Intra-aortic Balloon Pump Intra-aortic Balloon Pump (IABP)(IABP)

Intra-aortic Balloon Pump Intra-aortic Balloon Pump (IABP)(IABP)

By David KlodaBy David Kloda

HistoryHistory

Realization that coronary perfusion mainly occurs during diastole -1950s

Aspiration of arterial blood during systole with reinfusion during diastole decreased cardiac work without compromising coronary perfusion – Harkin-1960s

Intravascular volume displacement with latex balloons - early 1960s

BackgroundBackground

PreloadAfterloadCoronary flowMyocardial oxygen consumption in the

heart is determined by:– Pulse rate– Transmural wall stress– Intrinsic contractile properties

Myocardial Oxygen Myocardial Oxygen ConsumptionConsumption

Has a linear relationship to:– Systolic wall stress– Intraventricular pressure– Afterload– End diastolic volume– Wall thickness

Indications for IABPIndications for IABP

Cardiac failure after a cardiac surgical procedure

Refractory angina despite maximal medical management

Perioperative treatment of complications due to myocardial infarction

Failed PTCAAs a bridge to cardiac transplantation

IABP in Myocardial Infarction IABP in Myocardial Infarction and Cardiogenic Shockand Cardiogenic Shock

Improves diastolic flow velocities after angioplasty

Allows for additional intervention to be done more safely

IABP During or After Cardiac IABP During or After Cardiac SurgerySurgery

Patients who have sustained ventricular damage preoperatively and experience harmful additional ischemia during surgery

Some patients begin with relatively normal cardiac function an experienced severe, but reversible, myocardial stunning during the operation

IABP As a Bridge to Cardiac IABP As a Bridge to Cardiac TransplantationTransplantation

15 to 30 % of endstage cardiomyopathy patients awaiting transplantation need mechanical support

May decrease the need for more invasive LVAD support

Other Indications for IABPOther Indications for IABP

Prophylactic use prior to cardiac surgery in patients with:– Left main disease– Unstable angina– Poor left ventricular function– Severe aortic stenosis

Contraindications to IABPContraindications to IABP

Severe aortic insufficiencyAortic aneurysm

Insertion TechniquesInsertion Techniques

Percutaneous– sheath less

Surgical insertion

PositioningPositioning

The end of the balloon should be just distal to the takeoff of the left subclavian artery

Position should be confirmed by fluoroscopy or chest x-ray

Timing of CounterpulsationTiming of Counterpulsation

ElectrocardiographicArterial pressure tracing

Weaning of IABPWeaning of IABP

Decreasing inotropic supportDecreasing pump ratio

ComplicationsComplications

Limb ischemia– Thrombosis– Emboli

Bleeding and insertion site– Groin hematomas

Aortic perforation and/or dissection Renal failure and bowel ischemia Neurologic complications including paraplegia Heparin induced thrombocytopenia Infection

IABP RemovalIABP Removal

Discontinue heparin six hours prior Check platelets and coagulation factors Deflate the balloon Apply manual pressure above and below IABP

insertion site Remove and alternate pressure to expel any clots Apply constant pressure to the insertion site for a

minimum of 30 minutes Check distal pulses frequently

Cardiopulmonary BypassCardiopulmonary Bypass

The heart lung machine

The pump

The bypass machine

HistoryHistory

Concept of diverting the circulation to an extracorporeal oxygenator – 1885

Mechanical pump oxygenators – 1953Controlled cross circulation – 1954First series of intracardiac operations using

a pump oxygenator – 1955

The ApparatusThe Apparatus

Pumps– Simple roller pump– Centrifugal pump

Venous reservoirOxygenatorHeat exchangerOther

Venous ReservoirVenous Reservoir

Siphons blood by gravityProvide storage of excess volumeAllows escape of any air bubbles returning

with the venous blood

OxygenatorOxygenator

Provides oxygen to the bloodRemoves carbon dioxideSeveral types

– Bubble oxygenator– Membrane oxygenator– Microporous hollow-fiber oxygenators

Heat ExchangerHeat Exchanger

Also called the heater / coolerControls perfusate temperature

– Warm and cold

Cardiopulmonary BypassCardiopulmonary Bypass

HeparinizationTotal bypassPartial bypassFlowrates 2-2.5 l/min. per square meter

– Flowrates depend on body size– Flowrates depend on cannula sizes

Hypothermia

Shed BloodShed Blood

Is aspirated with a suctioning apparatus, filtered and return to the oxygenator

A cell saving device may also be utilized during and after bypass

Blood PressureBlood Pressure

Decreases sharply with onset of bypass (vasodilatation)

Mean arterial pressure needs to the above 50-60 mm Hg.

After 30 minutes perfusion pressure usually increases (vasoconstriction)

Oxygen and Carbon Dioxide Oxygen and Carbon Dioxide TensionsTensions

Concentrations are periodically measured in both arterial and venous lines

Arterial oxygen tension should be above 100 mm Hg

Arterial carbon dioxide tensions should be 30-35 mm Hg

A drop in venous oxygen saturation suggests underperfusion

Myocardial ProtectionMyocardial Protection

Cold hyperkalemic solutions– Produces myocardial quiescence – Decreases metabolic rate– Provides protection for 2-3 hours– Blood vs. crystalloid

Termination of PerfusionTermination of Perfusion

Systemic rewarmingFlowrates are decreasedHemodynamic parametersVenous line clampingPharmacologic supportNeutralization of heparin

Complications of Cardio- Complications of Cardio- Pulmonary BypassPulmonary Bypass

– Post perfusion syndrome– Duration of bypass– Age– Anemia– Other