Exam 6

Question 1

How have LVADs been used?

Answer 1

-used a bridge to transplant
-used as destination therapy
-used as a bridge to transplant candidacy
-used as a bridge to recovery

Question 2

Two types of CF LVADs and consequences

Answer 2

• Heart Mate II: impeller is below the diaphragm
• HVAD: impeller is above diaphragm within pericardial sac - impeller can cause artifact

Question 3

Temporary form of cardiac mechanical support

Answer 3

• Intra-aortic balloon pump
• ECMO
• Impella - may confirm position of catheter in LVOT
• Tandem

Question 4

Red Flag Findings

Answer 4

• LV Dysfunction: DCM typical, LV size: mod to severely increased, LVEF <25% indicator for LVAD, LV thrombus: poses increased risk of stroke
  -RV dysfunction: LVAD can cause severe RV dysfunction
• Valve disease: significant MS corrected before LVAD impedes flow into cannula, significant AI causes blind loop
• Congenital Heart Disease: common shunts need to be closed, LVAD can reverse shunt; hypoxemia/embolization
• Other: determine integrity of Aortic Root

Question 5

LVAD Views/ modalities/ reportings

Answer 5

-LV size and function / 2D / n/a
-Valvular Assessment AV / Color M-mode / frequency and duration of AV opening (opening/ opening intermittingly/ remaining closed)
-Valvular Assessment MV / Color / MR should reduce
-Valvular Assessment TV/PV / Color / insufficient LV unloading or excessive LV unloading
-IVS Position / 2D / neutral, rightward shift, leftward shift
-Inflow Cannula Position / Color, PW, CW / Peak Systolic and Diastolic velocities
-Outflow Graft Interrogation / Color, CW, PW / LVAD output

Question 6

Velocity norms: Inflow and Outflow

Answer 6

-Inflow Cannula: Norm ≤ 1.5 m/s ; increased may suggest obstruction
-Outflow Graft: Norm ≤ 2 m/s ; Obstruction > 2 m/s

Question 7

BP determination and Norms

Answer 7

Mean Arterial Pressure: < 85 mmHg
increased pump speed with increased MAP: Hypertension
decreased pump speed with MAP < 60 mmHg: Hypotension

Question 8

LVAD optimization protocol

Answer 8

-Speed Change (ramp) Test: limited imaging at various pump speeds for optimization
-Comprehensive TTE at baseline speed followed by stepwise incremental adjustment to LVAD speed with collection of prespecified echocardiographic parameters
-Reasons to stop: completion of test, a suction event, symptoms of hypotension < 60mmHg, symptoms of hypertension > 100mmHg

Question 9

Suction Event

Answer 9

• Cannula directed towards septum may cause septum to be sucked into cannula due to LV decreasing in size, moving the septum towards the cannula

Question 10

Signs of too low LVAD speeds

Answer 10

-LVIDd increased
-Rightward shift IVS
-More prominent MR
-Frequent AV opening
-RA and RVSP increased

Question 11

Signs too high LVAD speeds

Answer 11

-Leftward shift IVS
-IVS impedes flow into cannula
-Worsening TR and AI

Question 12

Optimal LVAD speeds

Answer 12

-Keeps AV closed
-Only Intermittent AV opening
-Speed just one below max speed

Question 13

LVAD Recovery Protocol

Answer 13

• determines suitability of LVAD removal
• identify a pump speed at which there is no forward or reverse pump flow (neutral flow)
• hemodynamic measurements assessed at this low speed after 5 mins, 15 mins, and after a 6 min walk