Ventricular Assist Devices

Slide 1 · Ventricular Assist Devices

Mechanical support, hemodynamics and clinicopathologic complications

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning outcomes

Explain why mechanical circulatory support is used in selected patients with severe cardiac failure.

Trace the blood-flow circuit and predict the physiologic effects of LV unloading.

Recognize the mechanisms of device-related thrombosis, bleeding, infection and organ injury.

Integrate gross/device findings with clinical presentation and device function.

Slide 3 · Clinical problem: Inadequate forward cardiac output

Myocardial injury or dysfunction

Ventricular pumping fails

Reduced effective forward flow

Organ perfusion becomes inadequate

Elevated filling pressure

Pulmonary or systemic congestion

Slide 4 · Robbins: Causes that may require VAD support

Potentially reversible dysfunction

Transient postoperative myocardial stunning

Acute severe dysfunction following myocardial infarction

Progressive disease

Advanced dilated or other cardiomyopathy

End-stage ventricular failure despite treatment

Slide 5 · Why medical therapy may not be enough

Advanced heart failure can persist despite guideline-directed medications and device-based therapies.

Continuous inotropic dependence or recurrent low-output admissions may indicate exhausted reserve.

An assist pump provides forward flow without replacing the whole heart.

The treatment is reserved for carefully selected patients—not routine heart failure care.

Slide 6 · Low output and congestion are distinct targets

Low forward output

Fatigue, hypoperfusion and end-organ dysfunction

VAD flow can augment systemic delivery

High filling pressure

Pulmonary venous congestion and dyspnea

Left ventricular unloading may reduce left-sided pressure

Slide 7 · The conceptual task of a VAD

Blood enters the pump

Inflow from a ventricular chamber

External mechanical

Work

Rotor creates forward pressure / flow

Blood exits to artery

Flow returns to systemic or pulmonary circuit

Slide 8 · VADs supplement rather than replace cardiac anatomy

The native ventricle, valves and vessels remain present in conventional VAD support.

The implanted circuit diverts some blood through a mechanical pump.

Native ejection may continue, depending on residual ventricular function and settings.

Device performance depends on interactions with both ventricles and vascular resistance.

Slide 9 · What transplantation shortage changes

Advanced refractory

Heart failure

Need for sustained circulation

Donor heart

Unavailable now

Transplant access is limited

Durable VAD support

Survival and conditioning during wait

Slide 10 · Bridge to transplantation

Durable support sustains circulation while an eligible patient awaits a donor heart.

Improved mobility and end-organ function may make transplantation more feasible.

VAD-related complications can still alter candidacy during the waiting period.

The intent is to transition from support to transplant when an organ becomes available.

Slide 11 · Bridge to myocardial recovery

Temporary support can provide time for reversible dysfunction to improve.

Recovery is plausible in selected postoperative or acute-injury settings.

Durable support can occasionally enable reassessment for sufficient native recovery.

Explantation requires documented physiologic reserve—not symptoms alone.

Slide 12 · Long-term support without planned transplant

Destination therapy is an established pathway for selected transplant-ineligible patients.

Increasing use outside the transplant-candidate population.

Long-term benefit must be weighed against bleeding, stroke, infection and device dependence.

Transplant ineligibility requires individualized assessment, not a single historical label.

Slide 13 · Bridge to decision: When prognosis is uncertain

Shock or rapidly

Changing condition

Immediate hemodynamic instability

Temporary

Stabilization

Acute mechanical support when appropriate

Repeated evaluation

Recovery, durable VAD, transplant or other care

Slide 14 · Distinct indications, shared mechanical principle

Strategy

Main therapeutic goal

Reassessment point

Bridge to transplant

Maintain support until a donor is available

Transplant eligibility

Bridge to recovery

Permit native function to recover

Demonstrable ventricular reserve

Destination therapy

Long-term circulation without planned transplant

Ongoing benefits and complications

Bridge to decision

Stabilize while next step is clarified

Reversibility and candidacy

Slide 15 · Temporary and durable support are not interchangeable

Temporary mechanical support

Designed for acute instability or short stabilization

Duration and invasiveness vary by platform

May bridge to recovery or durable therapy

Durable VAD

Intended for sustained support in selected patients

Requires long-term monitoring and external support systems

Device-related complications accrue over time

Slide 16 · A left-sided VAD supports systemic output

Left ventricle

Native LV cavity

LVAD pump

Rotary blood pump

Aorta

Systemic outflow

Inflow cannula

Outflow graft

Controller + external power

Percutaneous driveline

Schematic: Conventional LV-to-aorta bypass. Not a surgical diagram.

