Conduction pathway

no premature/escape/eptopic beats

sinus node is pacemaker

Pathophysiology/Effects:

HR >100bpm

Max HR 160-180bpm

initially increases CO and BP

continued increases in HR decrease coronary perfusion time, diastolic filling time, and coronary perfusion pressure while increasing myocardial oxygen demand

if rhythm is not well tolerated pt may have fatigue, weakness, SOB, orthopnea, neck vein distension, decreased O2 sat, decreased BP.

anginal pain

palpitations

Causes:

• pain
• medications (catecholamines, atropine, alcohol, nicotine, aminophylline, and thyroid medications)
• caffeine
• exercise
• compensatory response to decreased cardiac output or BP, hypovolemic shock, MI, infection, HF

Treatment:

• know cause to determine treatment

Conduction pathway:

sinus node fires <60bpm

Pathophysiology/Effects:

syncope

dizziness and weakness

confusion

hypotension

diaphoresis

shortness of breath

ventricular ectopy

anginal pain

Causes:

parasympathetic nervous system stimulation

vagal nerve stimulation

may result from hypoxia, inferior wall MI, or administration of beta-adrenergic blocking agents, calcium channel blockers, or digitalis.

Treatment:

Atropine

Pacing (external/internal)

oxygen

Conduction pathway

system is fine

atrial myocytes having excitability

ectopic focus fires an impulse before the next sinus impulse is due

Pathophysiology/Effects

pt usually has no symptoms except for possible heart palpitations

Extra P wave

usually followed by a pause on an EKG

Causes:

stress

fatigue

anxiety

inflammation

infection

facceine, nicotine, or alcohol

drugs such as catecholamines, sympathomimetics, amphetamines, digitalis, or anesthetic agents

myocardial ischemia, hypermetabolic states

electrolyte imbalance

atrial stretch

hypoxia

Treatment:

avoid triggers

correct electrolytes

solve underlying problem

#1 dysrhythmia for hospitalization

Conduction Pathway

multiple rapid impulses from many atrial foci depolarize the atria in a totally disorganized manner at a rate of 350-600times a minute.

chaotic rhythm

no clear P waves, no atrial contractions, loss of atrial kick, and an irregular ventricular response

Pathophysiology/Effects:

decreases ventricular filling

reduces cardiac output (further imparing the heart's perfusion ability)

assess for fatigue, weakness, SOB, distended neck veins, dizziness, decreased exercise tolerance, anxieyt, syncope, palpitations, chest discomfort or pain, and hypotension

Causes/Risk Factors:

HTN

DM

male gender

congestive heart failure

valvular disease

alcohol intake

cardiac surgery

electrocution

MI

pericarditis

myocarditis

PE

Treatment:

Coumadin (more of prevention)

BB, CCB, digoxin

Cardioversion (ablation)

Conduction Pathway:

rapid atrial depolarization occurring at a rate of 250-350 times per minute

AV node blocks the number of impulses that reach the ventricles as a protective mechanism

Pathophysiology/Effects

typically no s/sx

depend on the rate of ventricular response

Causes:

rheumatic or ischemic heart disease

HF

AV valve disease

pre-excitation syndromes

septal defects

PE

thyrotoxicosis

alcoholism

pericarditis

Treatment:

Carotid Massage

BB, CCB, diltiazem, digoxin

cardioversion/ablation

Conduction Pathway

starting from AV junctional node

40-60bpm

escape beat

Occasionally AV junctional cells do generate impulses as an escape pacemaker when the sinus node is excessively slow, or the cells may do so as irritable rhythms

most commonly temporary and pt usually remain stable

Conduction Pathway:

supraventricular impulses are excessively delayed or totally blocked in the AV node or intraventricular conduction system

SA node continues to function normally, and the atrial depolarization and P waves occur regularly

Treatments:

depend on on the severity of the block

Oxygen, drug thearpy, pacing, and/or permanent pacemakers

adenosine

take away drugs

(complete heart block)

none of the sinus impulses reach the ventricles.

the ventricles are therefore depolarized by a second, independent pacemaker

Conduction Pathway

rapid stimulation of atrial tissue at a rate of 100-280bpm

usually due to a re-entry mechanism in which one impulse circulates repeatedly throughout the atrial pathway, restimulating the atrial tissue at a rapid rate

Pathophysiology/Effects:

depend on the duration of the SVT and the rate of the ventricular response

Cardiovascular deteriorization

result in angina, heart failure, cardiogenic shock

Causes:

may occur in healthy young people, especially women

Treatment:

adenosine (drug of choice)

diltiazem

both slow the ventricular rate by increasing the AV block

Warning sign for MI

Conduction Pathway:

result from increased irritability of ventricular cells and are seen as early ventricular complexes followed by a pause

Pathophysiology/Effects:

may be asymptomatic

palpitations

chest discomfort

increased stroke volume

diminished peripheral pulses

decreased peripheral perfusion

Causes:

*postmenopausal women often find that caffeine causes palpitations and PVCs

Treatment:

eliminating any contributing c ause

With myocardial ischemia or MI, O2 is administered and pt is given amiodarone

very concerning

Conduction Pathway:

occurs with repetitive firing of an irritable ventricular ectopic focus, usually at a rate of 140-180bpm or more

the sinus node may continue to discharge independently, depolarizing the atria but not the ventricles

VTach is commonly the initial rhythm before deterioration into VFIB as the terminal rhythm

Pathophysiology/Effects:

can cause cardiac arrest

Life threatening

Conduction Pathway:

impulses from many irritable foci fire in a totally disorganized manner so that ventricular contraction cannot occur

Pathophysiology/Effects:

ventricles quiver, consuming a tremendous amount of oxygen

no cardiac outpulse or pulse

no cerebral, myocardial, or systemic perfusion

may be the first manifestation of CAD

Causes:

hypokalemia

hypomagnesemia

hemorrhage

antidysrhythmic therapy

rapid SVTs

shock

Treatment:

resolve VFIB promptly

defibrillate the patient immediately