FEATURE CARDIAC IMAGING
pulmonary embolus as a diagnosis in the right clinical scenario. In a patient with shock, a collapsed
vena cava should prompt an ultrasound evaluation of the peritoneal cavity to look for abdominal hemorrhage.
DYSPNEA/SHORTNESS OF BREATH
Dyspnea is a Class I indication for comprehensive echocardiography. Three main goals for FOCUS in this
instance are to rule out pericardial effusion, identify global LV systolic dysfunction, and assess the size of the right ventricle as a proxy for indicating the presence or absence of a hemodynamically significant pulmonary embolus. Complete evaluation of dyspnea in patients requires comprehensive echocardiography to evaluate diastolic function and pulmonary artery pressures, as well as to evaluate for pericardial disease and valvular heart disease.
CHEST PAIN The life-threatening chest pain syndromes where FOCUS may be helpful are in the evaluation of patients with a hemodynamically significant pulmonary embolus (as discussed above) or in screening patients with suspected aortic dissection. FOCUS in patients with suspected
aortic dissection is to look for pericardial or pleural effusions and to assess the diameter of the aortic root. An aortic root greater than 4 cm is suggestive of type A dissection. Chest pain is also a Class I
indication for the use of comprehensive echocardiography in patients with chest pain due to suspected acute myocardial ischemia when the baseline electrocardiogram is non-diagnostic. Given that segmental wall motion and wall thickening analysis are some of the most technically demanding aspects of echocardiographic interpretation (see figure 8).
CARDIAC ARREST The patient in cardiac arrest requires initiation of Advanced Cardiac Life Support (ACLS) treatment and rapid diagnostic evaluation for potentially treatable or reversible causes of cardiac arrest. The goal of FOCUS in the setting of cardiac arrest is to improve the outcome of cardiopulmonary resuscitation by: Identifying organized cardiac contractility to help the clinician distinguish among asystole, pulseless electrical activity (PEA), and pseudo-PEA Determining a cardiac cause of the cardiac arrest Guiding lifesaving procedures at the bedside. In a patient with no ventricular
cardiac contraction and an asystolic electrocardiogram, the survival rate is low despite aggressive ACLS resuscitation. In patients presenting to the emergency department with asystolic rhythms and no ventricular contractility by FOCUS after attempts at resuscitation with pre-hospital ACLS, survival is unlikely. True PEA is defined as the clinical absence of ventricular contraction despite the presence of electrical activity, whereas pseudo-PEA is defined as the presence
of ventricular contractility visualized on cardiac ultrasound in a patient without palpable pulses. Therefore, making the diagnosis of pseudo-PEA can be of diagnostic and prognostic importance. Patients with pseudo-PEA have some observable, although minimal, cardiac output and have a higher survival rate, in part because there are often identifiable and treatable causes of their arrest.
FIG 4, 5, 6 4
5
6
FIG 4: Inferior vena cava (IVC) view. Measurement of the IVC . The diameter (solid line) is measured perpendicular to the long axis of the IVC at end -expiration, just proximal to the junction of the hepatic veins that lie approximately 0.5-3.0 cm proximal to the ostium of the right atrium (RA).
FIG 5: Tracing of the RA is performed from the plane of the tricuspid annulus (TA), along the interatrial septum (IAS), superior and anterolateral walls of the RA. The right atrial major dimension is represented by the green line from the TA center to the superior right atrial wall, and the right atrial minor dimension is represented by the blue line from the anterolateral wall of the IAS.
FIG 6: Cardiac Systolic function Imaging & Diagnostics Issue 3 2011 23
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