Term
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Definition
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Term
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Definition
o Atropine 0.5 mg is given IV every 3-5 min until 3 mg to treat symptomatic brady, this blocks vagal stimulation
o Slower than normal rate (< 60 bpm)
o Causes include low metabolic need (sleep, athletes), vagal stimulation, MI (especially in the inferior wall)
o Other signs and symptoms include the H’s & T’s:
§ Hypovolemia
§ Hypoxia
§ hydrogen ions (acidosis)
§ hypokalemia or hyperkalemia (normal: 3.5-5.2 mEq/L)
§ hypoglycemia (random: 70-125 mg/dL (3.9-6.9 mmol/L)); (normal sugar level is currently considered to be less than 100 mg/dL when fasting and less than 140 mg/dL two hours after eating)
§ hypothermia (temp <95 F)
§ toxins
§ tamponade (cardiac)
§ tension pneumothorax
§ thrombosis (coronary & pulmonary)
§ trauma |
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Term
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Definition
o Same as NSR except over 100 BPM
o Caused by stress, acute blood loss, pain, illness, exercise
o As the HR increases, diastolic filling time decreases, possibly resulting in reduced cardiac output and subsequent symptoms of syncope and low BP
o Treat underlying cause |
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Term
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Definition
o Sinus nodes create an impulse at an irregular rhythm; the rate usually increases with inspiration and decreases with expiration
o Does not cause any significant hemodynamic effect and usually is not treated |
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Term
Premature Atrial Complex (PAC) |
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Definition
§ Atrial depolarization that occurs earlier than expected; "my heart skipped a beat"
§ may be the result of atrial enlargement or ischemia or may be caused by stress, caffeine, alcohol or nicotine
§ Often seen with tachycardia
§ Irregular due to early P waves followed by a normal QRS complex, creating a PP interval that is shorter than others
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Term
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Definition
§ Conduction defect in the atrium and causes a rapid, regular, atrial rate faster than the AV node can conduct
§ “saw tooth”
§ Unlike a-fib, QRS complexes tend to appear at regular intervals.
§ many impulses begin and spread through the atria. The resulting rhythm is organized, but so rapid that the atria are not able to fully empty their contents into the ventricles
§ abnormally rapid, well organized contraction of the atria at a rate of 250 to 350 per minute
§ Caused by COPD and valvular disease
§ Treat with vagal maneuvers or adenosine (given rapidly IV), if serious enough then electrical cardioversion is used
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Term
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Definition
§ Uncoordinated atrial electrical activation that causes a rapid, disorganized, irregular twitching of the atrial musculature; causing the atria to quiver
§ Because the atria are quivering, they are unable to pump blood
§ reduction of blood expelled from the atria
§ Increased risk of stroke and premature death; thrombi formation
§ Rapid, irregular ventricle response reduces the time for ventricular filling, resulting in a smaller stroke volume; the atrial kick is also lost
§ Electrical cardioversion is indicated for patients with A-Fib that is hemodynamically unstable unless they have digitalis toxicity or hypokalemia
§ Because of the high risk of embolization of atrial thrombi, cardioversion of this that has lasted longer than 48 hours should be avoided unless the patient has received Warfarin for at least 3-4 weeks prior to cardioversion
§ Medications that can be given include antiarrhythmics like amiodarone and calcium channel blockers (cardizem)
§ Antithrombotic therapy is indicated
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Term
Premature Junctoinal Complex
(PJC) |
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Definition
§ Treat the same as PAC (treat underlying cause)
§ arises from irritable focus at the AV junction. Characteristic includes absent or inverted P wave and also a shortened PR interval. |
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Term
Junctional (Idionodal) Rhythm |
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Definition
§ occurs when the impulse originates from the AV junction-AV node and the bundle of His.
§ rate is about 40-60 bpm.
§ absence of P wave or an inverted P wave. Normally has narrow QRS complex
§ Treat like sinus brady |
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Term
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Definition
§ rate of 70-120 originating from the AV node
§ Results from enhanced automaticity, increased sympathetic activity (catecholamines), and ischemia
§ Inverted or absent P wave, shortened PR interval, QRS complex usually narrow
§ Ischemia (usually from right coronary artery occlusion) and digitalis intoxication are the two most common causes |
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Term
Atrioventricular Nodal Reentry Tachy
(AVnRT) |
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Definition
§ Impulse is conducted to an area in the AV node that causes the impulse to be rerouted back into the same area over and over again at a very fast rate
§ Aim of therapy is to break the reentry of the impulse primarily through catheter ablation
§ Vagal maneuvers, carotid massage, gagging, holding your breath may help because it stimulates the parasympathetic system slowing the conduction through the AV node and blocking the reentry
§ If vagal maneuvers are ineffective, the patient may then be given adenosine
§ If patient is unstable or does not respond to medications, cardioversion is the treatment of choice |
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Term
Supraventriclar Tachycardia
(SVT/PSVT) |
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Definition
o P wave cannot be identified
o Impulses stimulating the heart are not being generated by the sinus node, but instead are coming from a collection of tissue around and involving the atrioventricular (AV) node
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Term
Ventricular Tachy
(Monomorphic) |
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Definition
§ 3 or more PVS’s in a row at a rate over 100 bpm
§ Often results in hemodynamic compromise due to minimal vertricular filling time and the absence of atrial kick
§ Causes include myocardial ischemia, cardiac drug toxicity, and electrolyte
§ Usually but not always pulseless and unresponsive
§ Results from abnormal tissues in the ventricles generating a rapid and irregular heart rhythm
§ vulnerable to going into ventricular fibrillation
§ The rate is extremely high ranging from 100 to 250 bpm. QRS complex is wide and bizzare. Can intervene by giving amiodarone or lidocaine or cardioversion. Must be managed properly as it can soon deteriorates to ventricular fibrillation.
