Temporary Mechanical Circulatory Support

Question 1

What is the incidence of requirement for temporary MCS after cardiac surgery?

Answer 1

0.2-0.6%

Question 2

Who invented the IABP and in which year?

Answer 2

Adrian Kantrowitz 1967

Question 3

What is the major effect of IABP? What are the minor/secondary effects?

Answer 3

Decreased afterload (15%) and increased coronary perfusion (21% increase in flow to ischemic areas)

Decreased LV wall tension, decreased O2 consumption, reduced LVEDV, LVESV, reduced preload

Question 4

What is the IABP timed to activate towards?

Answer 4

ECG R wave and arterial pressure tracing

Question 5

What are the 3 major indications for IABP?

Bonus: name 5 more indications for IABP

Answer 5

Cardiogenic shock, post-pericardiotomy low cardiac output, uncontrolled myocardial ischemic pain

Bonus: high risk/failed PCI, high grade left main, poorly controlled ventricular arrhythmias before or after operation, post-MI VSDs or post-MI acute MR

Question 6

What is the landmark for puncture of the femoral artery? What are the access sites for IABP?

Answer 6

1-2 cm below the mid-inguinal point (mid point of the ASIS and pubic symphysis not to be confused with the mid point of the inguinal ligament which is the landmark for the femoral nerve) or 1-2cm above the inguinal fold (not always accurate)

Femoral (most common), abdominal aorta, iliac arteries, axillary arteries, direct insertion into ascending aorta (intra-op)

Question 7

What size is the IABP?

Answer 7

7 Fr (1 Fr = 0.33mm)

Question 8

What is the complicate rate associated with IABP? What are the complications?

Answer 8

20%

Leg ischemia, balloon rupture, balloon thrombosis, pseudoaneurysm, lymphocele, lymphatic fistula, AV fistula, infection, septicemia, femoral neuropathy

Question 9

How can you tell if a balloon ruptures and what do you do if the balloon ruptures?

Answer 9

Blood will be seen in the balloon catheter and an alarm may go off
Deflate the balloon forcibly and remove the balloon

Question 10

What do you do if pain, decreased sensation and compromised circulation occur in a IABP?

Answer 10

Promptly remove the balloon and if the patient is balloon dependent, place an IABP in the contralateral groin

Question 11

What is the IABP SHOCK II trial and what did it show?

Answer 11

This trial randomized 600 patients with acute MI and cardiogenic shock who were planned to undergo revascularization to either IABP or medical therapy. There was no difference in the 30 day mortality and no difference in adverse advents

Question 12

What is the average overall survival for patients put on temporary MCS?

Answer 12

21-41%

Question 13

What are the criteria for cardiogenic shock?

Answer 13

Cardiac index < 2.2L/m2, sBP <90, mean PCWP or CVP >20mmHg and concomitant use of high doses of 2 or more inotropes

Question 14

What are three drugs commonly used in RV failure?

Answer 14

Milrinone, NO and vasopressin

Question 15

What are the differences between CPB and ECLS?

Answer 15

ECLS is a continuous flow circuit, without areas for stasis like the venous reservoir or cardiotomy suction reservoir, which means lower doses of heparin are required and less activation of the inflammatory response and coagulopathy. ECLS provides partial cardiorespiratory support. ECLS has a diffusion membrane instead of a microporous membrane. There is no way to de-air in the ECMO circuit, there is no blood air interface.

Question 16

What are the components of the ECMO circuit?

Answer 16

Venous cannula, Membrane oxygenator, Centrifugal pump, Heat exchanger, Arterial cannula

Question 17

What are the cannulation sites for central and peripheral ECMO?

Answer 17

Central: ascending aorta and right atrium
Peripheral: axillary, femoral

Question 18

What size cannula are typically used?

Answer 18

Arterial 16-20Fr

Venous 18-25Fr

Question 19

What must you be concerned about with axillary artery cannulation?

Answer 19

Progressive arm edema. Treatment is partial occlusion of distal axillary artery with vessel loop. Make sure you have a right radial artery arterial line to ensure you know the right arm is perfused when you cannulate the right axillary.

Question 20

What does ECLS do to the heart in terms of preload/afterload to the right/left hearts? What can be done to fix this?

Answer 20

ECLS can unload the RV, but will not unload a compromised LV. It can reduce LV preload but will increase LV afterload slightly. A poorly contractile LV may not be able to eject and can remain dilated, which increases myocardial O2 consumption. A LV vent can be inserted to decompress a dilated LV.

