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68wm6 p2 Car. Dys.
Cardiac Dysrhythmias
| Question | Answer |
|---|---|
| How does the sympathetic nervous system affect the heart rate? | Speeds it up. |
| How does the parasympathetic nervous system affect the heart rate? | Slows it down. |
| Define cardiac automaticity: | inherent (intrinsic) ability to contract in a rhythmic pattern. Abiity of the heart to sustain its own impulses. |
| Define cardiac irritability: | ability to respond to a stimulus. |
| At what rate does the SA node generate impulses? | 60-100 a minute |
| When the impulse leaves the SA node, how does it travel through the atria? | Through the bachmans bundle and internodal pathways. |
| At what rate can the AV node generate impulses if not recieved from the SA node? | 40-60 per minute (the back-up pacemaker of the heart) |
| Define purkenje fibers | A diffuse network of muscle fibers located just beneath the endocardium, resulting in contraction and emptying of the ventricles. |
| At what rate can the purkenje fibers generate impulses if not recieved from the SA and AV nodes? | 20-40 per minute |
| The electrocardiogram gives how many views of the hearts electrical activity with how many electrodes? | 12 leads(views) from 10 electrodes |
| What is the cardiac cycle composed of? | Electrical activity caused by automaticity and the mechanical response of contraction. |
| What are the two phases of the ELECTRICAL activity of the heart? | Depolorization and Repolarization. |
| What are the two phases of the MECHANICAL activity of the heart? | Systole and Diastole |
| a 1mm square (small box) on an EKJ sheet represents how many seconds? | 0.04 seconds |
| a 5mm section (large box) of and EKG sheet represents how many seconds? | 0.20 seconds |
| What does the vertical axis of the EKG represent? | Voltage |
| A 1 mm grid interval on the verticle axis represents what? | 0.1 mV (one millivolt) |
| What is the most exact method to determin a regular rhythm using an EKG? | 1500 method |
| What is the Positive (upward) Complex? | Heart’s current flows towards the positive electrode |
| What is the Biphasic Complex? | Heart’s current flows perpendicular to the positive electrode |
| What is the Negative (Downward) Complex | Heart’s current flows away from the positive electrode |
| What are the augmented leads? Why are they called 'augmented'? | aVR, aVL, and aVF. Because the ECG machine increase the voltage |
| Are unipolar leads positive or negative? | Positive. |
| How many large boxes on an EKG are required to equal a full second? | Five |
| What is the isoelectric line? | The flat baseline of an EKG reading |
| What does the horizontal axis of an EKG represent? | Time |
| What is the first positive deflection? | The P-wave |
| What does the P-wave normally indicate? | that the SA node initiated the impulse that depolarized the atrium |
| What does the PR interval measure? | the time it takes for the impulse to depolarize the atria, travel to the AV node, and then dwell there briefly before entering the Bundle of His |
| What is the normal PR interval? | 0.12 to 0.20 seconds (3-5 small boxes) |
| Where is the P-wave measured? | from beginning of the P wave to where the QRS complex begins |
| What is the first negative deflection after the P-wave? | The Q-wave. |
| True or False: If the Q-wave isnt present, it indicates a serious heart condition. | False. May or may not be present |
| What Q-wave readings indicate a pathological condition? | Pathologic if > 0.04 seconds or more than ¼ height of R wave (Seen in patients who have had MI) |
| What is the first positive deflection after the P-wave? | The R-wave |
| True or False: The S-wave MUST go below the isoelectric line | True. |
| What is the term for the waveforms that indicated ventricular depolarization | QRS complex |
| What is the normal QRS interval? | 0.06-0.12 seconds (1.5-3 small boxes) |
| What represents ventriculare repolarization on the EKG? | The T-wave |
| The T-wave should be upright no greater than what? | 5mm high (5 small boxes or one big box) |
| Changes in T wave amplitude can indicate what? | electrical disturbances resulting from ELECTROLYTE IMBALANCE or MI |
| What can cause tall, peaked T-waves? | Hyperkalemia |
| What can cause inverted T-waves? | Ischemia or an old MI |
| What connects the QRS complex to the T-wave? | The ST segment |
| True or False: The ST segment is usually isoelectric | True |
| What can ST depression indicate? | Ischemia |
| What can ST elevation idicate? | Injury or Infarct |
| How is the QT interval measured? | From the beginning of the QRS complex to the end of the T-wave |
| What does the QT interval measure? | the time taken for the ventricular depolarization and repolarization |
