Download Ventricular Assist Devices - cardiac anesthesia basics

Ventricular Assist Devices
Brian Schwartz, CCP
February 25, 2003
Criteria for Ventricular Assist
Devices
• Cardiac Index < 2.0 L/m2/min
• SVR > 2,100 dyn/sec/cm2
• Systolic Pressure < 80 mmHg
• Atrial Pressure > 20 mmHg
• Assisted (diuretics) Urine Output < 20
ml/hr
• Metabolic Acidosis
Criteria for Ventricular Assist
Devices
• Failure to separate from CPB
• Irreversible cardiac injury
Short Term Support
• Cardiopulmonary bypass Resuscitation
– 15 % survival rate
– Immediately able to support patient
– Need to fully heparinize patient
• CPR
– Provides support temporarily
Devices Used to Assist the Ventricle
(Moderate Setting)
• Intra-aortic balloon pump
• Cardiopulmonary Support (CPS)
• Centrifugal Pump “Bio-Head”
• Abiomed (BVS-5000) Bi-Vad
Intra-aortic Balloon Pumps
• The least complicated means of circulatory
assistance
• Effects of IABP
– Augmentation of Diastolic Pressure
– Decrease Afterload
– Decrease myocardial oxygen consumption
– Augments C.O. by 10% (500-800 cc/min)
• Relatively inexpensive
Intra-aortic Balloon Pumps
(Indications)
• Cardiogenic shock following MI
• Unstable Angina
• Left Main Disease
• Ventricular Dysrhythmias
• Septic Shock
Intra-aortic Balloon Pumps
(Contraindications)
• AI
• Aortic Aneurysm
• Severe Femoral Disease
Cardiopulmonary Support (CPS)
• Percutaneous insertion
• Need oxygenator and heat exchanger
• Cannulate both femoral artery and femoral
vein
• Needs continuous monitoring, therefore
very labor intensive
• Maximum support…48 hours
Centrifugal Pump
• Easy to prime and set up
• Requires continuous monitoring
• Kinetic assisted venous drainage
• ACT’s around 180-200 seconds
• Moderate cost
Abiomed
• Quick set-up
• Minimal bedside monitoring
• Supports large children and adults
• Flow rates up to 5 L/Min
• Maximum use….1 week
• Patients are not mobile
• High cost
Long Term Devices for Ventricular
Support
• TCI ( Heartmate IP 1000) Pneumatic
– LVAD only
• TCI (VE) Vented Electric
– LVAD only
• Novacor (N 100P) Electric
– LVAD only
• Thoratec Pneumatic
– LVAD, RVAD, Bi-VAD
Heartmate Pneumatic LVAD
• Allows blood flows to exceed 10 liters per
minute
• Inserted during CPB
• Minimum BSA required…1.7
• Very costly to insert
Heartmate Vented Electric LVAD
• Allows flows exceeding 10 liters
• Need CPB for placement
• BSA requirement…greater than 1.7
• Patients are able to go home
• Minimal anti-coagulation
• High cost
Total Artificial Heart
• CardioWest ( C-70 ) Pneumatic total
artificial heart
– C.O. is approximately 7.0 L/M
– BSA>1.7
– Need CPB for implant
– Native heart not excised
– Need Anti-coagulation
– Patient in-house but mobile
Total Artificial Heart
• Abiomed’s total artificial heart
– Still in clinical trials
– First patient lasted several months on device
– If successful, will save hundreds of thousands
of live because there will be no waiting like
the transplant list
Signs indicating Left Ventricular
Failure
• Decreased contractility
• Elevated left ventricular filling pressures
• Elevated pulmonary capillary wedge
pressures
• Decrease pulmonary oxygenation
Signs of Right Ventricular Failure
• Cardiac Index less than 1.8 L/min/m2
• Aortic pressure less than 90 mmHg
• Atrial pressure greater than 20 mmHg
• Pulmonary capillary wedge pressure less
than 10 mmHg
Cannulation sites for LVAD’s
• Inlet
– Left atrium
– Left ventricle
– Left superior pulmonary vein
• Outlet
– Aorta
Cannulation sites for RVAD’s
• Inlet
– Right atrium
• Outlet
– Pulmonary artery
Heparin Management in Patients
with VAD’s
• ACT’s are maintained around 180-200
seconds…as long as the cardiac output is
above three liters per minute
• ACT’s are maintained above 300 seconds
while the cardiac output is below three
liters per minute
– WHEN IS THIS IMPORTANT???????
Discontinuing a VAD
• If possible, the heart is allowed to rest for 48-72
•
•
•
hours
Weaning the patient off the assist devices is
then performed. ( Patient needs to have a
native C.I. of at least 2.2 L/min/m2)
ACT’s are increased to compensate for the low
flows
If the patient tolerates the low flows, he/she is
separated from the assist devices and the
cannulae are removed
VAD Protocol for Your Institution
• Know your protocol
• Know your equipment
• Be able to predict those patients at risk
• Be able to prime in an orderly fashion
• Be prepared to assist the surgeons
• Help educate all staff working with the
patient