IABPINTRA-AORTIC BALLOON COUNTERPULSATION

Dr. VISHAL VANANIJASLOK HOSPITAL AND RESEARCH CENTRE

APRIL 2015

HISTORY

Kantrowitz described augmentation of coronary blood flow by retardation of the arterial pressure pulse in animal models in 1952.

In 1958, Harken suggested the removal of some of the blood volume via the femoral artery during systole and replacing it rapidly in diastole as a treatment for left ventricular (LV) failure, so called diastolic augmentation.

HISTORY

In the 1960s, Moulopoulos and colleagues from the Cleveland Clinic developed an experimental prototype of an IABP whose inflation and deflation were timed to the cardiac cycle.

In 1968, Kantrowitz reported improved systemic arterial pressure and urine output with the use of an IABP in two subjects with cardiogenic shock, one of who survived to hospital discharge.

HISTORY

Balloon catheters were 15 French and needed to be surgically grafted into the femoral arteries.

Percutaneous IABs in sizes 8.5-9.5 French (rather than 15 French used earlier) were introduced in 1979, and shortly after this, Bergman and colleagues described the first percutaneous insertion of IABP.

The first prefolded IAB was developed in 1986.

CARDIAC PHYSIOLOGY

PRELOAD

Preload refers to the amount of stretch on the ventricular myocardium prior to contraction.

Starling’s law described how an increase of volume in the ventricle at the end of diastole resulted in an increase in the volume of blood pumped out.

Preload is often referred to as “filling pressure”. Factors affecting preload include:

Aortic insufficiency Circulating blood volume Mitral valve disease Some medications (i.e. Vasoconstrictors, vasodilators)

AFTERLOAD

Afterload is the resistance that the heart must overcome in order to eject the blood volume from the left ventricle

Afterload takes several forms: The mass of blood that must be moved, measured by the

hematocrit Aortic end diastolic pressure (AEDP). Arteriole resistance

Afterload can be affected by: Aortic stenosis Arterial vasoconstrictors and vasodilators Hypertension Peripheral arterial constriction

OXYGEN CONSUMPTION

Myocardial Oxygen Consumption Depends on Systolic wall stress

Intra-ventricular pressure

Afterload

End diastolic volume

Wall thickness

HOW IABP HELPS?

IABP – HOW IT WORKS

A flexibile catheter – into the descending aorta. Correct positioning – Important When inflated, the balloon blocks 85-90% of the aorta.

This balloon displaces the blood that is in the aorta.

This is known as counter pulsation

This sudden inflation moves blood superiorly and inferiorly to the balloon.

When the balloon is suddenly deflated, the pressure within the aorta drops quickly.

WHY HELIUM?

Helium: Low Density Soluble

IABP – HOW IT HELPS

Inflation of the balloon occurs at the onset of diastole.

At that point, maximum aortic blood volume is available for displacement because the left ventricle has just finished contracting and is beginning to relax, and the aortic valve is closed.

The pressure wave that is created by inflation forces blood superiorly into the coronary arteries. This helps perfuse the heart.

Blood is also forced inferiorly increasing perfusion to distal organs (brain, kidneys, tissues, etc.)

IAB INFLATION

Balloon inflated during diastole Increasing aortic

pressure and

Increasing coronary blood flow

Increases Myocardial O2 delivery

IAB DEFLATED

The balloon remains inflated throughout diastole.

At the onset of systole, the balloon is rapidly deflated. The sudden loss of aortic pressure caused by the deflation reduces afterload.

The left ventricle does not have to generate as much pressure to achieve ejection since the blood has been forced from the aorta.

This lower ejection pressure reduces the amount of work the heart has to do resulting in lower myocardial oxygen demand.

Hemodynamic Effects of IABP

Aorta ↓ systolic pressure, ↑ diastolic pressure

Left ventricle↓ systolic pressure, ↓ end-diastolic

pressure,↓ volume, ↓ wall tension

Heart ↓ Afterload,↑ Cardiac Output, ↓ O2 Demand

Blood flow ↑ coronary blood flow

HEMODYNAMICS : Summary

Afterload

Myocardial oxygen demand

Coronary flow

Cardiac output

INDICATIONS

Refractory unstable angina Persistent myocardial

ischemia (preop or postop) Acute myocardial infarction Complications of acute MI Cardiogenic shock Refractory LV failure Acute MR and VSD Support for high-risk

catheterization or failed PCI Refractory ventricular

arrhythmias

As a bridge to cardiac transplantation

Support during transport Preoperative IABP (high-

risk patients) Cardiac surgery, High risk

CABG Weaning from

cardiopulmonary bypass Postcardiotomy LV systolic

failure unresponsive to inotropes

CONTRAINDICATIONS

Severe aortic insufficiency

Dissecting aortic aneurysm

Descending thoracic aortic atheroma

Aorto-iliac-femoral occlusive disease

Lower extremity ischemia

Dynamic LVOTO

Chronic end-stage heart disease with no anticipation of recovery

Aortic stents

End-stage cardiomyopathies

Severe atherosclerosis

End stage terminal disease

Abdominal aortic aneurysm

Uncontrolled sepsis

Severe peripheral vascular disease

Major arterial reconstruction surgery

Blood dyscrasias (Thrombocytopenia)