| What is the normal time for a QT interval? | 0.32-0.50 seconds |
| True or False: A fast heart rate has a long QT interval | False. The slower the HR, the longer the normal QT .The faster the HR, the shorter the normal QT |
| What represents refractory periods of the ventricles | QT interval |
| Systemic analysis of dysrhythmias focuses attention on what following areas | *Rhythm Regularity (Rhythmicity) *Rate *Waveform Configuration and Location *Intervals |
| What are measured to establish atrial regularity? | P-waves |
| What are measured to establish ventricular regularity? | R-waves |
| What is used to calculate the APPROXIMATE rate of regular/irregular rhythms? | Rule of 10 |
| Any cardiac rhythm that deviates from normal sinus rhythm (normal conduction and intervals) is a what? | Dysrhythmia |
| S&S and treatment of a dysrhythmia depends on what? | Type and Severity |
| Define SupraVentricular Tachycardia (SVT): | SUDDEN onset of a rapid rhythm originating above the AV node (usually in the atria)characterized by a regular rythm and a RATE of 150 - 250 bpm |
| What is the medical management of SVT? | *Eliminate the underlying cause *Vagal maneuvers (carotid massage, increase intrathoracic pressure) *Pharmicologic cardioversion such as Adinosine *Electrical Cardioversion *radiofrequency catheter ablation |
| Define Atrial Fibrillation: | Electrical activity in the atria is disorganized, causing the atria to fibrillate or quiver rather than contract as a unit (irregular, irregular). P-waves and PR interval not measurable, but QRS usually normal. |
| What leads to atrial fibrilation | Widespread irritability and increased automaticity |
| What is the goal of therapy for atrial fibrillation? | To prevent atrial thrombi from becoming embolisms. |
| Define atrial flutter | A dysrhythmias that arises from a single irritable focus in the atria. P-waves replaced wiht multiple flutters and PR not measurable. |
| True or False: F-waves associated with atrial flutter are highly irregular. | False. Flutter waves usually occur continually and with perfect regularity |
| What is the atrial rate of atrial flutters? | 250-350 |
| Are T-waves present in atrial fibrillation or in atrial flutter, or both? | T-waves are found in atrial fibrillation, NOT atrial flutter. |
| What wave form has the appearance of 'teeth of a saw blade' and usually occur continually and with perfect regularity | F-waves from atrial flutter |
| Who is atrial flutter most commonly seen in? | patients with heart (valvular) disease |
| What is the treatments for atrial flutter? | *Electrical cardioversion via SYNCRONIZED ELECTRIC SHOCK *Pharmacological cardioversion *Anti-coagulants/blood thinners to prevent thrombi formation in the atria. |
| Define AV block: | Defect in the AV Node (Junction) impairs conduction of impulses from the SA node to the ventricles |
| What is a 1st degree AV block? | Delayed conduction through the AV junction |
| How is a 1st degree AV block shown on an EKG? | As a prolong PR interval greater than 0.20 seconds |
| What is the impulse rate on an EKG for a 1st degree AV block? | Regular to bradycardic |
| Who are 1st degree AV blocks common in? | the elderly and in patients with cardiac disease (Atherosclerosis, CHF) |
| What kind of AV block is a Wenckebach? | 2nd degree: Type 1 |
| How is a 2nd degree Type 2 block illustrated? | a steadily lengthening of PR interval until the AV Node is unable to conduct one or more electrical impulses to the ventricles. |
| What is the rythm of a Wenckebach block? | Regularly (P-P) Irregular (QRS-QRS) |
| What is the impulse rate of a wenckebach block? | Normal (Often Sinus Bradycardia with Pause); P wave > QRS |
| What is the PR interval of a Wenckebach block? | Progressive lengthening until QRS complex is dropped |
| True or False: Type 2 2nd degree AV block is the same severity as Type 2 1st degree AV block | False. Mobitz II is a more severe form of AV Block |
| Whats another name for 2nd Degree type 1 and 2 AV blocks? | Mobitz I, Mobitz II |
| How does the conduction delay vary between Mobitz I (wenckebach) and Mobitz II? | Mobitz I (winckebach) the delay occurs ABOVE the AV node, while Mobitz II occurs BELOW (often at the bundle branches) |
| How does the QRS count differ between Mobitz I (wenckbach) and Mobitz II? | Mobitz I (winckebach) has a regularly irregular PR lengthening and predictable QRS disappearance. Mobitz II has random QRS disappearances and PR lengthenings. |
| True or False: Both Mobitz I and Mobitz II have more P-waves than QRS complexes | True. |
| What constitutes a 3rd degree AV block? | Complete Heart Block, AV Dissociation |
| Whats the rythm of a 3rd degree AV block? | P-P is regular, R-R is irregular |
| Whats the impulse rhythm of 3rd degree AV blocks | Atrial normal, Ventrical 20-40 bpm |
