockers, morphine, and sedatives.
40-59 BPM
May become dangerous if patient shows poor signs of cardiac output
A fibb
Dysrhythmia originating from many atrial sites
Atria makes ineffective quivering movements without any actual contractions, only the ventricles contract
Rapid atrial rate of 350-600 BPM
Regularly irregular
No P waves
What are some complications of atrial fibrillation?
1 complication is formation of an embolus/thrombus
Thrombus formation may lead to stroke!
Also, poor impulse generation from atria can cause irregular ventricular rhythms which can cause failure of the pumping action of the heart, the blood will back up into the lungs, and the patient will have congestive heart failure
What are typical treatment options for a fibb?
Catheter ablation
Anti-arrythmic drugs: sotalol, procainamide, flecainide, amiodarone (convert to sinus rhythm and maintain)
Digoxin - typically prescribed to CHF patients, but can slow conduction through AV node and slow heart rate
CCBs
Beta-blockers - slow conduction through AV node
Anticoagulants
Verbally describe what A fibb looks like on a monitor
Absence of P wave is the **hallmark feature**
P wave is seen as a wavy line instead
Normal QRS complex
Regularly irregular rhythm
Atrial flutter
Flutter waves are present instead of P waves
SAW-TOOTH FLUTTER WAVES
atrial rate 250-35- beats/min
normal QRS
rhythm is usually regular, but can be irregular
Would you rather have Afibb or atrial flutter?
Flutter is more serious
Paroxysmal atrial tachycardia
Paroxysmal tachycardia can arise fro atria, AV node, ventricles
Paroxysmal VENTRICULAR tachycardia is VERY SERIOUS (QRs complexes are wide)
Dangerous condition
high rate of 160-250
P wave morphology usually varies
normal QRS
PR interval may be variable
What are treatment options for ventricular tachycardia?
Lidocaine and amiodarone
Recurrent - digitalis, beta blockers, CCBs
supraventriculat - adenosine
what is a PVC?
premature ventricular contraction
premature ventricular beat (extra systole)
ectopic beat - the most common form of arrhythmia
What is the etiology of a PVC?
Anxiety
hight levels of adrenaleine (caffeine, exercise)
cocaine, amphetamines, alcohol
Digoxin, sympathomimetics, TCAs, and aminophylline have known to be triggers
When are PVCs ominous?
4-6 per minute or 3 in a row (triplet)
During a premature ventricular contraction (PVC), the heartbeat is initiated by the Purkinje fibers rather than the SA node. Given that a PVC occurs before a regular heartbeat, there is a pause before the next regular heartbeat. PVCs can occur in isolation or in repeated patterns. Two consecutive PVCs are termed doublets while three consecutive PVCs are named triplets
three or more consecutive PVCs are classified as ventricular tachycardia.
For those with heart disease, PVCs are an indicator of increased mortality risk.[13]
what is the normal pathway of electrical activity in the heart?
Regular heartbeats occur when specialized cells in the right atrium of the heart, called the sinoatrial (SA) node, conduct an electrical signal down to the atrioventricular (AV) node which is another set of specialized cells. This electrical signal then works its way down the bundle of His and Purkinje fibers to the heart ventricles. The result is the contraction of the ventricles and pumping of blood from the heart out to the body’s arteries.[1]
descrive to me what a PVC looks like on a monitor?
p wave is usually onscured by the QRS, PST, or T wave of the PVC
QRS complex is wide > 0. 12 seconds,
ST segment and T wave will be opposit in polarity
irregular rhythm
Ventricular tachycardia
What is V tach? What is the etiology? What is the treatment?
Dysrthynmia that originates from a single site from the ventricles
ALmost always occurs in diseased hearts
Rapid heart rate with wide and bizzare QRS complexes
needs defibrillator if pulse is absent
what is the difference between v tach and v fibb?
ventricular tachycardia continues to make the heartbeat regularly, but it goes so fast that the heart never gets a chance to fill with blood. There’s not an opportunity to build up the pressure, so the blood stops flowing.
During ventricular fibrillation, the heart stops beating normally and simply begins quivering uncontrollably.
both can be considered lethal dysrhyhmias
What is the treatment for V fibb?
Patients in V fibb will have no pulse and are in cardiac arrest
Perform CPR - highest priority is getting these patients atttached to an AED
do not delay defibrillation
epi can be used IV (1 mg every 3-5 minutes)
epi will maintain coronary artery bloof flow while CPR preserves the blood flow to the brain
V fibb
