# Mechanical Circulatory Support and Heart Transplant

## Classification of Cardiogenic Shock

### SCAI Cardiogenic Shock Stages

| Stage | Name | Key Features | Lactate | Interventions |
|---|---|---|---|---|
| A | At Risk | Large AMI, prior MI + HF, acute decompensated HF; no hypoperfusion | Normal | Optimize medical therapy |
| B | Beginning | SBP <90 or MAP <60; requires vasopressors/inotropes; tachycardia; no hypoperfusion markers | Normal | Single vasopressor/inotrope |
| C | Classic | Overt hypoperfusion (elevated lactate, renal/hepatic impairment); elevated filling pressures | Elevated | Vasopressors, inotropes, or MCS |
| D | Deteriorating | Worsening despite initial interventions; escalation required | Rising | Multiple agents + MCS consideration |
| E | Extremis | Near-pulseless; pH <7.2; lactate >8; cardiac arrest or impending | >8 | MCS + multiple vasopressors; ECPR |

### Temporary MCS Device Comparison

| Device | Mechanism | Flow Rate | LV Unloading | Key Advantage | Key Limitation |
|---|---|---|---|---|---|
| IABP | Counterpulsation (diastolic augmentation) | ~0.5 L/min augmentation | Modest (afterload reduction) | Simple insertion; lowest risk | No mortality benefit (IABP-SHOCK II) |
| Impella CP | Axial flow pump across aortic valve | Up to 4.0 L/min | Direct and effective | Active LV unloading | Hemolysis; vascular complications (15-20%); DANGER trial negative |
| Impella 5.0/5.5 | Axial flow pump (surgical cutdown) | Up to 5.5 L/min | Direct and effective | Greater support than CP | Requires surgical axillary cutdown |
| VA-ECMO | Centrifugal pump + oxygenator | 4-7 L/min | Does NOT unload LV (increases afterload) | Biventricular + respiratory support | LV distension; requires venting strategy |
| ECPELLA (ECMO + Impella) | Combined | ECMO 4-6 + Impella 3-4 | Best LV unloading | Maximizes support + unloading | Complexity; dual-device management |
| Impella RP | Axial flow (femoral vein to PA) | Up to 4.4 L/min | N/A (RV support) | Percutaneous RV support | Limited to isolated RV failure |
| ProtekDuo | Dual-lumen cannula (RIJ to PA) | Up to 4.5 L/min | N/A (RV support) | RV support without sternotomy | Requires fluoroscopic placement |

The Society for Cardiovascular Angiography and Interventions shock classification provides a standardized framework for categorizing cardiogenic shock severity and guiding escalation of therapy. Stage A, designated "At Risk," includes patients with large acute myocardial infarction, prior myocardial infarction with heart failure, or acute decompensated heart failure without evidence of hypoperfusion. Stage B, "Beginning," is characterized by systolic blood pressure below 90 mmHg or mean arterial pressure below 60, or the need for vasopressors or inotropes to maintain blood pressure, accompanied by tachycardia but without markers of tissue hypoperfusion. Stage C, "Classic," represents the hallmark shock presentation with overt hypoperfusion manifesting as elevated lactate, impaired renal and hepatic function, and elevated filling pressures, requiring vasopressors, inotropes, or mechanical circulatory support. Stage D, "Deteriorating," describes patients who worsen despite initial interventions, requiring escalation of support with multiple vasopressors and consideration of mechanical circulatory support. Stage E, "Extremis," represents refractory shock with near-pulseless state, multiple vasopressors plus mechanical support, pH below 7.2, lactate above 8, and cardiac arrest or impending arrest.