| True or False: The T-wave is inverted in 3rd degree AV block like it is in PVC | True |
| Medical management of a 3rd degree AV block | Pacing. 1st transcutaneous, 2nd transvenous, and most likely placement of a permanent pace maker. |
| Define Premature Ventricular Contraction (PVC): | Common ventricular dysrhythmia; the beat can be generate anywhere in the ventricles. P-waves not visible, PR interval not measurable, QRS wide >0.12 sec, T-waves inverted. |
| What electrolytes do you measure for in the medical management of PVC? | K+ and Mg++ |
| Define ventricular tachycardia (VT) | VT is a rapid, life-threatening dysrhythmia that originates in the ventricles |
| What constitutes ventricular tachycardia? | Three or more PVCs in a row. VT is sustained PVCs |
| What is the impulse rate in VT? | 140-240 beats per minute |
| What is the QRS interval of VT? | Prolonged; Wide (greater than 0.12 secs) and Bizarre |
| What drug toxicity can cause VT? | Digitalis |
| Management of stable VT with pulse: | Medications leading up to Synchronized Cardioversion |
| Management of unstable VT with pulse: | Cardioversion |
| Management VT without pulse: | Basic Life Support (BLS), DEFIBRILLATION, ACLS ASAP |
| Define Ventricular Fibrillation (VF): | VF is a chaotic, life-threatening dysrhythmia characterized by a quivering of the ventricles that results in total loss of cardiac output (CO) |
| True or False: Though the heart is still trying to work, VF is still a case of clinical death. | True |
| What drug toxicity can cause VF? | Digitalis or Quinidine |
| Define Ventricular Standstill / Asystole: | Complete cessation of all electrical activity, where a flat baseline is seen without any evidence of P, Q, R, S, or T waveforms. Ventricular standstill is also called Asystole because all contraction of the heart muscle stops |
| What is the treatmeant of Ventricular Standstill/ Asystole? | Basic Life Support (BLS) and ACLS ASAP (Medications) |
| What is the mechanism of action of Adenosine and Digoxen | Slows conduction through the AV node. Decreases conduction velocity and prolongs the effective refractory period in the AV node. |
| What are two major precautions of anti-dysrhythmic agents? | *Hepatic or renal insufficiency (dosage reduction recommended if CCr <=40 ml/min). *Geri: appears on Beers list. May induce heart failure in elderly patients. |
| What pulse do you check before administering anti-dysrythmic medication? | Apical pulse |
| How should PO anti-dysrhythmic medication be taken? | administer medication on an empty stomach, 1 hr before or 2 hr after meals |
| What do you need to instruct the PT to report while taking anti-dysrhythmic medications? | Facial flushing, shortness of breath, or dizziness. |
| If a dose of anti-dysrhythmic medication is missed, when should it be taken? | as soon as remembered unless within 4 hr of next dose. |
| True or False: Since it is not a narcotic, Anti-Dysrhythmic drugs are safe to take while driving. | False. Medications may cause dizziness. |
| How should vials of lidocaine for dysrhythmias read? | “lidocaine for dysrhythmias” or “lidocaine without preservatives” |
| When MUST dysrhythmias be treated | When patient has S/Sx of DECREASED CARDIAC OUTPUT. |
| What are some S/Sx of decreased cardiac output to indicate the need of anti-dysrhythmia drugs | chest pain, SOB, decrease LOC, hypotension, pulmonary congestion, heart failure, and shock. |
| Explain synchronized electrical shock cardioversion. | Disrupts the ectopic pacemaker that is causing the dysrhythmia and allow the SA node to take control. Used for Tachydysrhythmias |
| What is electric cardioversion synchronized to? | Ventricular depolarization (R-wave) |
| Why is electric cardiversion synchronized to the R-wave. | to prevent shock from being delivered during repolarization T-wave (R on T phenomenon leads to VF) |
| True or False: Electrical cardioversion disrupts the rythm by depolarizing the heart. | False. Purpose is to disrupt the rhythm rather than completely depolarize the heart |
| What is the energy used for electrical cardioversion? | low energy is used (50J-100J) |
| What mode must the defibrillator be turned to before electrical cardioversion? | synchronous mode |
| What lead is used for observation of an eletrical cardiogram patient? | Lead II |
| True or False: You dont need to look for any specific waves before shocking, because the purpose of the shock is to set the waves right. | False. You must determine that the R-wave is properly detected since shocking on the T-wave can lead to VF. |
| After a pacemaker is inserted, what should be done with the affected arm? | Imobilized for the first few hours after placement and the arm should not be raised above the head for several days. |
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