Good site with VAD Review: http://perfusioneducationonline.com/vad TIMELINE 1905- Carrel & Guthrie: heterotopic transplant- canine heart into neck of another animal (A3) 1934- DeBakey first conceives of a roller pump for blood transfusions 1940s- Demikhov early experiments with animal heart transplant (A4) 1940s- Bigelow use hypothermia in cardiac surgery 1951- Dennis in Univ Minnesota uses first pump-oxygenator for interatrial defect repair in a 6yo, pt did not survive but they reported the machine worked well (C3) 1952- Helmsworth use a pump-oxygenator in a 45yo w cor pulmonale for 27min w relief of cyanosis, dyspnea, orthopnea, but pt died 14 days after being disconnected fr the machine (C4) 1953- Gibbon uses cardiopulmonary bypass clinically (A5), showing machines can effectively replace the heart's pumping function ( 18yo ASD closure, CPB x26 min) - This was the first CPB success. -but the subsequent 4 patients all died, so he recommended we stop using his device. John Kirklin at Mayo clinic later improves the CPB device. (N6-7) 1954- Lillehei (Univ Minnesota) cross circulation use of blood compatible human donors for temporary circulatory support to allow for direct visualization of intracardiac surgery 1956- first successful open heart surgery in Houston- by Cooley (N), w help of CPB machine, --> wide acceptance of the machine... and opening up field of open heart surgery 1957- Akutsu&Kloff report 1st Total Artificial Heart experiments in dogs w pneumatic device x90min (A11) (N36) 1961- Liotta reports on a total artificial heart (F2) 1961- Dennis is first to use roller pump fr LA to FemArt as VAD (M11) 1962- Moulopoulos/Topaz, Kolff introduces the Intra-aortic balloon pump, the first device to be used clinically (A6,7) (M8) IABP = latex balloon in desc Tx Ao, inflates w diastole, deflates w systole -1968- Kantrowitz- first clinical use of IABP in cardiogenic shock fr MI (8), later used for postcardiotomy cardio shock unable to wean fr CPB (A9,10) 1962- Dennis reports LVAD + native LV decreases myocardial VO2 w maint good Qs and Qcoronary (A13, C 25) -uses tube from LA thru PFO thru external jugular vein to take LA blood and bypass the LV, with an external roller pump, to a tube into femoral artery, to provide postop support. 3 pts for up to 17hrs 1963- Liotta/DeBakey first implantable artificial ventricle in human- supported for 4 days w mech vent (A14, B15) -LVAD used in pt s/p Ao valve replacement w LV failure. It was a double lumen tube with a blood chamber, compressible bladder, and ball valves at each end to --> unidirectional Q, w inlet attached to atrium and outlet to Desc Tx Ao-->improved postop pulm edema, then pt died ?2y to brain damage fr cardiac arrest 1963- Spencer use extracorp roller pump to support pt in postcardiotomy shock (M12) (N13) 1964- Report from proceedings discussing the need for VADs to help wean patients off of CPB (looking to support heart for hours/days postop until heart recovers (C12) 1964- Artificial Heart Program started by NIH (A2, C28) -DeBakey chairs it, enlists multiple departments at Rice Univ (B3,5-8) -Dacron reinforced Silastic with air pumped between 2 layers to compress the inner wall and expell blood from its cavity, with ball valves to --> unidirectional Q (B9) -Intraventricular Pumping Device w Silastic sleeve with a ball type ventricular valve (B5, C31) -Silastic balloon molded to fit inside the pericardial sac, then inflated to force blood fr ventricle (B, C31) - All of these abandoned because they felt they had no clinical use 1965- Spencer uses DeBakey roller pumps in 4 pts w postcardiotomy CV shock, 1 survived discharge (A12) 1964- Hardy does 1st human heart xenotransplant w a chimpanzee heart into human, but only maint circ for 1 hour (A15) 1966- Lower does human to chimpanzee heart transplant, fx x2 hours then elective termination (A4) 1966- DeBakey's team uses LVAD- gas-enregized, synchronized pump that was a hemisphere w a Dacron reinforced Silastic, molded diaphragm separating the gas chamber fr the blood chamber. The blood chamber was lined w Dacron velour surface to "enhance the firm adrerence of the fibrinous material deposited by the blood, and thus to prevent thrombus formation" (B3, 17-19); inlet at LA, outlet at R axillary artery 1966- DeBakey implants extracorp LVAD in pt who can't be weaned off CPB after double valve replacement, heart improves after 10 days so VAD removed, pt lives till car accident 6yrs later (N16) 1967- Christiaan Barnard does first human heart transplant (A16) 1968- Baylor-Rice collaborative under the NIH's Artificial Heart Program--> pneumatic biventric cardiac prosthesis made of Dacron embeddid in Silastic, w a diaphragm separating the blood chamber from the gas chamber (B9); Inflow attached to atrial wall after removal of Nl heart, and woven DeBakey arterial grafts used to connect the ventricle to the PA and the Asc Ao. Implanted in 7 calves. Problems mainly w the anastomosis initially. No survivors more than 13hours. 1968- Intraaortic balloon pump (first perQ device) (G1)- decr AL, incr Qcor, incr diast BP, slight incr CO on initial eval, but not proven prospectively, so ppl focused on external devices (see 1962 above) (G1-2) 1969- Cooley reports use of a TAH as mechanical bridge to heart transplant (A17) --Per DeBakey this was actually a version of the device made by DeBakey's team at Rice-Baylor, which per DeBakey was taken covertly and used in a patient at St Lukes, without IRB/NIH approval. Per Cooley, the device was the work product of Dr Liotta fr Argentina...; The patient died. (B10, 11) 1967-1969- DeBakey changes his team's focus to just LVAD because of the difficulties with the TAH despite modifications to the initial designs (B13-16) and because of the 1963 success with an LVAD 1970- NIH forms the National Heart, Lung, and Blood Institute, which sponosrs a program to dvp LVAD used to wean patients off CPB... (A2) 1970s- pneumatically actuated pulsatile devices introduced in mid 1970s -1975- Bernhard trials extracopr VA LV to AscAo (M21) -1975-1980- Norman & Cooley trial intracopr LVAD- TECO Model VII (M22) w silicone valves, 1978 implantation into a woman with ischemic contracture = 1st VAD for BTT in pt w no fx 1975- Norman (at THI) starts 1st trial of short term abdom LVAD (ALVAD) for inability to wean CPB (L18) -generally poor outcome (~100% mortality) bc took too long to get consent so pt on long CPB 1977- NHLBI seeks proposals for long term (>2yrs of support) implantable pumps, because heart transplants were having poor outcomes bc they didn't have the current immunosupressive regimens (A2) -NOvacor LVAS and HeartMate LVAS dvpd bc of this 1978- Norman reports first successful use of LVAD (w ALVAD) as bridge to transplant (A19) (L20) done a 21yo M w ischemic contracture after double valve replacement, after 6 days VAD, got OHT and died of infection after 15 days 