### Hemodynamic Profiles

Cardiogenic shock is further characterized by the predominant hemodynamic pattern. Left ventricular failure predominant shock, the most common pattern, presents with elevated pulmonary capillary wedge pressure, low cardiac index, and high systemic vascular resistance. Right ventricular failure predominant shock, characterized by elevated right atrial pressure, low cardiac index, and normal or low pulmonary capillary wedge pressure, occurs in the setting of right ventricular infarction, post-left ventricular assist device implantation, massive pulmonary embolism, and right ventricular myocarditis. Biventricular failure, with both elevated right atrial pressure and pulmonary capillary wedge pressure, carries the worst prognosis. Mixed or vasoplegic patterns with low systemic vascular resistance and initially elevated cardiac index suggest a distributive component such as sepsis or systemic inflammatory response syndrome following cardiopulmonary bypass, requiring vasopressor support.

## Temporary Mechanical Circulatory Support

### Intra-Aortic Balloon Pump (IABP)

The intra-aortic balloon pump operates through counterpulsation, with balloon inflation during diastole augmenting coronary and cerebral perfusion and balloon deflation during systole reducing left ventricular afterload. The hemodynamic effect is modest, providing approximately 0.5 L/min/m squared increase in cardiac index along with afterload reduction and improved coronary perfusion pressure. The IABP-SHOCK II trial demonstrated no mortality benefit for intra-aortic balloon pump counterpulsation in cardiogenic shock complicating acute myocardial infarction, and the device has been largely supplanted by more potent mechanical circulatory support platforms for the treatment of shock. Its current role is limited to stabilization in specific scenarios such as mechanical complications awaiting surgery, severe mitral regurgitation, and refractory angina, as a bridge during transport, and for lower-acuity shock states. Contraindications include moderate-to-severe aortic regurgitation, which is worsened by diastolic augmentation, aortic dissection, and severe peripheral vascular disease.

### Impella

The Impella family of devices consists of axial flow pumps placed across the aortic valve in a retrograde fashion via the femoral or axillary artery. The Impella CP, the most commonly deployed device in cardiogenic shock and high-risk percutaneous coronary intervention, provides up to 3.5 to 4.0 L/min of flow through a 14 French system. The Impella 5.0 and 5.5 devices provide up to 5.0 to 5.5 L/min of flow but require surgical cutdown of the axillary artery, offering greater hemodynamic support for more severe shock. The Impella RP provides right-sided support, placed via the femoral vein across the tricuspid and pulmonic valves into the pulmonary artery, delivering up to 4.4 L/min for right ventricular failure occurring post-left ventricular assist device, post-myocardial infarction, or post-cardiotomy.

The Impella's mechanism involves drawing blood from the left ventricle and ejecting it into the ascending aorta, directly unloading the left ventricle. This reduces left ventricular end-diastolic pressure and myocardial oxygen demand while increasing mean arterial pressure and cardiac output. Complications include hemolysis requiring monitoring of plasma-free hemoglobin, limb ischemia from femoral access, device migration, aortic valve injury, stroke at 1 to 3%, and vascular complications in 15 to 20%. Evidence for the Impella in cardiogenic shock has been mixed. Data from the DTU registry support early Impella deployment in acute myocardial infarction cardiogenic shock. However, the DANGER trial found that Impella CP did not reduce 180-day mortality compared to standard of care in STEMI cardiogenic shock, though the trial may have been underpowered with a heterogeneous enrolled population.

### VA-ECMO (Venoarterial Extracorporeal Membrane Oxygenation)

Venoarterial extracorporeal membrane oxygenation provides the most comprehensive temporary circulatory support available. The system drains deoxygenated blood from the right atrium via a venous cannula placed in the femoral vein or internal jugular vein, passes it through an oxygenator and heat exchanger, and returns oxygenated blood to the arterial system via a cannula in the femoral artery. This configuration provides biventricular circulatory support plus respiratory support, delivering 4 to 7 L/min of flow.

A critical physiologic consideration is that venoarterial ECMO does not unload the left ventricle. The retrograde aortic flow from the arterial return cannula increases left ventricular afterload, which may worsen left ventricular distension, pulmonary edema, and myocardial oxygen demand. This necessitates a left ventricular venting strategy in many patients. Options for left ventricular venting include the intra-aortic balloon pump providing modest unloading, the Impella providing the most effective unloading in the so-called "ECPELLA" configuration, atrial septostomy, and a surgical left ventricular vent.

