2. Scope of presentation
• Historical Perspective
• Implant Strategies
• Biological Concepts
• Engineering Concepts
• Generations Of Devices
• Patient Selection
• Device Selection
• Indications
• Surgical Techniques for Durable LVAD
• Post op Management and Anticoagulation
• Complications
• Landmark Studies
3. Definition
• VAD is a means of imparting energy for forward flow of blood in the
body by mechanical devices. Its intent is to remove some or all the
work of cardiac output from either or both the ventricles.
• These are surgically placed and can be used for variable duration
depending upon the pathology for which it is required.
4. HISTORICAL PERSPECTIVE
• Major interest in the mechanical support of human circulation came
after the dawn of open heart surgery in 1950s.
• Failure to successfully wean some patients off CPB stimulated
surgeons to seek additional methods for circulatory supports while
awaiting myocardial recovery.
• 1966 - First application of a true ventricular assist device is attributed
to DeBakey who reported successful application of a pneumatically
driven diaphragm pump for 10 days in a 37 years old woman unable
to be weaned from CPB following aortic and mitral valve
replacements.
5. • 1978 – Dr Denton Cooley subsequently reported the first successful
bridge to transplant for 64 hours in a 47 years old man with the
‘LIOTTA HEART’ (pneumatically driven artificial heart)
6. • The research then focused on pneumatic, electric and even nuclear
powered devices.
• After an initial hiatus, cardiac transplantation had reappeared as an viable
therapeutic modality for heart failure after an advancement in
immunosuppression (with cyclosporin) in 1980s.
• Cardiac transplantation provided the stimulus for proliferation of
ventricular assist systems as a bridging therapy to transplantation. With
nearly 30% of patients dying while awaiting cardiac transplantation, a clear
need developed for effective and durable MCDs that could safely support
patients until suitable donor hearts could be identified.
• 1980 – NHLBI (US) accepted proposals by Abiomed, Baxter, Thermo
Cardiosystems and Thoratec to develop VADs.
• 1984 – Oyer, Portner and collegues reported successful cardiac transplant
following bridging with Novacor LVAD.
• 1985 – Hill and collegues reported successful transplantation following
support with a Pierce Donachy pneumatic LVAD.
7. • 1994 - US FDA approved implantable device as a BTT, first of which
was HeartMate by Thoratec.
• Despite the early focus being the VADs as a bridging therapy, the clear
intent of the scientific and engineering community was to develop
devices capable of safe and long term circulatory support.
• 2001 - Major victory for VADs as a long term MCS came with the
REMATCH trial (Rose and collegues) – HeartMate XVE VAD provided
excellent survival benefit at 1 and 2 years when compared with
medical therapy in patients with very advanced heart failures who are
not suitable for transplant.
• 2002 - After the REMATCH trial, FDA approved VADs as a ‘Destination
Therapy’.
8. • In recent years, device technology has increasingly focused on smaller,
simpler, and likely more durable continuous flow (rotary) pumps that
lack the pulsatile characteristics of earlier first-generation pumps.
• 2009 - Slaughters, Rogers and Milano demonstrated (REMATCH II NEJM)
that a continuous flow pump significantly improved 2-year survival and
device-related morbidity as compared with a pulsatile device.
• As VAD therapy entered the mainstream, INTERMACS (Interagency
Registry for Mechanically Assisted Circulatory Support) a national (US)
registry for patients who are receiving MCS devices was established in
2006. Analysis of the data collected is expected to facilitate further
improvements in patient evaluation and management.
9. IMPLANT STRATEGIES
Five broad indications can be defined with regard to the clinical intent
at the time of implantation.
1. Bridge to Transplant (BTT)
2. Destination Therapy (DT)
3. Bridge to Candidacy (BTC)
4. Bridge to Decision (BTD)
5. Bridge to Recovery (BTR)
10. Bridge to Transplant
BTT is a strategy for patients actively listed for heart transplant
who would not survive or would develop end organ dysfunction as
a result of low cardiac output before an organ becomes available.
While the patient remains on the waiting list, insertion of a
durable LVAD can improve survival, functional status, and quality
of life.
11. Destination Therapy
DT is a strategy for patients requiring long-term, lifelong circulatory
support who are not eligible for heart transplant because of
relative or absolute contraindications.
12. Bridge to Candidacy
For patients who are not currently listed for heart transplant, with
no absolute or a permanent contraindication to transplant. VAD
may allow these patients to be eligible for transplant by improving
their end-organ function and nutrition, decreasing pulmonary
vascular resistance, as well as resolution of comorbidities or
lifestyle-related problems (e.g., weight loss, smoking cessation).
13. Bridge to Decision
In circumstances when a patient is in acute cardiogenic shock, it
may not be possible to determine the candidacy for transplant,
long-term VADs or myocardial recovery. Additionally, the patient
may or may not have multisystem organ failure, and the patient’s
neurologic status may or may not be known. A short-term MCS
may be used to stabilize the patient’s condition and to assess
reversibility, as a bridge to more definitive therapies. The next step
can be planned while the patient is on the VAD.