§ Pulseless or unconscious person requires defibrillation.
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Term
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Definition
§ Most common dysrhythmia in pts in cardiac arrest
§ Rapid, disorganized ventricular rhythm that causes ineffective quivering of the ventricles; results in no CO
§ Blood circulation stops after a few seconds, causing brain damage and death within a few minutes.
§ No atrial activity is seen on the ECG
§ Most common cause is CAD resulting in MI
§ Never a pulse or respirations
§ Immediate treatment by defibrillation is indicated followed by CPR
§ Epinephrine should be given ASAP after the second rhythm check and the next cycle an antiarrhythmic should be given
§ Once the patient is intubated CPR should be given continuously, not in cycles
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Term
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Definition
§ The heart rate is around 20-40bpm.
§ absence of P wave and QRS complex is widened
§ occurs when SA and AV node are not firing properly or firing slower than the ventricular pace maker
§ Impulse starts in conduction system below the AV node
§ Treat the same as asystole or PEA (pulseless electrical activity) if the patient has no pulse; if they do than treat like sinus brady |
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Term
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Definition
§ Absent QRS confirmed in 2 different leads
§ No heart beats or respirations
§ Do not defibrillate
§ CPR for 2 minutes followed by epi, then 2 min of CPR, then atropine should be given, continue pattern and begin looking at the Hs & Ts as causes |
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Term
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Definition
§ PR interval is greater than 0.20 seconds
§ caused by a conduction delay through the AV node but all electrical signals reach the ventricles.
§ This rarely causes any problems by itself and often trained athletes can be seen to have it
§ P-R Interval - Prolonged |
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Term
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Definition
§ Occurs when there is a repeating pattern in which all but one of a series of atrial impulses are conducted through the AV node into the ventricles (every 4 or 5 are conducted)
§ Each atrial impulse takes longer for conduction than the one before until one impulse is fully blocked
§ There is progressive lengthening of the PR interval and then failure of conduction of an atrial beat, this is seen by a dropped QRS complex
§ occurs when there is progressive slowing at the AV node
§ Irregular rhythm
§ Can be caused by myocardial ischemia, enhanced vagal tone, or the effects of drugs such as beta blockers, calcium channel blockers and digitalis |
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Term
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Definition
§ Occurs when only some of the atrial impulses are conducted through the AV node into the ventricles
§ PR interval stays the same length throughout
§ One or more QRS complexes are dropped with the PR intervals remaining equal
§ Can cause decrease CO
§ Can lead to 3rd degree block |
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Term
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Definition
§ No atrial impulse is conducted through the AV node into the ventricles
§ Two impulses stimulate the heart causing the P wave and QRS to have their own regular beats completely separate from each other
§ occurs when atrial contractions are 'normal' but no electrical conduction is conveyed to the ventricles. The ventricles then generate their own signal through an 'escape mechanism' from a focus somewhere within the ventricle. The ventricular escape beats are usually 'slow'
§ May occur during VT |
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Term
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Definition
§ Capture is a term used to denote that appropriate complex is followed by this
§ These are seen in someone whose implanted pacemaker is firing
§ followed by a wide and bizarre QRS |
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Term
Waves, Complexes & Intervals |
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Definition
§ P waves – electrical impulse starting in the SA node and spreading through the atria (atrial depolarization), 0.11 sconds or less in duration
§ QRS Complex – ventricular depolarization, less than 0.12 seconds, atrial repolarization also occurs but is not visible on ECG
§ T Wave – ventricular repolarization
§ U Wave – thought to represent repolarization of the Purkinje fibers, but is sometimes seen in patients with hypokalemia, HTN, and heart disease
§ PR Interval – represents the time needed for SA node stimulation, atrial depolarization, and conduction through the AV node before ventricular depolarization, usually between 0.12-2.0 seconds in duration
§ ST segment – represents early ventricular repolarization, it is normally on the isoelectric line if it is above or below it may indicate cardiac ischemia
§ QT interval – represents the total time for ventricular depolarization and repolarization, between 0.32-0.40 seconds |
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