1. when cardiac impulses encounter a block in conduction, instead if being extinguished, the impulse is carried along the unopposed side and re-enters the conduction branch from the opposite side causing repetitive cardiac stimulation 

affecting the speed with which impulses pass through the conduction system;

positive dromotrophic medications increase speed of impulses negative dromotropic medications decrease speed of impulse

affecting the heart rate

positive chronotropic medications increase HR,

negative chronotropic medications decrease HR

affecting force of contraction;

positive inotropic medications increase the force of contraction and therefore increase CO (cardiac output)

negative inotropic drugs decrease the force of contraction and therefore decrease CO

sodium 

Class I antiarrhythmics are sodium channel blockers and have direct membrane action upon the sodium channel

beta receptors

Class II antiarrhythmics are the beta-blockers and affect the heart by sympatholysis (beta blocking).

potassium channels

Class III antiarrhythmics prolong repolarization by affecting the potassium channel 

calcium channel

Class IV antiarrhythmics are calcium channel 

  In addition to these classes what other

antiarrhythmics are there?

How does depolarization occur?

Wha ions are involved

What happens tothe heart?

cell membrane becomes more permeable to sodium. Calcium ions follow sodium 

As sodium and calcium ions move into the cells, potassium moves out of cells.  The movement of the ions changes the membrane from its resting state of electrical neutrality to an activated state of electrical energy buildup.

When the electrical energy is discharged (depolarized),

muscle contraction occurs

All the Class I agents are sodium channel blockers that affect Phase 0 of depolarization.

What does this mean?

1A - quinidine, procainamide, and disopyramide. 

1B-  lidocaine, mexiletine, and phenytoin.  

IC- flecainide and others 

 ventricular and supraventricular dysrhythmias— PAC’s, PVC’s,

 maintenance of SR after AF, VT and prevention of VF

How does Class IA agents such as Quindine work?

 Depresses: conduction, excitability, and contractility

Prolongs refractoriness of the atrial His-purkinje and ventricular tissue

These antidysrhythmics are:

vagolytic:  A therapeutic or chemical agent that has inhibitory effects on the vagus nerve

negative inotropes: decrease the force of contraction and therefore decrease CO 

What EKG changes will you likly see with

Class IA agents such as Quindine?

What is a sing of Toxicity of Class IA agents such as Quindine

 R/T an EKG change?

Toxicity occurs as the corrected QT interval increases

-this can be as much as 30% increase

What Class IA agents also has calcium channel blockade making it a potent anticholinergic.

What are the most common adverse effect of  Class IA agents such as Quindine?

GI Related: N/V, diarrhea, abdominal pain, anorexia

Syndrome of cinchonism: auditory changes, dizziness, vertigo, disturbed vision

If a pt has a small heart block a Class IA agents such as Quindine may be used because the benifit outways the risk.

True or False?

False

Don’t give to those with any degree of AV block!!! 

 Cardiotoxicity: increased PR and QT intervals, Vtach, asystole, arterial embolism, PVC’s, complete heart block

Lupus-like syndrome (long-term use)

Your pt is taking Quinidine (Quinora).

What labs do you want to look at?

Why?

CBC-  discrasias r/t lupis- like syndrome 

LFT’s- can be hepatotoxic

K⁺ level  -  low levels will reduce effects and induce torsades de pointes

(a lethal form of ventricular tachycardia)  

 2-6 mg/mL

What is the nusres action if the QRS complex increase >25%, disappearance of P waves, or restoration of sinus rhythm

 and the pt is taking Quinidine (Quinora) ?

Acute treatment of ventricular tachycardia

r/t cardiac surgery or acute MI

A nurse is preparing to give  Lidocaine (class 1B) IV.

How should the nurse give this med?

       Short half-life:

First phase: 5-10 min

  Second phase: 80-110 min

CHF, reduced CO, digitalis toxicity w/ AV block, hypovolemia

and shock, all heart blocks

 CV effects: arrhythmias and hypotension, cardiac arrest

CNS effects: hallucinations, seizures, LOC

Seizures and coma >6 µg

What are the most common sife effects of

Flecainide/ propafenone?

 Conduction of the heart

Profound negative inotrope

How does Class II propanolol work?

 Nonspecific beta blocker

Slows HR, ↓ O₂ demand

Depress AV conduction

Decreases CO 

Reduces BP

Reentry and ectopic supraventricular tachycardia-  s/t digoxin toxicity

  Sinus tachycardia s/t thyrotoxicosis

Exercised-induced ventricular tachycardia

  COPD, bronchospasm

    Sinus bradycardia

Second and Third degree HB

postural hypotension. bronchospasm 

Sudden Discontinuation can cause rebound tachycardia.

