LV Failure after CPB:
Differential Diagnosis:
1. Ischemia
a. Graft failure
i. Clot, particulate in graft
ii. Distal suture causing constriction
iii. Kinking of graft
iv. Air in graft
v. Graft sewn in backwards (no flow)
vi. Inadequate flow through IMA
b. Inadequate coronary blood flow
i. Incomplete revascularization (secondary to distal disease or
inoperable vessels)
ii. Inadequate CPP
iii. Emboli in native coronary arteries (air or particulate matter)
iv. Coronary spasm
v. Tachycardia (decreased diastolic filling time)
vi. Increased myocardial O2 demand
vii. Surgical injury to native coronary artery
c. Myocardial ischemia leading to myocardial damage
i. Incomplete myocardial preservation during CPB
ii. Evolving MI
2. Valve Failure
a. Prosthetic valve
i. Sewn in backwards
ii. Perivalvular leak
iii. Mechanical obstruction (immobile disc)
b. Native valve
i. Acute mitral regurg (papillary muscle ischemia or rupture)
3. Gas exchange problems
a. Hypoxemia
i. Inadequate FIO2
ii. Residual atelectasis
iii. Ventilator failure
iv. Airway disconnection
v. Bronchospasm
vi. Pulmonary edema
b. Hypoventilation
4. Preload
a. Inadequate preload
i. Hypovolemia
ii. Loss of atrial kick
b. Excessive preload (can lead to distension of cardiac structures)
5. Reperfusion Injury
6. VSD
7. Miscellaneous causes of decreased contractility
a. Medications
i. Beta blockade
ii. CCBs
iii. Inhalational agents
b. Acidemia
c. Electrolyte abnormalities
i. Hyperkalemia
ii. Hypocalcemia
d. Preexisting LV failure
Treatment of LV failure after CPB
1. Inotropic drug administration (Ephedrine 5-20mg or epinephrine 4-10
mcg bolus given while commencing inotrope infusion)
i. Epinephrine or dopamine if HR is normal and SVR is low or
normal
ii. Dobutamine or milrinone if SVR is increased
iii. Low dose epinephrine or milrinone if HR is elevated
iv. Dobutamine or dopamine is HR is low and pacing not being used
v. Norepinephrine or phenylephrine if SVR is low and CO
normal/elevated
vi. Milrinone will significantly reduced SVR so use of an arterial
vasoconstrictor is often necessary
vii. Start NTG is ischemia is present