Indications for a VAD

In order to qualify for a ventricular assist device, one must have serious problems:

  • Cardiogenic shock
  • Cardiac arrest
  • Fulminant myocarditis
  • Failure to wean off bypass

There are also situations in which you might anticipate a VAD might be needed, and would have one on standby:

  • High-risk PTCA
  • High-risk cardiac surgery with poor preoperative function

Contraindications for a VAD

  • Aortic regurgitation
  • Aortic aneurysm or dissection
  • Left heart thrombus
  • Uncontrolled bleeding
  • Uncontrolled sepsis

Basic physics of VAD

  • They are either an axial (Archimedes' screw) or a centrifugal pump; flow is non-pulsatile, which results in poor end-organ function
  • The action of pumping blood in this way provokes haemolysis
  • The insertion usually requires a sternotomy
  • It can be implanted for up to a month, but you cant walk around with this thing. You need to stay in hospital, largely confined to your bed.

Anticoagulation during VAD

  • Heparin is the poison of choice
  • APTT is used to monitor the level of anticoagulation; an APTT of 150-200 is aimed for.

Major complications of VAD

  • Infection is the major cause of morbidity; something like 50% of the implated devices get infected.
  • The LV gets (understandably) irritated by the presence of an LVAD, and in 25% of patients ventricular arrhythmias develop
  • Thrombi form on the walls of the device in spite of anticoagulation, and 10-16% of people have thrombotic complications.
  • Some degree of haemolysis and thrombocytopenia occur in everybody

References

UpToDate has a nice chapter on VADs.

EMCrit brandishes the expertise of somebody who works with these things, and I take that seriously.

Additionally, there is an insanely colourful brochure which has device-specific recommendations.