Which part of the heart is the strongest and largest of the four chambers? Why?
Left ventricle because it is responsible for pumping blood throughout the body.
Which vena cava vein is the largest?
Inferior
What is the intrinsic rate of the SA node, AV node, conduction below the AV node?
SA : 60 to 100
AV : 40 to 60
Below AV : 20 to 40
Describe electrical pathway of a contraction in the heart.
Impulses start in SA node, travel through R and L atria, resulting in atrial contraction.
Impluse travels to the AV where it transitions slowly down to the bundle of His.
Proceeds rapidly to the R and L bundle branches stimulating the interventricular septum.
Then the impulse spreads through the rest of the conduction system resulting in ventricular contraction.
Define excitability.
Ability of cells to respond to electrical impulses.
Define conductivity.
Ability of cells to conduct electrical impulse.
Define automaticity.
Allows cardiac muscle cells to contract spontaneously w/o stimulus from a nerve source.
What happens if the SA node does not fire an impulse?
Other myocardial cells with create their own impulses to stimulate the heart at a slower rate.
What controls the chronotropic, dromotropic, and inotropic states of the heart?
Autonomic nervous system, hormones, and heart tissues.
Describe the chronotropic, dromotropic, and inotropic states of the heart?
Chronotropic state controls the rate of the contraction.
Dromotropic state controls electrical conduction.
Inotropic state controls the strength of contraction.
Where does the electrical stimulus of heart contraction originate from?
Autonomic nervous system
Systole
Contraction of the ventricles and pumping of blood into the systemic circulation.
Diastole
Relaxation of heart.
Preload
Amount of blood returned to the heart to be pumped out. Directly affects afterload.
Afterload
Pressure in the aorta or the peripheral vascular resistance, against which the left ventricle must pump blood.
Stroke volume (SV)
Amount of blood ejected per contraction.
Cardiac output (CO)
Amount of blood pumped through the circulatory system in 1 minute.
CO = SV x HR
Starling law
The more cardiac muscle is stretched, the greater the force of its contraction, the more completely it will empty, and, therefore, the greater the SV.
What are the major controllable factors for AMI?
Cigarette smoking HTN Hyperlipidemia DM Lack of exercise Obesity
What are the major factors that cannot be controlled for AMI?
Older age Fmhx atherosclerotic CAD Race Ethnicity Male
Stable angina.
Occurs at a fixed frequency and is relieved by rest and/or medication.
Unstable angina.
Occurs w/o fix frequency and may or may not be relived w/ rest and/or medications.
Progressive angina
Stable or unstable angina that accelerates in frequency and duration.
Preinfarction agina
Pain that occurs at rest when the pt is sitting or lying down.
What part of the hear is an AMI more apt to occur?
Left ventricle
s/s AMI
Sudden onset of weakness, nausea, and sweating
Chest pain, discomfort, or pressure described as crushing or squeezing
Pain radiating to lower jaw, arms, back, abd, or neck
Irregular heartbeat
Syncope
N/V
Pink, frothy sputum
Sudden death
How does pain of an AMI differ from pain of angina?
May or may not be caused by exertion, but can occur at anytime.
Does not resolve in a few minutes.
May or may not be relieved by rest or NTG.
What is a silent MI?
AMI w/o classic chest pain
What are three serious consequences of an AMI?
Sudden death
Cardiogenic shock
CHF
Ventricular tachycardia
Rapid heart rhythm averaging between 150-200 beats/min.
Electrical activity start in ventricle rather than atrium.
Rhythm does not allow adequate time between beats for the left ventricle to fill causing a drop in BP.
Can deteriorate into v-fib
Ventricular fibrillation
Ineffective quivering of the ventricles caused by unorganized electrical activity.
No blood is pumped through the body resulting in unresponsiveness w/in seconds.
What is the only way to treat ventricular fibrillation?
Electrical defibrillation of the heart.
What does electrical defibrillation do to the heart?
It sends an electric current to stop all electrical activity in order to give the conduction system a chance to normalize.
Asystole
Absence of all cardiac electrical and mechanical activity.
Unstable VT and VF will results in asystole.
Due to long periods of ischemia, nearly all pts die.
How would you differentiate cardiogenic shock and hypovolemic shock?
One or more of the following: CC (CP, dyspnea, tachy) HR (brady, tachy) Peripheral edema Dysrhythmias JVD Rales
Tx for cardiogenic shock.
