Cardiogenic Shock, Acute Coronary Syndrome and Congestive Heart Failure

Posted by e-Medical PPT Wednesday, December 28, 2011

Cardiogenic Shock
Inadequate tissue perfusion resulting from cardiac dysfunction
Clinical definition - decreased cardiac output and tissue hypoxia in the presence of adequate intravascular volume
Hemodynamic definition - sustained systolic BP<90 mm Hg, cardiac index <2.2 L/min/m2, PCWP >15 mm Hg

Causes of Cardiogenic Shock
Acute MI
Pump failure
Mechanical complications
Right ventricular infarction

Other conditions
End-stage cardiomyopathy
Myocarditis (fulminant myocarditis)
Myocardial contusion
Prolonged cardiopulmonary bypass
Septic shock with myocardial depression
Valvular disease

Initial Approach: Management
Assure oxygenation
Intubation and ventilation if needed
Venous access
Pain relief
Continuous EKG monitoring
Hemodynamic support
Fluid challenge if no pulmonary edema
Vasopressors for hypotension
- Dopamine
- Norepinephrine

Intra-aortic Balloon Counterpulsation
Reduces afterload and augments diastolic perfusion pressure
Beneficial effects occur without increase in oxygen demand
No improvement in blood flow distal to critical coronary stenosis
No improvement in survival when used alone
May be essential support mechanism to allow for definitive therapy

Early Revascularization in Acute Myocardial Infarction Complicated by Cardiogenic Shock
ACC/AHA Class I Indication
Patients with ST segment elevation MI who have cardiogenic shock and are less than 75 years of age should be brought immediately or secondarily transferred to facilities capable of cardiac catheterization and rapid revascularization (PCI or CABG) if it can be performed within 18 hours of onset of shock.

Pathophysiology of Cardiogenic Shock
Average LVEF is only moderately severely depressed (30%), with a wide range of EFs and LV sizes noted.
Systemic vascular resistance (SVR) on vasopressors is not elevated on average (~ 1350), with a very wide range of SVRs measured.
A clinically evident systemic inflammatory response syndrome is often present in patients with CS.
Most survivors (85%) have NYHA functional Class I-II CHF status.
Cardiogenic shock IS NOT simply the result of severe depression of LV function due to extensive myocardial ischemia/injury.
Depressed Myocardial Contractility combined with  Inadequate Systemic Vasoconstriction resulting from a systemic inflammatory response to extensive myocardial ischemia/injury results in cardiogenic shock .

The Overproduction of Nitric Oxide May Cause Both Myocardial Depression and Inappropriate Vasodilatation.Thus, excess nitric oxide and peroxy nitrites may be a major contributor to cardiogenic shock complicating MI...

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