19-04-2012, 12:15 PM
Intra-Aortic Balloon pump (IABP)
[attachment=20346]
• Mechanical device, temporarily used to improve cardiac function
• Helps in cases to patients as they are waiting for their heart transplant, coronary artery bypass grafting (CABG) or percutaneous coronary interventions such as stent placement.
• May be used along or with pharmacotherapy to assist left ventricular function.
Goal of IABP Therapy
• Improve cardiac function (cardiac output) by decreasing left ventricular end diastolic volume (preload).
• Improves myocardial oxygen supply by increasing blood flow to coronary arteries.
• Decrease myocardial oxygen demand by decreasing left ventricular wall tension (afterload).
• Stabilize cardiac function in patients with dysrhythmias and myocardial ischemia.
Component of AN IABP
• Consist of two main parts (1) catheter with an inflatable balloon attached to the distal end (2) console that regulates the inflation and deflation of the balloon.
• Here one end of catheter tip is attached to a pressure-transducer device that monitors the patient’s arterial aortic pressure and other end is attached to gas reservoir.
Physiology of Balloon function
• Is timed to inflate and deflate in the opposition to cardiac cycle.
• Goal of IABP is to enhance perfusion.
• Balloon inflates at the beginning of DIASTOLE (relaxation of heart, filling of blood in the heart) and deflates before ventricular systole (contraction of heart), a process known as counterpulsation.
• This process is correlated with ECG, ie balloon begins to inflate in the middle of T wave and to deflate before the end of the QRS complex.
• Inflation of the balloon at the beginning of diastole displaces/push blood upward towards the aortic root. This causes increase in diastolic pressure, forcing blood back into the coronary arteries which are normally perfused during diastole. Consequently blood flow to the coronary arties is increased with improvement in myocardial oxygen supply.
• This IABP inflation further causes decrease in heart rate and afterload and enhances LV function. Similarly during inflation blood is pushed forward to the periphery. In this way blood flow is increased below the inflated balloon, which may enhance perfusion of the renal arteries and systemic blood vessels.
• Deflation of balloon occurs during systole which helps in forward blood flow (pushing blood forward away from the Left ventricle) allowing for more complete emptying. This enhance LV emptying decreases preload and myocardial oxygen demand. Also this decrease the afterload pressure that is exerted by the wall of ventricles during ejection.
• This further decreases myocardial oxygen demand and increasing CO and ejection fraction.
• Other secondary effects of IABP placement result improvement in
1. Heart rate
2. Pulmonary artery diastolic (PAD) are decreased
3. Pulmonary aartery occlusive pressures
4. Mean arterial pressure, CO and perfusion to vital organs are increased
INDICATIONS FOR IABP THERAPY
• IABP is used in a variety of clinical situations such as cardiogenic shock. This therapy may be used to reduce myocardial ischemia and improve cardia function especially as the patient is prepared for revascularization procedure.
• For patient with unstable angina who are receiving maximum medical therapy but who still experience chest pain/discomfort IABP has been successful used to reduce or eliminate symptoms.
CONTRADICTION OF IABP THERAPY are divided into absolute and relative contraindications.
• Absolute contraindication are those in which the patients hould not receive IABP therapy. They include abdominal aortic aneurysm, aortic dissection, aortic insufficiency and irreversible brain damage.
• Relative contraindication are those in which the potential risk of using the IABP must be weighed against the potential benefit. They include patients with peripherial vascular disease, coagulatopathies or thromobocytopenia, terminal diseases and end-stage cardiomyopathies are not suitable for transplant.
INSERTION OF IABP
• May be performed at the bedside in the ICU, in the catherization lab or in the operating room.
• Balloon catheter is inserted into either the right or left femoral artery. It is threaded up into the descending aorta so that the tip of the catheter is located 1 to 2 cm below the subclavian branch of the aortic arch and above the branches of the renal arteries.
• Appropriate volume of He or CO2 is used.
• Helium is beneficial because it is lighter in density than CO2 and can travel faster in and out of the balloon circuit. In case of fatal accident, it can be very dangerous and fatal complication can come up.