Position of comfort
Administer high-flow oxygen
Assist ventilations as necessary
Conserve heat by covering pt
Establish IV access and give 250 mL bolus up to 1,000 mL
Prompt transport
Call ALS for timely administration of vasopressors.
When the heart muscle can no longer contract effectively, two specific changes in heart function occur:
HR increases
Left ventricle enlarges in an effort to increase the amount of blood pumped each minute.
Where does fluid collect when the right side of the heart is failed?
Legs and feet
s/s of heart failure
Orthopnea Agitated Chest pain may or may not occure JVD Pedal edema HTN Tachycardia Tachypnea Uses accessory muscle in the neck and ribs Rales midway or apex Productive cough Delayed cap refill
Tx for heart frailure
Obtain vital signs, monitor heart rhythm, and administer oxygen. Ventilate if needed.
CPAP
Semi-fowler position
Gain IV access. May give fluids if hypotensive.
NTG if systolic above 100.
Prompt transport
s/s HTN emergencies
Strong bounding pulse Tinnitus N/V Dizziness Dry or moist, warm skin Epistaxis AMS Sudden onset of pulmonary edema
When is BP considered hypertensive?
Systolic BP greater than 140.
Diastolic BP greater than 90.
What is the primary cause of dissecting aortic aneurysm?
Uncontrolled HTN
Two most common rhythms that require defribilattion.
Ventricular fibrillation and Pulseless ventricular tachycardia.
What is the initial and subsequent energy setting of monophasic and biphasic AEDs?
Monophasic : 360 joules
Biphasic : 120 for initial and subsequent or 120 for initial and 200 for subsequent.
What is the advantages of AED machines?
Easy to use
Shock delivered w\in 1 minute of arrival
Shock can be given remotely
Pads are larger than manual paddles making transmission of electricity more efficient
When does defibrillation work best?
When the defibrillation occurs 2 minutes after onset of cardiac arrest.
What are the five links in the chain of survival?
- Recognition of early warning signs and immediate activation of EMS.
- Immediate CPR w/ emphasis on high-quality chest compressions.
- Rapid defibrillation/
- Basic and advanced EMS.
- ALS and postarrest care
What does the ALS and postarrest care link in the chain of survival entail?
Controlling temperature to optimize neuro recovery.
Maintaining CBG levels if hypoglycemic.
Continue ventilations to achieve an ETCO2 of 35-40 mm Hg.
Maintaining oxygen saturations above 94%.
BP above 90 mm Hg.
Cardiopulmonary and neuro support at the hospital.
The factors involved in the defibrillation include…
voltage, current, and impedance.
Indications for not initiating resuscitative techniques
rigor mortis, dependent lividity, decapitation, DNR, and advanced directives.
Ventricular fibrillation will recur after ROSC if :
The heart is not receiving optimal amounts of oxygen.
When should you being transport during a cardiac arrest?
If ALS is not reposing and local protocols agree:
Pt regains pulse
6-9 shocks delivered or directed by local protocol
Machine gives 3 consecutive messages that no shock is advised or as directed by local protocol
How often should you check an unconscious patient’s pulse?
Every 30 seconds
If an unconscious patient becomes pulseless during transport what do you do?
- Stop the vehicle.
- If AED no immediately available, perform CPR until machine is available.
- Call for ALS
- Analyze rhythm.
- Deliver one shock, if indicated, and immediately resume CPR.
- Continue resuscitation according to local protocol.
Management of ROSC
Monitor for spontaneous respirations.
Provide oxygen via BVM to maintain ETCO2 between 35-45 mm Hg.
Maintain oxygen sat above 95%
Asses BP and see if they can follow simple commands (such as, “Squeeze my fingers.”)
Transport to closet appropriate hospital.
Describe placement of 12- lead EKG electrodes.
V1 - 4th intercostal space, right sternal border
V2 - 4th intercostal space, left sternal border
V3 - between V2 and V4
V4 - 5th intercostal space, midclavicular line
V5 - lateral to V4 at anterior axillary line
V6 - lateral to V5 at midaxillary line
White - right arm
Black - left arm
Green - right leg
Red - left leg
What view does each EKG electrode show?
V1, V2 - ventricular septum
V3, V4 - anterior wall of left ventricle
V5, V6 - lateral wall of left ventricle
Order of 12-lead EKG placement
V1, V2, V4, V3, V6, V5,