Indications for venoarterial ECMO include SCAI Stage C through E cardiogenic shock, refractory ventricular tachycardia or fibrillation for extracorporeal cardiopulmonary resuscitation, and as a bridge to decision, recovery, durable mechanical circulatory support, or transplant. Complications are significant and include limb ischemia, which necessitates a mandatory distal perfusion cannula in the ipsilateral superficial femoral artery; bleeding from anticoagulation with heparin targeting an activated clotting time of 180 to 220 seconds; hemolysis; thromboembolism; differential hypoxemia known as North-South syndrome, where the upper body is desaturated while the lower body is oxygenated, addressed by placing an upper body arterial cannula or adjusting flows; and infection. The ARREST trial provided evidence supporting early venoarterial ECMO for out-of-hospital refractory ventricular fibrillation arrest, demonstrating improved survival to discharge.

### Tandem Heart and Other Devices

The TandemHeart employs a centrifugal pump with inflow from the left atrium via a transseptal cannula and outflow to the femoral artery, providing effective left ventricular unloading but requiring technical expertise for transseptal puncture, using a 15 to 21 French system. The ProtekDuo is a dual-lumen cannula inserted via the right internal jugular vein that drains the right atrium and returns blood to the pulmonary artery, providing isolated right ventricular support at up to 4.5 L/min without requiring sternotomy.

<image>
A comparison illustration of four temporary MCS devices showing their placement and hemodynamic effects. Four panels arranged in a 2x2 grid, each showing a schematic heart with the device in position. Panel 1 (IABP): balloon catheter in descending aorta; arrows showing diastolic inflation (augmented coronary flow) and systolic deflation (afterload reduction); flow rate: 0.5 L/min augmentation; hemodynamic box: modest CI increase, reduces afterload, improves coronary perfusion. Panel 2 (Impella CP): axial flow catheter across aortic valve with inlet in LV and outlet in ascending aorta; arrows showing blood drawn from LV to aorta; flow rate: up to 4.0 L/min; hemodynamic box: directly unloads LV, reduces LVEDP, increases MAP and CO. Panel 3 (VA-ECMO): venous cannula in RA/IVC (via femoral vein), arterial return in femoral artery (with distal perfusion cannula to leg); external circuit showing oxygenator and centrifugal pump; flow rate: 4-7 L/min; hemodynamic box: biventricular support + oxygenation, but increases LV afterload (caution icon). Panel 4 (ECPELLA): combined VA-ECMO + Impella setup showing both devices in the heart simultaneously; annotation explaining that Impella unloads LV to counteract ECMO-induced LV distension; flow rate: ECMO 4-6 L/min + Impella 3-4 L/min; hemodynamic box: best LV unloading + biventricular support. Each panel with clear labels of cannula positions, flow directions (blue for venous, red for arterial), and key clinical advantages/disadvantages.
</image>

## Durable Left Ventricular Assist Devices (LVAD)

### Indications and Strategies

Durable left ventricular assist device implantation serves several strategic purposes. Bridge to transplant provides circulatory support while the patient awaits a donor heart, allowing clinical optimization and end-organ recovery. Destination therapy offers permanent support for patients ineligible for transplant. The REMATCH trial demonstrated LVAD superiority over medical therapy with 52% versus 25% 1-year survival. Bridge to candidacy supports patients with potentially reversible contraindications to transplant such as obesity, pulmonary hypertension, deconditioning, or substance abuse, allowing optimization before reassessment. Bridge to recovery, occurring in approximately 5 to 10% of cases, applies to conditions with potential for reverse remodeling such as myocarditis, peripartum cardiomyopathy, and acute decompensation, with device explantation if myocardial recovery is confirmed.

