Cardiology Nursing 1 Humber Final exam |302 questions and answers(including diagrams).

sinus rhythm regular rhythm Set by SA node at 60 to 100 bpm P waves normal normal qrs PR 0.12 - 0.2 normal qrs less than 0.10 wide qrs is greater than 0.12 Sinus Tachycardia 100-160 bpm SA node reduced time for ventricle filling assess for SOB or chest pain a prolonged QT interval more prone to arrhythmia NSR reflects the heart's normal electrical activity, providing synchrony between the atria and the ventricles. Sinus tachycardia occurs when the sinus node discharges impulses too fast (100 - 160 beats/minute). All other parameters are normal Facts about sinus tachycardia Normal response of heart in certain circumstances (for example exercise) •Begins and ends gradually in contrast to other tachycardias •Usually benign arrhythmia that goes away when underlying cause is treated •Common causes: Anxiety, hypoxia, hypovolemia, hypotension, heart failure, pain, drugs that increase sympathetic tone (epinephrine, norepinephrine, dopamine, dobutamine, isoproterenol, nitroprusside), and drugs that decrease parasympathetic tone (atropine) •Persistent sinus tachycardia may result in decreased cardiac output due to a decrease in stroke volume. Cardiac output = stroke volume ×heart rate. A decrease in either stroke volume or heart rate may result in a decrease in cardiac output. Sinus bradycardia occurs when the sinus node discharges impulses too slow (40 - 60 beats/minute). All other parameters are normal. Sinus bradycardia features regular rhythm, rate 40-60 bpm Normal p waves PR interval normal 0.12 to 0.2 QRS normal less than 0.1 Facts about sinus bradycardia Normal response of heart in certain circumstances (for example relaxation, sleep) •Most common arrhythmia associated with acute inferior wall myocardial infarction •Other causes: Reperfusion rhythm following myocardial reperfusion procedures (thrombolytic administration, angioplasty); vagal stimulation; sleep apnea; hyperkalemia; increased intracranial pressure; disease of SA node; and administration of drugs, such as digitalis, calcium channel blockers, and beta blockers •Persistent bradycardia may result in decreased cardiac output due to a decrease in heart rate. Cardiac output = stroke volume ×heart rate. A decrease in either stroke volume or heart rate may result in a decrease in cardiac output. Treatment of sinus bradycardia No treatment is necessary if patient is asymptomatic. •Symptomatic bradycardia is initially treated with oxygen and atropine IV push. If unsuccessful, external pacing or transvenous pacing may be used. •Chronic sinus bradycardia may require a permanent pacemaker. Sinus arrhythmia occurs when the sinus node discharges impulses irregularly. The heart rate may be normal range or slow. All other parameters are normal. Sinus arrhythmia ECG features irregular rhythm rate normal or slow P waves normal PR interval normal 0.12 to 0.20 QRS normal less than 0.1 Facts about sinus arrhythmia Normal phenomenon usually associated with phases of respiration (heart rate increases with inspiration and decreases with expiration) •Most commonly observed in infants, children, and young adults, although it may occur in any age-group •Frequently occurs along with sinus bradycardia, in which case it is usually called sinus arrhythmia with a bradycardic rate •Treatment: Does not require intervention unless accompanied by symptomatic bradycardia (follow symptomatic bradycardia protocols) Sinus pause A broad term used to describe a sudden pause in the basic rhythm with one or more missing beats; two rhythms fall under this category: Sinus arrest and Sinus exit block sinus arrest SA node fails to initiate impulse; represents a problem with SA node automaticity; basic rhythm does not resume on time following pause. Sinus exit block SA node initiates impulse, but impulse is blocked as it exits SA node; represents a problem with SA node conductivity; basic rhythm resumes on time following pause. Sinus arrest and sinus exit block ECG Rhythm: basic is regular with sudden pause with one or more missing beats, HR may slow for several beats after pause but then return to basic rate. P waves: sinus with basic rhythm, absent during pause PR interval: normal during basic, absent during pause QRS normal during basic, absent during pause Sinus block: basic rhythm resumes on time after pause Sinus arrest: basic rhythm does not resume on time after pause irregular sinus rhythm can be associated with phases of respiration During Inspiration, the Sinus Node fires faster During Expiration, the Sinus Node slows down Depolarization the spread of the electrical stimulus through the heart muscle, producing the P wave from the atria and the QRS complex from the ventricles Repolarization the recovery of the stimulated muscle to the resting state, producing the ST segment, the T wave, and the U wave Five lead system lead placement white - right arm black - left arm green - right leg red - left leg brown - chest The 6 chest leads are... V1—4th interspace, right sternal border V2—4th interspace, left sternal border V3—midway between V2 and V4 V4—5th interspace, left midclavicular line V5—5th interspace, left anterior axillary line V6—5th interspace, left midaxillary line False high rate alarms— Patient turning in bed or extremity movement. Solution: Problem is usually intermittent and no correction is necessary. Movement artifact can be reduced by avoiding placement of electrode pads in areas where extremity movement is greatest (bony areas such as the clavicles). Seizure activity can also produce high voltage artifact potentials False low rate alarms Continuous straight line related to dried conductive gel, disconnected lead wire, or disconnected electrode pad. Solution: Check electrode system; re-prep and reattach electrodes and leads as necessary. Note: A straight line may also indicate the absence of electrical activity in the heart; the patient must be evaluated immediately for the presence of a pulse. Cause: Intermittent straight line related to ineffective contact between skin and electrode pad. Solution: Make sure hair is clipped and electrode pad is placed on clean, dry, skin; if diaphoresis is a problem, prep skin surface