1980- NHLBI again seeks proposals for longterm LVADs (A2) 1980- Japan starts clinical use of VADs at Mitsui Hospital for postcardiotomy heart failure (E27) 1980- Bregman describes perQ insertion of IABP(G3) 1980s- cyclosporine is dvp, making OHT much more successful 1981- Jarvik-7 Total artificial heart developed (F4) 1981- Akutsu and Cooley implant 2nd TAH w the Akutsi Model III series 3 (F3, M4) - 2 double chambered pneumatic diaphragm pumps- w Bjork-Shiley convexo-concave disc valves, 36yo w sev HF s/p CABG (N9) -lived 55hrs till OHT, ided of infection/multiorgan failure at 2 weeks 1982- Joyce, DeVries implant 1st permanent TAH (Jarvik 7) (M5), lived for 112 days; later changed fr Bjork-Shiley tilting disc valves to Medtronic-Hall tilting disk valves, subsequent 4 pts died--> halt use 1984- DeVries implants first TAH intended for permanent support (other devices had been used for temporary support until now). It lasted 112 days. (A20) 1984 thru 1994- DeBakey starts working with NASA engineers on an axillary VAD- flow tube w an inducer-impeller, the only moving part, a flow straigtener, and a diffuser..., propelled by magnets in the blades of the impeller..., --> 5L/min against 100mmHg, uses <10W input power, with little hemolysis (B) 1984- Novacor VAD first becomes available (M33)- first successful BTT system (dvpd by Portner, implanted first at Stanford in 1984)- electromechanically actuated pump w external driver, pusher plate (1993 version had wearable controller/battery) (M34) (A21) 1980s- Immunosuppressive meds become available, improving OHT outcomes (N38) 1985- Univ Arizona, Copeland- first successful TAH to BTT w Jarvik-7 (aka Symbion) (N39) 1986-1988- VADs used to at BTT (C34-44) - 1986 first HeartMate used at TCH for BTT (N25) 1987- Clinical trials of ABIOMED BVS 5000 (N33) 1986-1988 Wampler develops the first axial flow LVAD, the Hemopump (D7), based on the Archimedes screw, surprisingly minimal hemolysis -used by Frazer at THI initially (1988), then avail in Eu and not US (M), bc FDA didnt endorse it (N47) 1991- Lowe working on implantable devices that compress the heart (A25) 1991- electrically powered Heartmate's first successful BTT, battery powered--> ok to discharge home 1993- CardioWest buys Symbion Company (Jarvik) (N41) 1993- FDA approves Abiomed BVS 5000 for postcardiotomy - provides longer support than centrifugal pumps, good for L or R VAD, and no perfusionist needed (A24) (First FDA approved VAD!) (M28) 1992- first Japanese BTT- Saitama Univ Med School & OSaka Univ Hospital, for DCM pt with a Nipro LVAD (Japanese VAD company), with transfer to Texas and subsequent OHT after 150 days 1992- Berlin Heart makes first pediatric VAD- pulsatile w various sized cannulae, called Excor (L) -10-80mL pump chamber, hep coated, uni/biventric, polyurethane casing and valves -up to 350mmHg pressure, 140bpm 1994- FDA approves Thermo Cardiosystems Pneumatic LVAD as BTT (A) 1995- FDA approves Thoratec VAD for BTT (A) 1998- FDA approves Thoratec VAD for postcardiotomy (A) (advantage of Thoratec is that it's extracorp and thus able to support biventric. (N30-32) 1998- FDA approves Novacor LVAD for BTT (A) (per N it's 1996) 1998- FDA approves Thermo Cardiosystems Electric LVAD (Heartmate) for BTT (A) (per N it's 1996) 1998- MicroMed DeBakey VAD begins clinical trials in Europe (C49) (O43) 1998- REMATCH study starts- Randomized Eval of MEch Assist for Tx of CHF Trial -21 US centers; study non OHT candidate pts on VADs vs standard HF Tx 1999- first OHT in Japan (after 1997 law allowing organ transplant)- Univ of Osaka (E) 2000- Abiomed completes the AbioCor (E23) total implantable heart 2001- first AbioCor implantation (F17) 2001- REMATCH Trial (Randomized Eval of Mechanical Asisstance for the Tx of CHF)--> LVAD better than medical Tx for pts w irreversible heart failure w Heartate VE (C51, E33) 2001- HeartMate II reported in clinical use, the 2nd gen of axial flow LVAD after the Hemopump (D8) 2002- FDA approves HeartMate VE LVAD for DT (E) 2003- CentriMag (Levtronix) begins clinical trials (O50) 2004- Jarvik 2000 Heart reported in clinical use, the 2nd gen of axial flow LVAD after Hemopump (D9) -Jarvik is intraventricular -Because Jarvik & HeartMate II are so small, the risk of pump-pocket infection is reduced (E34) 2004- Jamanese Min of Health approves Novacor for BTT 2004- FDA approves the Cardiowest TAH (Syncardia Systems) as BTT 2004- First Duraheart implantation (O46) 2005- Impella percutaneous VAD first reported by Valgimigli (G31) in pt w high risk cor intervention 2006- FDA approves the Abiocor TAH as under Humanitarian Use Device provision 2009- AHA reports Heartmate XVE (pulsatile) vs HeartMate II in the HeartMate II Destination Therapy Trial -HM II had better 2yr survival (46% alive w/o disabling stroke or reoperation) vs 11% w HM XVE -the 46% survival rate was very good considering how sick the patients were. avg age 62.5yrs -Postop xx- renal failure, pump exchange, infection, arrhythmia, breathing problems- much improved with HM II (-0.06/yr vs 0.51/yr) 2009- Japanese Ministry of Health approves HeartMate XVE (E)
2010- Japanese Min of Health approves DuraHeart & EVAHEART; Jarvik 2000 & HeartMate II pending (E)
2010- FDE approves Heatmate II for DT after AHA reports improved results vs HM XVE in 2009 (E34)
___-Extracopropreal centrifugal pumps (Bio-medicus and 3M Sarns) for postcardiotomy (A22, 23), but limited by bleeding risk, staff requirements, so they are short term use only -As of the 2000 article, ABIOMED working with Texas Heart Institute and 3M Sarns working with Penn State Univeristy to develop Total Artificial Hearts First came pulsatile VADs (H1-3) Then came rotary VADs (smaller, no need for external venting or prosthetic valves) -2nd Gen = axial flow pump w blood immersed bearing or pivotal bearing (H4-6) -3rd Gen = no mechanical contact inside the blood chamber- via a magnetic bearing (magnetic levitation) or hydrodynamic bearing between the impeller and housing. Frictionless impeller rotation --> reduce hemolysis, reduce thrombi, incr mech durability for long term use. These 3rd Gen are in diff stages of dvp (H7-8) Problems of Pulsatile VADs -extensive surgical dissection -large pump -large diameter percutaneous lead -limited durability <2 years...) Advantages of Continuous VADs -smaller size -no need for external venting Continuous Flow Device Considerations -GI bleed risk: 14% (D37) with Jarvik, 15% with HeartMate II (D14)
-Unsure if it is due to the anticoagulation vs continuous Q
-Ao Stenosis is assoc w GI bleed, ? bc of acquired von Willebrand dz (D40)
-The Minnesota group would stop all anticoag Tx if +GI bleed and reduce the flow to incr PP and then restart Tx/incr Q after GI bleed stopped--> no recurrence in bleeding, and there weren't any thromboemboli w stopping the anticoag Tx
-End-Organ Fx
-?effect of nonpulsatile flow to end organs.
