Intra-aortic Balloon Pump (IABP)

Intra-aortic Balloon Pump (IABP) By David Kloda

History • 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

Background • Preload • Afterload • Coronary flow • Myocardial oxygen consumption in the heart is determined by: • Pulse rate • Transmural wall stress • Intrinsic contractile properties

Myocardial Oxygen Consumption • Has a linear relationship to: • Systolic wall stress • Intraventricular pressure • Afterload • End diastolic volume • Wall thickness

Indications for IABP • Cardiac failure after a cardiac surgical procedure • Refractory angina despite maximal medical management • Perioperative treatment of complications due to myocardial infarction • Failed PTCA • As a bridge to cardiac transplantation

IABP in Myocardial Infarction and Cardiogenic Shock • Improves diastolic flow velocities after angioplasty • Allows for additional intervention to be done more safely

IABP During or After Cardiac Surgery • 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 Transplantation • 15 to 30 % of endstage cardiomyopathy patients awaiting transplantation need mechanical support • May decrease the need for more invasive LVAD support

Other 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 IABP • Severe aortic insufficiency • Aortic aneurysm

Insertion Techniques • Percutaneous • sheath less • Surgical insertion

Positioning • 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 Counterpulsation • Electrocardiographic • Arterial pressure tracing

Weaning of IABP • Decreasing inotropic support • Decreasing pump ratio

Complications • 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 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 Bypass The heart lung machine The pump The bypass machine

History • Concept of diverting the circulation to an extracorporeal oxygenator – 1885 • Mechanical pump oxygenators – 1953 • Controlled cross circulation – 1954 • First series of intracardiac operations using a pump oxygenator – 1955

The Apparatus • Pumps • Simple roller pump • Centrifugal pump • Venous reservoir • Oxygenator • Heat exchanger • Other

Venous Reservoir • Siphons blood by gravity • Provide storage of excess volume • Allows escape of any air bubbles returning with the venous blood

Oxygenator • Provides oxygen to the blood • Removes carbon dioxide • Several types • Bubble oxygenator • Membrane oxygenator • Microporous hollow-fiber oxygenators

Heat Exchanger • Also called the heater / cooler • Controls perfusate temperature • Warm and cold

Cardiopulmonary Bypass • Heparinization • Total bypass • Partial bypass • Flowrates 2-2.5 l/min. per square meter • Flowrates depend on body size • Flowrates depend on cannula sizes • Hypothermia

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

Termination of Perfusion • Systemic rewarming • Flowrates are decreased • Hemodynamic parameters • Venous line clamping • Pharmacologic support • Neutralization of heparin

Complications of Cardio- Pulmonary Bypass • Post perfusion syndrome • Duration of bypass • Age • Anemia • Other

Intra-aortic Balloon Pump (IABP)

Intra-aortic Balloon Pump (IABP)

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