Khalid Swenia MBBCH, FRCSC

Cardiac Surgeon

Libyan Cardiac Society

Heart Failure Scientific day

July 1 st 2010

TMC

Cardiac Dysfunction Post-Pump: ddx

Ischemia: graft dysfunction or spasm

Valve thrombosis or dehiscence

Uncorrected valvular pathology

Pneumothorax/hemothorax

Pericardial tamponade

Malposition of endotracheal tube (low PO2 and/or pH)

Inadequate volume resuscitation

Intracardiac shunt

Aortic dissection

Most important cause of post-op LV failure is inadequate myocardial protection

If Unable to Separate From CPB…Check:Ventilator O2 sat’n, Exhaled CO2

ABGLytes, CBCSGCO, PAP, Wedge (ie. Adequate filling pressures)

EchoCardiac contractilityValvular functionShunt

ECG

Options for Temporary MechSupport

IABP

Uni or Biventricular FailureECMO

Univentricular Failure (LV)Biomedicus

VAD

Heart Transplant

Wean From Support

DeathSurvival w/o Support

Rule out reversible causes of ventricular dysfunction

Maximize/Optimize medical therapy

IndicationsNote that there is no absolute indication for temporary mechanical support

Rather, based on a clinical assessmentCI < 2.0

SBP < 90

PCWP > 20 (ie. Low CO despite adequate fill)

Evidence of poor tissue perfusion

Oliguria

Acidosis

Low SVO2 (< 50)Refractory ventricular arrhythmias

Note that patients may have low C.O. due to excessive peripheral vasoconstriction (for a weakened heart)

Thus making a peripheral vasodilator very useful in this situation

Eg. Milrinone

Establish a rhythm – sinus, otherwise A/A-V paced if possible, or VVI (last)

%25–10 by C.O.Loss of sinus rhythm can

Especially in LVH or diastolic dysfx

Aim for rate 90 - 100

Finally, ensure sufficient medical support:

Epi ≥ 10 g/min

Dobutamine and Dopamine ≥ 10 g/kg/min

Milrinone ≥ 0.5 g/kg/min

After a 50 g/kg bolus

Inhaled NO if pulmonary hypertension

IABP: IndicationsPre-operative uncontrolled ischemic pain

Pre-operative uncontrolled ischemia

Pre-operative critical left main + RCA disease Especially if ongoing ischemia and/or poor LV function

Or ventricular arrhythmias

Pre-operative severe MR or VSR with CHF

Post-operative failure to wean or low CO syndrome

IABPEffects:

Reduction of afterload

Increased C.O. by up to 25%

Reduces wall stress (which is directly related to peak systolic wall stress) and therefore reduces oxygen consumption

Augmentation of diastolic pressure, with augmented coronary perfusion

IABPTip of balloon should be just distal to L subclavian ACan check position with TEE

Balloons usually in 2 sizes30 – 40 cc is optimal in most adults

Timing is criticalBy ECGDeflation on the R wave (just before aortic valve opens)

By arterial pressure tracingInflate at the dicrotic notch (ie. With closure of aortic valve

Early inflation causes…

Decreased C.O. (stroke volume)

Increased afterload

VERY important to have a regular rhythm, therefore pacing may be necessary

Heparinize if in longer than 24 hours

Wean by turning down from 1:1 to 3:1 augmentation (then off)

Pressure on femoral A x 30-45 minutes

To OR if puncture above inguinal ligament

IABP: ContraindicationsSevere Aortic regurgitation

Calcification or significant atheroma or aneurysm of descending thoracic aorta

Dissection of descending aorta

Severe peripheral vascular disease

AAA

Complications (~ 20% incidence)

Related to insertion

Lower limb ischemia (Most common, up to 25%)

BleedingDon’t forget possible iliac injury/retroperitoneal bleed

Arterial dissection

Thromboembolism if diseased aorta

Infection (1%)

Occlusion of major branches (renal, mesenteric)

Related to removalFalse aneurysm (1-2%)

Thromboembolism to lower limb

Related to deviceBalloon rupture (< 2%)

See blood in the catheter, ± lack of augmentation

Deflate balloon immediately and remove (b/c of thrombus risk)

A guidewire should be placed through the existing balloon to allow placement of a new one over it!

