Cardiogenic shock resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Zaghw, M.D. [2]

Definition

It is a state of end-organ hypoperfusion due to myocardial dysfunction, associated with hemodynamic changes for 30 mins or more which is not due to hypovolemia and not responsive to fluids alone:

• SBP < 80 mmHg or MAP < 30 mmHg than baseline
• Cardiac index ( CI ) < 1.8 L.Min^-1·M^-2 without vasopressors support or CI 2.0 to 2.2 L.Min^-1·M^-2 with vasopressors support.
• Elevated filling pressures LVEDP > 18 mmHg, RVEDP > 10 mmHg

Causes of Cardiogenic Shock (CS)

• Pump problems: LV failure mainly in anterior wall MI still is the most common cause for CS and cardiomyopathy post-MI is the second most common.
• Mechanical problems: Ventricular septal rupture, contained free wall rupture, and papillary muscle rupture. Mechanical problems are strongly suspected in non anterior MI. However cardiac tamponade, tension pneumothorax) and aortic stenosis are recently considered as obstructive shock.
• Electrical problems: is the least commonly cause for CS and most commonly occurs due toVF or VT and AF.

Prognosis

• CS occurs in 8% of hospitalized STEMI patient with a mortality rate of 50-60% within 30 days.
• Risk factors for CS are age > 70 years, systolic blood pressure < 120 mm Hg, sinus tachycardia > 110 bpm or heart rate < 60 bpm, and increased time since onset of symptoms of STEMI.

• CS is associated with more severe lesions in coronary territories with 53% with three vessel diseases and 16 with only left main disease.
• The mortality rate is significantly higher when the culprit lesion is in a left main or saphenous vein graft than in those with circumflex, left anterior descending, or right coronary artery lesions.
• There is no difference in CS mortality rate between STEMI and NSTEMI.
• The left ventricular ejection fraction (LVEF) and severity of mitral regurgitation (MR) are echocardiographic predictors for mortality in the outcomes of CS.
• The only way to prevent CS or to improve the outcomes is the early reperfusion therapy for MI. As the early revascularization therapy particularly by PCI shows global improvement in echocardgiographic indicators as LVEF and MR grade.

Management

Shock

ABCD Airway / O2 / 2 wide bore IV access / 12-lead ECG / focused H&P / CXR PA / Arterial line monitoring

Hemodynamic optimization ❑ Fluid therapy(guided by PCWP,SaO2,CO) ❑ Contributing factors(-ve inotropes,diuretics) ❑ Vasopressors (Norepinephrine,Dopamine) ❑ Correct Acidosis (affect vasopressors) ❑ Correct Hypoxemia (affect vasopressors) ❑ Medications (Aspirin,Heparin,GP IIb/IIIa)

Do Not give β Blockers Ca Channel antagonist

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ECG evidence of STEMI †

ECG inconclusive No ST/Limited ST/delayed CS

ECG: - ve Clinical history of HF

STEMI

Echocardiography rule out Acute valvular lesions

Heart failure

Echocardiography to associated valvular causes ††

Pump failure RV/LV

Acute severe MR VSR Critical AS,MS

Aortic dissection Tamponade

Treatment of heart failure ❑ oxygen ❑ Diuretics ❑ Morphine ❑ Vasodilators

PCI capable center

IABP

PCI Non-capable center

Urgent PCI

severe 3 vessels CAD

Surgical correction Valve surgery ± CABG

PTCA1-2 vessels

Transfer to PCI center¶ < 90 min

Transfer to PCI center > 90 min

Urgent Transfer to PCI

Thrombolytics

Get stable

Still Non stable * Hypotension * ECG evidence

Transfer to PCI center within 3-24 hrs after Thrombolytics

Urgent Transfer to PCI center

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† New ST elevation at the J point in at least 2 contiguous leads of 2 mm in men or 1.5 mm in women in leads V2-V3 and/or of 1 mm in other contiguous chest leads or the limb leads. †† Early echocardiography should be done before PCI as long as the patient is not crashing, as it may change the treatment course. ¶ Door To Baloon, D2B

Special Consideration in CS with STEMI

• Donot give negative inotropic medications (Ca channel blocker-β Blockers)
• Clopidogrel should be stopped till after angiography.
• Lidocaine shouldnot be used in ventricular arrythmia, and if used must be with the lowest dose.

Do's

• 250 mL of isotonic saline should be given empirically as an intravenous volume challenge before the right heart catheterization in patients with suspected CS as long as no clinical evidence of respiratory distress or radiological evidence of pulmonary congestion.
• Correct metabolic acidosis caused by global tissue hypoperfusion, as acidosis can significantly reduce the responsiveness of the vasopressors.
• Monitor the hypovolemic state and hemodynamic status as cardiogenic shock occurs in 5-8% of hospitalized STEMI patient.
• Using smaller combined doses of vasopressors and inotropes is preferable over a single agent used at higher doses to avoid dose-related adverse effects.
• Cardiac Echocardiography (Transthoracic) is helpful to rule out mechanical problems when the initial ECG findings are not conclusive or when the cardiogenic shock occurs with the first non anterior MI.
• Echocardiography should be performed early before PCI unless the diagnosis is extensive anterior MI and the patient is undergoing prompt percutaneous coronary intervention (PCI).
• Transfer the STEMI patients with cardiogenic shock to PCI irrespective to time delay from time of presentation.
• Use IABP with rapid initiation of Thrombolytics <30 min prior transfer, when there is anticipated very long delay in transfer, low risk of fibrinolysis and MI symptoms > 3 hours.
• Use the fibrinolytic agents combined with vigorous vasopressor and IABP

Don'ts

• Do not routinely use an intraaortic balloon pump (IABP)in all MI patients complicated by cardiogenic shock (CS) whom are planned to have primary percutaneous coronary intervention (PCI) is attempted or performed or in whom fibrinolytic therapy is administered.