CC Chapter 7
QRS interval
0.06-0.10 or 1.2-2.5 boes
The patient is admitted with a heart rate of 144 beats/min and a blood pressure of 88/42 mm Hg. The patient complains of generalized weakness and fatigue. He states, "Just let me sleep." The nurse determines that the presence of the patient's symptoms is due to: A) decreased cardiac output. B) the absence of ischemic heart disease. C) improved cardiac filling time allowing the patient to relax. D) increased coronary artery filling time.
A
The patient with a pacemaker shows pacemaker spikes that are not followed by a QRS. This is known as: A) failure to capture. B) failure to pace. C) failure to sense. D) demand mode.
A
The patient is complaining of midsternal chest discomfort and nausea. The nurse calls for a 12-lead ECG and notices that the ST segment is newly elevated in two related leads. The nurse should: A) call the provider because the ST segment may indicate myocardial injury. B) continue to monitor the patient, as the ST segment is non-diagnostic. C) monitor the patient for increased signs of GI upset. D) assure the patient that the ST elevations are normal and of no concern.
A A displacement in the ST segment can indicate myocardial ischemia or injury. If ST displacement is noted and is a new finding, a 12-lead ECG is performed and the provider notified. The patient is assessed for signs and symptoms of myocardial ischemia.
Which of the following patients might require a pacemaker? A) A 45-year-old acute myocardial infarction patient with a heart rate of 45 beats/min and a blood pressure of 80/50 mm Hg B) A 65-year-old patient with chronic obstructive pulmonary disease, a heart rate of 120 beats/min, and a blood pressure of 120/80 mm Hg C) A 70-year-old postoperative patient with a heart rate of 130 beats/min and a blood pressure of 90/60 mm Hg D) An 18-year-old athlete with a heart rate of 52 beats/min and a blood pressure of 110/70 mm Hg
A A pacemaker is often implanted to treat symptomatic bradycardia, which may occur from a number of different pathophysiological conditions. These include second-degree AV block type II, third-degree AV block, and sick sinus syndrome. The need for a pacemaker may be temporary or permanent. The patient in this scenario with a myocardial infarction has a low heart rate and low blood pressure. The patients with COPD and postoperative status have accelerated heart rates not requiring override pacing. The heart rate of the athlete is probably due to his conditioning as evidenced by his acceptable blood pressure.
The nurse notices ventricular tachycardia on the heart monitor. The nurse's first action should be to: A) determine patient responsiveness and presence of a pulse. B) immediately defibrillate the patient and provide CPR. C) administer intravenous amiodarone or lidocaine. D) cardiovert electrically into a more sustainable rhythm.
A Determine whether the patient has a pulse. If no pulse is present, provide emergent basic and advanced life-support interventions, including defibrillation. If a pulse is present and the blood pressure is stable, the patient can be treated with intravenous amiodarone or lidocaine. Cardioversion is used as an emergency measure in patients who become hemodynamically unstable but continue to have a pulse. It may also be used in nonemergency situations, such as when a patient has asymptomatic VT.
symptoms of decreased CO
ALOC, chest discomfort, hypotension, sob, crackles, rapid or slow pulse, dizzy, fatigue, restless
The nurse is calculating the rate for a regular rhythm. There are 20 small boxes before each R wave. The rate is: A) 50 beats/min. B) 75 beats/min. C) 85 beats/min. D) 100 beats/min.
B
The nurse is caring for an individual who is admitted for chest pain and shortness of breath. The patient states, "I can't believe I'm having chest pain. I'm a marathon runner and in good shape." During the night, the patient develops a sinus bradycardia with a heart rate of 40 beats/min. The nurse should: A) ignore this rate since the patient is an athlete. B) assess the patient and assess for signs of decreased cardiac output. C) take the patient's temperature and expect to find hyperthermia. D) perform carotid massage (a maneuver to stimulate a vasovagal response).
B
The nurse is interpreting a patient's cardiac rhythm and notes that the PR interval is 0.16 seconds long. The nurse determines that this PR interval indicates: A) slower than normal conduction from the SA node through the AV node. B) normal conduction from the SA node through the AV node. C) faster than normal conduction from the SA node through the AV node. D) abnormally fast depolarization of the atria and ventricles.
B
The patient has a temporary, transvenous, demand-type ventricular pacemaker. The rate on the pacemaker is set at 60 beats/min. Which of the following situations would be of concern? A) A paced rhythm of 60 beats/min is seen on the monitor; no other waveforms are seen. B) A pacemaker spike is seen on the T wave of the preceding beat. C) The patient's inherent (own) rate falls to 58 and the pacemaker fires. D) The patient's inherent rate is 70 beats/min; no pacemaker spikes are seen.