-Terumo DuraHeart LVAD study looked at end organ fx in sheep (D43): incr renin and RAA sys but no incr in BP
-2 small studies w Jarvik & HM did not show adverse effects to end organ fx (D45-46)
-In fact, continuous flow VADs ARE pulsatile, just less so than others- when LV contracts, it increases PL to the device--> increases output; if LV doesn't fx well, then they'll be less Q thru pump during systole. Increasing flow rate increases how much Q goes thru the pump, and thus reduces the native CO thru the Ao, thus reducing pulsatility. (D)
-Pulmonary Hypertension
-While pulsatile VADs have been shown to improve phtn, there is no proof w continuous flow VADs until some recent reports (D52)
-Ventricular Arrhythmias
-VAD increases toleration of arrhythmias (D)
-Cont Q VAD increases risk of suction arrhythmias compared with pulsatile LVAD
-Heartmate II study- incr ventric arrhythmias (D53)
-due to mechanical irritation by inflow cath, or bc of ventric suction/collapse from too high a pump speed (D54), or in states of hyopvolemia...
-RV fx will be reduced w increased LV collapse bc of septal shift to the left
-high flow VAD can--> collapse LV--> obstruct inflow, so use echo early postop to optimize settings (D55-56)
-Serial Opening of Ao Valve
-to prevent LV thrombi/Ao thrombi and prevent Ao vlv fusion
-intermittently slow the flow rate to allow more Q thru Ao vlv
-Pulsatile devices, when in an asynchronous mode, can allow for intermittent Ao flow...
-Continuous devices, if at a high speed, might --> the Ao vlv to remain closed--> thrombi/fuson -As LV fx improves at 1-2 days postop, then you can gradually incr Q speed to optimum -Minnesota, w Heartmate, adjust Q rat to maximize LV decompression and improve CO, and at same time allow for at least 1:3 ratio of Ao vlv opening. (D) VAD TYPES Pulsatile VADs: -Heartmate I XVE (1st Gen/Electric/Long Term) -Novacor -Thoratec PVAD & IVAD (1st Gen/Pneumatic/Short-Med) -Abiomed BVS5000 & AB5000 (1st Gen/Pneumatic/Short Term) -Cardiowest (Syncardia) (TAH) -Berlin Heart Excor (Pediatric/Pneumatic/Long Term) -Novacor II LVAS (3rd Gen/Electric, Magnetic Pusher Plate/Long) NonPulsatile (Continuous) VADs: -Centrifugal Pumps -Biomedicus -Sarns -Nikkiso -Levitronix CentriMag (2nd Gen/Electric, Magnetic/Short) -HVAD (HeartWare) (3rd Gen/Electric, Magnetic/Long) -DuraHeart (3rd Gen/Electric, Magnetic/Long) -VentrAssist (3rd Gen/Electric/Long) -PediVAS/UltraMag (3rd Gen/Ped/Electric, Magnetic/Long) -Levacor (3rd Gen/Electric, Magnetic/Long)
-Heartmate III (3rd Gen/Electric, Magnetic/Long)
-Synergy (BOTH axial & centrifugal) (3rd Gen/Electric, Magnetic/Long) -Axial Flow Pumps -HeartMate II (2nd Gen/Electric/Long) -Jarvik Heart (2nd Gen/Electric/Long) -MicroMed DeBakey (2nd Gen/Electric/Long) -Berlin Incor -Synergy (BOTH axial & centrifugal) (3rd Gen/Electric, Magnetic/Long) Percutaneous VADs: -IABP -TandemHeart (Cardiac Assist Inc, Pittsburgh) (2nd Gen/Electric/Short) -Impella 2.5 (Abiomed Europe, Aechen, Germany) (2nd Gen/Electric/Short)
VAD CLASSIFICATION -3 Generations (I19):    -Gen1 was mainly pneumatic/electric, Gen2 also had rotary pumps w axial flow, Gen3 also has magnetically suspended impellers (I20-21).