Slide 17 · Right- and biventricular support

RVAD

Drains systemic venous / right-heart blood

Returns flow into pulmonary artery

Selected when RV output is inadequate

Biventricular support

Supports both circulations when both ventricles fail

Requires matched systemic and pulmonary flows

Adds device and management complexity

Slide 18 · The LVAD circuit: Four crucial components

Component

Function

Failure mode to recognize

Inflow cannula

Directs LV blood into pump

Obstruction or malposition

Pump

Adds energy and drives forward flow

Thrombosis or mechanical malfunction

Outflow graft

Delivers blood toward aorta

Kinking or obstruction

Driveline / controller / power

Supplies and regulates pump operation

Infection, cable or power problems

Slide 19 · Flow path is parallel to native LV ejection

Left ventricle

Native LV cavity

LVAD pump

Rotary blood pump

Aorta

Systemic outflow

Inflow cannula

Outflow graft

Controller + external power

Percutaneous driveline

Native ventricular ejection may also pass through the aortic valve (not shown in this simplified circuit).

Slide 20 · Rotary continuous-flow pump physiology

Blood contacts

Engineered surfaces

Rotary element generates pressure

Continuous pump output

Less pulsatile arterial waveform

Blood–material

Interaction

Thrombotic and bleeding tradeoffs

Slide 21 · Continuous flow does not mean zero cardiac pulsatility

Native ventricular contraction can contribute a varying pulse waveform.

Pulse amplitude depends on residual native ejection and degree of pump support.

Absent or weak peripheral pulses do not by themselves indicate circulatory arrest.

Clinical assessment uses the patient, device parameters and appropriate pressure measurement.

Slide 22 · LV unloading reduces myocardial wall stress

Pump withdraws LV

Blood

Lower ventricular volume

LV filling pressure

May fall

Less pulmonary venous congestion

Wall stress may

Decrease

Altered cardiac loading conditions

Slide 23 · Preload is a limiting condition for pump output

Insufficient LV

Filling

Hypovolemia or reduced RV output

Low inflow

Availability

Unstable LVAD flow

Excessive unloading

Risk of suction event

Slide 24 · Afterload also matters to LVAD performance

Higher systemic

Vascular resistance

Larger pressure gradient to aorta

Rotary pump flow may

Decline

At unchanged pump setting

Hemodynamic

Optimization

Requires individualized assessment

Slide 25 · Interventricular coupling is central

Potential benefit

Lower LV filling pressure can reduce pulmonary congestion

Systemic perfusion may improve

Potential hazard

Greater systemic flow increases RV venous return

Leftward septal displacement can worsen RV mechanics

Slide 26 · Why right-ventricular failure can appear after LVAD

LVAD augments systemic

Flow

More venous return reaches RV

RV must deliver

Pulmonary flow

Limited contractility or elevated PVR

RV decompensation

Low LV filling and systemic congestion

Slide 27 · RV dysfunction versus pump malfunction

Finding

Consider RV failure

Consider inflow / device issue

Systemic venous congestion

Often present

Not necessarily

LV filling

May be inadequate

May be inadequate

Device alarms

Can occur indirectly

May suggest direct malfunction

Best interpretation

Echo + hemodynamics

Device log + imaging + labs

Slide 28 · Aortic valve opening may diminish

Increased LVAD

Unloading

Lower LV systolic pressure

Aortic valve may open

Less often

Dependent on native contractility

Valve and root

Dynamics change

Potential contribution to late complications

Slide 29 · Aortic regurgitation can create recirculation

Left ventricle

Native LV cavity

LVAD pump

Rotary blood pump

Aorta

Systemic outflow

Inflow cannula

Outflow graft

Controller + external power

Percutaneous driveline

Regurgitant recirculation (if aortic valve leaks)

Schematic only

Slide 30 · Who deserves evaluation for durable VAD?

Selected patients with advanced refractory heart failure despite appropriate treatment.

Patients dependent on intravenous inotropes or short-term mechanical support may warrant review.