### Current Devices

The HeartMate 3 from Abbott represents the current standard in durable left ventricular assist device technology. This centrifugal-flow, fully magnetically levitated pump is positioned intrapericardially and has no mechanical bearings, dramatically reducing thrombosis and hemolysis. An outflow graft connects to the ascending aorta. The MOMENTUM 3 trial demonstrated HeartMate 3 superiority over the HeartMate II axial-flow device for the composite of survival free of disabling stroke or device malfunction at 2 years, with pump thrombosis virtually eliminated. The HeartWare HVAD from Medtronic, a centrifugal-flow intraventricular device, was withdrawn from the market in 2021 due to higher adverse event rates, though patients with existing HVADs continue to require ongoing management.

### Surgical Implantation

Implantation is performed through a median sternotomy or, increasingly, a less-invasive lateral thoracotomy approach for the HeartMate 3. The inflow cannula is inserted into the left ventricular apex, and the outflow graft is anastomosed to the ascending aorta. The driveline, a percutaneous cable connecting the pump to the external controller and batteries, exits through the right lower abdominal wall and requires lifetime exit site care. Cardiopulmonary bypass is typically used during implantation, with off-pump techniques under development.

### Hemodynamic Assessment Post-LVAD

Post-implantation hemodynamic assessment relies on monitoring pump parameters including speed in revolutions per minute, flow in liters per minute, pulsatility index reflecting native cardiac contractility, and power consumption. A pattern of high flow with low pulsatility index indicates adequate pump support with minimal native cardiac contribution. Low flow should prompt evaluation for hypovolemia, right ventricular failure, inflow obstruction from thrombus or cannula malposition, outflow obstruction, or pump malfunction. Suction events occur when the inflow cannula is intermittently obstructed by the ventricular wall or septum, producing reduced flow and device alarms, and are managed with volume resuscitation and speed reduction. The continuous-flow physiology of modern devices produces diminished or absent pulse pressure. Blood pressure measurement requires Doppler assessment targeting a mean arterial pressure of 70 to 90 mmHg, as automatic blood pressure cuffs are unreliable.

### LVAD Complications Summary

| Complication | Incidence | Mechanism | Key Management |
|---|---|---|---|
| RV failure | 20-40% (early) | Increased venous return; leftward septal shift; preexisting RV dysfunction | Volume optimization; milrinone/dobutamine; inhaled NO/epoprostenol; Impella RP/ProtekDuo |
| Pump thrombosis | <1% at 2 yrs (HM3) | Thrombus formation in pump | Elevated LDH (most sensitive marker); optimize anticoagulation; TPA; pump exchange |
| Driveline infection | 15-20% | Percutaneous driveline exit site | Staph/Pseudomonas/Candida; prolonged antibiotics; immobilization; surgical debridement |
| Stroke (ischemic or hemorrhagic) | 10-15% at 2 yrs | Thromboembolism or anticoagulation-related bleed | Standard stroke protocols; INR target 2.0-3.0 + aspirin 81-325 mg |
| GI bleeding | 20-30% | Acquired von Willebrand syndrome + AV malformations from reduced pulsatility | Endoscopy; reduce pump speed; hold anticoagulation; octreotide/thalidomide |
| Aortic insufficiency | 10-30% at 2 yrs | Continuous retrograde aortic flow; commissural fusion | Speed optimization; surgical valve closure; transplant |

### Complications

#### Right Ventricular Failure

Right ventricular failure is the most common early complication following left ventricular assist device implantation, occurring in 20 to 40% of patients. The mechanism involves right ventricular dilation from increased venous return as the left ventricle is unloaded, leftward septal shift reducing right ventricular-left ventricular interdependence, and preexisting right ventricular dysfunction. Predictors include the RV Failure Risk Score incorporating central venous pressure-to-pulmonary capillary wedge pressure ratio exceeding 0.63, blood urea nitrogen exceeding 39, preoperative inotrope use, elevated pulmonary vascular resistance, and preexisting right ventricular dysfunction on echocardiography. Management includes volume optimization, inotropes such as milrinone and dobutamine, inhaled nitric oxide or epoprostenol for pulmonary vasodilation, and temporary right ventricular assist device support with Impella RP or ProtekDuo if refractory. Biventricular assist device implantation or total artificial heart placement represents a last resort.

