Valencia College: Paramedic Program P2 - Cardiac A&P/Electrophysiology Test Study Guide

Tricuspid Valve

lies between right atrium and right ventricle; closed during systole to prevent backflow

Mitral (Bicuspid) Valve

lies between left atrium and left ventricle; closed during systole to prevent backflow

Pulmonic Valve

lies between right ventricle and pulmonic artery; closed during diastole to prevent backflow of blood from vessels into the ventricles

Aortic Valve

lies between left ventricle and aorta; closed during diastole to prevent backflow of blood from vessels into the ventricles

What is happening during the diastole phase of the cardiac cycle?

period of relaxation during which the chambers are filling

The area where the heart and great vessels reside

mediastinum

Mechanical phases of the cardiac cycle:

1. Diastole

2. Depolarization

3. Systole

4. Repolarization

3 components that create BP:

1. Stroke Volume(Cardiac Output)

2. Heart Rate(Cardiac Output)

3. Peripheral Vascular Resistance

What happens on phase 1 of cardiac cycle?

K+ channels open and K+ leaves the cell; CA2+ channels open and CA2+ rushes in (plateau); cellular contraction happens

What is the inner most layer of the heart?

endocardium

SA node Intrinsic rate:

60-100 bpm

AV Intrinsic rate:

40-60 bpm

Purkinjes Intrinsic rate:

20-40 bpm

Negative ECG waves have what deflection?

wave of depolarization moving towards a negative electrode; negative deflection

What is role of the myocardium?

Middle layer; thick, muscular layer that is responsible for pumping action

What electrolyte is prevalent in phase 1 and 2 of the cardiac cycle?

Calcium (Ca++)

Resting Potential

The difference in electric charge between the inside and outside of a neuron's cell membrane; -90mV

How many ECG leads are required to detect a life threatening dysrhythmia?

1

The epicardium is contagious with what structure?

serous pericardium

What nerve is associated with the parasympathetic system and what effect does it have on the heart?

Vagus nerve (Cranial X); innervates heart at SA and AV nodes causing a drop in heart rate

What ECG wave represents the depolarization of the atrium?

P wave

What role does BNP play play in congestive heart failure?

a hormone that is secreted by the ventricles to counteract the RAAS system, which is released during CHF, by stimulating loss of water, sodium, and vasodilation

What is considered the pacemaker of the heart?

SA Node

What does ejection fraction represent?

the amount of blood your heart pumps each time it beats

How does preload effect BP?

it is the amount of blood that is returned to the heart from the venous side during diastole so it determines how much blood gets back into the heart

What is an ECG monitor capable of doing?

can provide information about rate and rhythm, the orientation of the heart, in the chest, conduction disturbances, the electrical effects of medications and electrolytes, the mass of cardiac muscle, and the presence of ischemic damage

How does the myocardium receives its blood?

Coronary Arteries

What happens during phase 0 of the cardiac cycle?

K+ leaks out, threshold potential (-70mV) is reached, fast Na+ channels open and drives membrane positive; cell depolarization occurs

Compare the right ventricle and left ventricle:

Right Side - low pressure system; smaller; pumps deoxygenated venous blood to the lungs

Left Side - high pressure system; bigger; pumps oxygenated arterial blood to systemic circulation

Anatomical location landmark of Heart: Apex

5-6th rib above diaphragm

Anatomical location landmark of Heart: Base

2nd rib

How are positive waveforms represented on ECG?

wave of depolarization moving towards the positive electrode; positive deflection

What is the prevalent electrolyte in phase 3 and what role does it play?

Potassium (K+); K+ leaves the cells and the cell becomes negative; Repolarization occurs

What is the typical stroke volume of the left ventricle?

about 70mL

How is Time measured on ECG paper?

on the horizontal axis; each small box = 0.04 secs(40ms) and each large box(5 small boxes) = 0.20 secs(200ms)

How is Amplitude(Voltage) measured on ECG paper?

on the vertical axis; 10mm = 1mV

The absolute refractory period is represented by what 2 EKG landmarks?

from the onset of QRS complex to the peak of the T wave

What is the function of the atrium?

Atrial kick

300 Rule

count the number of large boxes between 2 consecutive waveforms (R-R interval and P-P interval) and divide into 300(must be regular); 1 box = 300, 2 boxes = 150, 3 boxes = 100, 4 boxes = 75, 5 boxes = 60, 6 boxes = 50

Trace the path of electrical depolarization in the pathway:

What does T wave represent?

ventricular repolarization

Starling's Law

the more a myocardial muscle is stretched, the greater the force of contraction (and stroke volume); influenced by preload and afterload

Afterload

the pressure/resistance against which the ventricles must pump to eject blood; increased afterload usually means an increase in the work of the heart

Anatomic Location of Lead V1

right side of sternum, 4th intercostal space

Anatomic Location of Lead V2

left side of sternum, 4th intercostal space

Anatomic Location of Lead V3

midway between V2 and V4

Anatomic Location of Lead V4

left midclavicular line, 5th intercostal

Anatomic Location of Lead V5

left anterior axillary line, same level as V4

Anatomic Location of Lead V6

left midaxillary line, same level as V4

End Diastolic Volume

the volume of blood in the left ventricle at the end of ventricular filling (diastole)