with liquid adhesive, allow to dry, and reapply electrode pad. Electrical interference (AC interference) Cause: Patients using electrical equipment (electric razor, hair dryer), multiple electrical equipment in use in the room, improperly grounded equipment, loose electrical connections, or exposed wiring. Solution: If patient is using electrical equipment, problem is transient and will correct itself. If patient is not using electrical equipment, unplug all equipment not in continuous use, remove from service and report any equipment with breaks or wires showing, and ask the electrical engineer to check the wiring. Wandering baseline artifact Cause: Exaggerated respiratory movements usually seen in patients in respiratory distress (patients with chronic obstructive pulmonary disease). Solution: Avoid placing electrode pads in areas where movements of the accessory muscles are most exaggerated (which can be anywhere on the anterior chest wall). Place the pads on the upper back if necessary. Determine Regularity (Rhythm) of R Waves Measure from R wave to R wave across the rhythm strip, marking on the index card any variation in R wave regularity. If the rhythm varies by 0.12 second (3 small squares) or more between the shortest and longest R wave variation marked on the index card, the rhythm is irregular. If the rhythm doesn't vary or varies by less than 0.12 second, the rhythm is considered regular. Calculate the Heart Rate Rapid rate calculation—Count the number of R waves in a 6-second strip (Figure 5.6) and multiply by 10 (6 seconds × 10 = 60 seconds, or the heart rate per minute). The R waves must be counted within the 6-second markers (some strips in this book are longer than 6 seconds). This method provides an approximate heart rate in beats per minute, is fast and simple, and can be used with both regular and irregular rhythms. If you only have a 3-second strip, count the number of R waves in a 3-second strip and multiply by 20 (3 seconds × 20 = 60 seconds or the heart rate per minute). Precise rate calculation—Count the number of small squares between two consecutive R waves (Figure 5.7) and refer to the conversion table printed on the inside back cover of the book. A removable conversion table is also provided. Although this method is accurate, it can be used only for regular rhythms. If a conversion table isn't available, divide the number of small squares between the two consecutive R waves into 1,500 (the number of small squares in a 1-minute rhythm strip). The heart rates for regular rhythms in the answer keys were determined by the precise rate calculation method. Irregular Rhythms Only rapid rate calculation is used to calculate heart rate in irregular rhythms. Count the number of R waves in a 6-second strip and multiple by 10 (Figure 5.8), or count the number of R waves in a 3-second strip and multiply by 20. When rhythm strips have a premature beat the premature beat isn't included in the calculation of the heart rate. The premature beat is a beat from a different pacemaker site in the heart and must be assessed separately. When rhythm strips have more than one rhythm on a 6-second strip rates must be calculated for each rhythm Identify and examine the P waves Analyze the P waves. One P wave should precede each QRS complex and should be identical (or near identical) in size, shape, and position Measure the PR Interval Measure from the beginning of the P wave as it leaves baseline to the beginning of the QRS complex. Count the number of small squares contained in this interval and multiply by 0.04 Measure the QRS Complex Measure from the beginning of the QRS complex as it leaves baseline until the end of the QRS complex when the ST segment begins. Count the number of small squares in this measurement and multiply by 0.04 second. a cardiac arrhythmia is is any deviation from the normal pattern of the heartbeat (normal sinus rhythm) Sinus arrhythmias result from disturbances in impulse discharge or impulse conduction from the sinus node. The sinus node retains its role as pacemaker of the heart but discharges impulses too fast (sinus tachycardia) or too slow (sinus bradycardia); discharges impulses irregularly (sinus arrhythmia); or fails to discharge an impulse (sinus arrest), or the impulse discharged is blocked as it exits the sinus node (sinus exit block). Sinus bradycardia does not require treatment unless the patient becomes symptomatic Sinus brady requiring treatment include hypotension (systolic BP less than 90 mm Hg), syncope, reduced consciousness or cognitive function, decreased urine output, and development of heart failure. If sinus bradycardia persists, the treatment of choice is atropine, a drug that increases the heart rate by decreasing parasympathetic tone. The usual dose is 0.5 mg IV push every 5 minutes until the bradycardia is resolved or a maximum dose of 3 mg is given. Atropine should not be given too slowly or in doses less than 0.5 mg as this can further decrease the heart rate instead of increasing it. If the rhythm still does not resolve after the atropine is administered, a transcutaneous (external) or transvenous pacemaker may be needed. Hypotension can be corrected with either a dopamine drip or an epinephrine drip. All medications that cause a decrease in heart rate should be reviewed and discontinued if indicated. For chronic symptomatic bradycardia, permanent pacing may be indicated. The distinguishing feature of sinus arrythmia is the sinus origin and the rhythm irregularity. Sinus Arrhythmia does not require treatment unless it is associated with bradycardia that causes symptoms SA block is a disorder of impulse conduction from the SA node Sinus arrest is a disorder of automaticity of the SA node to differentiate between sinus block and sinus arrest mark the R-R intervals of the underlying rhythm and through the pauses. If the R-R matches after the pause it is sinus block if the R-R does not match after the pause it is sinus arrest. If the underlying rhythm is irregular it cannot be distinhuished and referred to as sinus pause Causes of sinus arrest of sinus block increased vagal tone ischemic or inflammatory disease of SA nide damage to SA from MI drugs: digitalis, beta blockers, CCB