Newman Flashcards
What do the leads of an ECG do?
look at the electrical activity of the heart from many different angles
What leads look at the bottom of the heart (inferior)?
II, III, aVF
What leads are precordial (anterior) or located over the sternum?
V leads
Can the heart work without atrial depolarization (P wave)?
yes
What is the PR segment?
conduction from atrium to the ventricle
What are Q waves?
depolarization of intraventricular septum
What part of the ECG will tell you a lot about ischemic heart disease?
ST segment
What are the 2 major reasons for ischemia?
1) coronary arteries are not supplying enough oxygen
2) heart is demanding too much oxygen
* supply demand mismatch
What would you see on an ECG of myocardial ischemia?
ST segment depression
What are the two major determinants of myocardial oxygen demand? *on test
1) heart rate
2) systolic blood pressure
What is a STEMI?
myocardial infarction that is shown by ST elevation in either II, III, AVF (inferior) or V leads (anterior)
How do you calculate HR from the ECG?
300/ # of large boxes between QRS
What is the most common cause of stroke?
atrial fibrillation
What causes atrial fibrillaiton?
multiple “whimpy” depolarizations in the artrium that are not coming from SA node
What causes QT prolongation?
medications and metabolite abnormalities: alteration of potassium channel
What does an ECG of 3rd degree heart block look like?
P waves are independent of QRS
How do you treat someone at risk of ventricular fibrillation?
implanted cardioverter defibrillator (shock goes off when HR gets around 180-200 beats/min)
What does a “pacemaker” treat? What triggers it?
complete heart block
low heart rate (below set point) triggers this
What is the definition of CHF? What causes it?
Symptoms and signs resulting from cardiac dysfunction. Dysfunction may be caused by damage to the heart or external forces preventing the adequate forward flow of blood from the heart to the peripheral organs.
What does increased proload do to SV?
increases
What does increased afterload do to SV?
decreases (it is a form of resistance)
What are the 2 determinants of afterload?
1) size of ventricle
2) systolic BP
What is contractility?
ability of heart to contract (how well are myocytes working) that is independent of preload or afterload
What is the ejection fraction?
EF= SV/EDV