14. Bridge to Recovery
VAD may be used as a temporary circulatory support to unload
the ventricle. During this time, VAD use may enhance myocardial
recovery from an acute injury enough to wean off the device
without the need for transplan
16. • BIOMATERIAL - a natural or artificial material that remains in
contact with one or more internal components of the human
body for the purpose of replacing organ function or treating an
abnormal condition.
• BIOCOMPATIBILITY - effect of a specific biomaterial on exposed
host tissues.
• HEMOCOMPATIBILITY - the specific effects of a biomaterial on
blood components, coagulation cascade, and the tendency for
thrombus formation.
17. • The ideal biocompatible surface for blood is functioning
endothelium, but the creation of a functioning endothelial layer
on a bioprosthetic surface remains elusive.
• Currently hemocompatible materials that minimize thrombogenicity
are limited which can be titanium, polymers (primarily
polyurethanes), silicone, graphite, and pyrolytic carbon.
• A fundamental concept for the understanding of bloodpump
surface interaction is the process of protein adsorption to
biomaterial surfaces. Following exposure of pump surfaces to
circulating blood in vivo, a protein layer develops that covers the
biomaterial surface. The make-up of this protein layer is
determined by the protein composition of the patient’s blood,
the chemical composition of the biomaterial surface (more
specifically, surface charge and hydrophobicity), and surface
topography (rough vs. smooth, porous vs. nonporous).
18. • Concentration of proteins in blood, net protein charge relative to
the biomaterial surface, distribution of charges on the protein
surface, and ability of the protein to undergo conformational
changes all contribute to the propensity for a given protein to
adsorb to the pump surface.
• Protein interactions with the biomaterial vary over time and are
therefore dynamic. The change in composition of proteins that
adsorb to the pump surface over time is termed the Vroman
Effect.
• The specific details of these protein-surface interactions
contribute directly to the likelihood of pump thrombogenicity,
because these proteins are biologically active and can initiate
platelet adhesion and activation and trigger coagulation cascades.
19. • Both smooth and rough surface designs have been used
successfully in pump design. The textured titanium surface of
the HeartMate pulsatile LVAD stimulates the formation of a thin,
stable coagulum that, although counterintuitive, has proven to be
effective in minimizing development of pump thrombus.
• Application of computer simulations called Computational Fluid
Dynamics (CFD) analyses has greatly facilitated the ability to
predict the effects of shear stresses in the pump flow pathway
and areas of relative stasis.
• Contact between the pump surfaces and specific plasma
proteins, can initiate the coagulation cascade via the intrinsic
pathway particularly in areas of relative blood stagnation.
20. • The additional critical component of thrombus formation is
platelet adhesion, aggregation, and activation.
• Under laminar flow conditions, the platelets cannot accumulate,
but when flow is nonlaminar, platelets are more likely to
aggregate and accumulate. Thus it is absolutely essential to maintain
laminar blood flow without any turbulence in the circuit.
21. • It remains controversial whether VADs differ in their propensity
to induce an immunologic response.
• HeartMate XVE has shown defects in T-cell function post implant,
inducing T-cell apoptosis and possibly decreased resistance to
infection.
• A major disadvantage of LVAD as a bridge to transplantation is
the frequency of patient sensitization against foreign HLA
antigens, which increases the likelihood of developing anti-HLA
antibodies against a potential donor.
• Although the pump surface has been implicated in this process,
it is more likely that transfused blood products, particularly
platelets, account for sensitization. Platelets exhibit high
concentrations of MHC class I and class II HLA antigens, and
patients receiving more than 6 platelet units are more likely to
develop IgG antibodies against MHC class I antigens.
23. • Specific technologic barriers challenging successful VAD include
development of corrosion-resistant materials with minimal toxicity
and a high level of structural integrity, management of specific
blood-contacting surfaces to minimize thrombogenicity and
damage to blood elements, blood pump design, and methods to
store energy.
• First came the pulsatile pump mechanism (which was inspired the
actual myocardial pumping action) and now the evolution in the
technology has brought us to magnetically levitated no friction
pumps.
24. Pulsatile Pumps
• Pulsatile pumps cyclically change the internal volume of a pumping
chamber, displacing a specific volume of blood with each ejection.
• Such pumps require one-way valves to generate forward flow, typically
utilizing valves in the inflow and outflow portions of the pump.
• In sealed pulsatile pumps (not vented to the atmosphere), cyclic
displacement of blood volume within the pumping chamber must be
accompanied by an equal increase of volume elsewhere within the
casing. This usually occurs via a compliance sack placed outside the
device but within the patient.
• The principles of Starling’s law also apply to circulatory pumps, in that
the pump must respond to higher inflow into the pump by increasing
output. As in the natural heart, this balance is maintained in pulsatile
pumps by variations in stroke volume or pump rate.
25. Continuous Flow Pumps
• Continuous flow pumps consist of a rotating component that has
one or more impellers (usually a disk or cylinder). One or more
bearings support the impeller.