Propanolol  has a 3 hour half life so a nurse knows that the pt should recive the drug:

A. Q3Hr while awake

B. Q6Hr around the clock

C. BID

 Produces prolonged phase of repolarization

 Negative chronotropic effect from blocking slow calcium channels

U waves appear and T waves are altered

IV: relaxes smooth muscle, ↓ peripheral vascular resistance

Life-threatening ventricular dysrhythmias

 Suppression of supraventricular tachycardias

IV in initiation of therapy and prophylaxis for recurring V fib and hemodynamically  unstable V tach

 Severe sinus bradycardia

  2^nd or 3^rd degree AV heart block

Hx. Of bradycardia w/ syncope

CNS: dizziness, fatigue, drowsiness, paresthesia, tremor, HA, insomnia.

GI Related: N/V, constipation, abdominal pain, anorexia  Photosensitivity (IV): blue-gray discoloration

IV most common is hypotension: slow rate

 Pulmonary toxicity: cough, progressive dyspnea, phosopholipidosis, abnormal tests

  Exacerbation of treated arrhythmia

    Liver disease

  Pregnancy D

causes Gasping syndrome in premature infants

Baseline LFT’s, thyroid function, respiratory

A pt is to recive amiodarone (Cordarone) what to monitering devices should the nurse know to have in place?

Why?

pulse ox and ABG’s for resp. function

MED can cause Pulmonary toxicity

Report new onset of cough, SOB, and changes in visual acuity!!!!!

What is the class IV antidysrhythmic?

Inhibits movement of Ca²⁺ across cardiac and arterial muscle cell membrane.

Slows conduction through AV node

Depresses myocardial contractility, automaticity

Dilates coronary and peripheral arteries

 IV for supraventricular tachycardia

Temporally control the rapid ventricular response to A-fib or flutter

Prophalactic w/ Digoxin tor repetitive SVT

Angina resulting from coronary artery spasms

HTN

Sick sinus syndrome: ↓ cardiac function, CHF

Second or third degree HB

Hypotension: systolic <90 mmHg

What are the most common sede effects of 

Class IV Verapamil?

     Constipation

 Dizziness, weakness, fainting (bradycardia or hypotension)

Swelling of the lower extremities

Rash

HA

Difficulty breathing or wheezing (worsening HF)

Lethal ventricular arrhythmias

May cause abnormal LFT’s

What age groups should you use caution when giving Class IV Verapamil?

Why?

Elderly- more prone to hypotensive events.

 neonates/infants- no IV administation

JVD, cardiac signs, mentation, edema,

hx of palpitations, and PND.

Take apical pulse, hold drug if too low or irregular beats and call MD.

Education should include: compliance, report weight gain

Increase fluids and fiber to ↓ constipation

Relaxes vascular smooth muscle

Dilates peripheral arteries and veins

Reduces preload and afterload

 Moderate doses induce renal vasodilation

Lower BP in acute hypertensive crisis

Reduce bleeding during surgery

Acute CHF

 Compensatory HTN from aortic coarctation or arteriovenous shunting

 Inadequate cerebral circulation in surgery

 N/V, HA

Palpitations, Ectopic Beats

Dyspnea, angina

 Ventricular dysrhythmias

Increased pulmonary shunting

Decrease splanchnic perfusion

Increase pulmonary wedge pressure

 Need invasive monitoring arterial lines and Swan-gantz lines

A nurse has a pt that is taking nitroprusside (Nitropress) what labs should the nurse be most concerned about checking?

Why?

Watch the pt electrolytes to make sure adequate renal perfusion (Creatinine and K+)

Blood gases to detect acidosis as this will decrease effectiveness of dopamine

A nurse is about to give nitroprusside (Nitropress) IV.

How should the nurse give this med.

A. Use in a dedicated central line

 B. Use a pic line that has been flushed

C. Use any patent IV sight

·         Monitor BP, UO, CO, PWP

No effect on renal perfusion

Increase HR w/ less decrease in peripheral vascular resistance

No norepinephrine release

 Hypersensitivity: Sulfite allergies

Ventricular fibrillation or uncorrected tachycardia

What are the most common side effects of

dobutamine (Dobutrex)

Ventricular ectopic activity

N, HA, SOB, palpitations

Anaphylactic Reaction

Increase of 30 bpm and systolic BP of 50 mmHg leading to tachycardia

Monitor ECG, HR, BP, Cardiac output, and pulmonary wedge pressure continuously

Hypovolemia should be corrected before administrating drug by giving plasma expanders