Functional limitation, repeated admissions and end-organ injury add important context.

Indication requires multidisciplinary assessment rather than one laboratory cutoff.

Slide 31 · Anatomic and clinical feasibility must align

Cardiac and vascular factors

Size and geometry of ventricular cavity

Right ventricular performance and valve lesions

Pulmonary vascular resistance

Patient and systems factors

Neurologic, renal, hepatic and infectious comorbidity

Ability to manage external power and driveline

Patient goals, caregiver resources and follow-up

Slide 32 · Contraindications are context-dependent

Irreversible severe end-organ disease may limit meaningful benefit.

Active uncontrolled infection and inability to tolerate requisite therapy raise major concerns.

Uncorrectable anatomy or profound right-heart dysfunction may change device strategy.

Eligibility decisions depend on device, timing, goals and expert review.

Slide 33 · What to assess before implantation

Domain

Main question

Typical assessment

Ventricular function

Can the RV support pulmonary flow?

Echocardiography / hemodynamics

Peripheral organs

Is injury reversible?

Renal, hepatic and perfusion assessment

Hemostasis / infection

Can device therapy be sustained?

Bleeding and infectious evaluation

Patient factors

Is ongoing device care feasible?

Shared decision-making and support evaluation

Slide 34 · Early postoperative physiology can change rapidly

New pump circuit

Immediate LV unloading

Volume / RV / vascular

Adaptation

New biventricular equilibrium

Monitoring and

Optimization

Balance inflow, output and tissue perfusion

Slide 35 · Living with a durable implanted system

Implanted components

Pump, inflow and outflow connections

Percutaneous driveline in many systems

Daily external dependence

Controller and reliable power supply

Aseptic exit-site care and alarm response

Regular specialist surveillance

Slide 36 · The central hemocompatibility paradox

Thrombosis risk

Foreign surface activates coagulation and platelets

Flow stasis or disturbed flow favors thrombus

Embolism and pump dysfunction may result

Bleeding risk

Antithrombotic treatment reduces thrombotic risk

Rotary shear changes von Willebrand function

Fragile mucosal vessels may bleed

Slide 37 · Why artificial blood-contacting surfaces thrombose

Protein adsorption

Plasma proteins coat foreign surface

Platelet adhesion / activation

Cellular thrombotic response

Coagulation cascade

Thrombin and fibrin generation

Thrombus formation

Local occlusion or embolization

Slide 38 · Mechanical shear can damage erythrocytes

High shear / abnormal

Flow

Mechanical red-cell stress

Intravascular

Hemolysis

Plasma free Hb and LDH rise

Possible clinical

Signals

Dark urine, anemia or organ injury

Slide 39 · Acquired von Willebrand syndrome

High shear in

Continuous-flow

Circuit

Von Willebrand factor unfolds / is altered

Loss of large

Functional multimers

Impaired primary hemostasis

Increased mucosal

Bleeding tendency

Especially with other bleeding risks

Slide 40 · Why gastrointestinal bleeding is multifactorial

Circulating factors

Required antithrombotic therapy in many devices

Acquired von Willebrand abnormalities

Other patient-specific coagulation risks

Vascular factors

Gastrointestinal angiodysplasia or vascular lesions

Changes in pulsatility and local perfusion may contribute

Mechanisms of lesion development remain incompletely settled

Slide 41 · Hemorrhage versus thrombus: Diagnostic tension

Clinical problem

Priority question

Important tradeoff

GI hemorrhage

Where is the bleeding source?

Interrupting therapy may increase thrombosis

Suspected pump thrombus

Is flow impaired and blood being hemolyzed?

Therapy may increase bleeding

Ischemic stroke

What mechanism and brain territory?

Bleeding risk affects management

Intracranial hemorrhage

What is the extent of bleeding?

