Cath Flashcards
Oxygen capacity formula
Amount of oxygen that can be carried by Hgb if 100% saturated
- 13.6 x Hgb
Oxygen content
Oxygen in blood (bound to Hgb and dissolved)
- 13.6 x Hgb x O2 sat + 0.03 x PaO2
What causes falsely elevated O2 sat
High bili
Carboxyhemoglobin (smokers)
Qp:Qs quick calc
SA - SV / PV - PA
Fick equation
VO2 / 13.6 x Hgb x (difference in sat / 100)
Need to add paO2 if not on room air
Q effective calculation
VO2 / 13.6 x Hgb x (PV - SVC / 100)
Volume of blue blood that goes to lungs and volume of red blood that goes to body
Left to right shunt calculation
Qp - Qeff
Right to left shunt calculation
Qs - Qeff
PVR/SVR calculations
Change in pressure / flow over that bed
If indexed Q then its WU * m2
If not indexed need to MULTIPLY PVR times BSA to get indexed (not divide)
What is a wave in RA pressure and what causes elevation
Atrial systole - immediately after p wave
Corresponds with RVEDp if no TV abnormalities
TV closes at end of atrial contraction
Increased a wave in stiff RV (PS, RVH, tamponade), TS, arrhythmia (cannon A waves)
What is x descent in RA pressure
Fall of RA pressure after TV closes
What is v wave in RA pressure and what causes elevation
- Rise in atrial pressure during atrial filling and ventricular contraction
- At peak of v wave, RV pressure falls below RA pressure and TV opens
- Increased in TR, ASD, LV to RA shunt
What is y descent in RA pressure
- Rapid fall in RA pressure during ventricular filling
- Prominent in restrictive physiology
Normal A and V wave in LA pressure
A is lower than V in LA (opposite of RA)
- Mean LA pressure about 2 higher than RA pressure
Increased v wave in LA pressure
- MR, tri atresia with ASD
Increased a wave in LA pressure
- MS, poorly compliant LV, large ASD, TAPVR, arrhythmia
Different causes for high ventricular pressure with flat plateau vs early systolic rise that falls
- Broad flat = VSD, severe PH, systemic hypertension
- Early systolic rise = pulmonary valve stenosis/aortic valve stenosis
Cath features of DCM
- Increased LA pressure and LVEDp
- Normal RA pressure
- Normal/low CO
- Decreased PVR
Cath features of RCM
- Increased LA pressure
- Normal RA pressure
- Prominent y descent
- Square root sign on ventricular tracing (due to rapid filling)
- Increased PVR
Cath features of HCM
- Sub aortic gradient (spike and dome look)
- Decreased pulse pressure after PVC
What happens with contrast and metformin
Risk for lactic acidosis with renal insufficiency
- Hold 24 hours pre and post
Max contrast dose
6 cc/kg
Acute risk (most common side effect) with radiation
Dermal injury (erythema) which is often transient
AP cranial imaging good for
PV annulus, RVOT, supravalvar PS, RV-PA conduit
AP caudal imaging good for
Underside of arch, branch PAs
LAO imaging good for
Arch, proximal LPA, L pulmonary veins
RAO imaging good for
LVOT (subAS, AV annulus), anterior muscular/outlet VSDs, R pulmonary veins
RAO and long axial oblique imaging good for
Like a parasternal long echo image
LVOT, AV annulus, membranous and anterior VSDs
Hepatoclavicular imaging good for
Like a 4 chamber view
Crux of the art, AV valves, AVSD, inlet/posterior VSDs
Indication for balloon pulmonary valvuloplasty
Peak > 40
Or peak < 40 with symptoms or RV dysfunction or cyanosis (critical PS)
Balloon:annulus 1.2-1.4
Indication for balloon aortic valvuloplasty
Peak > 60 (echo) if asymptomatic, peak > 50 (echo) if wanting to play competitive sports or get pregnant
Or peak < 50 with LV dysfunction or PGE dependence
Balloon:annulus 0.8-1
Indication for balloon mitral valvuloplasty
Rheumatic heart disease is only class 1 indication
No if supravalvar mitral ring or in HLHS patients
Indications in RHD are peak > 20 or mean > 15
PA balloon vs. stent pros and cons
- Balloon if proximal PA stenosis or too small or stent, genetic conditions have poor response
- Balloon size 2.5-3.5x diameter of lesion but < 2x surrounding vessel – use high pressure, low compliance balloons
- Stent if can get big enough stent in, better in fold/kink or longer segment, risk for reperfusion injury
Coarc balloon vs stent pros and cons
- Indication is re-coarc gradient > 20 or < 20 with ventricular dysfunction or single ventricle
- Need to get to adult size for stent
- No balloon if arch hypoplasia
- Balloon 2-3x diameter of stenosis but < 1 mm larger than surrounding vessel
- Increased risk recurrence and aneurysm with ballooning vs stent
- Stent size smaller than surrounding vessel - risk for embolization and femoral injury
Indications for intervention on RV-PA conduit
- RVOT gradient > 35 or moderate PI or 2/3 systemic RV pressures
- Stent if going to prolong life of conduit
- Valve if big enough
- Risk for conduit disruption as well as coronary injury
Indications for ASD cath lab closure
- Qp:Qs > 1.5
- RV volume load or dysfunction or elevated pressures
- 5 mm rims
What issues can happen with aortic root injection
Acute arrest in graft rejection, coronary disease, aortopathy or cardiomyopathy
- Issue likely not related to the contrast but potentially due to injection time limiting myocardial oxygen delivery
Definition of adequate result for aortic valuloplasty
Decrease in peak gradient to 20-35 mmHg
Risk for sub-optimal result for aortic valuloplasty
Age < 3 months or > 40 years
Higher pre-dilation valve gradient
Smaller annular Z score
Vale calcification
Prior procedure
Undersized balloon
Tachypnea and lower saturations with edema post PA angioplasty
Re-perfusion injury
Indication for intervention on PA
- Peak gradient > 20-30 across the stenosis
- RV pressure or MPA pressure > 1/2 to 2/3 systemic
- Flow discrepency between two lungs of > 35/65%
- Angiographic appearance of significant narrowing
Goal stent size for pulmonary vein to limit risk for re-stenosis
6-10 mm
Is re-intervention rate higher for coarc stents or balloons
Stents – but most are planned re-interventions
Risk of endocarditis in implantable valves
2% per year
Risks with ASD cath lab closure
- Minor arrhythmia
- Thrombus formation
- Device embolization
- Serious arrhythmia
- Cardiac erosion (0.1%) –> oversizing device, absent/deficient aortic rim
- Mortality from erosion
- Stroke
- Allergic reaction –> Nickel allergy
Formula to calculate PVR in differential Qp
- Need lung perfusion scan
- Calculate individual PVR for each lung based on pressures and flow (use proportion of flow to that lung)
- Total resistance formula: 1/total = 1/right + 1/left
Protamine reaction
Flushing, vasodilation, hypotension, cardiovascular collapse
Higher risk in patients taking NPH insulin
Incidence of device erosion with Amplatzer ASD device
0.1%