#### Pump Thrombosis

Pump thrombosis has been dramatically reduced with the HeartMate 3, occurring in less than 1% at 2 years compared to 5 to 10% with older devices such as the HeartMate II. Diagnosis relies on elevated lactate dehydrogenase, which is the most sensitive laboratory marker, along with decreased pump flows, hemolysis evidenced by elevated plasma-free hemoglobin, low haptoglobin, and elevated bilirubin, and the development of heart failure symptoms. Management options include optimization of anticoagulation, fibrinolysis with tissue plasminogen activator, pump exchange if refractory, and emergent transplant listing if available.

#### Driveline Infection

Driveline infection is the most common infectious complication, occurring in 15 to 20% of patients, caused most commonly by Staphylococcus aureus, Pseudomonas, and Candida species. Prevention requires driveline immobilization, daily exit site care, and adherence to showering protocols. Treatment involves prolonged antibiotic courses, local wound care, and surgical debridement, with chronic suppressive antibiotics used for deep infections and pump exchange or transplant considered for refractory cases.

#### Stroke

Stroke affects 10 to 15% of patients at 2 years, involving both ischemic and hemorrhagic events, with the HeartMate 3 reducing stroke rates compared to the HeartMate II. Anticoagulation with warfarin targeting an INR of 2.0 to 3.0 plus aspirin at 81 to 325 mg balances thrombotic and bleeding risks. Management follows standard acute stroke protocols with neurosurgical consultation for hemorrhagic events and anticoagulation optimization.

#### GI Bleeding

Gastrointestinal bleeding occurs in approximately 20 to 30% of patients, driven by two interconnected mechanisms: acquired von Willebrand syndrome from loss of high-molecular-weight multimers due to shear stress through the pump, and the development of arteriovenous malformations from reduced pulsatility. Management includes endoscopy, reduction of pump speed to increase pulsatility, temporary withholding of anticoagulation, and octreotide or thalidomide for refractory arteriovenous malformation bleeding.

#### Aortic Insufficiency

De novo aortic regurgitation develops in 10 to 30% of patients at 2 years. The mechanism involves continuous retrograde flow through the aortic valve, which rarely opens in the setting of continuous-flow assist, causing commissural fusion and leaflet remodeling. Management strategies include ensuring the valve opens intermittently through speed optimization, medical management, and for severe regurgitation, surgical valve closure or replacement or transplant listing.

## Heart Transplantation

### Indications

The INTERMACS profiles guide the timing of transplant evaluation and listing. Profile 1, "Critical Cardiogenic Shock" or "crash and burn," represents patients requiring immediate mechanical circulatory support or transplant. Profile 2, "Progressive Decline," describes patients declining despite inotropes and requiring urgent left ventricular assist device or transplant. Profile 3, "Stable but Inotrope-Dependent," includes patients stable only on continuous inotropes who require listing and/or device implantation. Profiles 4 through 7 represent ambulatory heart failure patients with varying degrees of functional limitation, with listing based on projected survival and quality of life assessment.

### Listing Criteria

Listing criteria for heart transplantation include Stage D heart failure refractory to guideline-directed medical therapy, peak oxygen consumption below 12 to 14 mL/kg/min or less than 50% of predicted, ventilatory equivalent for carbon dioxide slope exceeding 35, recurrent heart failure hospitalizations of 2 or more per year despite optimal therapy, refractory angina or arrhythmias not amenable to other treatments, and the need for continuous inotropes or temporary mechanical circulatory support.