Device still requires safe circulation

Slide 42 · Pump thrombosis: A mechanically amplified problem

Disturbed flow /

Prothrombotic state

Thrombus develops in pump circuit

Flow obstruction or

High shear

Worsened mechanical efficiency

Hemolysis and low-flow

Signals

Systemic hypoperfusion or embolization

Slide 43 · Stroke can be ischemic or hemorrhagic

Ischemic mechanisms

Thromboembolism from pump, heart or vessel

Underlying vascular disease also contributes

May cause sudden focal neurologic deficits

Hemorrhagic mechanisms

Antithrombotic exposure

Hemostatic abnormalities and other vascular risks

Requires urgent neurologic evaluation

Slide 44 · Suction events reflect excessive local unloading

Low LV preload or high

Relative support

LV cavity becomes small

Inflow cannula

Intermittently

Contacts wall

Reduced inflow / abnormal flow

Hemodynamic

Instability

Assess patient, RV and device together

Slide 45 · Mechanical obstruction: Locate the problem

Site

Illustrative problem

Effect

Inflow

Cannula malposition or thrombus

Poor ventricular drainage

Pump

Internal thrombosis or malfunction

Unreliable forward energy transfer

Outflow

Graft kink, twist or thrombus

Resistance to aortic delivery

Power / control

Disconnected or failing components

Interrupted or abnormal pump function

Slide 46 · Aortic insufficiency can reduce effective output

Pump delivers blood to

Aorta

Aortic pressure maintained

Regurgitant leak into

LV

Part of blood returns to chamber

Blood recirculates

Through pump

Effective systemic flow may fall

Slide 47 · Right-heart failure remains a major limitation

A left-sided pump cannot compensate for completely inadequate RV output.

Right atrial and systemic venous pressures may rise despite apparently functioning LVAD.

Hepatic and renal congestion can persist or worsen.

RV mechanics, pulmonary circulation and pump flow must be assessed together.

Slide 48 · The driveline crosses an infection-prone barrier

External-to-internal cable

Percutaneous skin crossing

Barrier disruption

Potential microbial entry

Local exit-site infection

May track deeper along hardware

Systemic complication

Bloodstream or deep device infection

Slide 49 · Different infectious syndromes must be separated

Syndrome

Anatomic emphasis

Clinical implication

Exit-site infection

Skin / superficial tract

Local inflammation, possible drainage

Deep driveline infection

Internal tract or contiguous tissues

Higher burden of source control

Pump / pocket infection

Implanted device surroundings

Biofilm and difficult eradication

Bloodstream infection

Intravascular dissemination

Potential systemic organ injury

Slide 50 · Foreign bodies alter infection biology

Implanted surface +

Microbial access

Device colonization can occur

Biofilm-associated

Persistence

Organisms protected within matrix

Hard-to-eradicate

Focus

Treatment may be prolonged or complex

Slide 51 · Mechanical and power failures are time-critical

Potential causes

Cable or connector failure

Controller or power problems

Mechanical failure or obstruction

Clinical consequences

Declining forward flow

Hemodynamic compromise

Urgent device-team evaluation

Slide 52 · Evaluate the patient—not a number alone

Integrate perfusion, mentation, congestion, bleeding and infection signs.

Review pump speed, estimated flow, power use and alarm history.

Interpret echocardiographic anatomy and ventricular interactions.

Compare serial trends; Isolated device readouts may mislead.

Slide 53 · Differential of unexpectedly low VAD flow

Physiologic category

Examples

Initial interpretive clue

Low preload

Volume depletion, RV failure

Small or underfilled LV

High afterload

Elevated systemic resistance

Reduced pump flow at given speed

Flow pathway obstruction

Inflow or outflow problem

Anatomic or device abnormality

Electrical / device malfunction

Power or controller issue

Alarm and device-log context

Slide 54 · A practical workup for suspected pump thrombosis

Clinical / device concern

Low flow, power change or hemolysis

Laboratory and device evaluation

LDH, anemia / hemolysis, controller logs

Cardiac and vascular imaging

Echo and targeted conduit assessment

Expert integrated diagnosis

Differentiate thrombus from other causes

Slide 55 · Echocardiography links anatomy to device function

Heart assessment

LV size and septal position

RV size and systolic performance

Aortic valve opening and regurgitation

Mechanical-support questions

Does LV unload appropriately?

Could inflow be impeded?

Does physiology explain low flow?

Slide 56 · Pathologic examination of an explanted VAD

Maintain orientation

And chain of

Documentation

Identify inflow, pump, outflow and driveline

Inspect for occlusion

And surface deposits

Photograph and localize abnormalities

Correlate with

Microbiology and

Histology

Interpret with clinical and device data

Slide 57 · Thrombus pathology: Location matters

What may be present

Adherent thrombus on blood-contacting components

Inflow or outflow luminal material

Native ventricular thrombus

What must be established

Precise site and degree of obstruction

Relationship to local flow geometry

Potential embolic or hemolytic consequences

Slide 58 · Tissue response under sustained unloading

Ventricular loading conditions change substantially during LVAD support.

