Cardiogenic Shock

Introduction

Cardiogenic shock is failure of cardiac contractility which leads inadequate organ perfusion and oxygen delivery to tissues. It is clinically defined as SBP < 90mmHg or MAP > 30mmHg below baseline for > 30 mins

 

The most common cause of Cardiogenic Shock is Acute Myocardial Infarction causing LV failure. Mortality in this group is up to 70%. Other causes include;

  • Tachyarrhythmias causing acute heart failure

  • Acute decompensation in cardiomyopathies or an acute cardiomyopathy

  • Acute Myocarditis

  • Myocardial Contusion

  • Acute Valve Failure

  • Severe Outflow Obstruction (e.g. Aortic Stenosis, HOCM)

  • Drug overdose (Beta Blockers, Calcium Channel Blockers)

Clinical Features

 

Symptoms

Cardiovascular

  • chest pain, palpitations, diaphoresis, fatigue

Respiratory

  • SOB, cough productive of pink frothy sputum.

Signs

Signs of shock

  • Tachycardia, hypotension, pallor, hypoxia, delayed CRT, decreased U/O

Signs of heart failure

  • Tachypnoea, bilateral crackles, gallop rhythm, raised JVP, peripheral oedema

 

Differential Diagnosis

Other Causes of Shock

Clinical Investigations

 
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Bedside

  • ECG

    • assessing for presence of ST elevation + territory, presence of heart block

  • VBG

    • Low pH and high lactate indicating end organ hypoperfusion

  • POCUS

    • Echo – assessing for LV dilatation, LV Dysfunction. Dilated IVC

    • Lung US – presence of bilateral B lines consistent with pulmonary oedema, pleural effusions

 
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Laboratory

  • FBC, U&E, LFT, CRP

    • baseline bloods and seeking other causes

  • Troponin

  • Baseline Coag

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Radiology

  • CXR – cardiomegaly and findings consistent with pulm oedema. (ABCDE)

    • Alveolar Oedema

    • Kerley B Lines

    • Cardiomegaly

    • Dilated upper lobe vessels

    • Pleural Effusion

  • Formal Echocardiography

    • quantitative assessment of LV, RV and all valves

  • Coronary Angiogram

    • to seek and treat coronary artery disease causing myocardial ischaemia

Management & Disposition

 

Initial Resuscitation

  • Patient should be managed in a resus environment with immediate attention to any ABC issues.

  • O2 Therapy as required.

    • Patient may require Positive End Expiratory Pressure (PEEP) to maintain oxygenation. This can be administered non invasively (i.e. CPAP/BiPAP) or invasively (i.e. intubation)

  • Hypovolaemia should be looked for and if present treated with cautious alliquots of 250ml of crystalloid.

    • Fluids also NB if RV infarction in inferior STEMI to maintain preload

  • Persistent hypotension and shock is best treated with emergency revascularisation in the cath lab.

    • In the meantime or if nothing to stent patient should have CVC inserted and be commenced on inotropes e.g. noradrenaline, dobutamine

 

Specific Treatment

  • Emergency revascularization with PCI or CABG is the most important treatment and offers the best chance of survival to patients with AMI

  • Load with dual antiplatalets

    • e.g. Aspirin 300mg PO + Ticegralor 180mg PO in ED

  • STEMI patients in centre without access to primary PCI should be thrombolysed if early transfer to PCI centre is not available

Symptomatic Treatment

  • IV analgesia by titrated opioids as required.

 

Disposition

  • STEMI or Critical ischaemia patients = Urgent transfer to cath lab under cardiology

  • If other cause for cardiogenic shock patient should be admitted to ICU for ongoing inotropic treatment and organ support as required.

 

References

1.     Garrett P, Cameron P. Shock Overview. Textbook of Adult Emergency Medicine. 4th Edition.

2.     Case courtesy of Dr Tomas Jurevicius, Radiopaedia.org, rID: 48089

This blog was written by Dr Deirdre Glynn and was last updated in December 2020

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