Mod 5 Info To Know

Question 1

node is the heart’s primary pacemaker. It can spontaneously and rhythmically generate electrical impulses at a rate of 60 to 100 beats/min and therefore has the greatest degree of automaticity (pacing function).

The? node is richly supplied by the sympathetic and parasympathetic nervous systems, which increase and decrease the rate of discharge of the sinus node, respectively. This process results in changes in the heart rate.

Answer 1

Sinoatrial node-SA node

Question 2

• The ability of a cell to respond to a stimulus by initiating an impulse. Also called depolarization. In cardiac electrophysiology, it is the ability of non-pacemaker myocardial cells to respond to an electrical impulse generated from pacemaker cells and to depolarize.

Answer 2

Excitability

Question 3

• The ability of a cell to respond to a stimulus by initiating an impulse/ occurs when the normally negatively charged cells within the heart muscle develop a positive charge. Also called excitability. Impulses from the sinus node move directly through atrial muscle and lead to atrial depolarization, which is reflected in a P wave on the electrocardiogram (ECG).

The PR interval is measured from the beginning of the P wave to the end of the PR segment. It represents the time required for atrial depolarization, the impulse delay in the AV node, and the travel time to the Purkinje fibers. It normally measures from 0.12 to 0.20 second (five small blocks).

The QRS complex represents ventricular depolarization. The shape of the QRS complex depends on the lead selected. The Q wave is the first negative deflection and is not present in all leads. When present, it is small and represents initial ventricular septal depolarization. When the Q wave is abnormally present in a lead, it represents myocardial necrosis (cell death). The R wave is the first positive deflection. It may be small, large, or absent, depending on the lead. The S wave is a negative deflection following the R wave and is not present in all leads.

The QRS duration represents the time required for depolarization of both ventricles. It is measured from the beginning of the QRS complex to the J point (the junction where the QRS complex ends and the ST segment begins). It normally measures from 0.04 to 0.12 second (up to three small blocks).

The QT interval represents the total time required for ventricular depolarization and repolarization. The QT interval is measured from the beginning of the Q wave to the end of the T wave. This interval varies with the patient’s age and gender and changes with the heart rate, lengthening with slower heart rates and shortening with faster rates. It may be prolonged by certain medications, electrolyte disturbances, or subarachnoid hemorrhage. A prolonged QT interval may lead to a unique type of ventricular tachycardia called torsades de pointes.

Answer 3

Depolarization

Question 4

– refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value.

The ST segment is normally an isoelectric line and represents early ventricular repolarization.
The T wave follows the ST segment and represents ventricular repolarization.
The U wave, when present, follows the T wave and may result from slow repolarization
The QT interval represents the total time required for ventricular depolarization and repolarization.

Answer 4

Repolarization

Question 5

• is the property of cardiac cells to generate spontaneous action potentials. Spontaneous activity is the result of diastolic depolarization caused by a net inward current during phase 4 of the action potential, which progressively brings the membrane potential to threshold. (pacing function).

Answer 5

Automaticity

Question 6

• Having equal electric potentials. The baseline is the isoelectric line. It occurs when there is no current flow in the heart after complete depolarization and also after complete repolarization. Positive deflections occur above this line, and negative deflections occur below it.

Deflections represent depolarization and repolarization of cells.

The PR segment is the isoelectric line from the end of the P wave to the beginning of the QRS complex, The ST segment is normally an isoelectric line and represents early ventricular repolarization.

Answer 6

Isoelectric line

Question 7

1. What is the electrical pathway of the heart?

Answer 7

The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles.

Question 8

2. What are the components of ECG waveform and what do they represent?

Answer 8

The wave of depolarization causes the deflections in the ECG waveforms that are recognized as the P wave and the QRS complex. Disturbances in conduction result when conduction is too rapid or too slow, when the pathway is totally blocked, or when the electrical impulse travels an abnormal pathway.
There are three main components to an ECG: the P wave, which represents the depolarization of the atria; the QRS complex, which represents the depolarization of the ventricles; and the T wave, which represents the repolarization of the ventricles.

Question 9

3. Name at least 3 symptoms of bradycardia

a. What is the treatment for bradycardia if the patient is nonsymptomatic?

Answer 9

S/s??

If the patient is stable, treatment includes identification and treatment of the underlying cause.

Question 10

b. What is the treatment for bradycardia if the patient is symptomatic?

Answer 10

If the patient has any of these symptoms and the underlying cause cannot be determined, the treatment is to administer drug therapy with atropine 0.5 mg IV, increase intravascular volume via IV fluids, and apply oxygen. Drugs suspected of causing the bradycardia are discontinued. If beta-blocker overdose is suspected, administration of glucagon may help by increasing the heart rate and blood pressure. If the heart rate does not increase sufficiently, prepare for transcutaneous or transvenous pacing to increase the heart rate. If treatment of the underlying cause does not restore normal sinus rhythm, the patient will require permanent pacemaker implantation.

Question 11

4. Name at least one medication for each medication class and its use? Chart 34-4 pg.676
   a. Calcium channel blockers
   b. Beta blockers-
   c. Potassium channel blockers-

Answer 11

a. Calcium channel blockers
Amlodipine (Norvasc)-Used to decrease the force of contraction of the muscle cells and dilates arteries. Often used for hypertension and abnormal and rapid heart rhythms.
b. Beta blockers- Atenolol, Propranolol-Reduces blood pressure and pulse, Blocks the effects of the hormone epinephrine, AKA adrenaline which causes your heart to beat more slowly and with less force.
c. Potassium channel blockers- Aminopyridine, Diaminopyridine: inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of action potentials. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.

