Cardiovascular Lecture ❤️

what is the order of a normal conduction pathway

SA Node

AV Node

Bundle of His

L + R bundle branch

Purkinje

Systole

– contraction and ejection of blood

Diastole

– chambers relax and allow for ventricular filling

P wave represents

Atria contracting

• Represents the depolarization (contraction) of the atria

PR interval represents

Represents the conduction time of the electrical impulse from the atria to the ventricles.

QRS complex represents

Represents the depolarization (contraction) of the ventricles

ST segment represents

represents the time when the ventricles are fully depolarized and before they start repolarizing.

T wave represents

Represents the repolarization (relaxation) of the ventricles.

QT interval represents

The time interval between the start of the QRS complex and the end of the T wave.

Represents the total duration of ventricular depolarization and repolarization.

CO equation

• CO = SV × HR

Stroke volume equation

SV = EDV - ESV

(End-Diastolic Volume minus End-Systolic Volume

Ejection fraction:

percent of end diastolic volume ejected with each heart beat (left ventricle)

Stroke volume(SV):

amount of blood ejected with each heartbeat

Cardiac output (CO):

amount of blood pumped by ventricle in liters per minute

Preload

preload is stretch caused by being filled with blood. volume of blood affects degree of stretch.

afterload

resistance to ejection of blood from ventricle

contractility

contractility is force of contraction.

what can increase preload?

• increased volume (ex fluids, blood transfusion)

• increase BP (giving volume, high sodium diet, medications vasopressors to cause vasoconstriction)

• slow HR to increase filling time (medications ex beta blockers, CCB)

what can decrease preload

• decrease volume (diuretics)

• decrease BP via vasodilation (nitroglycerin)

• increase HR (epinephrine, atropine)

what are the risks of having too much preload

too much preload can cause the heart muscles to stretch out. chambers become over dilated. 

what are the risks of having too little preload

not enough preload can cause not enough perfusion and poor CO

what can decrease afterload

• decrease BP 

• vasodilate 

what can increase afterload

• increase BP

• vasoconstriction

  (typically we don't try to increase afterload)

what are the risks of having too much afterload

high pressure damage 

what are the risks of having too little afterload

poor perfusion and decrease CO

what can decrease contractility

• medications with -intropy (beta blockers, CCB)

• increase afterload, reduce preload 

• parasympathetic NS (dont need as much force in rest and digest.)

what can increase contractility

• medications with +inotropy (digoxin)

• sympathetic NS (high force needed in fight or flight)

• decrease afterload, increase preload 

why would we want to decrease contractility?

reduce workload of heart (ex after MI, in heart failure)

why would we want to increase contractility?

increase CO

physical assessment of the CV system

• fluid overload 

• edema 

• distended jugular (JVD)

• cyanosis 

• shortness of breath

• activity intolerance 

• cap refil 

• pain

• orthostatic changes in BP

poor urine output may indicate

inadequate blood flow to kidneys 

what is Homocysteine

 is a common amino acid in your blood. You get it mostly from eating meat. High levels of it are linked to early development of heart disease. In fact, a high level of homocysteine is a risk factor for heart disease.

what can cadiac enzymes tell us?

tell us if theres damage to the heart itself

what does Brain Natriuretic Peptide (BNP) tell us?

• released when the ventricles are stretched

• more BNP will be released the more the ventricles are stretched

• high levels can inidicate ventricles are over stretched

• more stretch often seen in HF

what are some important chemicals we would see on a CMP

• NA

• K

• CA

• MAG

• LFTs 

  • increased lipids and cholesterol. risk factor piece. if there is high cholesterol and stuff

what does CPK tell us?

tells you there is muscle breakdown, but doesnt tell you where specifically 

CK-MB tells you

there is damage in heart muscle

myoglobin and troponin tells us

how long since damage occured

x ray can tell us

a little bit. could tell us if heart is too big

CT can tell us

if there is inflammation or fluid around heart. can see outer structural issues

echocardiogram shows us

chambers of the heart. shows distinct structural issues 

MRI can show us

see dye through vessels. shows us obstructions

ECG vs Telemetry

• ECG is a snapshot. 12 leads (angles). 12 snapshots of 12 angels of heart.  

• telemetry is continuous. only 5 leads (angels). 

