Cardiac System Flashcards
Name the 3 component of the CV system
heart, blood vessels, blood
Name the chambers of the heart
right atrium, right ventricle, left atrium, left ventricle
What are the heart valves
aortic valve, mitral valve, pulmonic valve, tricuspid valve
Coronary circulation
aorta (main supplier to the body) branches off into two main coronary blood vessels (also called the arteries). these coronary artereries branch off into smaller artereies, which supply oxygen rich blood into the entire heart muscle,the right coronary artery supplies blood mainly to the right side of the heart. The right side is smaller because it only pumps to the lungs. The left cornonary artery (which branches off into the left anterior descending artery and circumflex artery) supplies blood to the left side of the heart. The left side is larger and more muscular because it pumps to the rest of the body
3 Physiologic characteristics of cardiac tissue
- The heart beats powerfully and continuously throughout an entire lifetime without any rest, so cardiac muscle has evolved to have incredibly high contractile strength and endurance
- At the ends of each cell is a region of overlapping, finger-like extensions of the cell membrane known as intercalated disks. The intercalated disks form tight junctions between the cells so that they cannot separate under the strain of pumping blood and so that electrochemical signals can be passed quickly from cells to cell.
- Another feature that is unique to cardiac muscle tissue is autorhythmicity. Cardiac muscle tissue is able to set its own contraction rhythm due to the presence of pacemaker cells that stimulate the other cardiac muscle cells.
CV blood flow throughout the body
deoxygenated blood from the body returns to the heart via the superior and inferior vena cava—empties into the RA–through the tricuspid valve–into the RV–through the pulmonic valve–into the pulmonary artery–lungs through pulmonary circulation, contracting alveoli, and exchanging gasses–to the pulmonary vein—into the LA—through the mitral valve—into the LV—through the aortic valve—into the aorta—then to the capillary beds throughout the whole body for gas exchange
What is the normal pacemaker of the heart
the SA node is the normal pacemaker that initiates each heart beat
What is CO
Cardiac Output= SVxHR. It is the total volume of blood pumped through the heart in 1 minute. Normal CO is 4-7 L/min
relationship between pressure, flow, and resistance
pressure=flow x resistance
pressure is force exerted on the liquid (mmHg)
flow is the amount of fluid moved over time (L/min or mL/min)
resistance is a measure of the ease with which the fluid flows through the lumen of a vessel
Define hemodynamics…what happens with instability
Hemodynamics is the study of blood movement; when this movement is compromised you get hemodynamic instability. If left untreated, it will cause multi-organ failure and death.
Signs and symptoms related to decreased cardiac output
Reduced blood pressure, Weakness, Fatigue,Exercise intolerance, ECG changes, Abnormal heart rhythm, Rapid breathing, Abnormal arterial blood gases, Edema
Weight gain, Dizziness, Reduced urine output ,Fainting, Restlessness,Anxiety,Cold clammy skin,Reduced peripheral pulse,Altered mental status,Chest pain,Confusion
what is preload
the volume of blood stretching the left ventricle at the end of diastole. Preload is determined by the total circulating blood volume and is increased by an increased by an increase in venous return to the heart.
what is afterload
the force against which the heart has to pump to eject blood from the left ventricle. Factors and conditions that would impede blood flow increase the left ventricle afterload
what is contractility
the inherent ability of the myocardium to alter the contractile force and velocity. Sympathetic stimulation increase myocardial contractility, so SV increases. Conditions that decrease myocardial contractility reduce SV.
what is systole
the phase of contraction of the heart, especially of the ventricles, during which blood is pushed to the aorta and pulmonary artery
what is diastole
the phase of the cardiac cycle in which the heart relaxes between contractions. Represents the period of time when the two ventricles are dilated by blood flowing to them.
what is depolarization
an electrical cell generates and electrical impulse, this electrical impulse causes the ions to cross the cell membrane and causes the action potential
what is repolarization
return of ions to their previous resting state, which corresponds to relaxation of the myocardial muscle
What are the 5 basic properties of cardiac muscle
Contractility, rhythmicity, conductivity, automatacity, excitability
normal heart sound
S1 is heard as the AV close and is heard loudest at the apex. S2 is heard loudest as the semilunar valves close and is heard loudest at the base
abnormal heart sounds
S3 may be heard if ventricular wall compliance is decreased and structures in the ventricular wall vibrate. Can occur in heart failure or valvular regurgitation may be normal in an individual younger than 40.