• The assembly comprising all rotating elements is termed the
pump rotor.
• As the impeller rotates, it imparts rotational velocity to the
blood, and this rotational energy must be converted into
pressure energy to achieve forward blood flow.
• To facilitate this process, additional stationary blades or other
structures redirect the swirling blood to create pressure and
forward blood flow.
26. • The forward flow of blood through an axial flow pump is determined
primarily by the speed of the rotor and the pressure difference across
the inlet and outlet orifices of the pump.
• In the absence of obstruction to pump inflow, pressure at the outlet
orifices (aorta) always exceeds inlet pressure (left ventricle).
• At any given pump speed, blood flow through the pump increases as
the pressure difference across the inlet and outlet orifices decreases.
At any pressure difference across inlet and outlet orifices, blood flow
will increase with increasing pump speed.
27.
28. • In most situations, even in the presence of severe left ventricular
dysfunction and absence of opening of the aortic valve, continuous
flow devices contribute some degree of pulsatility to the aortic
pressure waveform secondary to the changing differential pressure
across the inlet and outlet orifices.
• Nonpulsatile blood flow occurs in situations of ventricular fibrillation,
operation of the pump at too high a pump speed, or with negative
inflow pressure causing left ventricular collapse around the inflow
orifice.
• Ideally, pump speed should be adjusted to permit intermittent
aortic valve opening, which minimizes the risk of a suction event
and may promote more effective washout of the sinuses of
Valsalva, decreasing the likelihood of thrombus formation along
the aortic valve.
29.
30. • The major cause of hemolysis in blood pumps is rapid
acceleration or deceleration of red cells through the pump (more
in pulsatile pumps), which can induce red cell membrane fracture.
• In general, pump-induced hemolysis is considered acceptable if
the plasma free hemoglobin is maintained at less than 19 mg/dL.
• The rate of pressure increase and flow-channel velocities are
maintained at levels designed to avoid high shear stress.
• Proper application of fluid dynamics is critical to minimize
thrombus formation. Because blood stasis, particularly flow
cessation promotes clot formation.
• Stationary vortex flow must be avoided because the central
stagnant portion of the vortex can become a nidus for thrombus
formation.
31. • Power sources and alarms must provide reliability and durability
backed up by software programs designed to activate
appropriate alarm systems when deviations from normal function
occur.
• Approximately 1.6 watts of power are needed to pump 6 L/min
at 120 mmHg.
• Power in excess of 1.6 watts is both wasted and converted to
heat that must safely dissipate within the body.
32. Bearings & Seals
• Bearings are devices that provide support, guide movement, and
reduce friction of motion between fixed and moving parts.
• A moving part may be a bladder or pusher plate in a pulsatile pump,
or a rotary impeller in a rotary pump.
• Bearings pose a risk of wear, and therefore failure, secondary to
continuous physical contact between solid components.
• Bearings that remain dry (without direct contact to blood) require
special seals that are themselves subject to wear and failure.
• More recent second generation pumps avoid seals by using blood
itself as the lubricant fluid, with so called blood-immersed bearings.
• The third generation of rotary pumps incorporates electromagnetic
levitation; these magnetic bearings provide support through magnetic
force fields.
37. PERCUTANEOUS DEVICES FOR SHORT TERM USE
• TandemHeart
• Impella
• HeartMate Percutaneous Heart Pump
38. TandemHeart
• Cardiac Assist, Pittsburgh
• Centrifugal
• Inflow from LA (femoral
vein - RA – Transeptal – LA)
• Outflow in Femoral artery
• 5L/min at 7500rpm
• Less popular as relatively
complex mode of insertion
39. Impella
• Abiomed, Massachusetts, US
• Intravascular microaxial rotary pump
• Inserted across AV
• Inflow from LV and outflow in the ascending aorta
• Sizes range from 2.5 to 5 (Flow 2.5L/min to 5L/min)
• Impella 5.0 is inserted by a cardiac surgeon into aorta or other large
arteries (axillary/femoral). Preliminary reports suggest better survival in
acute cardiogenic shock as compared to IABP.
• Smaller sizes are inserted percutaneously by Cardiologists.
• Impella RP is specifically designed for RV support (currently under trial)
41. HeartMate Percutaneous Heart Pump
• Thoratec, California
• Sits across AV (similar to Impella)
• Can generate 4 to 5L/min flows
• SHIELD 1 trial (2018) shows encouraging results when used in high
risk PCI.
43. Abiomed BVS5000 & AB5000
• Abiomed, Massachusetts, US
• Dual chambered, pneumatically driven, extra corporeal pump
• Univentricular or Biventricular use
• Flows upto 6L/min
44. CentriMag
• Thoratec, CA
• Extracorporeal centrifugal pump
• Magnetically levitated
• Can flow upto 10L/min
• Speed of the device can be kept at any desired level as per the clinical
scenario
• Can be used as LVAD or RVAD or BIVAD.
45.
