**2. Cardiogenic shock**

Cardiogenic shock occurs most frequently as a result of acute myocardial infarction (MI) [6], though any disease process that impairs the functional capacity of the left ventricle (LV) or right ventricle (RV) can lead to cardiogenic shock [1]. For years, numerous definitions and clinical criteria for cardiogenic shock have existed [7–10], but in 2019 the Society for Cardiovascular Angiography & Interventions published a consensus statement on the classification of cardiogenic shock [2] that has been useful for assessment of patients as well as predicting outcomes [11]. In this consensus document, stages of cardiogenic shock are described based on physical exam findings, biochemical markers, and hemodynamic parameters [2]. A standardized, team-based approach to management of cardiogenic shock has been recommended due to the complexity of disease and number of treatment options [12]. Though a complete discussion of cardiogenic shock is beyond the scope of this chapter, a brief discussion of LV and RV failure follow.

#### **2.1 Left ventricular failure**

Numerous diseases can cause LV failure and cardiogenic shock though the most common are acute MI and acute decompensation of end-stage heart failure [3, 6]. In the setting of acute MI, there is impairment of regional myocardial contractility, which if significant, can become self-perpetuating as a result of further worsening coronary ischemia [6, 13]. Patients with chronic, end-stage heart failure may enter into an acutely decompensated state and progress to cardiogenic shock due to a number of factors including disease progression, medication or treatment non-adherence, or an acute cardiac insult [3]. Numerous other conditions can also lead to acute LV failure including, but not limited to, acute myocarditis, stress cardiomyopathy, and post-cardiotomy syndrome [13].

Management of cardiogenic shock with predominant LV failure begins with prompt recognition based on clinical criteria followed by a team-based approach to assessment including echocardiogram and hemodynamic values [12]. If acute MI is suspected or confirmed, a coronary angiogram should be performed with revascularization if able [13]. Patients are treated with inotropes and vasopressors to maintain adequate cardiac index and blood pressure. Failure to achieve goals with medications alone should prompt consideration of acute MCS [1, 12].

#### **2.2 Right ventricular failure**

Right ventricular failure is a complex clinical syndrome of fluid overload, low systolic function and cardiac output, and atrial or ventricular arrhythmias [14]. The two pathophysiologies of RV pressure and volume overload typically occur as a result of injury or stress and can occur alone or in combination to cause acute RV failure and reduced cardiac output [14, 15]. Acute rise in RV afterload can occur in the setting of acute pulmonary embolus or subacutely in the acute respiratory distress syndrome due to prolonged hypoxia and/or respiratory acidosis. Acute reductions in right ventricular

*Perspective Chapter: The ProtekDuo® Cannula for Acute Mechanical Circulatory Support DOI: http://dx.doi.org/10.5772/intechopen.111537*

contractility can occur from either ischemic etiology such as MI or from inflammatory etiologies such as myocarditis. Patients may also have chronic RV failure for which they are normally able to compensate yet may become acutely decompensated in the setting of additional increases in RV afterload or reduction in RV contractility [14, 16, 17].

Medical management of acute RV failure begins with fluid volume management, enhancing myocardial contractility, and optimizing RV afterload often with echocardiographic and pulmonary artery catheter (PAC) guidance [2, 13, 15, 17, 18]. Additionally, for patients with hypotension, peripheral vasopressors and inotropes may be required. If the shock state does not resolve with medical management, utilization of acute mechanical circulatory support (MCS) must be considered. Acute RV failure is a major cause of morbidity and mortality [17], thus timely evaluation and initiation of acute MCS is essential [15, 16].

Acute MCS can be used as a bridge to recovery for up to 75% of patients with acute RV failure [16], or if recovery is not possible, a bridge to durable assist devices or heart transplant. Multiple acute MCS devices capable of directly or indirectly bypassing the failed RV are available [16, 17]. In this chapter we will focus particularly on the ProtekDuo® cannula as a component of a right ventricular assist device (RVAD) system.
