Chp.5 Arrhythmias
Under normal conditions the SA node is responsible for doing what in the heart?
Impulse formation
Are capable not only of delivering a shock but of providing antitachycardia pacing (ATP) and ventricular bradycardia pacing
Implantable Cardioverter Defibrillators
Classified on the basis of their effect on sodium, potassium, or calcium channels and whether they block beta receptors
Antiarrhythmic drugs
Patients with atrial fibrillation often are given what kind of therapy to prevent thrombus formation, embolism, and stroke. And are at increased risk for bleeding?
Anticoagulation therapy (Warfarin)
Any tachycardia arising above the Atrioventricular junction for which the ECG shows a P wave configuration different from that for sinus rhythm.
Atrial Tachycardia
Characterized by a rapid disorganized and ineffective atrial contractions that occur at a rate of 350 to 600 beats per minute
Atrial fibrillation
What's the most common type of persistent arrhythmia?
Atrial fibrillation
Characterized by a rapid regular atrial rate of 250 to 350 beats per minute
Atrial flutter
A disturbance of impulse conduction that may be permanent or transient depending on the underlying anatomic or functional impairment
Atrioventricular (AV) Block
Sinus node disturbance defined as a heart rate less than 60 beats per minute with otherwise normal ECG
Bradycardia
Refers to any variation in the normal heartbeat which includes disturbances in rhythm, rate, and conduction pattern of the heart.
Cardiac arrhythmia
Antiarrhythmic drugs that work primarily by blocking the fast sodium channels
Class 1
Antiarrhythmic drugs that are B-adrenergic blocking agents
Class 2
Antiarrhythmic drugs that prolong duration of the cardiac action potential and enhance refractoriness through their effects on potassium channels
Class 3
Antiarrhythmic drugs that are calcium channel blockers
Class 4
Patients with atrial fibrillation may be taking the newer anticoagulant to prevent thrombus formation embolism and stroke and is said to cause no increase in major bleeding
Dabigatran (Pradaxa)
What is the primary tool used to identify cardiac arrhythmias
ECG
Treatment of atrial flutter or Atrial fibrillation is usually what?
Elective
Treatment of Ventricular Tachycardia can be what?
Elective or emergent
Treatment of Ventricular fibrillation is always what
Emergent
Heart block degree when conduction time is prolonged, but all impulses are conducted?
First degree
Whats a rare complication of pacemaker placement
Infective endocarditis
Disorder of the conduction system in which the recharging of the heart during repolarization is delayed. Caused by a genetic mutation in myocardial ion channels and by certain drugs?
Long QT syndrome
Is Antibiotic prophylaxis indicated for patients with pacemakers or ICD's
NO
Should you use a gingival retraction cord in patients with cardiac arrhythmias?
NO
Sinus node disturbance where unrelated to respiratory effort and seen with digitalis intoxication
Nonrespiration
consists of lithium battery powered generator implanted subcutaneously in the left infraclavicular area that produces an electrical impulse
Permanent implanted pacemaker
Impulse arising from ectopic foci anywhere in the atrium may result in premature atrial beats
Premature atrial complexes
Premature occurrence of an abnormally shaped QRS complex followed by a pause.
Premature ventricular complexes
Technique where a catheter is introduced percutaneously into a vein and is threaded into the heart.
Radiofrequency Catheter Ablation
What occurs when accessory or ectopic pacemakers re excite previously depolarized fibers before they would become depolarized in the normal sequential impulse pathway typically producing tachyarrhythmia
Reentry arrhythmias
Sinus node disturbance where heart rate increases with inhalation and decreases with exhalation
Respiratory
What regulates the functions of the atria and is responsible for the production of the P wave(atrial depolarization) of the ECG. Simultaneous depolarization of the ventricles produces the QRS complex on the ECG?
SA Node
What is the primary anatomic pacemaker for the heart is the what?
Sinoatrial node (SA) node
Phasic variation in sinus cycle length?
Sinus arrhythmia
Arrhythmias are classified by?
Site of orgin
What can Long QT syndrome cause?
Syncope, seizure, sudden death
Supraventricular cardiac arrhythmias may be broadly categorized into what two things?
Tachyarrhythmia and Bradyarrhythmias
Sinus node disturbance when heart rate greater than 100 beats per minute with otherwise normal ECG
Tachycardia
Degree of heart block where no impulses are conducted
Third degree
Second degree heart block characterized by progressive lengthening of conduction time until an impulse is not conducted
Type 1
Second degree heart block occasional or repetitive sudden block of conduction of an impulse without previous lengthening of conduction time
Type 2
What in a dental office can cause an electromagnetic interference to a pacemaker or ICD?
Ultrasconic
Lethal arrhythmias characterized by chaotic disorganized electrical activity that results in failure of sequential cardiac contraction and inability to maintain cardiac output
Ventricular flutter and fibrillation
The occurrence of the three or more ectopic ventricular beats at a rate of 100 or more per minute is defined as ventricular tachycardia
Ventricular tachycardia
Additional electrical bridges connect the atria and ventricles bypassing the normal pathways and forming the basis for preexcitation syndrome called?
Wolff-Parkinson White syndrome
Normal cardiac function depends on what 4 things?
cellular automaticity, conductivity, excitability, and contractility
Signs of Toxicity include
hypersalivation, nausea, drowsiness, visual distortions
To manage arrhymias more than 500,000 people in North America have what?
implanted pacemakers
What two things effect the outcome of the arrhythmia?
nature of the arrhythmia and the physical condition of the patient
What two things could lead to life threatening cardiac arrhythmias in a dental office?
stress and large amounts of injected epinephrine
Any arrhythmia that arises above the bifurcation of the HIS bundle into the right and left bundle branches is classified as what?
supraventricular
Many antiarrhythmic drugs have very narrow
therapeutic ranges
If vasoconstrictor is necessary for patients with low to intermediate risk of cardiac arrhythmias how much should they receive?
two cartridges containing 1:100,000 epinephrine (intravascular injections should be avoided)