Disadvantages

Can only expect up to 25% increase in C.O.

Patient is immobilized

No improvement in RV function

ECMO

ECMO Extra-corporeal Membrane Oxygenation

ECLS (Extra-corporeal life support)

Initially developed for treatment of respiratory failure (veno-venous)

Useful also for uni or biventricular failure

Is the most commonly used form of ventricular support in neonates and infants

Is the first-line for ventricular support after IABP

Typically used for 48 – 72 hours, then either try to wean or move on to more permanent solution (LVAD, Transplant)Can perform hemofiltration at the same timeThermodilution C.O. is inaccurate on ECMO but SVO2 can be used insteadAim for 75 – 80%

ECMO for Respiratory FailureIndications

PaO2:FiO2 < 100

A-a gradient > 500

pH < 7.0 due to high pCO2

Eg. Status asthmaticus, airway obstruction

For lung transplant:

Usually only effective for early (ie. Within 1st week of transplant) graft failure

ECMO: ApplicationsAcute cardiogenic shock (either RV or LV)

Cath lab emergencies and support during complex catheter-based procedures

PE with RV failure and shock

Bridge to recovery/LVAD/transplant in acute myocarditis

In RV or Biventricular failure, ECMO is beneficial because of elimination of hypoxia, which then causes a decrease in PVR (also unloads RV)

ECMO: componentsPumpUsually rotary or roller

OxygenatorCan be membrane

Hollow-fibre has advantage of being quick to prime, and can be heparin-coated

Heater/cooler

Cannulas and tubing (± percutaneous)Arterial 16 – 20Fr

Venous 18 – 28Fr

Entire system can be heparin-coated

ECMO: anticoagulationOverall risk of intracardiac thrombus formation withoutheparinization is ~20%

Risk of pumphead thrombus formation is 5 - 10%

For arterio-venous ECMO, aim for ACT of 180 – 200

-venois not as important for heparinizationSystemic ECMOvenous

ACT 160 – 200 if prolonged support

ECMO: Arterio-venousCannulation options:

RAA to Asc Ao

Femoral vein (catheter to RA) to Asc Ao

Femoral vein to Femoral artery

Can be done percutaneously

If intra-thoracic cannulation, tunnel catheters through skin like chest tubes

Unloads RV, and decreases preload to LV

ECMO: Veno-venousCannulation options:Outflow from R int jug, inflow to a common femoral vein (classic, “atriofemoral”)

Femoro-atrial recently shown to be better

Bilateral common femoral veins

May need ASD to allow decompression of right side (to bypass lungs if excessively high PAP or RV dysfunction initially – should improve with reversal of hypoxia, acidosis) – eg. PECan be done with percutaneous balloon septostomy if necessary

ECMO: ComplicationsArterial and venous tears, dissections, hemotomas, false aneurysms

Bleeding

Re-op for bleeding in up to 60%!

Higher incidence if thoracic (central) cannulation

Thrombosis of lines, oxygenator, pump

Emboli

Cerebral emboli in up to 10%

Renal dysfunction in up to 1/3rd !

Can add CVVHD to the circuit if needed

Lower limb ischemia

Infection (mediastinitis)

ECMO: WeaningReadiness for weaning may be indicated by:

Increasing wave-form on arterial line

Improved function on echo

Weaning should be echo-guided

Decrease flows, increase inotropes, and increase ventilation as necessary

Keep ACT > 300 while pump flows are less than 2L/min

ECMO: Results~75% are successfully weaned from ECMO

However, survival to hospital discharge is usually about 30 – 50%

Higher if pt eventually gets a VAD or Tx

Much lower if emergency surgery

ECMO allows screening of pts for VAD and Tx candidacy

ECMO: ContraindicationsIncurable malignancy

Advanced MOF

Severe CNS injury

Relative c/i is pt who is not VAD or Tx candidate

Biomedicus

Biomedicus = ECMO w/o oxygenatorThis is one example of rotary pump used to provide unior biventricular support for a period of hours to days

One pump for either L or R ventricular support, two pumps for both

Cannulation for L heart

R sup pulm vein to asc Ao

Cannulation for R heart

RA to PA (either direct, or via RV puncture and threading of catheter into main PA)

Thank You