Mechanical assist devices used in the treatment of heart failure
Mechanical assist devices used in the treatment of heart failure
Mechanical circulatory assist devices (MCADs) are used in advanced or refractory heart failure to support cardiac output when optimal medical therapy is insufficient. They may be used as temporary support, bridge strategies, or destination therapy.
1. Short-term / Temporary Mechanical Circulatory Support (MCS)
Used in acute decompensated HF, cardiogenic shock, post-MI, post-cardiotomy, or as a bridge to decision.
A. Intra-Aortic Balloon Pump (IABP)
- Mechanism: Diastolic augmentation + systolic afterload reduction
- Support: ~0.5 L/min
- Benefits: Improves coronary perfusion, reduces LV afterload
- Limitations: Minimal CO support
- Key trials: IABP-SHOCK II → no mortality benefit in cardiogenic shock
- Current role: Selected cases (mechanical complications, ischemia)
B. Percutaneous Ventricular Assist Devices (pVADs)
1. Impella (2.5 / CP / 5.0 / 5.5)
- Type: Axial-flow LV assist device
- Support:
- Impella 2.5 → 2.5 L/min
- Impella CP → ~4 L/min
- Impella 5.0/5.5 → ≥5 L/min
- Advantages: Direct LV unloading
- Indications: Cardiogenic shock, high-risk PCI
- Complications: Hemolysis, vascular injury, aortic valve issues
2. TandemHeart
- Mechanism: LA → femoral artery centrifugal pump
- Support: Up to 5 L/min
- Limitations: Requires transseptal puncture
C. Veno-Arterial ECMO (VA-ECMO)
- Support: Full cardiopulmonary support (4–6 L/min)
- Indications: Refractory cardiogenic shock, cardiac arrest (ECPR)
- Major issue: ↑ LV afterload → may require LV venting (IABP/Impella)
- Role: Bridge to recovery, VAD, or transplant
2. Intermediate-term Devices
Used as bridge to recovery or bridge to transplant.
A. Surgically Implanted Temporary VADs
- Examples: CentriMag, Abiomed BVS 5000
- Can support LV, RV, or BiV
- Used in postcardiotomy shock or severe myocarditis
3. Long-term Durable Ventricular Assist Devices (LVADs)
Used in Stage D chronic heart failure.
A. Continuous-Flow LVADs (Current Standard)
1. HeartMate 3 (MagLev centrifugal pump)
- Indications:
- Bridge to transplant (BTT)
- Destination therapy (DT)
- Advantages:
- Lower pump thrombosis
- Artificial pulse
- Trials: MOMENTUM-3 → superior to HeartMate II
2. HeartWare HVAD (withdrawn)
- Higher stroke risk → no longer implanted
B. BiVADs and Total Artificial Heart (TAH)
1. BiVAD
- For severe biventricular failure
- Combination of LVAD + RVAD
2. Total Artificial Heart (SynCardia)
- Complete replacement of ventricles
- Indication: End-stage biventricular failure awaiting transplant
4. Special / Emerging Devices
A. Right Ventricular Assist Devices (RVAD)
- Impella RP
- ProtekDuo (dual-lumen cannula)
B. Partial Support Devices
- Investigational / niche use
- Aim to unload LV earlier in HF progression
5. Clinical Use by Strategy
| Strategy | Device Examples |
|---|---|
| Bridge to recovery | ECMO, Impella, CentriMag |
| Bridge to decision | ECMO, pVADs |
| Bridge to transplant | LVAD, BiVAD, TAH |
| Destination therapy | HeartMate 3 |
| High-risk PCI | Impella, IABP |
Key Exam Pearls (NEET-SS / DM Cardiology)
- HeartMate 3 = preferred durable LVAD
- ECMO increases LV afterload → consider venting
- Impella unloads LV directly
- IABP has minimal CO augmentation
- TAH only as bridge to transplant
1. Primary mechanism by which Impella improves systemic perfusion?
↑ Diastolic augmentation
Direct LV unloading with forward flow
RV preload reduction
Afterload increase
Impella directly unloads LV by aspirating blood from LV and expelling into ascending aorta.
2. VA-ECMO increases LV afterload because of:
Reduced venous return
Retrograde aortic flow
Pulmonary vasodilation
Reduced SVR
Retrograde arterial flow from ECMO increases LV wall stress and afterload.
3. Best LV venting strategy during VA-ECMO?
Dobutamine
Impella
Phenylephrine
Nitroprusside
Impella provides active LV unloading during ECMO.
4. Impella CP provides approximate flow of:
1.5 L/min
4 L/min
6 L/min
8 L/min
Impella CP provides ~3.5–4 L/min of flow.
5. IABP improves coronary perfusion by:
Diastolic augmentation
Increasing systolic pressure
LV aspiration
Pulmonary artery unloading
Balloon inflation in diastole augments coronary perfusion.