### Absolute Contraindications

Active systemic infection precludes transplantation. Active malignancy requires a 5-year cancer-free interval for most solid tumors, with shorter intervals acceptable for low-risk cancers. Irreversible pulmonary hypertension, defined by pulmonary vascular resistance exceeding 5 Wood units, pulmonary artery systolic pressure exceeding 60 mmHg unresponsive to vasodilators, or a transpulmonary gradient exceeding 15 mmHg, represents the most important hemodynamic contraindication because the donor right ventricle cannot handle elevated pulmonary vascular resistance, resulting in acute right ventricular failure post-transplant. Severe irreversible renal dysfunction with estimated glomerular filtration rate below 30 without a reversible cause should prompt consideration of combined heart-kidney transplantation. Severe irreversible hepatic dysfunction may warrant combined heart-liver transplantation. Active substance abuse including tobacco within 6 months, psychiatric illness precluding reliable medication adherence, and body mass index exceeding 35 kg/m squared are additional contraindications.

### Donor-Recipient Matching

ABO blood group compatibility is mandatory, and size matching targets a donor weight within 0.8 to 1.2 times the recipient weight. Panel-reactive antibody levels exceeding 25 to 50% indicate preformed anti-HLA antibodies, requiring prospective crossmatch and desensitization protocols using intravenous immunoglobulin, rituximab, plasmapheresis, or bortezomib for highly sensitized patients. Virtual crossmatch using HLA typing and antibody screening reduces ischemic time by avoiding the need for physical crossmatch. Ischemic time should be kept below 4 to 6 hours for cold-stored organs. Extended criteria donors using normothermic machine perfusion, such as the TransMedics Organ Care System, allow longer ischemic times and enable the use of donation after circulatory death hearts, significantly expanding the available donor pool.

### Immunosuppression

Induction therapy at the time of transplant uses either anti-thymocyte globulin or basiliximab, an anti-interleukin-2 receptor antibody. Maintenance triple therapy consists of a calcineurin inhibitor, with tacrolimus preferred targeting levels of 8 to 12 ng/mL in the early period and 5 to 8 ng/mL later, combined with mycophenolate mofetil at 1 to 1.5 grams twice daily and corticosteroids, with prednisone tapered to 5 mg by 6 months and some centers withdrawing steroids by 1 year. Mammalian target of rapamycin inhibitors such as everolimus and sirolimus may be substituted for mycophenolate in selected patients, particularly those with renal dysfunction, cardiac allograft vasculopathy, or elevated malignancy risk, though they should be avoided in the first 3 to 6 months post-transplant because of impaired wound healing.

### Rejection

Acute cellular rejection is T-cell mediated and graded from 0R indicating no rejection through 3R indicating severe rejection on endomyocardial biopsy according to the ISHLT grading system. Treatment of Grade 2R or symptomatic Grade 1R rejection consists of pulse intravenous methylprednisolone at 1 gram daily for 3 days, with anti-thymocyte globulin reserved for severe or hemodynamically compromising rejection. Antibody-mediated rejection involves B-cell and antibody-mediated mechanisms with donor-specific antibodies and complement activation demonstrated by C4d staining on biopsy. Treatment includes plasmapheresis, intravenous immunoglobulin, rituximab, bortezomib, and eculizumab for refractory cases. Surveillance endomyocardial biopsy follows a protocol of biopsies every 1 to 2 weeks initially, tapering in frequency over the first year, with less frequent biopsies beyond 1 year. Gene expression profiling with AlloMap may reduce biopsy frequency in selected patients.

### Cardiac Allograft Vasculopathy (CAV)

Cardiac allograft vasculopathy represents a diffuse, concentric intimal proliferation of the transplanted coronary arteries and is the leading cause of late mortality after heart transplantation. Unlike classic atherosclerosis, allograft vasculopathy involves the entire vessel length, is concentric rather than eccentric, and commonly affects distal vessels. Diagnosis requires annual angiography with or without intravascular ultrasound, which provides greater sensitivity for detecting early disease, supplemented by stress testing for functional assessment. Risk factors include cytomegalovirus infection, dyslipidemia, diabetes, donor-specific antibodies, and prior rejection episodes. Prevention relies on statin therapy, with pravastatin or simvastatin started early post-transplant, as these agents reduce both allograft vasculopathy development and mortality. Mammalian target of rapamycin inhibitors also reduce intimal proliferation. Treatment options include percutaneous intervention for focal stenoses and retransplantation for diffuse severe disease.