-5.3 US people have HF, prevalence 10/1000 ppl over 65yrs (I1), w 660,000 new cases per yr for ppl over 45yrs; 2008: 1 million US admissions for HF, costing $34.8 billion -HF stages (ACC/AHA) (I2-3) -A & B- mild/ASx but risk of Sx or refractory dz -C- progression w ventricular fx maintained by adrenergic stim, activating RAA sys, neurohormonal/cytokine system activation (I4-5) -D- compensation mechs fail, and ventricle fails--> Sx at rest -by stage D, ACC/AHA recs inotropes, OHT, mechanical card support, hospice -ACEI, Betablockers, diuretics, inotropes, antiarrhythmics reduce Sx but NOT mortality (I) -Stage D patients have 75% 2yr mortality -OHT: 93% 1yr survival, 88% 5 year survival, and improved fxl capacity (I6) -median OHT survival (adults) is 10 years (J7) -2200 donors for 100,000 pts in need (I7) -Donor hearts usually reserved for pt <65yo even though HF more prevalent in older pts -1/3 of OHT pts get transplant vasculopathy by 5yrs,1/2 by 10 yrs (J7), but there is response to statins bc of antiinflmy effect (J12), and you can intervene with stent/angioplsaty (J13) -Transplant survival curve (J7):  VAD BASICS -Myocardium does self repair while on mechanical cardiac support (I8-15), and QOL will improve subsequently. -Device & Pt selection matter (I8) -c/s duration, type- R/L/BiVAD, cost, mobility needs, FDA approval, reimbursement, -Pt selection for DT VADs is key to good outcome (I18) -earlier VAD use--> better outcome -Acute HF options: IABP, TandemHeart, Impella -c/i xx for VAD is irreversible end organ failure, sepsis, mets cancer Gen1 VADS Thoratec Paracorporeal VAD (PVAD) -FDA Approved for short & Intermed term use for BTT/BTR (I22-23) Specs: - rigid plastic housing w a blood sac of polyurethane multipolymer, then air compresses the sac from an external driver. Mech valves at inflow/outflow-->unidirectional Q -Paracorporeal w transQ in/outflow cannulae (I24) -Pumping modes: asynchronous (Fast), synchronous (per HR), or volume mode- "fill to empty", w a sensor to detect when the sac is filled--> trigger ejection, but this d/o preload so more PL--> incr rate (I25) -SV 65mL, Max Rate 100, CO 6.5L/min -Advantages: R, L, or BiVAD fx, easy exchange if malfx, pts as small as 17kg (I22) -Longest duration 1204 days -ok to d/c home bc of a portable driver -Unlike AbioMed BVS5000, the PVAD has higher pump output, more mobility, longer duration, less morbidity (I26) -Anticoag: heparin then warfarin, ASA too in some pts Thoratec Implantable VAD (IVAD) -goal to incr QOL by letting pt go home (I23) -FDA approved for intermed-chronic support, for BTT or BTR (I27) -Similar Specs/mech as PVAD, but here the housing is titanium alloy, for implant w shorter cannulae and longer transQ driveline (I23) -Smaller, less heavy than PVAD, but still no good for smaller pts -Same survival, less complications than PVAD (I23) -Longest duration support 979 days (I28) -Thoratec Dual Drive Console (DDC) powers both PVAD and IVAD for inpts (I25) -can adjust mode (sync/async/vol), pump rate, ejection drive P, vacuum P, ejection time -Ejection drive P must be at least 10mmHg >pt SBP (Nl set at 230-245) -Vacuum P is the suction during diastole, incr to help filling (Nl set at -25 to -40) -Minimum ejection time is 300msec to allow complete emptying -TLC+II portable driver allows for discharge home, but only in async or sync modes HeartMate I/Extended Lead Vented Electric LV Assist System -by Thoratec -intracorporeal -for intermed-chronic support as BTT or DT in pt that cannot get OHT -Electrically driven, motor is within pump housing -Diaphragm separates the motor with its pushing plate and the blood sac. Sac is refilled by the recoil force. The negative P also helps fill the flaccid LV. -Chamber housing that has the motor must be vented to air to maint atm P, using a single tube that contains the wire for the motor. -Tube has woven polyester to promote skin growth into tube surface to decrease infection risk and anchor tube in place. -Porcine valves. All internal surfaces are textured to promote deposition of stable biologic lining to --> pseudointima like that of a blood vessel, and thus eliminate need for long term anticoagulation. -Auto mode- device responds to incr L venous return by increasing Pump rate and output (like vol mode in PVAD/IVAD) (I30) -SV 83mL, max rate 120 -Implant preperitoneal/intraperitoneal pocket. -must have BSA >1.5m2, can only implant 1 (no no BiVAD) -xx - early satiety--> malnutrition (I17) -Longest duration 1854 days (I32) -can be worn on a belt/holster. -NO ANTICOAGULATION needed (the only pulsatile intermed/ch device w no anticoag) (I30) AbioMed Biventricular Support 5000 -aka AbioMed BVS5000 -FDA approved for BTR in setting of reversible HF (first to be so) (I33) -external, mounted on a pole, for short term use- 7-10 days -pneumatic, 2 chambered, for 1 ventricle, but 2 can be used for BiVAD -transQ in/outflow cannulae -clear pump casting so you can check inside... (I34) -Unidirectional valves (I34) -Fill by gravity drainage, so adjust height of the VAD to account for pulm edema etc (I35) -3 diff consoles: BCS5000i, BVS5000t, and AB5000 -SV depends on intravascular volume, downstream resistances; driving console adjusts the rate to --> 5L/min CO based on the parameters detected (I36) -Anticoagulation0 start within 24hrs placement, heparin for ACT 180-200 -less expensive than Thoratec PVAD -Long term use--> xx: sepsis, multiorgan failure, cerebral infarct AbioMed AB5000 (I) -ambulatory version of the BVS5000 -similar survial/adverse events as BVS5000 -Short term (longest used 57 days) -Interchangable cannula w BVS5000, so you could change it up if needed -single chamber, pneumatic, paracorporeal, for uni or biVAD (I37) -Specs: rigid chamber of epoxy, aluminum, polycarbonate, titanium, w a polyurethane blader; polyurethane unidirectional valves--> unidirectional Q. Console drives air in/out -requires venting of air... -Incr PL or changing amt of vacuum will cahnge rate of filling--> change rate of ejection bc it only ejects when it is full (I38) -anticoagulation: heparin for ACT 180-200sec (I37) -max output 6L/min (I36, 39) Gen2 VADS Impella Recover System -AbioMed company -(G30) Caged blood flow inlet, placed retrograde into LV to aspirate oxygenate blood fr LV, then inject to Asc Ao via a microaxial pump (= LV to Asc Ao bypass) -Intracardiac axial flow pump w a rotor driven by electrical motor -continuously purge pump w D10 fluid with heparin to prevent thrombus -Insert via Fem Art, no need for transseptal puncture like Tandem -larger Impella Recover LP 5.0 needs fem cutdown for access, but the LP 2.5 is perQ -Fx for up to 5 days -CO of 2.5L/min -Indications- high risk coronary interventions -no increase in AR, no major hemolysis, no important device related adverse events (G31-32) -c/i xx = periph vasc dz, mechanical Ao vlv, heavily calcified Ao vlv -complications- limb ischemia in pts w sev periph vasc dz, incr infection risk Impella vs IABP -ISAR-SHOCK trial (G34)- signif improved cardiac index w Impella, but similar 30 day mortality & IABP had less adverse events Impella Recover LP 2.5 -circ support for up to 6hrs