S4 may be heard on atrial systole if resistance to ventricular filling is present; abnormal finding! Causes include cardiac hypertrophy disease, or injury to the ventricular wall
what are baroreceptors
specialized nerve endings affected by changes in arterial BP located in walls of the aortic arch and carotid sinuses
location of aortic area on assessment
second ICS, right sternal border
location of pulmonic area on assessment
second ICS, left sternal border
location of Erbs point on assessment
3rd ICS, left sternal border
location of Tricuspid area on assessment
4th of 5th ICS left sternal border
location of mitral area or apex on assessment
5th ICS left MCL
what heart sound occurs with ventricular systole
S1 (lubb)
what heart sound occurs with ventricular diastole
S2 (dubb)
is s1 or s2 softer at the base
s1
is s1 or s2 louder at the apex
s1
is a physiological split normal or abnormal
it is a normal variation
what is a physiological split
it is related to the respiratory cycle. Split occurs at the height of inspiration. Heard best with the diaphragm at the pulmonic area
is s3 heard best with diaphragm or bell
bell
what is s3 a sign of
heart failure..heard in some pts with heart block or increased venous return
is s4 heard best with diaphragm or bell
bell
when do you often hear s4? why is it heard?
often occurs after a MI. a forceful atrial contraction is what causes you to hear it
normal potassium range
3.5-5.5 mEq/L
normal sodium range
135-145 mEq/L
normal magnesium range
1.5-2.5 mEq/L
normal calcium range
9-11 mg/dL
normal cholesterol
less than 200 mg/dl
normal triglycerides
40-190 mg/dl
normal LDL
if no CAD or less than 2 risk factors less than 160 mg/dl. If CAD then
normal HDL
greater than 35 mg/dl
normal PT
11-16 sec 1.5-2.5 x normal
normal INR
normal PTT
60-70 sec 1.5-2.5 x normal
normal APTT
30-40 seconds 1.5-2.5 x normal
BP=
BP=flow x vessel resistance
what are high pulse pressures associated with
arterial damage and ventricular stress
what is MAP a good estimator of
overall organ perfusion
MAP=
MAP= systolic BP + 2 x diastolic BP/ 3
normal CO
4-8 L/min
normal SV
60-100 ml/concentration
normal ejection fraction
60-70%
CI=
CI= CO/body surface area
increased blood viscosity ______ blood flow
decreased
What are chemoreceptors sensitive to
Changes in the partial pressure of arterial oxygen, the partial pressure of carbon dioxide, and the ph blood levels
What is S1 caused by
The closing of the tricuspid and mitral valves
What is S2 caused by
Closure of the pulmonic and aortic valves
What is a TEE
Transesophageal echocardiography. Provides ultrasonic imaging of the heart from a view behind the heart. Inserted into the posterior pharynx and advanced into the esophagus
Nursing care after a cardiac catheterization and angiography
Bed rest, extremity used for catheter immobile, observe insertion site for bleeding or hematoma, assess for bruits, HOB no higher than 30 degrees, monitor peripheral pulses, color, and sensation distal to insertion site, monitor intake and output, observe for adverse reaction to dye, assess for chest pain, back pain, sob and notify provider
4 key electrolytes
Sodium, magnesium, calcium, potassium
What is Creatine Kinase
A enzyme that increases 2-5 hours after the onset of myocardial muscle damage. Peak levels occur 18-36 hours and levels return to baseline in 3-6 days.
