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