cvd Flashcards
stroke volume
o Stroke Volume is the amount of blood pumped with each heart beat
o Normal volume is 50ml to 100ml
o Determinants of stroke volume are preload, afterload, and contractility
o SV = End-Diastolic Volume – End-Systolic volume
o EDV: amount of blood in ventricles at the end of ventricular diastole
o ESV: amount of blood in the ventricles at the
total load
o Total load = preload + afterload
o Contractility may be seen as the ability to overcome load
o The Frank-Starling mechanism describes how contractility is a function of volume
o
what is starlings law (stroke volume)
Starling’s Law: The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart
ejection fraction
how effectively the hear works
percentages
Ejection Fraction
o Ejection Fraction (EF)
o EF = (SV / EDV) × 100%
o Low EF indicates heart failure or cardiomyopathy
o Normal EF: 50-70%
o High EF: indicative of hypertrophic cardio
cardiac output
-equation
-blood
- q
o Cardiac Output is the amount of blood ejected by the heart measured in Liters/minute
o Q = stroke volume x heart rate
diagnosis for heart disease ( invasive and non invasive)
o Non-invasive tests: ECG (Holter monitoring), Echocardiography, X-ray, magnetic resonance imaging, positron emission tomography, ultrafast computed tomography scan
o Invasive tests: blood test (heart-damage markers tests), stress test, Catheterization, electrophysiology studies, transoesophageal echocardiogram
what is the stages of the ecg
o The P wave represents atrial depolarization
o The PR interval is the time from onset of atrial activation to onset of ventricular activation
o The QRS complex represents ventricular depolarization
o The S-T segment should be iso-electric, representing the ventricles before repolarization
o The T-wave represents ventricular repolarization
o The QT interval is the duration of ventricular activation and recovery
what is holter monitoring
o Continuous ECG recording for 24 hours
o More likely to detect an abnormal heart rhythm compared to a short ECG
o Worn during the patient’s regular daily activities
o Correlate symptoms to any abnormal heart rhythm
what is exercise stress test
-treadmill and bike
-ecg
- no med
o Use treadmill or bicycle to exercise patient and carry out ECG
o Withdraw from medication for 24-48 hours before the test
what is echocardiogram
clue
- ultrasound
- what it can predict and identify
• Echocardiogram uses Doppler ultrasound to create images of the heart
• Provides detailed information on the size of the heart, including chamber size and wall thickness
• Estimates cardiac output, ejection fraction, and diastolic function
• Identifies valvular regurgitation and valvular stenosis
what is chest x ray
• Provides an image of the heart, lungs, and bones of the chest
• Does not provide information on the internal structures of the heart
• Identifies the location, size, and shape of the heart, lungs, and blood vessels
what is cardiac scintigraphy
clue
- radio labels like th….
- myocardial muscles
- cold spots
• Uses a radiolabelled contrast agent such as thallium201
• Contrast agent is taken up into heart muscle in proportion to localised blood flow and stays in myocardial cells during the scan
• Cold spots on the scan indicate areas of injury
what is coronary angiography
• Most direct means of detecting coronary stenosis
• Radiopaque contrast material is injected into an artery and visualized radiographically to locate site of obstruction or presence of atherosclerotic plaque
what are the different types of blood tests used to detect cvd
• Platelet function test
• Cardiac enzymes (troponin, myoglobin, CK-MB)
• C-Reactive Protein (CRP)
• Cholesterol/lipids
• Genetic testing for congenital heart disease and non-responders to some medicine
what is the platelet function
Platelet aggregation - specialised cell fragments in blood that clump together to prevent bleeding.
•Platelets cause aggregate at sites of vascular injury, stimulated by binding to collagen.
•Platelet clumping at certain sites leads to development of plaque.
•A platelet function test can tell a physician how fast a patient’s blood clots.
ck -
clue - damaged tissues
•measure blood levels of the enzyme creatine phosphokinase (CPK; also called creatine kinase (CK) and CK-MB.
•CPK is also released by other damaged tissues in the body (the brain, for example), so a CPK test must be used in conjunction with symptom evaluation and other tests (possibly including other cardiac enzyme tests) to confirm a heart attack.
•CK is an enzyme in muscle tissue throughout the body, including the heart, and CK-MB is an enzyme more specific to the heart.
what is creating converted into
creatine ———-> phosphocreatine - high energy compound for muscle contraction
or
creatine ——-> creatinine - used to monitor renal function this is converted through spontaneous cyckizatiob
troponin
clue - damaged heart muscles and renal
When the heart muscle is damaged, it releases myoglobin and troponin particular enzymes and proteins into the bloodstream.
•The presence of the protein troponin, which may remain high for one to two weeks.
•Good for diagnosing heart attacks after they have occurred.
•However, troponin levels may be high for non-cardiac reasons as well, most commonly renal (kidney) failure.
c reactive protein
clue ; inflammation
•C-reactive Protein (CRP) is a naturally occurring protein that is released at higher levels during inflammation.
•Normal physiological role is to bind to phosphocholine – found on the surface of dead/dying cells; synthesized by the liver in response to factors released by macrophages and adipocytes
•Activates complement system
•The American Heart Association and US Centres for Disease Control and Prevention have defined risk groups as follows:
•Low Risk: less than 1.0 mg/L
•Average risk: 1.0 to 3.0 mg/L
•High risk: above 3.0 mg/L