COMPLICATIONS

Transient loss of peripheral pulse

Limb ischaemia Thromboembolism Compartment syndrome Retroperitoneal hematoma Local vascular injury—false

aneurysm, haematoma, bleeding from the wound

Aortic perforation and/or dissection

Cardiac tamponade

Thrombocytopenia Infection / sepsis Malpositioning causing

cerebral or renal compromise

Renal failure and bowel ischemia

Heparin induced thrombocytopenia

Balloon rupture (can cause gas embolus)

Balloon entrapment

HOW TO INTRODUCE

IABP Kit Contents

Introducer needle Guide wire Vessel dilators Sheath IABP (34 or 40cc) Gas tubing 60-mL syringe Three-way stopcock Arterial pressure tubing

(not in kit)

IAB Sizing Chart

INSERTION TECHNIQUE

Percutaneous Sheath less With Sheath

Surgical insertion Femoral cut down Trans-thoracic

The IABP device has two major components:

1. A double-lumen 8.0-9.5 French catheter with a 25-50

ml balloon attached at its distal end; and

2. A console with a pump to drive the balloon.

The balloon is made of polyethylene and is inflated

with gas driven by the pump.

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

HOW TO ADJUST IABP

OPERATION MODE

OPERATION MODES

AutomaticTracks cardiac cycle, cardiac rhythm and adjusts automatically

SemiautomaticOperator must adjust inflation & deflation

ManualOperator must adjust inflation & deflation & can set fixed rate

TRIGGER SOURCE

• During a cardiac arrest, the IABP can provide very effective perfusion in conjunction with external compressions.• Since there is no ECG signal and no

arterial pressure wave to trigger the pump, an internal trigger is selected.

• This trigger detects the flow of blood caused by compressions and inflates the balloon providing improved circulation.

• Good, consistent compressions are a must for this to work!

IAB FREQUENCY

AUGMENTATION

TIMINGS

TIMING OF COUNTER PULSATION

UASBP UASBP

ADBP

UADBPUADBP

ASBP

DABP

INTRAAORTIC BALLOON COUNTERPULSATION

Timing of inflation:

• First identify the dicrotic notch (when the aortic valve closes)

If inflation is too early the balloon inflates before the aortic valve closes and pumps blood backwards into the LV, and ↑ LVEDV & LVEDP, Increased left ventricular wall stress or afterload, Aortic regurgitation, Increased MV02 demand.

• If inflation is too late there will be sup-optimal coronary perfusion

INTRAAORTIC BALLOON COUNTERPULSATION

Early inflation:

INTRAAORTIC BALLOON COUNTERPULSATION

Late inflation:

INTRAAORTIC BALLOON COUNTERPULSATION

Timing of deflation:

• If deflation is too early there will be inadequate afterload reduction and sub-optimal coronary perfusion

• If deflation is too late the balloon remains inflated too long, causing ↑ afterload because the heart is trying to pump against an inflated balloon

INTRAAORTIC BALLOON COUNTERPULSATION

Early deflation:

EARLY DEFLATION

Waveform Characteristics: Assisted aortic end diastolic pressure may be ≤ the

unassisted aortic end diastolic pressure.

Assisted systolic pressure may rise.

Physiologic Effects: Sub-optimal coronary perfusion.

Potential for retrograde coronary and carotid blood flow.

Sub-optimal after load reduction & Increased MV02 demand.

INTRAAORTIC BALLOON COUNTERPULSATION

Late deflation:

LATE DEFLATION

Waveform Characteristics: Assisted aortic end diastolic pressure may be equal

to the unassisted aortic end diastolic pressure. Rate of rise of assisted systole is prolonged. Diastolic augmentation may appear widened.

Physiologic Effects: Afterload reduction is essentially absent. Increased MV02 consumption due to

The left ventricle ejecting against a greater resistance IAB may impede left ventricular ejection and increase

the afterload

MAINTENANCE CARE

Ankle flexion and extension one to two hourly

Use pressure relieving mattress Change ECG electrodes daily. Change occlusive dressing daily Secure balloon catheter at several points

along the limb.

OBSERVATIONS

Observe hourly at catheter insertion site For signs of bleeding Signs of infection Signs of blood in sheath

If blood or brown dust is observed within the lumen, immediately place the IABP on 'Standby'.

The catheter will have to be removed immediately.

OBSERVATIONS

Check hourly for left radial pulse Put SaO2 probe on left hand Assess the limb distal to the insertion One hourly Observe and record peripheral

pulses, capillary refill, skin, temperature Observe the waveform to ascertain that

the timing is correct

WEANING of IABP

Timing of weaning Patient should be stable for 24-48 hours

Decreasing inotropic support Decreasing pump ratio

From 1:1 to 1:2 or 1:3 Decrease augmentation Monitor patient closely

If patient becomes unstable, weaning should be immediately discontinued

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 balloon while alternating pressure

above and below insertion site to expel clots Apply constant pressure to the insertion site

for a minimum of 30 minutes Check distal pulses frequently

KEY POINTS

The primary goal of intra-aortic balloon pump (IABP) treatment is to increase myocardial oxygen supply and decrease myocardial oxygen demand.

Decreased urine output after the insertion of IABP can occur because of juxta-renal balloon positioning.

Haemolysis from mechanical damage to red blood cells can reduce the haematocrit by up to 5%.

Suboptimal timing of inflation and deflation of the balloon produces haemodynamic instability.

An IABP is thrombogenic; always anticoagulate the patient.

Never switch the balloon off while in situ.

….THANK YOU….