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516 Cardio Diabetes Medicine 2017

Inotropes And Heart :

When to Use and When Not to Use

Dr. J. Cecily Mary Majella, DM (Cardio).,
Asst. Prof .Cardiology, Madras Medical College ,Chennai.
Dr. S. Anneprincy, Post Graduate in Cardiology

INTRODUCTION: tricles and reduced ejection fraction who present
Systolic heart failure is a systemic disease due to re- with low SBP (<90 mm Hg) or low measured cardiac
duced cardiac contractility. Although it is logical that output in the presence of signs of congestion and
this condition can be treated by employing therapeu- organ hypoperfusion such as decreased mentation
tic strategies to directly improve contractility, inotro- and reduced urine output. Its benefit are mainly due
pic agents in failure patients have universally failed to direct increase in cardiac output and reduction in
to live up to their expectations. Paradoxically, favor- neurohumoral activation.
able outcomes can be achieved by administering The conventional agents include adrenergic inotropes
drugs that acutely decrease contractility and block such as dopamine, dobutamine, and norepinephrine,
neurohormonal stimulation. The proven success of non adrenergic inotropes like milrinone, enoximone,
this latter approach, especially in combination with levosimendan and digoxin. The newer and emerg-
implantable cardioverter-defibrillator and cardiac re- ing agents includes omecamtiv mecarbil, istaroxime,
synchronization therapy (ICD-CRT), has drawn our SERCA2a gene therapy. (Table 1)
attention away from addressing the root cause of
the problem: reduced contractility. In this update, Inotropic agents are mainly used for AHF and should
we will discuss current options for inotropic therapy be used with close hemodynamic monitoring and
in HF, when it might be appropriate to employ ino- should be stopped as soon as adequate organ perfu-
tropes in HF patients, and what steps can be tak- sion is restored. This is because all of these agents in-
en to mitigate their risks while maximizing benefit. crease conduction through the atrioventricular node,
These inotropic agents acts via cyclic adenosine causing a rapid ventricular response in patients pre-
monophosphate (cAMP)-mediated inotropy increas- senting with atrial fibrillation. Other conditions where
es the cardiac output and through vasodilatation re- inotropes prove useful is in cardiogenic shock as a
duce PCWP. Although these drugs can successfully temporary therapy to prevent hemodynamic collapse
increase cardiac output, their use has been proved to or as a life-sustaining bridge to more definitive thera-
have excessive mortality due to increased tachycar- py for those patients awaiting mechanical circulatory
dia and myocardial oxygen consumption leading to support, ventricular assist devices, or cardiac trans-
arrhythmia and myocardial ischemia. Even the short plantation.
term use (hours to few days) of intravenous inotro- CONVENTIONAL INOTROPES
pes is associated with significant side effects such
as hypotension, atrial or ventricular arrhythmias, and ADRENERGIC AGENTS
an increase in long-term mortality. Thus the need for Dopamine
new inotropic agents that are devoid of these harmful Initiation of dopamine therapy causes a rapid release
effects i.e improve systolic performance without nec- of norepinephrine that can precipitate tachycardia,
essarily increasing the myocardial oxygen consump- atrial and ventricular arrhythmias. Dopamine has
tion.Inotropes have beneficial hemodynamic effects complex effects that vary significantly with dose.
especially in patients with heart failure with reduced
ejection fraction (HFrEF; also known as systolic HF) Low-dose dopamine (≤2 μg/kg/min) has been pro-
and should be limited to patients with dilated ven- posed to cause selective dilation of renal, splanchnic,

GCDC 2017