6. Trial showing no mortality benefit of IABP in shock?
SHOCK
IABP-SHOCK II
CULPRIT-SHOCK
DANSHOCK
IABP-SHOCK II demonstrated no mortality benefit.
7. TandemHeart withdraws blood from:
LV apex
Left atrium
RV
Pulmonary artery
TandemHeart drains LA via transseptal cannulation.
8. Most durable LVAD currently preferred?
HeartMate II
HeartMate 3
HVAD
Jarvik 2000
HeartMate 3 has lowest pump thrombosis rates.
9. MOMENTUM-3 trial compared:
HeartMate 3 vs HeartMate II
HVAD vs ECMO
IABP vs Impella
TAH vs BiVAD
MOMENTUM-3 established HeartMate 3 superiority.
10. Most common complication of Impella?
Hemolysis
Stroke
Endocarditis
Valve thrombosis
High shear stress causes hemolysis.
11. Primary reason VA-ECMO may worsen pulmonary edema?
Reduced RV preload
LV distension due to increased afterload
Pulmonary vasoconstriction
Increased venous capacitance
Retrograde ECMO flow increases LV afterload → LV distension → pulmonary edema.
12. Impella is contraindicated in:
Severe LV dysfunction
Mechanical aortic valve
Cardiogenic shock
Ischemic cardiomyopathy
Impella traverses aortic valve → contraindicated in mechanical AVR.
13. Best device for isolated acute RV failure post-LVAD?
IABP
Impella RP
HeartMate 3
VA-ECMO
Impella RP provides direct RV support.
14. TandemHeart advantage over Impella?
Higher achievable flow
No anticoagulation
No transseptal puncture
Lower bleeding risk
TandemHeart can deliver up to 5 L/min but requires transseptal access.
15. HeartMate 3 reduces thrombosis due to:
Axial flow design
Magnetic levitation with artificial pulse
Higher RPM
Smaller inflow cannula
MagLev centrifugal pump reduces shear stress and stasis.
16. INTERMACS profile best suited for durable LVAD?
Profile 1
Profile 3
Profile 7
Profile 6
Profile 3 = stable but inotrope dependent → optimal LVAD timing.
17. Most effective LV unloading strategy in ECMO shock?
Nitroglycerin
ECPELLA (ECMO + Impella)
High PEEP
IABP alone
ECPELLA provides active LV unloading and systemic support.
18. Primary cause of hemolysis in axial-flow devices?
High shear stress
Low RPM
Low preload
Valve regurgitation
Axial pumps generate high shear → RBC destruction.
19. Total artificial heart indication?
Isolated LV failure
End-stage biventricular failure awaiting transplant
HFpEF
Acute myocarditis
TAH replaces both ventricles as bridge to transplant.
20. Common late complication of durable LVAD?
Hemothorax
GI bleeding (AVMs)
ARDS
Pulmonary embolism
Continuous flow → acquired vWF deficiency → GI AVMs.
21. Why HVAD withdrawn from market?
Low flow
Higher stroke and mortality rates
Pump thrombosis only
Infection risk
HVAD showed higher neurological events.
22. Impella position confirmation best done by?
Chest X-ray
Echocardiography
Fluoroscopy only
Arterial waveform
Echo ensures inflow in LV and outflow in aorta.
23. Preferred anticoagulation with Impella?
Heparin
Warfarin
DOAC
Aspirin alone
Heparinized purge solution required.
24. ECMO flow primarily depends on?
LV contractility
Pump speed and venous return
SVR
Heart rate
ECMO is preload dependent.
25. Most common cause of LVAD low-flow alarms?
Pump thrombosis
Hypovolemia or RV failure
Hypertension
Stroke
Low preload is commonest trigger.
26. Device providing both oxygenation and circulation?
Impella
VA-ECMO
IABP
LVAD
Only ECMO provides gas exchange.
27. Major determinant of RV failure post-LVAD?
Pre-existing RV dysfunction
LV size
Aortic regurgitation
Heart rate
RV reserve is critical before LVAD.
28. Aortic regurgitation in LVAD causes:
Improved preload
Recirculation and reduced systemic output
Increased pulsatility
RV unloading
Blood cycles LVAD → aorta → LV.
29. Destination therapy LVAD means:
Temporary support
Permanent therapy without transplant intent
Bridge to recovery
Bridge to decision
DT patients are not transplant candidates.
30. Common infection site in LVAD patients?
Driveline exit site
Pump housing
Pericardium
Pulmonary artery
Driveline infections are common late issues.
31. IABP timing relative to ECG?
Inflation at dicrotic notch
R wave
P wave
Mid-systole
Inflation in diastole optimizes coronary flow.
32. Best marker of adequate LV unloading on Impella?
Blood pressure
Reduction in LVEDP
Heart rate
CVP
LVEDP reflects unloading effectiveness.
33. Common neurologic complication of ECMO?
Ischemic or hemorrhagic stroke
Myelitis
Neuropathy
Seizure only
Thromboembolism and bleeding cause stroke.
