Medical Grand Rounds

Cardiogenic shock: From ECMO to Impella and beyond

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For patients in cardiogenic shock, several devices can serve as a “bridge,” ie, provide circulatory support and allow the patient to live long enough to recover or to receive a heart transplant or a long-term device. Options include an intra-aortic balloon pump, TandemHeart, Impella, extracorporeal membrane oxygenation (ECMO), and CentriMag. Which device to use depends on individual patient needs, local expertise, and anatomic and physiologic considerations.


  • ECMO is the fastest way to stabilize a patient in acute cardiogenic shock and prevent end-organ failure, but it should likely be used for a short time and does not reduce the work of (“unload”) the left ventricle.
  • An intra-aortic balloon pump may provide diastolic filling in a patient on ECMO.
  • The TandemHeart provides significant support, but its insertion requires puncture of the atrial septum.
  • The Impella fully unloads the left ventricle, critically reducing the work of the heart.
  • Options for right-ventricular support include the ECMO Rotaflow circuit, CentriMag, and Impella RP.
  • The CentriMag is the most versatile device, allowing right, left, or biventricular support, but placement requires sternotomy.



A 43-year-old man presented to a community hospital with acute chest pain and shortness of breath and was diagnosed with anterior ST-elevation myocardial infarction. He was a smoker with a history of alcohol abuse, hypertension, and hyperlipidemia, and in the past he had undergone percutaneous coronary interventions to the right coronary artery and the first obtuse marginal artery.

Angiography showed total occlusion in the left anterior descending artery, 90% stenosis in the right coronary artery, and mild disease in the left circumflex artery. A drug-eluting stent was placed in the left anterior descending artery, resulting in good blood flow.

However, his left ventricle continued to have severe dysfunction. An intra-aortic balloon pump was inserted. Afterward, computed tomography showed subsegmental pulmonary embolism with congestion. His mean arterial pressure was 60 mm Hg (normal 70–110), central venous pressure 12 mm Hg (3–8), pulmonary artery pressure 38/26 mm Hg (15–30/4–12), pulmonary capillary wedge pressure 24 mm Hg (2–15), and cardiac index 1.4 L/min (2.5–4).

The patient was started on dobutamine and norepinephrine and transferred to Cleveland Clinic on day 2. Over the next day, he had runs of ventricular tachycardia, for which he was given amiodarone and lidocaine. His urine output was low, and his serum creatinine was elevated at 1.65 mg/dL (baseline 1.2, normal 0.5–1.5). Liver function tests were also elevated, with aspartate aminotransferase at 115 U/L(14–40) and alanine aminotransferase at 187 U/L (10–54).

Poor oxygenation was evident: his arterial partial pressure of oxygen was 64 mm Hg (normal 75–100). He was intubated and given 100% oxygen with positive end-expiratory pressure of 12 cm H2O.

Echocardiography showed a left ventricular ejection fraction of 15% (normal 55%–70%) and mild right ventricular dysfunction.

ECMO and then Impella placement

On his third hospital day, a venoarterial extracorporeal membrane oxygenation (ECMO) device was placed peripherally (Figure 1).

Figure 1. In one configuration of venoarterial extracorporeal membrane oxygenation (ECMO), blood is re-moved from the inferior vena cava, a centrifugal pump passes it over a membrane oxygenator, and it is ejected into the aorta.

His hemodynamic variables stabilized, and he was weaned off dobutamine and norepinephrine. Results of liver function tests normalized, his urinary output increased, and his serum creatinine dropped to a normal 1.0 mg/dL. However, a chest radiograph showed pulmonary congestion, and echocardiography now showed severe left ventricular dysfunction.

On hospital day 5, the patient underwent surgical placement of an Impella 5.0 device (Abiomed, Danvers, MA) through the right axillary artery in an effort to improve his pulmonary edema. The ECMO device was removed. Placement of a venovenous ECMO device was deemed unnecessary when oxygenation improved with the Impella.

Three days after Impella placement, radiography showed improved edema with some remaining pleural effusion.


Cardiogenic shock remains a challenging clinical problem: patients with it are among the sickest in the hospital, and many of them die. ECMO was once the only therapy available and is still widely used. However, it is a 2-edged sword; complications such as bleeding, infection, and thrombosis are almost inevitable if it is used for long. Importantly, patients are usually kept intubated and bedridden.

In recent years, new devices have become available that are easier to place (some in the catheterization laboratory or even at the bedside) and allow safer bridging to recovery, transplant, or other therapies.

This case illustrates the natural history of cardiogenic shock and the preferred clinical approach: ie, ongoing evaluation that permits rapid response to evolving challenges.

In general, acute cardiogenic shock occurs within 24 to 48 hours after the initial insult, so even if a procedure succeeds, the patient may develop progressive hypotension and organ dysfunction. Reduced cardiac output causes a downward spiral with multiple systemic and inflammatory processes as well as increased nitric oxide synthesis, leading to progressive decline and eventual end-organ dysfunction.

Continuously evaluate

The cardiac team should continuously assess the acuity and severity of a patient’s condition, with the goals of maintaining end-organ perfusion and identifying the source of problems. Refractory cardiogenic shock, with tissue hypoperfusion despite vasoactive medications and treatment of the underlying cause, is associated with in-hospital mortality rates ranging from 30% to 50%.1,2 The rates have actually increased over the past decade, as sicker patients are being treated.

When a patient presents with cardiogenic shock, we first try a series of vasoactive drugs and usually an intra-aortic balloon pump (Figure 2). We then tailor treatment depending on etiology. For example, a patient may have viral myocarditis and may even require a biopsy.

Figure 2. An intra-aortic balloon pump (IABP) deflates at the beginning of systole (left) and inflates at the beginning of diastole (right), increasing coronary perfusion and reducing left ventricular afterload.

If cardiogenic shock is refractory, mechanical circulatory support devices can be a short-term bridge to either recovery or a new decision. A multidisciplinary team should be consulted to consider transplant, a long-term device, or palliative care. Sometimes a case requires “bridging to a bridge,” with several devices used short-term in turn.

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