46. SURGICAL DEVICES FOR LONG TERM USE
• First Generation (Pulsatile)
1. Thoratec HeartMate XVE
2. Thoratec Paracorporeal VAD
3. Thoratec Intracorporeal VAD
• Second Generation (Axial Flow)
1. Thoratec HeartMate II
2. Jarvik 2000
3. Micromed DeBakey
• Third Generation (Centrifugal)
1. HeartWare HVAD
2. DuraHeart
3. Thoratec HeartMate III
4. Synergy
47. Thoratec HeartMate XVE
• FDA approved for both BTT and DT
• Older version had a pump operated by a pneumatically driven
mechanism and contained a large controller console. The newer-
generation device is electrically vented and contains a portable
console and batteries, giving patients more mobility.
• Produces a pulsatile flow with a stroke volume of 83 mL and a
maximal flow of 10 liter/min. A large landmark trial of this
device has demonstrated superior outcomes compared with
optimal medical management (REMATCH Trial 2001).
• However, its long-term use is limited by the high probability of
device-related complications.
49. Thoratec Paracorporeal VAD
• For univentricular and biventricular support
• The paracorporeal placement of the pumping chamber allows the device to
be implanted in patients with body surface areas of less than 1.5 sqm.
• consists of a polyurethane blood sac contained in a polycarbonate housing,
attached to a large pneumatic console, which is used to generate a pulsatile
flow with a maximal stroke volume of 65 mL.
• The device is capable of a flow up to 7.2 liter/min.
• Tilting disc mechanical valves maintain unidirectional flow.
• Because the device is placed paracorporeally, less dissection is required.
• Inflow for the LVAD is from the left atrium or LV apex, with outflow to the
ascending aorta. Inflow for the RVAD is from the right atrium or right
ventricle, with outflow to the pulmonary artery.
• The device requires systemic anticoagulation with either heparin or warfarin.
51. Thoratec Intracorporeal VAD
• Can provide isolated left, right, or biventricular support.
• Because it is implantable, it requires more dissection than the
paracorporeal VAD.
• It is the first FDA-approved implantable VAD with biventricular
capability for BTT and BTR.
• A multicenter trial including 39 patients supported with this
device reported a success rate of 70% for BTT and 67% for BTR.
52. SECOND GENERATION DEVICES
• Axial flow pumps are continuous flow pumps that operate with a
propeller revolving at a set number of revolutions per minute (rpm).
• Advantages over pulsatile pumps include reduced noise levels and
enhanced durability, the latter being attributed to fewer moving parts
and contact bearings.
• The smaller size of these pumps also allows the device to be inserted
with less dissection, because the size of the pocket is minimized and
sometimes completely eliminated.
• Disadvantages of an axial flow pump include the lack of a mechanical
backup mechanism in the event of major device malfunction,
hemolysis as a result of shear forces, and the potential for creating
negative intraventricular pressure, with resultant device thrombosis, air
embolism, or arrhythmia.
53.
54. Thoratec HeartMate II
• Axial flow rotary pump
• Constructed of titanium
• flows up to 10 liter/min operating at pump speeds of 6000 to 15,000 rpm
• Inflow is via the LV apex, and outflow is via the ascending aorta.
• The axial flow design eliminates the need for a bloodpumping chamber and
volume compensation necessary for volume-displacement LVADs.
• The pump housing is implanted in the small preperitoneal space and
requires only a small pocket.
• A small percutaneous driveline exits the skin in the right or left upper
abdomen.
• This feature makes the device more suitable for implantation in patients
with a smaller body size.
55. • Theoretical benefits over previous series of VAD system include a reduced
risk of infection, greater patient comfort and quality of life, and greater
device durability. Furthermore, it is substantially smaller than the HeartMate
XVE and requires a less invasive operative approach.
• A randomized control trial demonstrated the superiority of the HeartMate II
compared with the HeartMate XVE in terms of survival, quality of life, and
durability.
• HeartMate II is approved by the FDA for both BTT (85% 1 year survival) and
DT (63% 2 years survival).
• Most widely used LVAD in the last decade.
56.
57.
58. Jarvik 2000
• Jarvik Heart, New York
• Electromagnetically actuated pump constructed of titanium,
measuring 2.5 cm in diameter and weighing 90gm
• flow of up to 7 liter/min with 8000 to 12000 rpm.
• unique feature of this device is that the pumping chamber is
implanted in the left ventricle. The outflow graft is anastomosed
to the descending thoracic aorta.
• Surgical implantation of the device is typically accomplished
through a left thoracotomy.
59. • The multiple versions of the Jarvik 2000 device can be differentiated
by their energy source.
• The percutaneous model has a single driveline that exits through the
patient’s anterior abdominal wall.
• One version contains skull-mounted pedestals used with cochlear
implants: a titanium pedestal is screwed into the skull with a trans-
cutaneous connector that attaches to the power cord.
• The behind-the-ear cable system may have significant quality-of-life
advantages and reduced risk of infection compared with the
abdominal cables. Furthermore, it enables patients to shower and
bathe normally and even go swimming.