Question 12

5. What is the treatment for atrial fibrillation

Answer 12

• Correcting the rhythm and controlling the rate of the rhythm restore blood flow, which helps prevent embolus formation and increases cardiac output.
• Drug therapy is often effective for treating AF. The loss of coordinated atrial contractions in AF can lead to pooling of blood, resulting in CLOTTING.

The patient is at high risk for pulmonary embolism! Thrombi may form within the right atrium and then move through the right ventricle to the lungs. If pulmonary embolism is suspected, remain with the patient and monitor for shortness of breath, chest pain, and/or hypotension. Initiate the Rapid Response Team and notify the provider. In addition, the patient is at risk for systemic emboli, particularly an embolic stroke, which may cause severe neurologic impairment or death. Monitor patients carefully for signs of stroke. Initiate Rapid Response Team if stroke is suspected to facilitate timely diagnosis. Patients with AF who have valvular disease are particularly at risk for venous thromboembolism (VTE). In VTE, the patient may complain of lower extremity pain and swelling. Anticipate ultrasound of vasculature and initiation of systemic anticoagulation.

• *Traditional interventions for AF include antidysrhythmic drugs to slow the ventricular conduction or to convert the AF to normal sinus rhythm (NSR)
• *Treatments often include drugs, electrical shock (cardioversion), and minimally invasive surgery (ablation).

Question 13

6. What is the treatment for ventricular tachycardia?

Answer 13

Treatment for ventricular tachycardia involves managing any disease that causes the condition.

These treatments may improve or prevent the abnormal heart rhythm from returning.

In emergency situations, CPR, electrical defibrillation and IV medications may be needed to slow the heart rate.

Question 14

7. What is the treatment for ventricular fibrillation?

Answer 14

Medications. Doctors use various anti-arrhythmic drugs for emergency or long-term treatment of ventricular fibrillation.

A class of medications called beta blockers is commonly used in people at risk of ventricular fibrillation or sudden cardiac arrest. Implantable cardioverter-defibrillator (ICD)

Question 15

The client is on a cardiac monitor and the nurse must interpret the findings.  When interpreting the findings of cardiac monitoring, which step should the nurse do first?
​A. Determine the presence of P waves
​B. Examine the PR interval
​C. Assess the heart rate
​D. Calculate the QT interval

Answer 15

C

Question 16

A client with ventricular tachycardia (VT) is unresponsive and has no pulse. The nurse calls for assistance and a defibrillator. What is the nurse’s priority intervention while waiting for the defibrillator to arrive?
​A. Ask the family about code status
​B. Perform a precordial thump
​C. Insert an IV in the brachial vein
​D. Initiate cardiopulmonary resuscitation

Answer 16

B or d ?

Question 17

The client has the following cardiac rhythm and is unstable.  The nurse interprets this rhythm as which of the following?
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​
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​A. Premature ventricular contractions
​B. Atrial fibrillation
​C. Sinus tachycardia
​D. Ventricular fibrillation**

Answer 17

D

Question 18

Dysrhythmias

Who is more at risk? Why?

What to assess?

Treatment?

Pt. Education?

Most common dysrhythmia?

Answer 18

Special nursing considerations for the older patient with dysrhythmias are:
• Evaluate the patient with dysrhythmias immediately for the presence of a life-threatening dysrhythmia or hemodynamic deterioration.
• Assess the patient with a dysrhythmia for angina, hypotension, heart failure, and decreased cerebral and renal perfusion.
• Consider these causes of dysrhythmias when taking the patient’s history: hypoxia, drug toxicity, electrolyte imbalances, heart failure, and myocardial ischemia or infarction.
• Assess the patient’s level of education, hearing, learning style, and ability to understand and recall instructions to determine the best approaches for teaching.
• Assess the patient’s ability to read written instructions.
• Teach the patient the generic and trade names of prescribed antidysrhythmic drugs and their purposes, dosage, side effects, and special instructions for use.
• Provide clear written instructions in basic language and easy-to-read print.
• Provide a written drug dosage schedule for the patient, considering all the drugs the patient is taking and possible drug interactions. • Assess the patient for possible side effects or adverse reactions to drugs, considering age and health status.
• Teach the patient to take his or her pulse and to report significant changes in heart rate or rhythm to the primary health care provider.
• Inform the patient of available resources for blood pressure and pulse checks, such as blood pressure clinics, home health agencies, and cardiac rehabilitation programs.
• Instruct the patient about the importance of keeping follow-up appointments with the primary health care provider and reporting symptoms promptly.
• Include the patient’s family members or significant other in all teaching whenever possible.
• Teach the patient to avoid drinking caffeinated beverages, stop smoking, drink alcohol only in moderation, and follow his or her prescribed diet.

Older adults are at increased risk for dysrhythmias because of normal physiologic changes in their cardiac conduction system.

The sinoatrial node has fewer pacemaker cells. There is a loss of fibers in the bundle branch system. Therefore older adults are at risk for sinus node dysfunction and may require pacemaker therapy.

The most common dysrhythmias are premature atrial contractions, premature ventricular contractions, and atrial fibrillation.

Dysrhythmias tend to be more serious in older patients because of underlying heart disease, causing cardiac decompensation.

Consequently, blood flow to organs that may already be decreased because of the aging process may be further compromised, leading to multisystem organ dysfunction. Chart 34-5 highlights special considerations for older adults receiving antidysrhythmic therapy.