-perQ
-CO of 2.5L/min (I40)
Impella 5.0 and Impella 5.0
-CO of 5L/min (I44)
Levitronix CentriMag Blood Pumping System
-Made by Levitronix, distributed by Thoratec
-Extracorp, centrifugal, with a rotary motion of a spinning impeller
-Rotor is magnetically levitated, w magnetic field electronically regulated w the external processer to adjust rotor position and speed
-No bearings, rotor floats in the magnetic field of a stator w which it has no mechanical contact (I46)
--> less thrombi (I47)
-Q d/o motor speed, venous return to the pump, intravascular and circuit pressures at inflow/outflow
-Pump flow is measured w an ultrasonic flow probe (I46)
-Good for short term support, R/L/BiVAD support
-supports for up to 6 hours, currently being evaluated for use up to 30 days
-often use as a bridge to decision
TandemHeart (G) -LA to femoral bypass system--> rapid support and resolve pulm edema and metabolic xx within hrs of cardiogenic shock -Place a drainage cannula via transseptal puncture into the LA and aspirate the oxygenated blood, then inject it via an external centrifugal pump to the fem art -21Fr venous transseptal inflow cannula - polyurethane w large endhole, and 14 side holes to aspirate the blood. It is attached to a continuous flow centrifugal pump, supporting a six blade rotating impeller to --> 4L/min Q, with power fr a DC brushless electromagnetic motor, w 3000-7500RPM -Impeller has low blood contact surface, floats fre in housing w low friction functioning--> less heat generation, hemolysis, emboli formulation (G15) -Anticoagulation Heparin gtt at 10mL/hr (900IU/hr) via side port. -Used for up to 14 days -Benefits: Much improved cardiac index (1.7 to 2.4) avg), improved mean art BP, with 44$ 30 day mortality (G16) -Indications: -Bridge to longterm axial flow LVAD- case series 9 pts all survived to VAD, & were alive at 1yr (G17) -Acute fulminant myocarditis- case series of 2 pts (G18) -High risk coronary intervention- e.g. CABG, one series showed it might be better than IABP (G21-22) -Short term bridge to transplant- case reports described (G24) -HD support during percutaneous aortic balloon valvuloplasty- 11 pt series (G25) -HD support during arrhythmia ablation (G26) -ContraIndications (G27): RV failure bc lower LA P doesn't allow for enought pumping (G27) -VSD relative c/i xx bc risk of hypoxemia bc R to L shunting -AR- LV can become distended bc sev LV dysfx --> poor subendocardial Q -severe periph vasc dz -Complications: -transseptal puncture risk- puncture Ao root, CS, post RA free wall (G26) -thromboemboli (G16) -hypothermia, dislodgment, bleeding (esp at groin), infection TandemHeart vs. IABP -(G28) - similar 30 day mortality, with more bleeding/limb ischemia w TandemHeart, though cardiac index was better with TandemHeart -(G29)- TandemHeart had greater CO increase and mean art BP, with Tandem 64% 30 survival vs 53% by IABP (not stat signif), no diff in severe adverse events HeartMate II LVAD -by Nimbus Corp w Univ Pitt (D8) -Made of an internal blood pump w perQ lead connecting it to an external driver/power source (D8, 10) -Impeller spins on blood lubricated bearings, powered by an electromagnetic motor -Inlet & Outlet = woven polyester grafts, require preclotting -Pumpmotor and blood tube have smooth titanium surfaces, because similar surface in HeartMate XVE had good biocompatibility; Inlet/Outlet elbows are coated w titanium microsphere ---> implant volume = 63mL, --> 10L/min flow at mean P 100mmHg -Display Module- set settings, RPM, shows estimated flow in L/min and power in Watts (I53) -2 modes- fixed (for fixed RPM) and Power Saver, for emergency (8,000 RPM at fixed spd <8000) -continuous flow is augmented by the native ventricle, --> Flow Pulse (variation in Q), quantified by the PI- pulsatility index bn 1-10 (mo units)- PI d/o interaction bn ventric PL, myocard contractility, and amt of assistance given by the VAD. Incr PL--> Myocardial fibers stretch--> incr contractility via Frank Sterling Mech--> incr PI. Incr ventric filling or device gives less support --> higher PI -Must ensure that PI doesn't vary much. (I53); PI usually is bn 3-4 -Flow is estimated by pump speed and power input, w linear relationship to power, except at very low/high speeds. -Implantation (Univ Minnesota): pt put on CPB, inflow placed into LV apex w acoring knife, and a circular Teflon pledget in donut shape placed around the apical core. 2-0 Tevdek mattress sutures secure the inflow cuff to the ventricle using the Teflon strip. The outflow is sewn into the Asc Ao. Pump is placed in a preperitoneal pocket at diaphragm level. THe pt is weaned off CPB and the pump is started -CO maintained by pump speed and by the amount of preload, and inotropic support. -Set RPM to ensure enough CO, and achieve LV decompression, whiling maint pulsatility index of >3.5-4. Optimize the RPM at implantation per echo and hemodynamics, and readjust per clinical scenerio. -Anticoagulation: Thoratec HeartMate II study 6 step initiation: IV unfrac heparin for 12-24hr postop or until chest tube drainage is <50mL/hr, then titrate heparin infusion to PTT 45-50 for 24 hours, then titrate to PTT 50-60 for 24 hours, then heparin to PTT 55-65, then start antiplatelet therapy on POD 2-3 w ASA 81mg daily, then on POD 3-5 after removing the hest tube start anticoag with Warfarin to INR 2-3 and stop heparin when appropriate INR is reached. -THEY STOPPED USING HEPARIN after noting signif GI bleed and delayed pericardial tamponade in first 14 pts, and started to initiate warfarin on POD 3 for INR 1.5-2--> low rate of thromboembolism -Outcomes: studies show improved outcomes (D11-13) -80% 1yr survival (n=43) in BTT and BTD pts with improved QOL (D12) -89% survival at 1mo, 75% at 6mo in BTT multicenter study (D13) -xx = LVAD infections, need RVAD support, pump