Uses for ECG

Evaluate dysrhythmias 

Identify areas of ischemia

Tells us about conduction system

what is Holter monitoring

For long term EKG monitoring either 24 hours or up to 2 weeks. 

- Box downloads info and transmits to cardiologist for interpretation

what is Echocardiography. what is it used for

• Noninvasive ultrasound test that is used to:

  • Measure the ejection fraction

  • Examine the size, shape, and motion of cardiac structures

  • lets you see chambers, vales, pumping. clots

what is ejection fraction

Ejection fraction (EF) is the percentage of blood your heart's left ventricle pumps out with each beat, a key indicator of overall heart function.

transthorcic echocardiography

ultrasound wand over chest. cons are bones and anatomy in the way. client needs to sit still.

transesophegeal echocardiography

scope threaded down throat and looks from behind the heart for different angle. gold standard. super close to heart and more clear. patient sedated. more invasive

what are Electrophysiology (EP) Studies

• can find and target cells in your heart that are causing problems

exercise stress test

• Pt walks on treadmill with intensity progressing according to protocols

• ECG, V/S, symptoms monitored

• Terminated when target HR is achieved

important things to note with cardiac stress testing

• risky bc stressing heart. screen clients beforehand 

• a lot of people cannot do exercise stress test (ex immobility) so we give meds to stress heart. 

pre-procedure cardiac stress testing interventions

• dont eat 3 hrs before. NPO

  • cant eat before incase they have chest pains need to go to cath lab and be sedated and catheterized. 

• also avoid caffeine bc that would elevate HR and mess up test.

• no caffeine 24 hrs before.

• no chocolate.

• no stimulant medications 

cardaic stress testing post procedure

• cant feed until after cardiologist looks at results incase they decide need for catheterization

what is cardiac catheterization

• Invasive procedure used to diagnose structural and functional diseases of the heart and great vessels

Gold standard for Diagnosing Coronary Artery Disease

angiography

angioplasty

treatment. Balloon, stenting, atherectomy. minimally invasive medical procedure used to open narrowed or blocked blood vessels

femoral vs radial catheterization approach

• femoral traditional approach but being replaced by radial

• radial benefits- more sanitary location than groin. easier to see and assess. easier recovery and you can move rest of body (in femoral cannot move at all).

• prep both but priortize radial

balloon angioplasty

used to oen up vessel but does not stay

stent angioplasty

stays in vessel.

why are stents risky?

• monitor for signs of stroke and embolic events 

• body will try to clot off foreign object (stent) 

cardiac cath pre-procedure

• give aspirin or antiplatelet 

• give benadryl to prevent allergic reaction

• check for allergies to latex, shellfish, and iodine

• hematomas or excessive bleeding indicates they have clotting disorder and should NOT get cath

• check PT and INR

• NPO at least 3hrs 

• prep- patient teaching. shave and disinfect site. removing clothing and jewelry 

cardiac cath post-procedure

• monitor bleeding. apply pressure. check for hematomas and bleeding at site. 

• chec pulses

• check dyssrythmias, ECG

• 1 hr bedrest 

• arm movement should be restricted. 

• monitor chest pain and contrast induced nephropathy and nephrotoxicity 

• drink water 

pressure/closure devices

used to keep wound closed and reduce need for stitches

Hemodynamic monitoring measures

the blood pressure inside the veins, heart, and arteries. It also measures blood flow and how much oxygen is in the blood. It is a way to see how well the heart is working.

what is central venous pressure and what can it tell us

a direct measurement of the blood pressure in the right atrium and vena cava

one of best way to tell us about preload

Normal CVP is

2-6 mm Hg. 

low CVP means

not enough blood. not enough preload 

high CVP means

•  too much pressure, to much prelaod, too much volume 

aoritc valve function will effect

afterload

a cardiac murmur means

• murmur means increased afterload 

MAP tells us

if body is getting good perfusion

MAP range

65-100

• high map means

• too much afterload

MAP To perfuse vital organs requires the maintenance of a minimum MAP of

60 mmHg.

If MAP drops below this point for an extended period, end-organ manifestations such as ischemia and infarction can occur

MAP equation

MAP =  (DBP x2)   + SBP /  3

cheetah monitor

• client lays flat and you elevate their legs. the blood will rush fowards heart and cheetah will measure how heart handled that extra volume 

thermodilution

cold saline is injected into the right atrium, and the catheter measures the change in temperature as it passes by which calculates flow