60.
61. MicroMed DeBakey VAD
• MicroMed Cardiovascular, Houston
• was developed in collaboration with NASA
• made of titanium, weighs 95 g, and measures only 1.2 inches in
diameter and 3 inches in length.
• Capable of generating flows upto 10L/min
• A relatively high number of reports have described stroke and
microemboli formation with this device.
• The child version is approved by the FDA for BTT use in children aged
5 to 16 years.
62.
63. THIRD GENERATION DEVICES
• Newer generation devices have been designed to address several
shortcomings of second generation axial flow pumps, such as
thromboembolic complications and limited device durability.
• Many of these devices operate on the basis of magnetic levitation
technology, in which the rotating propeller is magnetically suspended in a
column of blood, obviating the need for contact-bearing moving parts and
providing the theoretical benefit of enhanced durability.
• These are generally smaller, can be inserted with only a small device pocket
or no pocket at all, are less traumatic, and may have a decreased risk for
associated infection.
• Some have been designed to be completely implantable with a
transcutaneous wireless energy transfer system.
64. HeartWare HVAD
• HeartWare International, Framingham US
• Centrifugal pump with no mechanical bearings
• Weighing 145 g, with a displaced stroke volume of 45 mL and a
flow of up to 10 liter/min at 2000 to 3000 rpm.
• The inflow cannula is integrated into the left ventricle. The
device is implanted in the pericardial space without the need for
an abdominal incision.
• This miniaturized device may be used as a biventricular assist
system as well as an LVAD.
• Approved by the FDA for BTT therapy (91% survival at 180 days).
65.
66. DuraHeart
• Terumo Heart, Michigan
• uses magnetic levitation technology
• can provide a flow of 2 to 8 liter/min at 1200 to 2400 rpm
• In case of magnetic failure, the device can levitate the Impella
hydrolytically
67. HeartMate III
• magnetically suspended centrifugal pump, powered by a
magnetically levitated centrifugal impeller
• can provide a flow of 10 liter/ min.
• has the ability to produce a pulsatile flow.
• MOMENTUM 3 trial (2019) has proven superiority of magnetic
levitation technology with respect to device durability and survival
free of disabling stroke or reoperation.
68.
69. Synergy
• HeartWare International, Framingham US.
• partial-support LVAD that can be placed intravascularly
• inflow cannula is placed through the subclavian vein, into the
right atrium, and across the interatrial septum into the left
atrium
• Outflow is to the subclavian artery
• Smallest LVAD
71. Common indications for VAD in advanced heart failure
• New York Heart Association (NYHA) class IIIb-IV symptoms
• frequent rehospitalizations for heart failure with unresponsiveness to
medical therapies (including neurohormonal antagonists and diuretics)
• recurrent/refractory ventricular tachyarrhythmia,
• inotrope dependence
• unresponsiveness to cardiac resynchronization therapy
• end-organ dysfunction as a result of low cardiac output,
• Peak myocardial oxygen consumption less than 14 mL/kg/min
• 6-minute walk distance less than 300 mtrs
72. INTERMACS Registry
• Interagency Registry for Mechanically Assisted Circulatory Support
has classified heart failure patients into 7 clinical profiles
73. • Currently, patients in INTERMACS levels 2, 3, or 4 are likely to
be appropriate candidates for a durable LVAD implantation.
• Level 1 patients are often compromised by end organ dysfunction,
uncertain neurological status, infection or major coagulopathy. Thus
they can be offered short term LVAD as a BTD or BTR.
• Level 6, 7 are generally too well to be considered invasive options.
74. RV Status
• RV failure after LVAD implantation can be a fatal complication.
• The implantation of an LVAD can decrease RV afterload by
reducing pulmonary artery pressure, however at the same time,
increasing cardiac output with an LVAD support may increase
systemic venous return to a diseased RV that may not be able to
accommodate the additional volume.
• LV pressure unloading by an LVAD can cause the interventricular
septum to shift leftward, leading to geometric changes in the RV that
reduce RV function and may increase TR.
75. Preoperative Predictors of RV Failure
• CVP/PCWP ratio of greater than 0.63
• Need for preoperative ventilator support
• BUN level greater than 39 mg/Dl
• RVSWI less than 300 mm Hg × mL/m2
• CVP greater than 15 mmHg
• Raised TC
• For patients with high risk of RV dysfunction, BIVAD can be
considered.
76. Absolute Contraindications for VAD
• Irreversible end-organ failure (particularly renal failure and hepatic
failure)
• Severe, unrecoverable neurologic injury
• Systemic sepsis (can cause a profound refractory vasodilatory state or
lead to an increased incidence of device endocarditis)
77. Predictors of 90 day Mortality (Cowgar,
Sundareswaran et al 2013)
• Older patients
• High degree of hypoalbuminemia
• Renal dysfunction requiring dialysis
• Hepatic dysfunction with coagulopathy
• Less experienced centres
• INTERMACS level 1, 2
• RV dysfunction
• Surgical complexity
78. • Poor hepatic function with coagulopathy increases transfusion requirements in
perioperative period, which can cause RV dysfunction.