thrombosis -bleeding needing re-exploration, stroke- increased in multicenter study than at Minnesota -Minn n=32- 97% survival at 1mo (alive or OHT), 87% at 6mo (D14) -16% needed reexploration -6% needed RVAD -12.5% had LVAD infection -6% (2pts) had neuro or thromboembolic xx -16% had GI bleeding -no pump pocket infections, like the BTT multicenter study -Anticoagulation & Thrombosis/Thromboembolism -Less thrombosis than pulsatile VADS (D33,34) -2001 Heartmate II trial stopped for excessive thrombi, but restarted in 2003 after the degree of texturing of the internal blood contacting surfaces were changed. Now, >1300 pts worldwide have been treated without signif thrombosis. The initial thrombis was because of texturing that was too close to small gaps in the pump. They changed the stators from textured to smooth--> improvement. -The smooth titanium surface of the blood tube and pump motor (like HeartMate XVE) & the elbows have titanium microsphere coatings. -The goal of the initial texturing on the HM XVE was to cause native tissue to line the surface, so the patient would not need anticoagulation in the future. (D35) -Though, they believe the improved thrombosis risk isn't because of the textured surfaces alone, but rather because of the higher pump flows, better fluid dynamics modeling, and continuous flow nature -They reported a case of pts (N=45) w avg flow rate >4--> less stasis, so less thrombi risk. -They also reduced anticoag need w lower INR goal (see above) -Both HM & Jarvik have risk of LV thrombus formation, so they allow for at least 1:3 rato of Ao valve opening, which may reduce LV thromboembolic risk. -Smaller size--> ok for teens/women (I)
-Longest use was for 4 yrs (I54)
 
 Jarvik 2000 -by Dr. Robert Jarvik -for intermed-ch support, still under FDA approval for BTT in US -has supported one pt for up to 7.5yrs (I58) -axial flow via single, rotating vaned impeller -made of a blood pump, 16mm outflow graft, perQ cable, pump speed controller, direct current power supply, 90gm, 2.5cm diam, (~C cell battery size) -housing has a DC motor to --> electromagnetic force to rotate the impeller -blood contacting surfaces are smooth titanium -Q directed thru outflow graft by stator blades near the pump outlet -power supply w pacemaker type wires, insulated with polycarbonate polyurethane, partly covered w Dacron -Impeller made of neodymium-iron boron magnet and hydrodynamic titanium blades held into position by 2 ceramic bearings -8000-12000RPM--> 3-7L/min flow, using 4-8Watts of power -Implantation: L thoracotomay or sternotomy -outflow to desc or Asc Ao, pump placed in LV, Silastic sewing cuff on LV apex to secure pump in place, perQ power cable via R abdomen or skull mounted pedestal -potentially don't need CPB to implant it, and may be able to do a subcostal approach -Optimize pump settings- usually 9-10000 RPM via echo guidance -Outcomes: -Single/Multicenter trials show it is safe/effective (D9, 19, 22-27) -mostly small studies w midterm survival rates -works by partially unloading LV, to normalize cardiac hemodynamics and improve LV fx by improving the Frank Starling response ; reduced stress on LV wall by abolishing isometric phase of contraction--> normalize LV EDP. -Only 5% had mech malfx over 1-4yrs postop -The first pt to get it was supported for 6 years! -much less infection rate compared to pulsatile VADs -in part because of the retroauricular skull-mounted pedestal (D30) used in cochlear implants too -no pump pocket infection because it's intraventricular -works best when it fx's in conjunction w native heart -some pts sustained for hours in VF, so it can do the full CO. -Anticoagulation & Thrombosis/Thromboembolism -Jarvik has had lower thrombi risk (D22-23) because of high flow stream w continuously washing the tiny bearings to prevent thrombi formation -There is concern about Asc Ao stasis and thrombi if it is anastomosed to Desc Ao -Both HM & Jarvik have risk of LV thrombus formation, so they allow for at least 1:3 rato of Ao valve opening, which may reduce LV thromboembolic risk.   MicroMed DeBakey Axial Flow Pump -aka HeartAssist 5 -In dvp since 1988 (I58) -similar to Jarvik 2000 design -axial flow pump -small- 30x76mm -electromagnetically driven, like Jarvik -implant in pericardial space, not within ventricle like Jarvik -Titanium inflow cannula -Vascutek Gelweave graft outflow conduit (Terumo CardioVascular Systems Corp) to direct Q into Ao -Ultrasonic flow probe around the outflow graft communicates with the external ctrl system -the pump can --> 10,000 RPM (I59) -Can be used as a pediatric pump bc it's so small (I60) -Currently under FDA studies for adult use in US; already used in peds/adults in Europe (I61)
Gen3 VADS DuraHeart -(Terumo Heart, Inc, Ann Arbor) -1st magnetically levitated centrifugal LVAD for long term support -LVAD - 3rd Gen implantable LVAD w combined magnet levitation and centrifugal pump (H9-12) -Specs: -Implant driveline, inflow, outflow, and externally worn controller/battery -Centrifugal pump made of titanium & stainless steel. Magnet suspends a rotating impeller in the blood chamber- magnetic bearing, impeller, housing, DC brushless motor. There's a magnetic coupling on motor that rotates the impeller via the magnet. It is kept suspended by 3 electromagnets. 3 Position sensors detect where the impeller is in the pump. -The titanium enclosure hermetically seals the electrical components against blood/tissue contact -Diameter 72mm, thickness 45mm ---> 8L/min Q at 120mmHg -blood contacting surfaces have a covalently bound heparin to incr compatibility, decr thrombus risk -Integrated Flow Estimation algorithm to ensure stable motor current needed t maint a set rotational speed and blood viscosity -computer stores 30 days data -battery lasts 7 hours
   Berlin INCOR -magnetically suspended, axial-flow pump (first of its kind) -first implanted 2002 -Titanium housing, heparin coated surfaces -silicone inflow cannula at LV apex, and silicone outflow to Asc Ao -axial levitation via electromagnets at either end of impeller -rotor position controlled by a sensor system --> creates constant laminar flow, avoid mech'l wear (O52)
