Cardiogenic Shock¶
Ashley Cozart
Definition¶
Impairment of cardiac output due to primary cardiac disorder that results in end-organ hypoperfusion and hypoxia
Etiology¶
- Cardiomyopathic: myocardial infarction with LV dysfunction, exacerbation of heart failure, myocarditis, myocardial contusion, drug-induced
- Arrhythmic: atrial tachycardias (atrial fibrillation/flutter, AVRT, AVNRT), ventricular tachycardia and fibrillation, complete heart block, second degree heart block
- Mechanical: valvular insufficiency, valvular rupture, critical valvular stenosis, ventricular septal wall defect, ruptures ventricular wall aneurysm, atrial myxoma
Presentation¶
- Cold (decreased perfusion) due to reduced cardiac output (can be wet- increased PCWP OR dry normal PCWP)
- Symptoms of volume overload + end-organ hypoperfusion (altered mental status, nausea, abdominal pain, decreased urine output)
- Hypotension; narrow pulse pressure
Evaluation¶
- EKG
- Labs: CBC, CMP, BNP, troponin, lactate
- Evidence of end organ damage: lactic acidosis, acute kidney injury, acute liver injury
- Echocardiogram: assess EF and valves
- LHC If ischemia (see ACS)
- Hemodynamic monitoring via Swan-Ganz or PA catheter:
- No benefit for general shock but does improve in-hospital mortality for those with cardiogenic shock
- PA catheter hemodynamic profile:
- Cardiac index \< 2.2, cardiac power \<0.6, SVR 800-1600, SVO2 \<60%
- LV-dominant: RA (CVP) \<15, PCWP >18, PAPi >1.5 (pulmonary artery pulsatility index)
- RV-dominant: RA >15, PCWP \<18, PAPi >1.5
- Bi-V-dominant: RA >15, PCWP >18, PAPi >1.5
- PAPi \< 1 indicates that patient will likely need RV support
- CP \< 0.5 strongest independent hemodynamic correlate of mortality in CS
- See right heart cath section for interpreting PA catheter profiles
Management (medical & mechanical circulatory support)¶
Medical management¶
Focus on optimizing preload, afterload, and contractility.
- Preload: IV diuresis
- Afterload: IV – nitroglycerine, nitroprusside; PO – hydralazine, isosorbide dinitrate; vasoconstricting pressors (phenylephrine, vasopressin) if needing BP support
- Contractility - Inodilators (increase contractility, decrease afterload – milrinone, dobutamine) or inoconstrictors (increase contractility and afterload – epinephrine, norepinephrine)
Mechanical circulatory support indications¶
- Shock refractory to >1 pressor
- Shock 2/2 MI (physiology: unloads LV, increases systemic perfusion, increases myocardial perfusion, and provides hemodynamic support during PCI)
Types of mechanical circulatory support (MCS)
| Intra-aortic Balloon Pump | V-A ECMO | Tandem Heart | Impella | |
|---|---|---|---|---|
| Dynamics | Inflates during diastole, deflates during systole | Blood from femoral vein is oxygenated and pumped to femoral artery | LV: blood aspirated from LA to femoral artery RV: blood aspirate from RA to PA |
Impella 2.5, 5.0 & CP: Blood aspirated from LV to aortic root Impella RP: Blood aspirated from IVC and delivered to PA |
| Flow | 1 LMP | 4.5 LPM | 4-5 LPM | 2.5: 2.5 L/min CP: 3.33 L/min 5.0: 5 L/min RP: 4 L/min |
| Support | LV | BiV | LV, RV, or BiV | LV or RV (RP) |
| Effects | Reduces afterload Increases stroke volume (SV) Increases coronary perfusion Reduces LV preload and PCWP |
Increases afterload Reduces SV Reduces LV preload and PCWP Improves tissue perfusion |
Increases afterload Reduces SV Reduces LV preload and PCWP Improves tissue perfusion |
Reduces SV Reduces preload and PCWP Improves tissue perfusion |
| Complications | Thrombocytopenia Thrombosis Arterial obstruction Aortic rupture or dissection Air embolism |
Circuit thrombosis LV dilation Hypothermia Gas embolism |
Tamponade d/t perforation Thrombosis Embolism (gas or thrombus) Arterial Shunt |
Pump migration Hemolysis Aortic regurg LV perf VT/VF |
Daily management of MCS devices:
- Ensure optimal placement of device with daily CXR
- Anticoagulation (based on device)
- Hematoma monitoring at device site
- Check distal pulses to monitor for limb ischemia
Pearls for MCS
- MCS devices are contraindicated in following situations: aortic regurgitation or metallic aortic valve, aortic aneurysm or dissection, severe aortic or peripheral artery disease, left ventricular or left atrial thrombi, bleeding diathesis, uncontrolled sepsis
- ECMO is placed by the cardiac surgery team, once a patient is cannulated they will move onto the cardiac surgery team
- Impella, tandem heart, and IABPs are placed in the cath lab
- MCS is a bridge to recovery/definitive therapy, durable cardiac support (VAD), or transplant