2.10 IABP

Question 1

a) What is meant by counter pulsation in the context of an intra-aortic balloon pump (IABP)? (1 mark)

Answer 1

Inflation of the balloon in diastole and deflation in early systole.

Question 2

b) Briefly explain the effect of counter pulsation from an IABP on coronary blood flow and the left ventricle. (4 marks)

Answer 2

Inflation:
» Forces blood proximally, increasing the pressure within the proximal aorta compared to the left ventricle, thus improving perfusion of coronary
arteries, increasing oxygen delivery.

> > Forces blood distally,
thus augmenting the apparent
output from the left ventricle.

> > Augments Windkessel effect.

Deflation:
» Decrease in afterload
reduces myocardial wall stress during systole,
thus reducing myocardial oxygen demand.

Question 3

c) What are the indications for (6 marks) the use of an IABP in an adult?

Answer 3

Indications:

1&raquo_space; Cardiogenic shock due to
myocardial infarction if
revascularisation planned.

2. > > Acute mitral regurgitation or
   ventricular septal defect
   due to acute
   myocardial infarction.
3. > > Refractory ventricular arrhythmias
   whilst awaiting definitive treatment.
4. > > Refractory unstable angina
   if treatment option available.
5. > > Refractory left ventricular failure
   if destination treatment planned.
6. > > Perioperative support for
   high-risk coronary artery bypass surgery.
7. > > Perioperative support for high-risk
   non-cardiac surgery.

Question 4

What are the contraindications to (3 marks) the use of an IABP in an adult?

Answer 4

Absolute
» Aortic regurgitation, dissection or stent.
» Chronic end-stage heart disease with
no further possible intervention.

Relative
>> Uncontrolled sepsis.
>> Abdominal aortic aneurysm, 
severe peripheral vascular disease or arterial
reconstruction surgery.
>> Uncontrolled bleeding disorder.
>> Tachyarrhythmias.

Question 5

d) List possible complications of an IABP. (6 marks)

Answer 5

> > Haemodynamic compromise
due to poor timing of
counterpulsation or malposition.

> > Limb, spinal cord or visceral
(especially renal) ischaemia.

> > Compartment syndrome.

> > Aortic dissection.

> > Vascular injury causing bleeding,
haematoma, false aneurysm,
arteriovenous fistula.

> > Cardiac tamponade.

> > Thromboembolism.

> > Thrombocytopaenia and haemolysis.

> > Infection.

> > Balloon rupture resulting in gas embolus.