Cardiogenic shock echocardiography or ultrasound

Echocardiography is an important imaging modality for the evaluation of the patient with cardiogenic shock. This test will allow the identification of certain characteristics that, when complemented by a proper medical history and physical examination, will likely prompt to the diagnosis. These may include: poor wall motion, papillary muscle rupture, pseudoaneurysms, ventricular septal defects, among others. The echocardiographic findings may also suggest or rule out a different diagnosis. The test will provide information about the overall hemodynamic status of the heart as well, which may reveal to be vital in order to plan further measures and predict the outcome. Transthoracic and transesophageal (in the case of inadequate visibility) echocardiography is increasingly used for non-invasive hemodynamic assessment and monitoring in the ICU setting. Using echocardiography, it is possible to assess preload, fluid responsiveness, systolic and diastolic cardiac function, and calculate cardiac output, intravascular and intra-cardiac pressures. It is the golden standard in the initial hemodynamic assessment and should be used as complementary tool in invasively monitored patients in the case of new circulatory or respiratory failure. Echocardiography is indispensable in the management of shock patients and is extremely powerful diagnostic role for the cardiac abnormalities (pericardial effusion and tamponade, acute cor pulmonale and acute or chronic valvular disorders) as a cause for hemodynamic instability. It is the most important and suitable method for assessment of right ventricular function, for diagnosis of septic cardiomyopathy and cardiac causes of weaning failure.

• In recent years noninvasive means of estimating cardiac function have seen their usage increased considerably.
• These methods, such as echocardiography, have helped reducing the use of invasive means, like right heart catheterization, in acute coronary syndrome patients.
• Echocardiography with Doppler imaging has become common practice in recent years across many institutions, for bedside evaluation of cardiac status, including: PA systolic pressure, PCWP, overall function, valvular competence and eventual mechanical complications arising from ACS, such as papillary muscle rupture or ventricular septal rupture, helping in the confirmation of the diagnosis.
• The collection of hemodynamic parameters through echocardiography also contributes to a timely management of these patients, when compared to other more invasive methods.
• However, some possible drawbacks may arise in the interpretation of echocardiographic data, such as: overestimation of cardiac output in patients whose reason for cardiogenic shock is VSD, as well as overestimation of PCWP in those with right ventricular myocardial infarction causing a leftward shift of the interventricular septum.
• Therefore, despite the importance of diagnostic imaging methods in assessing hemodynamic data and laboratory values, possibly confirming a suspected diagnosis, these must always follow a careful assessment of the patient by a physician.^[1][2]

Echocardiography may be performed by 2 different approaches, the transthoracic and the transesophageal approaches:

• Transthoracic – easily accessible, however, sometimes it does not provide an adequate image, particularly in critically ill patients on mechanical ventilatory support or with chronic obstructive pulmonary disease. It may underestimate certain conditions as well, such as a mitral regurgitation that may appear milder on this approach, later revealing to be more sever on the TEE.
• Tansesophageal – although not as accessible as the transthoracic approach, this allows for a better and more accurate visualization of the possible cause of cardiogenic shock, such as MR or VSR, particularly when complemented by color flow Doppler.

• In a patient with cardiogenic shock complicating left or right ventricular dysfunction, echocardiography may provide valuable findings to support the diagnosis, including:^[3][4][5]

• depressed left or right ventricle systolic function
• elevated filling pressures
• decreased stroke volume
• tamponade from increased pericardial fluid
• mitral regurgitation
• proximal aortic dissection
• ventricular septal rupture

• In the case of right ventricle myocardial infarction, echocardiographic findings may include:^[6][7][8]

• RV hypokinesis
• RV akinesis
• Right atrial enlargement
• Ventricular dilation
• Bowing of intraventricular septum into the LV

• In acute mitral regurgitation, the echocardiogram may be useful in:^[6][9]

• visualizing of the defect, thereby distinguishing it from VSR, whose clinical findings may be similar
• normal LV cavity concomitant with severe mitral regurgitation, suggesting an acute event
• visualization of the flail leaflet, along with the direction and size of the regurgitant jet
• in case of suspicion of papillary muscle rupture, not seen in transthoracic echocardiography, TEE may be necessary

• In ventricular septal rupture, echocardiographic findings may include:^[6][10]

• the presence and location of the VSR
• size of the shunt

• In free wall rupture and tamponade, echocardiographic findings may include:^[6]

• visualization of pericardial effusion
• signs of cardiac tamponade, such as:

• >25% of respiratory variation in mitral inflow
• diastolic collapse of RV

• evaluation of the ventricular wall defect

Once the cause for the cardiogenic shock and instability of the patient have been resolved, echocardiography constitutes a good method to monitor the hemodynamic status of the heart during patient’s recovery and follow-up.

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