34. LVAD patients often lack palpable pulse due to:
Low BP
Continuous-flow physiology
Atrial fibrillation
Bradycardia
Continuous flow reduces pulsatility.
35. Best imaging to detect LVAD pump thrombosis?
CT chest
Echocardiography + device parameters
MRI
PET scan
Echo + power/RPM trends are key.
36. LVAD reduces pulmonary pressures by:
Lowering LV filling pressures
Direct PA suction
RV bypass
Vasodilation
LV unloading lowers LA and PA pressures.
37. Impella RP draws blood from:
RA
IVC/RA and expels into PA
RV apex
LV
Provides RA/IVC to PA support.
38. Weaning from ECMO requires:
Normal EF only
Stable hemodynamics with reduced ECMO flow
Normal lactate alone
High vasopressor dose
Flow reduction trials assess native recovery.
39. Most definitive therapy for end-stage HF?
LVAD
Cardiac transplantation
ECMO
IABP
Transplant offers survival advantage.
40. ECMO + LVAD simultaneously implies:
Bridge to recovery only
Bridge to decision in refractory shock
Destination therapy
Palliative care
Used when trajectory unclear and recovery/transplant uncertain.
50 ULTRA-HARD ONE-LINER TRAPS (MCS / VAD)
- VA-ECMO increases LV afterload due to retrograde aortic flow, not increased SVR.
- Pulmonary edema on VA-ECMO implies LV distension until proven otherwise.
- Impella unloads LV by reducing LVEDP, not by augmenting diastolic pressure.
- IABP provides hemodynamic support but minimal cardiac output augmentation (~0.5 L/min).
- ECPELLA = ECMO for perfusion + Impella for unloading, not redundancy.
- Hemolysis is more common with axial-flow than centrifugal-flow pumps.
- Mechanical aortic valve is an absolute contraindication to Impella.
- Continuous-flow LVAD patients may have MAP without a palpable pulse.
- HeartMate 3 reduces pump thrombosis via magnetic levitation and artificial pulse.
- GI bleeding in LVAD is due to acquired von Willebrand syndrome, not anticoagulation alone.
- TandemHeart drains the left atrium, not the left ventricle.
- VA-ECMO provides oxygenation; LVADs do not.
- Impella CP provides ~4 L/min flow—not full cardiac replacement.
- Low LVAD flow alarms most commonly reflect hypovolemia or RV failure.
- INTERMACS 3 is the optimal timing window for durable LVAD implantation.
- INTERMACS 1 patients usually require temporary MCS before durable LVAD.
- RV failure post-LVAD is predicted best by pre-implant RV dysfunction.
- Aortic regurgitation in LVAD causes circulatory recirculation, not forward flow.
- HVAD withdrawal was driven by stroke risk, not pump thrombosis alone.
- ECMO is preload dependent—poor venous return limits flow.
- Impella RP draws blood from IVC/RA and expels into pulmonary artery.
- Stroke on ECMO may be ischemic or hemorrhagic due to anticoagulation balance.
- ECMO weaning requires stable hemodynamics at reduced flow—not normal EF.
- IABP inflation occurs at the dicrotic notch, not the R wave.
- LV unloading is best assessed by fall in LVEDP, not blood pressure.
- Durable LVAD destination therapy implies no transplant intent.
- Driveline exit site is the most common LVAD infection source.
- VA-ECMO alone may worsen myocardial recovery by increasing wall stress.
- Impella causes hemolysis due to shear stress, not anticoagulation.
- TAH is used only for biventricular failure as bridge to transplant.
- High PEEP reduces LV preload but does not unload LV on ECMO.
- MAP target in LVAD patients is usually 65–80 mmHg by Doppler.
- LVAD patients are prone to aortic valve fusion from chronic non-opening.
- ECMO + LVAD together signifies bridge-to-decision, not destination therapy.
- Pump thrombosis presents with rising power consumption and hemolysis.
- Impella position is best confirmed by echocardiography, not X-ray alone.
- Axial-flow pumps generate continuous non-pulsatile flow.
- ECMO cannulation itself increases afterload independent of vasopressors.
- Right heart failure worsens after LVAD due to increased venous return.
- LVAD lowers pulmonary pressures by unloading LA, not direct PA action.
- Stroke risk is higher early after LVAD implantation.
- LVAD patients often develop hypertension despite low pulse pressure.
- ECMO without LV venting risks intracardiac thrombosis.
- Impella reduces myocardial oxygen demand by decreasing wall stress.
- IABP mortality benefit in shock was refuted by IABP-SHOCK II.
- Continuous-flow LVADs predispose to AV malformations via low pulsatility.
- VA-ECMO does not correct LV ischemia unless unloading is added.
- Cardiac transplantation remains the only definitive cure for end-stage HF.
- INTERMACS profiles predict urgency, not etiology of heart failure.
- Absence of pulse does not equal absence of perfusion in LVAD patients.