-driveline exits via abdomen -200gm, 20mmx12cm, 5000-10000RPM==> 7L/min continuous flow (O53) -by 2006, 212 implanted HeartWare -small, cont flow, centrifugal (O54) -Hybrid: passive magnets and a hydrodynamic thruster - to suspend the impeller -the thruster's bearings establish a cushion of bld bn impeller and pump housing -no pts of mechanical contact within the pump... -up to 10L/min flow VentrAssist LVAS -centrifugal pump w hydrodynamic suspension of an open-flow rotor (P) --> blood flow thru center of the rotor and its outer surface--> wash all surfaces w blood so minimal thrombotic risk; special diamond like carbon coating minimizes thrombi -silicone inflow fr LV apex, outflow to Asc Ao via a gelatin impregnated polyester graft -externally warn battery and controller -thin perQ lead for power Total Artificial Hearts -Cardiowest TAH (Syncardia Systems) & AbioCor TAH (Abiomed) are the two current models available CardioWest TAH (TAH-t) -a new form of the Jarvik-7 (F) -prosthetic ventricles fr polyurethane, pneumatic, pulsatile flow (F) -70mL capacity (F) -4 flexible polyurethane diaphragms bn blood and airsac (F) -CO occurs in sync w native heart, and simultaneously bn the two sacs in the VAD, so it is in parallel fr L and R side (F) -sacs fill passively from atria, but can add some suction if you want (F) -mechanical valves at in/outflow ensure unidirectional flow (F) -Single leaflet Medtronic-Hall valves- 27mm inflow, 25mm outflow -larger valves w short outflow path --> less stasis and thrombosis -quick connect silicone cuffs connect the ventricles to the atria; the outflow is attached to Ao/PA via grafts sewn on. So, the atrial annuli MUST be maintained during cardiectomy to strengthen the connection and allows for hemostasis at the suture sites. The cuffs are trimmed to 3-5mm to minimize thrombosis risk (F) -2 independent controllers --> redundancy for emergent backup (F) -Max 70mL fill, but better to have partial fill w full ejection, 50-55mL, to allow for SV alteration w pt's volume status changes (F) -Full ejection--> max CO and ventricular washing (F) -Implantation (F7): -atrial cuffs, outflow grafts, and ventricles/drivelines must be implanted -Pretrim the atrial cuffs to 3-5mm to sew to tricusp/mitral valves -Stretch and preclot the outflow grafts w Coseal to coat the interstices of the graft -Perform ventriculotomy, keeping the annuli of the inflow valves, then remove leaflets/cords, oversew the cor sinus so no backflow, cut the Ao and PA at the valve level. The annuli are buttressed w Teflon felt strips along their outer walls -L sided driveline exits fr L midclavicular line, 5-10cm below costal margin; R sided driveline exits 5cm medial to L driveline. -Experience (F5, F13-15): ->700 used worldwide -longest was 602 days, 6 pts went >4mo with only 1 device malfunction AbioCor TAH -Thoracic unit with two blood pumps in a single housing, separated by an energy converter -Each pump = hard shell chamber w a blood sac with in/outflow valves (F) -Inner lining, including 3 leaf valves, is made of seamless Angioflex- a proprietary membrane. Hydraulic fluid fills the space between the blood sacs and energy converter. The fluid is moved from one side to the other causing blood to be ejected in alternated fashion. --> the ventricles eject in series, not in parallel like native heart or CardioWest (F) -The ventricles are filled actively, so low atrial or filling P can limit inflow--> decr CO fr pump -Energy converter = unidirectional hydraulic pump spinning at 3000-10000RPM to pressurize the fluid, with a control valve directing Q fr one side to the other... -Pumping chamber has 1 way in/outflow valve joined seemlessly with the sac -Settings: beat rate, balance, L &R motor speeds - increase CO by controlling the beat rate -The balance is set so L>R output, to compensate for bronchial art flow and keep LA P at 10-15 -Controller (controls the control valve and beat rate) is placed preperitoneally, -Battery is preperitoneal- allows for 25-30min without external power source -Transcutaneous energy Transmission (TET): electromagnetic coils receive radio waves and convert them to DC power. The coil is subclavicular, xx= thermal injury/discomfort if malpositioned. -Implantation (F): -Place the TET coil at infraclavicular area, and run coil down to lower sternotomy incisiion. Place battery & controller preperitoneally..., -Trim the atrial cuffs and anastomose with polypropylene, reinforced w felt strips -Use cast model of the AbioCor to position, to determine outflow graft lengths- Ao is ant, PA post -Outcomes -71% 30 day survival (predicted was 13% survival) w n=14 pts -longest survival >1yr -some pts discharged home -Thrombosis at the support struts--> thromboemboli, causing them to change the way they sew the cuffs in some pts studied (F18) -no serious device malfunction reported -TET system worked well, without power interruption      -Cardiowest in clinical trial- n=95, compared w 35 control patients (F) -success = 30 day survival, NYHA I-II, ambulatory, not on vent, not on dialysis -69% successful -79% got to OHT by avg 79 days (F5) -72% survived 30 days p OHT -device failed in 1 pt after 4mo w a tear in the diaphragm--> pt died (F6) -Ctrl: survival avg 8.5 days -FDA Indications- BTT for risk of imminent death fr BV failure -Currently trialing discharge from hospital -c/i xx = not OHT candidate, can't be anticoagulated, not suitable for implantation (BSA <1.7 and sternum to tent ant vertebral body <10cm) -AbioCor TAH- approved under humanitarian exemption -10-20% w LVAD need RVAD support too (F9) -BiVAD patients had worse outcome than TAH patients (F10) -BiVAD survival is 40-50% (F11,12) unlike 79% w TAH (F5) TAH Patient Management -No need for ECG monitor or pacer wires (!) -No need for cardiotropic Rx -Watch central line placement/position closely, bc they will interfere w fx if they go into the device -Aim for normal art BP, CVP, SaO2, LA P; cant use a Swan-Ganz cath. -Volume & Hemodynamics (F) -Hypovolemia --> limits inflow--> decr CO - see low CVP and LAP -can also occur w Tamponade (compress atria, decr filling) or mechanical xx (obstruction bc malpositioning, kinking of cavae) -Anticoagulation (F) -CardioWest- anticoag w heparin then warfarin & ASA, and adipyridamole (platelet sabilizer) and antiinflammatory drug (pentoxifylline) -Follow TEG studies -AbioCor- similar regimen, if no ASA, an use ticlopidine or clopidogrel (Plavix); Amicar or Trasylol for antiinflammatory Percutaneous Mechanical Support Intraaortic Balloon Pump -adjunctive Tx to heart failure Tx since 1968 initial use -best way for temp mech assist of heart -Indications: post acute MI cardioshock, sev coronary dz, CPB induction/wean, BTT, refractory arrhythmia -ContraIndications: sev periph vasc dz, Ao