Troponin I and T
Serum troponin levels are useful in the early diagnosis of AMI. Levels are normally undetectable in healthy people and elevate as early as 1 hours after myocardial cell injury. Normal value for Troponin I is less than 0.5 mcg/L and troponin T is less than 0.1 mcg/L
Myoglobin
Serum myoglobin is released writhing 30-60 minutes after AMI. Normal values are less than 72 mg/ml in men and less than 58 ng/ml in females
When does stable angina occur
Occurs on exertion and is relived by rest
Unstable angina
Pain often more severe, occurs at rest, and requires more nitrate therapy
What are the most common medications for Angina
Nitrates they are direct acting smooth muscle relaxants that cause vasodilation of the peripheral or systemic vascular bed
How are AMI classified
Acute myocardial infarctions are classified as STEMI or NSTEMI. STEMI usually occurs because plaque rupture leading to complete occlusion of the artery. NSTEMI usually results from a partially occluded coronary vessel.
Who is more likely to have atypical signs of a AMI
Women the signs are fatigue, diaphoresis, indigestion, arm or shoulder pain, N/V
What is one common treatment for STEMI
Thrombolytic therapy
What is the one risk factor for CAD that you want to change first in people
Smoking
What is the main action of nitrates
Smooth muscle relaxant they vasodilate and decrease oxygen demand
What is the action of beta blockers
They decrease oxygen demand on the heart by lowering Bp and slowing heart rate
What is the main action of calcium channel blockers
Inhibit the flow of calcium which increases coronary blood flow and increase myocardial perfusion
What is the action of ASA
Platelet aggregate makes platelets slippery and might decrease clotting
When should you get a new supply of NTG
Every 6 months because they lose potency
When should you not give NTG
Is MAP drops below 60 or systolic Bp drops below 90
What is going on with a AMI
Imbalance between myocardial oxygen supply and demand, from decreased coronary artery perfusion
If there is prolonged ischemia greater than ___ hours in a AMI then some of the myocardial cells die
3 hours
Skin during a AMI
Cool, clammy, pale, diaphoretic
What is MONA
Used for MI. Morphine, oxygen, NTG, aspirin
Why is morphine given for MI
Pain control, decrease anxiety, smooth muscle relaxant decreases preload and after load
aspirin given for MI
Try to give patient 2-4 baby aspirin have pt chew them so they have rapid onset through the buccal route
When are thrombolytics used with MI
Must be symptomatic for less than 6 hours with chest pain greater than 20 minutes unrelieved by nitro and with ST segment elevation
Administration guidelines for NTG
Check BP- hold if systolic less than 100
If using spray do not shake; spray under tongue
If using tablets check expiration date and protect from light
Innermost layer of artery
Intima
When do coronary arteries full
During diastole
When are thrombolytics given for a AMI
Patient must be symptomatic for less than 6 hours and chest pain greater than 20 minutes unrelieved by nitro with ST segment elevation. Also have no contraindications to thrombolytics
What do ace inhibitors do
Decrease SVR
What does dopamine do
Stimulates adrenergic receptors. Treatment of low CO
What does dobutamine do
Sympathomimetic. Direct action inotropic agent that enhances myocardial contractility, SV, CO, renal blood flow and UO
What are treatments for CAD and AMI
PTCA (percutaneous transvenous coronary angioplasty) and stents
A Patient just got a stent and needs a MRI . Can you schedule it?
NO! cannot have MRI for 4-6 weeks after stent placement
What does automaticity mean
The cells can generate a stimulus or action potential without outside stimulation
What is the primary function of myocardial cells
Mechanical - primary property is contractility
What is the primary function of pacemaker cells
Electrical- primary property is automaticity/conductivity
What may be performed to slow the heart rate
Vagal maneuver
What detect changes in BP
Baroreceptors
What is atrial kick
Amount of blood pumped into the ventricles as a result of atrial contraction; contributes approx 30% of total cardiac output
What do chemoreceptors detect
Changes in ph, O2, and CO2 levels in the blood
When does filling of coronary arteries happen
Diastole
Diastole is ____ as long as systole
Twice
What is the charge of myocardial cell at rest
-90 mv
Does systole or depolarization happen first?