B Failure to sense manifests as pacer spikes that fall earlier than the programmed rate. This can cause an artificial R-on-T phenomenon similar to when a PVC occurs during the T wave, and ventricular tachycardia may occur.
If the sinus node were diseased or ischemic and no longer firing as the heart's primary pacemaker, the nurse would anticipate which normal compensatory mechanism? A) Premature junctional beats B) Junctional escape rhythm, rate of 45 C) Junctional tachycardia, rate of 100 D) Accelerated junctional rhythm, rate of 75
B Junctional escape rhythm occurs when the dominant pacemaker, the SA node, fails to fire. The escape rhythm may consist of many successive beats, or it may occur as a single escape beat that follows a pause, such as a sinus pause. The normal intrinsic rate for the AV node and junctional tissue is 40 to 60 beats per minute. An accelerated junctional rhythm has a rate between 60 and 100 beats per minute, and the rate for junctional tachycardia is greater than 100 beats per minute. Irritable areas in the AV node and junctional tissue can generate premature beats that are earlier than the next expected beat.
The patient is admitted with the diagnosis of "Junctional Rhythm." The nurse places the patient on the cardiac monitor expecting to see: (Select all that apply.) A) P waves with a PR interval of 0.16 seconds. B) P waves with a PR interval less than 0.12 seconds. C) no P waves but a narrow QRS complex. D) P waves coming after the QRS complex. E) no P waves but a wide QRS complex.
BCD Because of the location of the AV node—in the center of the heart—impulses generated may be conducted forward, backward, or both creating three different P waveforms that may be associated with junctional rhythms: When the AV node impulse moves forward, P waves may be absent because the impulse enters the ventricle first. The atria receive the wave of depolarization at the same time as the ventricles; thus, because of the larger muscle mass of the ventricles, there is no P wave. QRS complex is normal. When the AV node impulse is conducted backward, the impulse enters the atria first. Conduction back toward the atria allows for at least partial depolarization of the atria. A short PR interval (
The nurse is interpreting the rhythm strip of a patient and measures the QRS complex as being three small boxes in width. The nurse interprets this width as: A) 0.04 seconds. B) 0.10 seconds. C) 0.12 seconds. D) 0.16 seconds.
C
The nurse is speaking with the patient when the monitor shows that the patient is in ventricular fibrillation (VF). The nurse should: A) immediately defibrillate the patient. B) initiate basic life-support protocols and call for help. C) assess the patient and check the patient's monitor leads. D) initiate advanced life-support protocols as soon as possible.
C
The patient complains of being "lightheaded," and feeling a "fluttering" in his chest. The nurse places the patient on the heart monitor and notices an atrial tachycardia at a rate of 160 beats per minute. The patient's blood pressure has dropped from 128/76 mm Hg to 92/46 mm Hg but appears stable at the lower pressure. The nurse should: A) prepare the patient for asynchronized defibrillation. B) give the patient digitalis IV, then call the provider. C) call the provider and prepare the patient for medical or electrical cardioversion. D) withhold beta-blocker and calcium channel blockers.
C Atrial tachycardia is a rapid rhythm that arises from an ectopic focus in the atria. Because of the fast rate, atrial tachycardia can be a life-threatening dysrhythmia. Causes: digitalis toxicity, electrolyte imbalances, lung disease, ischemic heart disease, and cardiac valvular abnormalities. Treatment: assessing tolerance of tachycardia. If the rate is over 150 beats per minute and the patient is symptomatic, emergent cardioversion is considered. Cardioversion is the delivery of a synchronized electrical shock to the heart by an external defibrillator. Med: adenosine, beta-blockers, calcium channel blockers, and amiodarone.
When an electrical signal in the heart is aimed directly at the positive electrode, the deflection seen on the 12-lead ECG or rhythm strip will be: A) equiphasic. B) negative. C) positive. D) invisible.
C When assessing the 12-lead, it is helpful to understand that the electrical activity is viewed in relation to the positive electrode of that particular lead. The positive electrode is the "viewing eye" of the camera. When an electrical signal is aimed directly at the positive electrode, an upright inflection is visualized. If the impulse is going away from the positive electrode, a negative deflection is seen, and if the signal is perpendicular to the imaginary line between the positive and negative poles of the lead, the tracing is equiphasic, with equally positive and negative deflection.
