Cardiogenic Shock
Cardiogenic shock is inadequate tissue hypoperfusion due to a primary cardiac dysfunction(Shankar et al., 2022). It is the most common cause of mortality in patients admitted to the hospital with AMI. Cardiogenic shock is complex and is characterized by profound depression of myocardial contractility resulting in a downward spiral in which progressive myocardial dysfunction leads to decreased stroke volume, cardiac output (CO), and low MAP, which reduces the myocardial perfusion(Shankar et al., 2022). The reduction in CO leads to severe tissue hypoperfusion, can worsen the ischemia, and may finally result in refractory shock and subsequent death. Systemic vasodilation also occurs with cardiogenic shock caused due to inflammatory mediators like interleukins and tumor necrosis factors and is associated with cardiogenic shock mortality(Shankar et al., 2022). Vasopressors and inotropes create vasoconstriction or increase cardiac contractility in patients with cardiogenic shock. While vasopressors increase vasoconstriction, leading to increased systemic vascular resistance (SVR), inotropes increase cardiac contractility and improve CO(Shankar et al., 2022). Fitzsimons and Nicoara (2021) wrote that the most used mechanical support device has been the intraaortic balloon pump (IABP). The balloon pump is positioned in the proximal descending aorta. Inflation of the balloon during diastole displaces blood toward the aortic root and into the coronary arteries, thereby augmenting diastolic BP to increase coronary blood flow and improve coronary perfusion. In addition, rapid deflation of the balloon during the systolic phase of the cardiac cycle just before aortic valve opening reduces LV afterload and LV end-diastolic pressure, thereby decreasing myocardial oxygen consumption and myocardial work through a reduction in the isovolumic phase of ventricular systole. Although IABP counter pulsation does not directly increase systemic blood flow, the resulting increase in myocardial performance typically increases CO by approximately 20%.
Adequate nutritional therapy for these hemodynamically unstable patients can improve patient clinical outcomes. Dietary recommendations for patients with cardiogenic shock are high caloric, high protein diet. Despite vasopressors, inotropes, mechanical circulatory support and adequate nutritional therapy, patient may require more interventions with cardiogenic shock. Most patients with CS after MI have significant left main coronary artery or three-vessel disease. In such patients, achieving complete revascularization makes CABG a potentially critical therapeutic strategy(Reyentovich, 2020). A surgical approach also permits the correction of concomitant severe mitral regurgitation, which is often present after an MI(Reyentovich, 2020).
References
Fitzsimons, M. G., Nicoara, A., & Maisonave, Y. (2021, May 28). Short-term mechanical circulatory support: Initiation and management considerations. UpToDate. https://www.uptodate.com/contents/short-term-mechanical-circulatory-support-initiation-and-management-considerations?search=intraaortic%20balloon%20pump&source=search_result&selectedTitle=2~87&usage_type=default&display_rank=2#H3923583124
Reyentovich, A. (2020, December 15). Prognosis and treatment of cardiogenic shock complicating acute myocardial infarction. UpToDate. https://www.uptodate.com/contents/prognosis-and-treatment-of-cardiogenic-shock-complicating-acute-myocardial-infarction?sectionName=Coronary%20artery%20bypass%20graft%20surgery&search=cardiogenic%20shock&topicRef=47&anchor=H36&source=see_link#H36
Shankar, A., Gurumurthy, G., Sridharan, L., Gupta, D., Nicholson, W. J., Jaber, W. A., & Vallabhajosyula, S. (2022). A clinical update on vasoactive medication in the management of cariogenic shock. Clinical Medicine Insights: Cardiology, 16. https://doi.org/10.1177/11795468221075064