aneurysm, AR, active bleeding, cant take anticoagulant, sev thrombocytopenia (G) though latter 2 are questionable (G11) -Limited compared to newer LVADs- depends on intrinsic cardiac rhythm, ineffective if pt in cardiac arrest or terminal LV dysfx -In 2002, 40,000 US pts used it (G4) bc its cheap and easy to insert, can insert at bedside, though now 2nd line due to new LVADs -Usually insert via Fem Art, some via brachial artery recently (G5) -Device used for up to 70 days (G6) -Benefits: decr HR, LVEDP, mean LAP, AL, myocardial VO2 by 20-30%, improved metabolic effects bc better DO2:VO2 to myocardium bc decr VO2 -The balloon inflates/deflates in Tx Ao in sync w heart (G8)--> augment diastolic Ao P bc the rapid inflation of the balloon during diastole, reduces systolic Ao P during deflation--> decr AL ==> up to 20% incr LV CO and decr HR by 10-20% -Complications: bleeding, emboli,limb ischemia, amputation, infection fr catheter, mech failure w balloon rupture, inadequate inflation, (G12) -7% pts get at least one xx (G12), with 2.6% pts a major complication -Risk factors: >75, periph vasc dz, DM, femaile, BSA <1.65 TandemHeart -see above Impella Recover System -see above VAD SIDE EFFECTS & OUTCOMES STATS -Heartmate XVE--> limited bearing durability, bioprosthetic valve wear and tear--> 15-24mo life (J17) -Novacor had better durability than HMXVE but had higher thromboembolic rate (J15)--> removed fr market -Novacor and HMXVE had signif infection fr driveline (J14-15), which was fixed by stabilizing the driveline which allowed tissue to grow into it to seal fr outside environment... -large device size--> more xx in smaller ppl, compress stomach--> early satiety, malnutrition -noisy bc of pusher plate and bearings--> decr QOL -Cont flow VADs are more durable, lighter, quieter. Nonpulsatile, but the pt's intrinsic pulsation of the LV (which primes the pump more during LV systole) -Expected durability (yet to be proven) of the continuous flow VADs is 5-10yrs -(J18) HMII cont flow lvad has much less xx than pulsatile- less thromboemboli, infection, device failure -(J19) No signif risk to end organs bc of lack of pulsatility -Most pts put on LVADs are on inotropic support +/- cardiogenic shock (J21), and outcome is worse the sicker they are when put on the VAD (J22) per INTERMACs. Now we will move to putting it into less sick pts as the technology has improved, so less xx, given improved QOL (J18) and survival (J23) -uncertain whether VADs are good for bridge to recovery pts (e.g. myocarditis), initially great result (J30) but then it wasn't reproduced (J18, 20, 31) -adults: VADs incr immuno sensitizat'n (K1,2) but doesn't effect long term posttransplant survival (K1-4) -in peds, one study of outcomes (K), showed: -ECMO- higher incidence of postop xx b4 discharge: cardiac reoperation (OR 1.26), dialysis need OR 2.09, infection OR 1.97, with higher 30 day postop mortality. -R/F on poor OHT outcome- <1yo OR 1.72, BSA<1 OR 1.64, CHD OR 2.15, porr pretransplant status OR 3..75, PGE infusion OR 1.73, vent support OR 2.62, ICU OR 1.62, recent transfusion OR 2.05 -need for ECMO (OR 2.88) predicted poor early mortality, but NOT need for VAD (OR 1.14) -Long term mortality: all pts 10yr survival 56.8%, better if VAD/no MCS -if you lived >5yrs p OHT, age >13yrs predicted death (88% at 1yr, 66% at 5yr, 45% at 10yr), versus pt <5yo 83% at 1yr, 72% at 5yr, and 62% at 10yr -Pt on MCS: R/F poor outcome: BSA<0.3 hazard ratio HR 1.7, need for ECMO HR 1.65, need for IABP HR 1.91 -No diff in cause of death in pts who had VAD b4 OHT than straight to OHT: graft fail 31%, infection 6%, cardiac arrest 7.6%, other CV cause 10.5%, multiorgan fail 6%, noncompliance 4/6% -If pt on ECMO, death more often resulted fr multiorgan fail- 17% (OR 2.43)) References: A) Helman, D. N., & Rose, E. a. (2000). History of mechanical circulatory support. Progress in cardiovascular diseases, 43(1), 1-4. doi:10.1053/pcad.2000.7194 B) Debakey, ME. (1997) Development of a ventricular assist device. Artificial Organs, Nov; 21 (11): 1149-53 C) DeBakey, M. E. (2005). Development of mechanical heart devices. The Annals of thoracic surgery, 79(6), S2228-31. doi:10.1016/j.athoracsur.2005.03.029 D) John, R. (2008). Current axial-flow devices--the HeartMate II and Jarvik 2000 left ventricular assist devices. Seminars in thoracic and cardiovascular surgery, 20(3), 264-72. Elsevier Inc. doi:10.1053/j.semtcvs.2008.08.001 G) de Souza, C. F., de Souza Brito, F., De Lima, V. C., & De Camargo Carvalho, A. C. (2010). Percutaneous mechanical assistance for the failing heart. Journal of interventional cardiology, 23(2), 195-202. doi:10.1111/j.1540-8183.2010.00536.x H) Badiwala, M. V., & Rao, V. (2009). Left ventricular device as destination therapy: are we there yet? Current opinion in cardiology, 24(2), 184-9. doi:10.1097/HCO.0b013e328323f58f I) Thunberg, C. a, Gaitan, B. D., Arabia, F. a, Cole, D. J., & Grigore, A. M. (2010). Ventricular assist devices today and tomorrow. Journal of cardiothoracic and vascular anesthesia, 24(4), 656-80. doi:10.1053/j.jvca.2009.11.011 J) Boyle, A. (2009). Current status of cardiac transplantation and mechanical circulatory support. Current heart failure reports, 6(1), 28-33. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19265590 K) Delgado, R. (2005, September). HeartMate. Expert Review of Medical Devices. doi:10.1586/17434440.2.5.529 L) Delgado, R. (2005, September). HeartMate. Expert Review of Medical Devices. doi:10.1586/17434440.2.5.529 M) Frazier, O. H., & Macris, M. P. (1994). Current methods for circulatory support. Texas Heart Institute journal / from the Texas Heart Institute of St. Luke’s Episcopal Hospital, Texas Children's Hospital, 21(4), 288-95. Retrieved from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=325191&tool=pmcentrez&rendertype=abstract N) Frazier, O. . (2003). Prologue: Ventricular assist devices and total artificial hearts. Cardiology Clinics, 21(1), 1-13. doi:10.1016/S0733-8651(02)00133-9 O) Frazier OH, Jacob LP. Small pumps for ventricular assistance: progress in mechanicalcirculatory support. Cardiol Clin. 2007 Nov;25(4):553-64; vi. P) Esmore, D. S., Kaye, D., Salamonsen, R., Buckland, M., Rowland, M., Negri, J., Rowley, Y., et al. (2005). First Clinical Implant of the VentrAssist Left Ventricular Assist System as Destination Therapy for End-Stage Heart Failure. Heart And Lung, 1150-1154. doi:10.1016/j.healun.2005.01.014 Q) |
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