Arrow AutoCAT 2 Series Operating Manual page 15

1 . C l i n i c a l U s e s
1 . 1 : C l i n i c a l U s e s o f I A B P
Threatening Extension of MI 16,17,18,23
If signs of myocardial ischemia continue after an infarction, a portion of the
myocardium is in jeopardy. IABP may salvage viable myocardium in these patients.
The IABP can be used to alleviate the hemodynamic instability caused by myocardial
ischemia while the physician evaluates further intervention options (e.g., coronary
bypass surgery). Early intervention is important. Includes post infarction angina.
Unstable (Refractory) Angina 18
Angina is a sign that oxygen supply to the heart is inadequate. Angina sometimes
becomes resistant to usual modes of therapy, and the pain continues. Patients with
intractable angina often find dramatic relief within 15 minutes of instituting IABP
support. This allows time for further evaluation of patient symptoms. Includes
impending infarction (MI).
Ischemia Related Ventricular Arrhythmias
Ventricular irritability may result from islands of ischemic myocardium. Cell
membranes of the hypoxic cells become unstable and discharge electrical currents in a
disorganized manner. IABP can relieve the hypoxic environment of the irritable cells by
increasing coronary artery perfusion. Reduced myocardial oxygen demand may also
help patients with these dysrhythmias.
Septic Shock
21
Septic shock is a state of vascular collapse due to a fall in systemic blood pressure.
Bacterial endotoxins paralyze the pre-capillary sphincters, causing a fall in blood
pressure. These pre-capillary sphincters are paralyzed in the open position and are
unable to maintain a driving pressure for tissue perfusion. At the onset of septic shock
syndrome, CO is very high (maintained by elevated Stroke Volume [SV] and HR) and
Systemic Vascular Resistance (SVR) is very low. Late in the course of septic shock,
profound vasoconstriction increases SVR and decreases CO. Also, it is thought that
circulating myocardial depressant factors begin to impair myocardial contractility in the
later stages of this syndrome. CO falls, and the patient's condition deteriorates rapidly.
In addition, the tissues become unable to utilize the oxygen that is delivered, and
increased arteriovenous shunting of oxygen occurs.
The IABP has been employed in some cases of septic shock, generally when the patient
is known to have compromised myocardial function. In the early stages of the
syndrome, when coronary perfusion is low due to arterial vasodilatation, the IABP may
help to increase Coronary Perfusion Pressure (CPP) and supply the heart with extra
oxygen. In the late stages, IABP may benefit the patient by reducing afterload when
vasoconstriction becomes prominent.
Medical Indications
1-5