• Although renal dysfunction may improve after improving the cardiac output,
those requiring dialysis should not be offered durable VAD as there is increased
risk of infections in them.
• Preop nutritional assessment, those with cardiac cachexia are predisposed to
poor healing, impaired immunity, and infections.
• Obesity is not a CI for LVAD but those BMI > 35 are not eligible for transplant.
However, with LVAD they can meet the criteria as their exercise tolerance
improves and comorbidities can be overcome. Thus BTC can be an option in
them.
• Understanding of VAD care by patient is very important, thus investigations of
prior psychiatric disorders, history of substance abuse, cognitive functions needs
to be conducted.
80. Factors to be considered
1) expected duration of support (short versus long-term support)
2) whether right, left, or biventricular support is required
3) patient’s neurologic status and overall prognosis
4) whether the intent is to bridge the patient to recovery or to
transplant, or if the device is to serve as DT
5) Patients body habitus, any contraindication to anticoagulation.
6) Surgeons preference, device availability
7) Affordability
82. • Roughly 2 categories
1. patients with acute cardiogenic shock
2. patients with chronic advanced heart failure
• Implantation of durable LVADs is associated with poor outcomes
in patients with acute cardiogenic shock after an acute MI,
myocarditis, acute on chronic heart failure, or after cardiotomy.
• Generally, transplant eligibility is uncertain in patients with a
combination of end-organ failure, uncertain neurologic status, and
uncertain social support.
• Also, the recent IABP-SHOCK II trial suggested that IABP confers no
benefit in cardiogenic shock associated with acute MI.
• Therefore, these patients should be offered short-term ventricular
support to provide BTD, BTT, or recovery.
83.
84. Cardiogenic Shock After Acute MI
• When cardiogenic shock complicates an acute MI, the reported
associated mortality rate is 85% to 90%.
• Also, SHOCK II trial suggested that, additional IABP treatment did
not result in a significant reduction in 30-day mortality rate
compared with medical therapy alone.
• By providing adequate circulatory support, short term LVAD can
reverse hypotension while maintaining vital organ perfusion and
adequate coronary perfusion pressures.
• Goal is to bridge the patient to a second procedure, which
includes PCI / CABG / CABG plus valve / implantation of a long-
term durable LVAD.
85. Cardiogenic Shock After Cardiotomy
• The goal of mechanical support in patients with cardiogenic shock
after cardiotomy, irrespective of which mechanical device is used,
is to bridge the patient to a second procedure, which includes
implantation of a long-term durable LVAD, as well as explantation
of the short-term device after myocardial recovery.
86. Cardiogenic Shock In Myocarditis
• seen typically in a younger patient population
• the probability of recovery is relatively high in these patients,
thus they should receive a short-term support.
• After normalization of end-organ perfusion and function,
myocardial function and recovery the support can be explanted.
87. Refractory Ventricular Arrhythmia
• This subgroup is offered ventricular assist device when
pharmacologic therapy failed to control arrhythmias.
• Among the patients with reduced LV function, RV function can
be either preserved or reduced.
• These patients can be candidates for both short-term and long-
term and both univentricular and biventricular VADs.
88. Chronic Advanced Heart Failure
• Depending on transplant eligibility can consider as BTT or DT.
• However, the initial management plan can change over time. For
example, comorbidities may improve in a DT patient who was
previously ineligible for transplant, making the patient transplant
eligible after LVAD support.
• Alternatively, a BTT patient may become transplant ineligible
because of device-related complications or progression of
comorbidities.
89. Patients Who Are Eligible for Heart Transplant
• The constant shortage of available donors has resulted in an
increasing number of patients with longer waiting times on the
transplantation lists.
• Use of a long-term durable LVAD as a BTT has become common in
patients who would otherwise not survive or who would develop
progressive end-organ dysfunction before an organ becomes available.
• The BTT strategy is especially reasonable in patients listed for
transplant who are expected to have an extended waiting time
because of their blood type.
• They are often discharged from the hospital after their VAD is
implanted and return at a later date for a transplant.
• Continuous flow, durable LVADs have favorable waiting list outcomes
when compared to medical management alone.
90. Patients Who Are Not Eligible for Heart Transplant
• Based on the REMATCH results, VAD has been approved as a DT.
• Current requirements for DT are patients with NYHA class IV end
stage ventricular heart failure who are not candidates for heart
transplant and but who meet all the following conditions:
1. have failed to respond to optimal medical management
(including beta blockers and ACE inhibitors, if tolerated) for at
least 45 of the last 60 days, or have been balloon pump
dependent for 7 days, or IV inotrope dependent for 14 days.
2. have a left ventricular ejection fraction less than 25%
91. • Currently, the FDA-approved continuous flow device for DT is the
HeartMate II.
• Given the improvements in technology, as well as in patient selection
and care over the past decade, there is a movement to use LVAD
therapy in patients who are less ill than those currently eligible for
DT.
