Thu7October0140PM 1

A 75-year-old man with ischaemic heart disease suffers an out-of-hospital cardiac arrest following an acute myocardial infarction.

Following emergency percutaneous angioplasty and stenting the patient is admitted to the critical care unit but is heavily reliant on high doses of adrenaline and milrinone for inotropic support. An intra-aortic balloon pump is inserted under echocardiographic guidance.

At which point of the ECG should balloon inflation be timed?

(Please select 1 option)

P wave

Middle of the T wave Correct

Peak of the R wave

Q wave

Beginning of the ST segment

Explanation

Balloon inflation is timed with diastole once closure of the aortic valve has occurred; this corresponds to the middle of the T wave. For blood to be ejected antegrade to perfuse the tissues and retrograde to perfuse the coronaries the aortic valve must be closed and competent.

Aortic regurgitation is therefore a contraindication to placement of an intra-aortic balloon pump.

Reference:

Anaesthesia UK. Intra-Aortic Balloon Pump Counterpulsation.

van den Berghe G, Wouters P, Weekers F, et al. Intensive insulin therapy in critically ill patients. N Engl J Med. 2001;345:1359-67.

Krishna M, Zacharowski K. Principles of intra-aortic balloon pump counterpulsation. Contin Educ Anaesth Crit Care Pain. 2009;9:24-28.

Answer Statistics

1

4%

2

57%

3

18%

4

3%

5

20%

Times answered: 276