Question 21

What are the complications of ECMO?

Answer 21

Bleeding, renal failure requiring dialysis (47%), stroke (10%), bacteremia or mediastinitis (23%), leg ischemia (70%), oxygenator failure requiring change (43%) and pump change (13%)

Question 22

What do you do when you find clot in the pump head?

What do you do when there is leakage of plasma across the membrane?

Answer 22

Pump head change

Monitor, but this may cause increased resistance to flows and necessitate oxygenator change

Question 23

How do you do central VA ECMO

Answer 23

The eopa cannula is inserted into the ascending aorta. The cannula is the same size as the regular cannula 20Fr.

The venous cannula is a single stage Bard cannula, large diameter (38Fr) and it is inserted to sit in the middle of the RA. The purse string is made halfway between the RAA and the IVC. The Bard cannula does not sit too deeply. They must be secured with double plegeted (bovine pericardium) sutures. Use special VAD tourniquets. Tunnel the cannula through the skin, the aortic cannula through near the left costal margin, the venous cannula through the right costal margin.

Question 24

How do you vent the LV?

Answer 24

IAS via balloon atrial septostomy, or LV via RSPV or LV via apex or Impella.

Hook up your vent to 1/4 inch tubing then use a 1/4 to 3/8ths connector, Y that into a 3/8-3/8-3/8ths connector. The benefit of this approach is reduced risk of stasis of the vent drainage and you can put a flow probe on the tubing.

Question 25

What is oxygenation dependent on?
What is sweep?
What is CO2 diffusion dependent on?

Answer 25

Blood flow
Gas flow
Gas flow

Question 26

What do you do in an LVAD with AI?

Answer 26

Park’s stitch to create aortic stenosis and reduce the AI

Question 27

What are the ACT targets in VV ECMO and VA ECMO?

Answer 27

VV ECMO - ACT 150

VA ECMO - ACT 180

Question 28

What are the predictor of needing MCS post-cardiotomy?

Answer 28

low MVO2 <60%, oliguria, low cardiac output, multiple high dose inotropes

Question 29

What is the Cardiohelp ECLS device?

Answer 29

It is a compact ECLS device with a low priming volume and integrated oxygenator which allows transport of patients on ECLS in and out of hospital.

Question 30

What is the TandemHeart? Where is it used and where do the cannulas sit? What are some alternative uses for the device? How much flow can it support?

Answer 30

It is a pVAD that is approved for up to 6 hours of continuous usage by the FDA. It is primarily used in high risk PCI. It can be inserted percutaneously or open, typically with the inflow cannula positioned transseptally into the LA and the outflow cannula positioned in the femoral artery. It can also be used as an RVAD with the inflow cannula in the femoral vein and the outflow cannula percutaneously placed into the main PA. If inserted percutaneously, it can be entirely removed in the ICU without opening the chest. It can provide up to 4L of flow.

It can be used off label with an oxygenator or for more than 6 hours.

Question 31

What is Centrimag? What can it support and what is it FDA approved for? How much flow can it support?

Answer 31

It is a centrifugal pump that can be used to provide both LVAD and RVAD support. It is FDA approved for RVAD support up to 30 days and LVAD support up to 6 hours. It is typically inserted via central cannulation via median sternotomy. It can be outfitted with an oxygenator and provides up to 10L of flow?

Question 32

How does the Impella work, what does it do for the heart physiologically?

Answer 32

It increases CO, reduces myocardial oxygen demand by unloading the LV, increases coronary perfusion

Question 33

What are the key ventilatory parameters during temporary MCS?

Answer 33

Peak inspiratory pressure < 35 cm H2O. O2 initially set at 100% and gradually decreased, partial pressure of O2 maintained between 85-100 mmHg, PEEP of 5 mmHg

Question 34

What are the anticoagulation/bleeding parameters?

Answer 34

Platelet counts decrease in the first 24 hrs of support, transfusion of platelets to maintain plts above 50k, or 100k if bleeding, FFP and cryo for fibrinogen over 250mg/dL. IV heparin starting at 8-10 ug/kg/h to maintain a pTT of 45-55.

Question 35

What are the fluid management parameters?

Answer 35

Aggressive diuresis to minimize 3rd spacing. If response to diuretic therapy is suboptimal, SLED or IHD is initiated.