• REVIVE-IT (Randomized Evaluation of the VAD intervention before the
Inotropic Therapy) trial is underway to test the LVAD therapy in
advanced heart failure patients with significant functional impairment
who are ineligible for transplant but who have not yet manifested
serious consequences of end-stage heart failure, such as end-organ
dysfunction, immobility, or cardiac cachexia.
93. (Techniques described for HeartMate II)
1. Skin incision
2. Creation of a preperitoneal pocket (prior to heparinisation)
3. Mediastinal exposure
4. Cannulation of the aorta and venous system
5. CPB commencement
6. Coring of the LV, placing core sutures on the LV, inserting the inflow
core into the LV apex
7. Outflow graft anastomosis to the ascending aorta
8. De airing of the device
9. Weaning off CPB and starting the LVAD
10. Hemostasis and cosure.
94. • Pocket of appropriate size is created, can use a model of the device to confirm
the size.
• Drivelines are tunneled through the right upper quadrant of the abdominal wall
and device is placed in the pocket.
• Aortic cannulation is to be done as distal as possible.
• RA cannulation is done unless any other concomitant valve surgery requires
bicaval cannulation.
• LV apex is cored clearing any thrombus in the cavity or any trabeculation that may
obstruct inflow into the device.
• 2-0 Tevdek pledgeted sutures (braided polyster with heavy PTFE coating) are used
on the LV apex for fixing sewing ring of inflow cuff.
• Outflow graft anastomosis on the aorta is done with 4-0 prolene.
• BioGlue is applied to the anastomoses.
• Device deairing id done through the outflow graft with creating a small hole
which is closed off later.
• With HeartMate II, the device is started only after completion of deairing. Started
at 6000rpm and then gradually increased to adequate rpm level to avoid
oversucking the LV.
95. Concomitant Valve Surgery
• Patients with mild or more severe AR should have their native aortic valve
repaired or oversewn at the time of VAD implantation.
• Any patient with a mechanical valve in the aortic position should have the
aortic valve oversewn with a patch or replaced with a tissue valve to
prevent thromboembolism.
• Severe MS needs to be repaired at the time of VAD implantation if it
significantly interferes with inflow to the device.
• Moderate to severe TR should be considered for repair or replacement to
optimize RV function.
• If the valve lesions cannot be repaired, a tissue valve is preferred because it
has a lower risk of thromboembolism than does a mechanical valve.
• Patients who require valve procedures are sicker and have a higher early
mortality rate.
96.
97. Early Postop Management
• Antibiotics
• Vasodilators to keep MAP at 70 to 80 mmHg.
• Vasopressors in case of vasodilatory hypotension.
• Optimisation of RV failure must be aggressively treated with
milrinone, dobutamine, nitric oxide and if refractory, to consider
RVAD early.
• Antiarrhythmics
98. Late Postop Management
• Encouraging ambulation and rehabilitation
• Patient education about the care and maintenance of the device
• Readmission because of bleeding, arrhythmia, infections, and
thrombosis is common within the first 6 months after discharge.
99. Anticoagulation
• HeartMate I XVE does not require anticoagulation with heparin or
warfarin.
• Newer devices need anticoagulation with Warfarin as well as
antiplatelet therapy with Aspirin.
• Intravenous heparin is generally used until the INR reaches target
range (2 to 3) in the postoperative period.
101. Postop Bleeding
• Bleeding after VAD insertion can be excessive and may result
from surgical causes or a diffuse coagulopathy.
• Significant bleeding can contribute to RV failure, infection, and
numerous adverse effects related to multiple blood transfusions.
• Coagulopathy can be due to deranged hemostatic system, including
dilutional thrombocytopenia and exposure to long-acting
antiplatelet or antithrombotic agents.
• For bleeding caused by a diffuse coagulopathy, platelets, fresh-
frozen plasma, or cryoprecipitate may be administered.
• Timely re exploration if warranted.
102. GI Bleeding and Epistaxis
• GI tract bleeding and epistaxis have emerged as major sources of
morbidity in patients with continuous flow LVADs.
• The bleeding event rate after HeartMate II implantation was 0.67
events per patient per year.
• Possible mechanisms associated are with obligate device
anticoagulation causing acquired von Willebrand disease, GI tract
arteriovenous malformations associated with reduced pulsatility,
and impaired platelet aggregation.
103. Infection
• Most common complications in LVAD patients.
• Can manifest as a driveline, pocket, blood, or device endocarditis.
• Sepsis occurs in 17% to 28% and driveline infection occurs in
14% to 27% of patients.
• Its important to prophylactically begin antibiotics preoperatively, as
well as to treat infections aggressively with antibiotics when they
do occur.
• More aggressive treatments including surgical drainage, wound
vacuum-assisted closure therapy, and pump exchange if necessary.
• The only way to definitively eradicate device endocarditis is to
explant the device.
104. Multisystem Organ Failure
• Despite effective restoration of adequate cardiac output for tissue
perfusion, some patients progress to develop multisystem organ
failure which is related to the preoperative severity of organ
dysfunction.