Depolarization
Does repolarization or diastole happen first?
Repolarization
Does a ECG provide information about the mechanical function of the heart?
NO!
What is a normal PR interval
0.12-0.20 seconds
What is blood flow affected by
Blood vessel changes(veins change most), turbulence, heart rate and contractility changes, renin/angiotensin/aldosterone cascade
What does JVP estimate
Intravascular volume (indirect measurement of CVP or RA volume)
What could a elevated JVP mean
Fluid overload, HF, R ventricular dysfunction
Normal lactate levels
0.5-1.6 mEq.L
What do lactate levels give us information about
Tissue perfusion
Who is pulmonary artery pressure monitoring done on
Sick of the sickest. High risk but does have benefits
How many mlHg are needed to cancel out atmospheric pressure
300mLhg
RA pressure=__________
CVP pressure
Where is the phlebostatic axis
4th ICS midaxilary line
What is the phlebostatic axis an approximate measurement of?
Right atrium
Normal value for right arterial pressure
2-6 mmHg
When do you read right arterial pressure
At the end of expiration because intrathoracic pressure we only want to read the pressure in the chamber
What does pulmonary artery pressure monitoring reflect
Left ventricular function
What is a normal systolic/diastolic and mean for pulmonary artery pressure monitoring
Systolic-25 mmHg
Diastolic- 10mmHg
Mean-15 mmHg
What is the Dicrotic notch
Happens when the aortic valve is closing
What is diastolic filling time determined by
Heart rate
What is a normal SvO2
60-75%
What is a normal ScvO2
65-85%
What are the sites for arterial pressure monitoring
Radial , brachial, femoral
Myocardial cell at REST
-90 mc
What does the P wave represent
Atrial depolarization
Normal PR interval
0.12-0.20 seconds
Normal QRS complex
0.06-0.12 seconds
What does QRS complex show
Ventricular depolarization
The ST segment is usually _______
Isoelectric
What does the T wave show
Ventricular repolarization
What could change the shape of a T wave
Electrolyte imbalance
Where is atrial repolarization
Hidden in QRS complex
One big box =
0.20 seconds
One little box =
0.04 seconds
How do you find heart rate on a 6 second strip
of R x 10
What does a PR Interval grater than 0.20 seconds mean
Conduction delay or AV block
Why is morphine administered to a patient with a MI
It decreases myocardial oxygen demand. Will also decrease pain and anxiety while causing sedation but those are not the primary reasons
What complication is indicated by S3
Ventricular dilation. Rapid filling of the ventricles causes vasodilation
What is the most common complication of a MI
Arrhythmias
In which type of cardiomyopathy does cardiac output remain the same
Hypertrophic
What class of drug is the most widely used treatment of cardiomyopathy
Beta blockers because they improve myocardial filling and cardiac output which decrease heart rate and contractility
What does the pulmonary Avery pressure monitoring reflect
Left ventricular function
What are treatments of sinus Bradycardia
Atropine 0.5-1 mg or synchronized cardioversion (only given if patient is symptomatic!)
What is a PAC
Premature atrial contraction-site within the atria fires before the sa mode impulses is due to fire
What do you see in a PAC
Early p wave that is a different contour from previous and a noncompensatory pause because the sa mode is trying to reset itself
Is a PAC an entire rhythm?
No it’s a single beat
Rate for a fib
400-600 Bpm
What drug is used for rhythm control with a fib
Cardizem
What drugs can be used for rate control of a fib
Beta blockers, digoxin, ca channel blockers
What is used for persistent a fib
Amiodarone
Rate of a flutter
250-300 Bpm SAW TOOTH
Where does a SVT happen
Above the Bundle of his
When is cardioversion used
Unstable a-fib, a flutter, and sometimes v tach
What wave is shocked with cardioversion
Synchronized delivery on R wave
How many joules for cardioversion
50
If the PR interval is greater than 0.20 what is it
Av block
If the QRS is greater than 0.12 what is it
Bundle branch block
When is atropine used
Symptomatic bradycardia
