Post
Infarct VSD
- A
severe complication of MI most often occuring within 2 weeks post infarct
- Opening
in the ventricular septum post MI
- Less common
than rupture of free wall on autopsy?
- Perforation
is usually single
- Diameter
of one to several centimeters
- Rupture
of septum occurs post transmural infarction
- Especially
associated with anterior & anterolateral MI
- Harsh,
loud holosystolic murmur
- Diagnosed by insertion of pulmonary
artery catheter to document left to right shunt
Haemodynamic
sequelae
- Left to
right shunt
- Size of
defect determines magnitude of left to right shunt and therefore likelihood
of survival
- Increased
pulmonary blood flow —> increased pulmonary vascular resistance ->
pulmonary hypertension
- Excessive
raised PVR —> reverses shunt [right to left]
- Right ventricular
hypertrophy
- Low
systemic cardiac output
- Deficient
systemic blood flow
- Biventricular
failure generally ensues within hours to days
- The
development of shock and the likelihood of survival depend critically on
impairment of the right ventricle
·
Patients
are desperately ill
With the background of coronary artery
heart disease will exacerbate myocardial ischaemia and subsequent systemic
hypotension
Surgery
- Repair
can be difficult due to friable tissue surrounding infarct leading to poor
suture support
Defects near ventricular
apex (LAD occlusion)
- Easier
to repair
- Repair
by suturing or apical septal patch
Defects of posterior VSD
(right coronary occlusion)
- Much
more difficult to repair requiring reconstruction and patching of the left
ventricle
Perfusion considerations
- As with
repair of ventricular rupture, weaning from CPB requires afterload
reduction to limit interventricular pressures