Myocardial size and geometry may remodel; Improvement does not ensure recovery.

Underlying cardiomyopathic injury may remain despite better perfusion.

Morphology alone cannot establish that device explantation is safe.

Slide 59 · Assessment of genuine myocardial recovery

Clinical stability on support

Symptoms and organ function improve

Serial structured testing

Imaging and hemodynamic reassessment

Trial of reduced support when

Suitable

Native reserve assessed by expert team

Explant only if recovery is

Sufficient

Durable native circulation expected

Slide 60 · The key device–pathology correlation

Observed problem

Potential mechanism

Evidence to seek

Dark urine / rising LDH

Shear-related hemolysis

Pump / circuit and laboratory correlation

Melena / anemia

Angiodysplasia + hemostatic defects

GI source and therapy review

Fever / driveline drainage

Device-associated infection

Exit tract, cultures, imaging

Systemic venous congestion

RV failure

Right-heart echo and hemodynamics

Slide 61 · Case: Stunned myocardium after surgery

Illustrative teaching case

A postoperative patient has profound but potentially reversible ventricular dysfunction and cannot maintain adequate perfusion without advanced support.

Discussion questions

What makes this a recovery-oriented scenario?

Why might temporary support precede a durable device?

Which organ-function trends would matter?

Slide 62 · Case: Cardiomyopathy awaiting a donor

Illustrative teaching case

A transplant-eligible patient with refractory cardiomyopathy is deteriorating while waiting for a donor heart.

Discussion questions

What is the main intent of durable support?

How might end-organ function and physical condition change?

Which device complications must be monitored?

Slide 63 · Case: End-stage failure without transplant plan

Illustrative teaching case

A patient with refractory LV failure is judged unsuitable for transplantation, but durable support might align with the patient’s goals.

Discussion questions

What is the intended therapeutic pathway?

Why is transplant ineligibility not equivalent to VAD ineligibility?

What must informed consent explicitly include?

Slide 64 · Case: Gastrointestinal bleeding on LVAD

Illustrative teaching case

A recipient of a continuous-flow LVAD develops recurrent melena and anemia despite no obvious device malfunction.

Discussion questions

Which nonmechanical hemostatic change can contribute?

What vascular lesion type is often implicated?

Why is the treatment balance difficult?

Slide 65 · Case: Hemolysis and altered device power

Illustrative teaching case

A long-term LVAD recipient develops dark urine, biochemical hemolysis and an unexpected change in pump parameters.

Discussion questions

What potentially serious device complication must be considered?

What alternative explanations should be assessed?

Why are clinical, laboratory and device records all needed?

Slide 66 · Clinical synthesis: Benefits and burdens

Physiologic benefit

Reason it matters

Associated vulnerability

Improved systemic flow

Tissue perfusion / functional status

Dependence on electrical pump

LV unloading

Less filling pressure / congestion

RV–LV interaction and suction

Long-term support

Transplant bridge or destination

Cumulative infectious / blood risks

Blood pumping across device surfaces

Sustained circulatory support

Thrombus, hemolysis and bleeding

Slide 67 · Five clinicopathologic principles

VADs restore forward flow; They do not erase underlying myocardial disease.

The intended trajectory—recovery, transplant or long-term support—determines the care pathway.

LVAD function depends on preload, afterload and adequate RV output.

Blood–device interaction creates competing risks of clotting and hemorrhage.

Infection and mechanical complications require anatomical as well as clinical evaluation.

Slide 68 · Selected primary and specialist references

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. Elsevier; 2026.

ISHLT Guidelines for Mechanical Circulatory Support: A 10-Year Update. 2023.

ISHLT/HFSA Guideline on Acute Mechanical Circulatory Support. 2023.

ISHLT Hemocompatibility-Related Adverse Events Consensus. 2024.

ISHLT Infection Definitions for Durable and Acute MCS Devices. 2024.

AHA/ACC/HFSA Guideline for the Management of Heart Failure. 2022.