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378 Mechanical Circulatory Support for
Advanced Heart Failure

(40-50% ofpatients) or 2 (25-35% of patients) and, as reduce intracardiac filling pressures (there by reduc-
consequence, the long-term survival was marginal. ing congestion and/or pulmonary edema), reduce
Most of the mortality occurred during the initial hos- ventricular volumes, wall stress, and myocardial oxy-
pitalization for assist device surgery, closely related gen consumption;and augment myocardial perfusion
to the degree of organ compromise and urgency at by increasing coronary blood flow(theoretically also
the time of implantation, which might have been as- limiting the infarct size in the setting of myocardial
sociated with irreversible organ dysfunction. infarction).Each of the currently available devices is
designed to tackle the entire equation (i.e. circulatory
These observations have led the heart failure com- support, ventricular unloading, myocardial perfusion)
munity to begin using temporary(acute) mechanical but primarily address specific aspects of that equa-
circulatory support devices in order to stabilize high- tion.
risk patients (profiles 1-2) and downshift the risks of
a durable assist devices implantinto defined popula- The temporary mechanical circulatory support devic-
tions with lower post-operative morbidity (e.g. profiles es can be largely divided into pulsatile and non-pul-
3-4)leading to better survival. Indeed, the most recent satile devices. The pulsatile device that has been
data from INTERMACS have shown that this strate- used since 1960s is the intra-aortic balloon pump
gy yields 80% one-year and 48% 5-year survival in that primarily functions to augment the diastolic
the current era, starting to approach the survival af- pressure and, as a result, increase coronary per-
ter heart transplantation in individuals older than 60 fusion. The ventricular unloading aspect of the in-
years of age (87% one-year and 69% 5-year survival). tra-aortic balloon pump (counter pulsation) relies on
Finally, theresults from the recently completed Risk an intact ventricular-vascular coupling and may be
Assessment and Comparative Effectivenessof Left diminished in patients with sicker left ventricles. The
Ventricular Assist Device and Medical Management third part of the equation (i.e. circulatory support) re-
in Ambulatory HeartFailure Patients (ROADMAP) tri- lies on the augmented mean arterial pressure that is
al have shown that in carefully selected profile 4-7 driven primarily by the augmented diastolic pressure.
patients, the 1 and 2 year survival were greater than Its usefulness is limited to patients in the early shock
continuing optimal medical therapy (80% vs. 63% for phase or in patients with active ischemia or ischemic
one-year, and 70% vs. 43% for two year survival in ventricular arrhythmias.The continuous flow devices
theventricular assist device and optimal medical ther- can be further divided into axial or centrifugal flowde-
apy groups, respectively). vices. The axial flow pumps that currently exist are
the Impella axial flow catheters(2.5 L, CP and 5 L) that
Acute (Temporary) Mechanical Circulatory use a rotodynamic pump and work by taking blood
Support Devices from the left ventricle and directly ejecting it into the
aorta. Axial flowdevices will effectively increase mean
These devices are used primarily in patients needing arterial pressure and directly unload the leftventricle,
high-risk percutaneous coronary interventions, or in thereby reducing ventricular pressure. As a result of
post-cardiotomy failure to wean from the cardiopul- the increased meanaortic pressure and lower ven-
monarybypass, or in cardiogenic shock. Cardiogenic tricular pressure, the transmyocardial perfusion gra-
shock occurs secondary to acute left or right ventric- dient changes and coronary perfusion will increase.
ular systolic dysfunction, acute (on chronic) aortic or The centrifugal flow pumps are extracorporeal and
mitral valvular disease, and vasodilator abnormalities include the TandemHeartdevice and veno-arterial ex-
in patients with acute myocardial infarction, out-of tracorporeal membrane oxygenation (VA ECMO). In
hospital cardiacarrest, and worsening chronic heart the Tandem Heart configuration for left ventricular
failure. In clinical practice, patients with cardiogenic support, blood is taken out of the left atrium (via a
shock represent a spectrum of disease that can be trans-septal catheter) and delivered into the systemic
classified as early shock,shock, and severe shock, circulationto the iliac artery. In the VA ECMO configu-
depending on the level of blood pressure, heart rate, ration, blood is taken from the right atrium, oxygenat-
intracardiac filling pressures, cardiac output, tissue ed, and delivered to the iliac artery into the systemic
perfusion (lactate, urine output) and need for vaso- circulation.The hemodynamic effect between these
active medications. Potential benefits of temporary two devices is very different. The Tandem Heart will
mechanical circulatory support devices in this set- effectively address all three components of the equa-
ting include the ability to provide circulatory support tion byunloading the left ventricle, by reducing left
(thereby maintaining vital organ perfusion and pre- atrial volume (reducing left ventricular preload), and
venting systemic shock syndrome); provide ventric- by increasing mean arterial pressure, which leads to
ular unloading (left, right, biventricular) in order to
increase in the coronary perfusion pressure. The VA

GCDC 2017