• Multisystem organ failure often results from a cascade of events,
such as bleeding, sepsis, RV failure, and other events.
105. Thromboembolism
• Thromboembolic complications are a major concern in LVAD
patients because of the blood-device interface.
• Reported to occur in 5% to 8% of cases
• Factors associated with development of stroke after LVAD
implantation are likely to include a previous history of stroke,
persistent malnutrition and inflammation, increased severity of
heart failure, and postoperative LVAD infections.
• Anticoagulation may needed to be stopped to avoid post infarct
haemorrhage.
106. RV Failure
• Adequate RV function is essential to achieve sufficient LVAD flow.
Significant RV failure is associated with poor outcomes in LVAD
recipients.
• Incidence of RV failure in LVAD recipients is as high as 20%.
• The proposed underlying mechanisms include intrinsic myocardial
dysfunction and insufficient RV afterload reduction.
• Patients with a continuous flow pump can develop RV failure from a
significant leftward septal shift and distortion of RV geometry caused
by LV oversucking.
• Postoperative ECHO should be performed routinely to monitor RV
function, and pump speed should be adjusted to adequate rpm.
• When RV failure is refractory to medical management, timely insertion
of a RVAD is mandatory before end organ dysfunction progresses.
107. Arrhythmia
• Cardiac arrhythmia, especially ventricular arrhythmia, is also a
common issue in the early and late postoperative periods.
• Although such arrhythmia may not be lethal in the presence of
LVAD, it could
• ECHO may be necessary to evaluate excessive LV unloading or
contact between the inflow cannula and LV wall put patients at
risk of RV failure.
108. Aortic Regurgitation
• After receiving continuous flow LVAD support for 3 years, 38% of
patients are expected to develop at least moderate AR.
• Significant AR can cause the recycling of blood flow from the LVAD
outflow graft into the LV, resulting in decreased forward cardiac
output, inadequate ventricular unloading, and increased pump work.
• This may require surgical correction.
• Non opening of the AV with continuous flow LVAD support is strongly
associated with de novo AR development.
• Optimization of pump speed under echocardiography may be
necessary to maintain some pulsatility with intermittent aortic valve
opening.
109. Device Malfunction
• In contrast to pulsatile devices (in which a hand-pumping device is
usually available), continuous flow pumps carry no manual option to
maintain forward pump flow in the event of pump stoppage.
• When pump stoppage occurs, most commonly resulting from damage
to the driveline, rapid decompensation and death are common
secondary to a combination of severe reduction in cardiac output and
a variable degree of “pump/ aortic” insufficiency due to the absence
of valves.
• If the patient is viable, emergency transport to an experienced center
is mandatory while cardiac output is maximized with inotropic
support.
114. • Patients were randomly assigned in a 1:1 ratio to receive either a vented electric
left ventricular assist device or optimal medical therapy.
• The primary end point was death from any cause and was compared between
groups with the use of the log-rank statistic.
• All patients completed the base-line assessments of the quality of life, and there
were no significant differences between groups.
• A total of 129 patients were enrolled from May 15, 1998, to July 27, 2001.
Enrollment ended once the predetermined number of 92 deaths had occurred.
• This trial demonstrates that long-term support with a left ventricular assist device
resulted in substantial improvement in survival in patients with severe heart
failure who were not candidates for cardiac transplantation. The patients in the
medical-therapy group received optimal medical care with digoxin, diuretics,
angiotensin-converting–enzyme inhibitors, and beta-blockers from heart-failure
specialists. The one-year mortality rate of 75 percent in this group.
• The implantation of a left ventricular assist device was associated with a relative
reduction in the risk of death of 48 percent during the entire follow-up period and
an absolute reduction in the mortality rate of 27 percent at one year.
• This study paved the way for approval of VAD (HeartMate I XVE) as a DT.
• Subsequently REMATCH II Trial proved superiority of HeartMate II (continuous
flow) over HeartMate I (pulsatile flow).
116. • This trial analysed that, patients with advanced heart failure who were treated
with a fully magnetically levitated centrifugal-flow left ventricular assist device
were less likely to have pump thrombosis or nondisabling stroke than were
patients treated with a mechanical-bearing axial-flow left ventricular assist device.
• The final analysis included 1028 enrolled patients: 516 in the centrifugal-flow
pump group and 512 in the axial-flow pump group.
• The primary end point was survival at 2 years free of disabling stroke or
reoperation to replace or remove a malfunctioning device.
• In the analysis of the primary end point, 397 patients (76.9%) in the centrifugal-
flow pump group, as compared with 332 (64.8%) in the axial-flow pump group,
remained alive and free of disabling stroke or reoperation to replace or remove a
malfunctioning device at 2 years.
117. DURABLE LVAD IN NH
Total 14
(2016 to 2021)
4 Ventracor
9 HeartMate II
1 HeartMate III
2 year survival with HeartMate II is 44%
1 patient had successful transplant post LVAD