The patient is admitted with an anterior wall myocardial infarction. With this diagnosis, the nurse would expect to see Q waves in which leads? (Select all that apply.) A) II B) III C) V3 D) V4 E) AVF
CD Pathological Q waves are found on ECGs of individuals who have had myocardial infarctions, and they represent myocardial muscle death. Anatomical regions are described as septal, anterior, lateral, inferior, and posterior. Septal leads are V1 and V2; anterior leads are V3 and V4; lateral leads are V5, V6, I, and aVL; and inferior leads are II, III, and aVF.
a fib
MC dysrhythmia rate: uncountable regularity: irregularly irregular PR: absent QRS: complex P: no T: yes pt response: may or may not show s/s of decreased CO cause: ischemic, valvular, lung disease, hf, aging meds: amoidarone and anticoagulants
Dominant pacemaker of the heart
SA node
a flutter
SAW TOOTH rate: 240-320 count flutter waves regularity: flutter waves are regular PR: none QRS: P: is the flutter T: pt response: no symptoms unless turns into tachy cause: lung disease, ischemic, hyperthyrdoisim, hypoxemia, hf, alcoholism treat: chronic antithrombotic, electric cardioversion after 6 weeks
P wave
atrial depoloarization.
failure to sense
does not sense the pts cardiac rhythm and inititates impulse. spikes fall too closely to the pts own rhythm cause: displacement of wire treat: turn pt on left side
epicardial pacemaker
epicardial wall during surgery
failure to pace
fails to initiate electrical stimulus when it should fire. seen by absence of spikes cause: battery or generator failure or displacement
failure to cpature
generates impulse and no depolarization is noted. packer spike is noted but not followed by a p wave cause: output set too low or displacement, dead battery, fracture of wire, increased pacing threshold. treat: adjust the output and place patient on left side bc it facilitates contract of transvenous pacing wire with endocardium and septum
Rate
how fast the heart is depolarizing. 60-100
regularity
if they are one box or less away it is essentially regular, if it is more than one small box away it is irregular
sinus arrhtmia
increase on inspiration and slow on exhalation rate: 60-100 regularity: irregular PR: normal QRS: normal P: normal T:yes pt response: tolerated cause: treat: none
QT interval
measures the time taken for ventricular depolarization and repolarization
What will a ECG show you?
myocardial ischemia, injury, cell necrosis, electrolyte disturbances, hypertrophy, conduction abnormalities, and heart rhythms
trasnvenous pacemaker
percutaneous in R ventricle to endocardium with external generator
torsades
rate: regularity: PR: QRS: positive and negative waves above and below isoelectric line P: T: pt response: cause: mag deficient treat: monitor mag. prevent with monitor of QT intervals meds:
sinus tachy
rate: 100-160 regularity: regular PR: 0.12-0.20 QRS: 0.06-0.10 P: may or may not be T: yes pt response: decrease in CO cause: hyperthyroidism, hypovelmia, hf, exercise, stimulants, fever, fear, pain, anxiety treat: treat cause
v tach
rate: 110-250 regularity: regular PR: no QRS: >0.12 wide and weird P: T: pt response: low CO or cardiac arrest cause: imbalances, hf treat: no pulse= de fib. pulse= iv amiodarone or lidocaine meds: amiodarone or lidocaine
A tach
rate: 150-250 regularity: regular PR: QRS: narrow P: yes T: yes pt response:the faster the more decreased CO cause: digitalis toxic, electrolytes, lung disease, ischemic heart treat: if over 150 and symptomatic then cardioversion. meds: adenosine, bb, ccb, amiodarone
normal sinus rhythm
rate: 60-100 regularity: regular PR:0.12-0.20 QRS: 0.06-0.10 P: present small and round T: present
sinus brady
rate: <60 regularity: regular PR: consistent QRS: consisten P: consisten T: yes pt response: decrease CO =hypotension and decreased perfusion cause: digoxin , ccb, bb, mi, athlete treat: atropine if symptomatic
v fib
rate: cant tell regularity: cant tell. wavy baseline PR: no QRS: no P: no T: no pt response: arrest cause: ischemic, imbalances, qt prolongation treat: ACLS meds:
transcutaneous pacemaker
skin
PR interval
the time it takes for the impulse to depolarize the atria, travel to the AV node, then enter bundle of HIS 0.12-.20
permanent pacemaker
transvenously through cephalic or subclavian into chambers to stimulate atrium and ventricle
QRS complex
ventricular depoliraztion Q- first negative downward deflection after PR. may or may not be present. has to be .04 seconds deep
T wave
ventricular repolarization