<image>
An INTERMACS profiles illustration showing the spectrum of advanced heart failure severity and corresponding treatment options. Display a horizontal gradient bar from left (most severe) to right (least severe), divided into 7 profile segments. Profile 1 "Critical Cardiogenic Shock" (dark red): patient on multiple inotropes/vasopressors + temporary MCS; arrow to "Emergent transplant or durable MCS." Profile 2 "Progressive Decline" (red): declining on inotropes; arrow to "Urgent LVAD or transplant." Profile 3 "Stable but Inotrope-Dependent" (orange): stable only on continuous inotropes; arrow to "LVAD (BTT or DT) or transplant listing." Profile 4 "Resting Symptoms on Oral Therapy" (yellow): frequent HF admissions; arrow to "Transplant listing, consider LVAD." Profile 5 "Exertion Intolerant" (light yellow): comfortable at rest but unable to perform activities; arrow to "Optimize GDMT, transplant evaluation." Profile 6 "Exertion Limited" (light green): can do some activities with significant symptoms; arrow to "GDMT optimization." Profile 7 "Advanced NYHA III" (green): stable with meaningful activity limitation. Below the bar, show survival curves diverging based on INTERMACS profile, demonstrating worse survival for lower profiles. Include a small inset showing the transplant waitlist allocation system (status 1-6 per 2018 UNOS allocation policy) with corresponding INTERMACS profiles.
</image>

## Key Clinical Pearls

- VA-ECMO does NOT unload the LV -- it increases afterload and may worsen LV distension and pulmonary edema; ALWAYS consider adding an Impella (ECPELLA strategy) or other LV venting method when VA-ECMO is initiated
- The DANGER trial showed no mortality benefit of Impella CP in STEMI cardiogenic shock, but clinical practice continues to evolve -- patient selection (earlier shock stages, confirmed LV failure, adequate hemodynamic assessment) may identify subgroups that benefit
- HeartMate 3 has virtually eliminated pump thrombosis compared to older devices -- this was the transformative advance in LVAD technology; however, driveline infection, GI bleeding, and stroke remain significant challenges
- Irreversible pulmonary hypertension (PVR > 5 WU) is the most important hemodynamic contraindication to heart transplant -- the donor RV cannot handle elevated PVR, leading to acute RV failure; LVAD may reduce PVR over months (bridge to candidacy)
- GI bleeding in LVAD patients is caused by acquired von Willebrand syndrome + AV malformations from reduced pulsatility -- increasing pulsatility (reducing pump speed) and holding anticoagulation are first-line strategies
- Normothermic machine perfusion (TransMedics OCS) has expanded the donor pool by enabling use of DCD hearts and extending ischemic time -- this technology is transforming heart transplantation availability

## References

- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation. 2022;145:e895-e1032.
- Mehra MR, et al. A Fully Magnetically Levitated Circulatory Pump for Advanced Heart Failure (MOMENTUM 3). NEJM. 2019;380:1618-1627.
- Costanzo MR, et al. The International Society of Heart and Lung Transplantation Guidelines for the Care of Heart Transplant Recipients. JHLT. 2010;29:914-956.
- Thiele H, et al. Intra-Aortic Balloon Support for Myocardial Infarction with Cardiogenic Shock (IABP-SHOCK II). NEJM. 2012;367:1287-1296.
- Moller JE, et al. Microaxial Flow Pump or Standard Care in Infarct-Related Cardiogenic Shock (DanGer Shock). NEJM. 2024;390:1382-1393.