CVR Investigations Flashcards
what is the function of the ECG?
detect PD changes between 2 electrodes on the heart surface and the limbs
what does the P wave of an ECG represent?
atrial depolarisation
what does the delay between P and Q mean on an ECG?
delay at AV node
what does point Q show on an ECG?
conduction through bundle branches (purkinje fibres)
what does the QRS wave show on an ECG?
ventricular depolarisation
what does the ST segment show on an ECG?
plateau phase of ventricular repolarisation
what does the T wave show on an ECG?
rapid ventricular repolarisation
explain what the ECG leads are and what they measure
ECG leads are electrical vectors
unipolar leads measure potential variation at a single point
bipolar leads measure PD at a single point
name the 12 ECG leads
chest leads: V1-6
augmented limb leads: aVR, aVL, aVF
limb leads: I, II, III
(I = RA-LA, II = RA-LL, III = LA-LL)
what can HR be determined by in an ECG?
QRS complex
what should a standard ECG have for interpretation?
paper speed of 25mm/s
determined QRS axis
gain of 10mV/mm
what is the general rule of interpreting HR from an ECG?
300 divided by number of large squares between each QRS complex
what is the normal range for:
PR interval
QRS
QT interval
PR interval: <200ms
QRS: <120ms
QT interval: <400ms
what does the QRS axis show and how is this approximated?
direction of average depolarisation in heart (mainly LV)
determined by limb leads
normal is -30 to +90 degrees
approximated by finding lead with most positive QRS
how can P waves be described?
positive, negative or biphasic
a normal P wave is upright in the inferior leads
how can ST segments be described?
isoelectric, elevated or depressed
a normal ST segment is flat
how can T waves be described?
upright, inverted or flat
a normal T wave has the same polarity as the QRS
how can the QRS complex be described?
R - positive deflection
Q - first negative deflection
S - additional negative deflection
capital letters = dominant waves
non-capital = non dominant waves
what are the purposes of cardiac imaging?
defines heart size/structure
details functions/physiology (valves, ventricular function)
image heart during stress (ischaemia)
what are the functions of echocardiography?
assesses heart structure/function
assesses valves/pericardium
assesses inducible ischaemia
what are the advantages and disadvantages of echocardiography?
adv - cheap, available, no radiation, portable
disadv - requires good acoustic window, user dependant
what does an increase of gadolinium indicate in cardiac MRI?
fibrosis
what are the functions of cardiac magnetic resonance imaging (CMR)?
assesses perfusion/stress
accesses great vessels
defines tissue characterisation
what are the advantages and disadvantages of cardiac magnetic resonance imaging?
adv - shows anatomy/volume/function, reproducible, no radiation
disadv - costly, poor availability
what are the purposes of coronary angiography?
indicates ischaemia
primary percutaneous coronary intervention (PCI)
assesses ventricular pressure/valves
can intervene during procedure (invasive and uses radiation)
describe nuclear perfusion imagine and state its advantages and disadvantages
assesses ischaemia and ejection fraction
adv - readily available
disadv - uses radiation, shows no structural assessment
describe cardiac CT imaging and state its advantages and disadvantages
assesses coronary artery and great vessel anatomy
adv - can rule out CAD, low risk
disadv - uses radiation, requires low HR
compare transthoracic and transoesophageal echocardiography
transthoracic (TTE) - takes pictures of anterior heart
thransoesophageal (TOE) - takes pictues of posterior heart
both image cardiac structure and valve function
what is bubble contrast echocardiography used for?
access interatrial septum
(looking for oatent foramen ovale or atrial septum defect)
what is LV contrast echocardiography used to look for?
LV apical thrombus
what structures are visible from the parasternal long axis (PLAX) view?
LA
mitral valve
LV
LV outflow tract (LVOT)
aortic valve
aortic arch
what structures can be seen from the parasternal short axis (PSAX) view?
LV
RV
all valves except mitral
interatrial septum
pulmonary artery
papillary muscles
how can the LV systolic function be measured?
calculating LV ejection function using figures from LV end diastolic volume and LV stroke volume
describe echo doppler imaging
assess valve flow
patterns present help assess diastolic function and valve disease severity
what are the pros of using MRI imaging in respiratory investigations?
used magnetic properties of H+
easily generated images in different planes
lower resolution
can determine chest wall/mediastinum invasion by cancer
describe the action of a PET scan
positron emission topography
uses radioactive liquid (tracer) to show areas of the body with overactive cells
how is a bronchoscopy carried out?
bronchoscope inserted down mouth/nose, passes down to bronchi allowing lung/air passage visualisation
biopsies can be performed during bronchoscopies
what can an EBUS technique be used for?
endobronchial ultrasound samping
diagnoses different lung disorders (inflammation, infection, cancer)
explain the process of a thoracoscopy
done under anaesthetic
visualises pleural cavity
pleural biopsy can be taken
what is a CT pulmonary angiography used for?
scans for perfusion and ventilation function of lungs
what 4 categories can respiratory sampling be categorised in to? give an example for each
ward tests: blood/urine
bronchoscopy: biopsy
percutaneous: fine needle aspiration
surgical: mediastinoscopy
what can pulmonary function be assessed through?
spirometry
arterial blood gases (ABG)
progressive exercise tests
sleep studies
describe the results of type 1 respiratory failure
low O2 (<8kPa) on an ABG
result of pneumonia, cardiac failure or pulmonary embolism
describe the results of type 2 respiratory failure
low O2 (<8kPa) and high CO2 (>6kPa) on an ABG
patient suffering severe respiratory fatigue
result of opiates overdose, neuromuscular weakness, advanced COPD
what factors are considered when choosing an investigation test?
patient - anxiety, discomfort, complications
test - sensetive, specific, reliable, repeatable
convenience - cost, ease, time
