define pre-load and after-load
pre-load = volume in ventricle at end of diastole
after-load = total peripheral resistance
what is Frank-Starling’s law?
more ventricular distension during diastole = greater volume ejected during systoe
How would you calculate the heart rate from an ECG strip?
Each strip is 10 seconds long
Count the amount of QRS and then multiply by 6
What lead is normally the most positive? What would be the most positive in LBBB and RBBB respectively?
Lead II is normally the most positive
LBBB - Lead aVL
RBBB- Lead III
State the normal parameters for the PR interval, the QRS interval and the QT interval
PR - 120-200ms QRS - <120ms QT - 2 large squares
RBBB can be present without heart disease, however name three common causes of LBBB
Describe the diagnostic features of a STEMI
What are the parameters for ECG changes in a STEMI?
ST elevation in atleast 2 leads
Elevation greater than 1mm in limb leads and 2mm in chest leads
Describe the ECG changes in an NSTEMI
may show: ST segment depression T wave inversion Normal
When might an STEMI be mistaken for an NSTEMI?
If you have ST segment depression in V1-V4, it may be the reciprocal changes of a posterior STEMI
Describe the pathophysiology of ACS
What layer of the heart do the coronary arteries lie in?
Epicardium
Describe 5 of the classical presentations of ACS
Some ACS can be ‘Silent’, what groups of people can this occur in? How would they present?
What is the S4 heart sound?
Blood striking against a non compliant ventricle
What happens to Troponin I in an MI
Begin to rise 3-4hrs post MI Remain elevated for up to 2 weeks
what level of hs-TnI is highly likely of myocardial necrosis in men and women?
34 in men
16 in women
When should Troponin I be sampled?
One sample on admission If onset of the symptoms was less than 3 hours ago, take another sample one hour after the original
Give 4 false positives of Troponin I
Give 3 possible features of an MI on a CXR
In four steps describe the initial medical management of suspected ACS
1) Morphine and Antiemetic (Metacloperamide)
2) Oxygen (Sats>94% or <88% if COPD)
3) Nitrates (GTN Spray)
4) Asparin 300mg Loading Dose
What are the four requirements for Prasugrel in an MI?
non-pharmacological management long term post MI (other than the 5 drugs what else can be done?
what are the 5 drugs patients must have following an MI?