Transient cardiac arrest

Diagnosis

Transient cardiac arrest.

Findings

The CT scan that was acquired 70 seconds after the start of IV contrast administration showed a contrast agent deposit with a blood-contrast level in the dependent portion of the superior vena cava (Figure 1A) and the inferior vena cava (Figure 1B), dense opaci&#64257;cation of the right portal and right hepatic veins (Figure 1C), contrast material pooling in the right renal parenchyma (Figure 1D), and a nonenhanced small abdominal aorta (Figure 1B, C, and D). The other abdominal organs and vessels were unenhanced. The late-phase CT scan, acquired 4 minutes after contrast administration, revealed homogeneous enhancement of the abdominal organs and vessels (Figure 2) and a signi&#64257;cantly increased abdominal aorta diameter (Figure 2C). A diagnosis of transient cardiac arrest was made. Seven hours later, the patient collapsed with hypotension and cardiovascular shock. Aggressive management (including inotropic support and &#64258;uid resuscitation) was instituted in the intensive care unit, and the patient temporarily revived but remained comatose. The patient died 8 days after the CT scan. </<span class="end-tag" />P

Discussion

Burns on &gt;10% of the total body surface area are responsible for systemic perturbations, which, in cases of very severe &#64258;uid volume abnormalities and electrolyte changes, can eventually lead to burn shock, and can represent a vital risk. Removal of necrotic tissue is a priority in treating the burn wound, but it may cause a signi&#64257;cant blood loss.<Sup>1 </<span class="end-tag" />Sup>CT &#64257;ndings during cardiac arrest are very infrequently reported, and the incidence of this disorder during CT scanning is, in fact, unknown. However, the current wide availability of and high demand for CT scanning on seriously injured patients has made it possible to document states of shock or death during a CT examination. </<span class="end-tag" />P
><P

>The small caliber of the aorta, the &#64258;attened inferior vena cava, and the decreased volume of cardiac chambers are well-known CT signs that are associated with hypovolemic shock.<Sup>2,3 </<span class="end-tag" />Sup>In this patient, a small abdominal aorta and a &#64258;attened inferior vena cava were associated with the stasis of contrast material in the venous system and the dependent portions of the right side of the body on the CT images acquired 70 seconds after the start of IV contrast administration. The pooling of contrast material in the venous system and in the dependent parts of the right side of the body has been described in very few previous reports, and it was suggested that these CT &#64257;ndings were indicative of cardiac arrest during or immediately after CT scanning.<Sup>4-8 </<span class="end-tag" />Sup>This peculiar distribution of contrast material in severly hypotensive patients has been attributed to the combination of the pushed pressure of injection, the heavier hydrostatic pressure of the contrast material, and the force of the arti&#64257;cial ventilation.<Sup>5 </<span class="end-tag" />Sup>Our patient was hypotensive during the CT scan, but he did not suffer cardiac arrest until 7 hours later. One possible explanation for the uniform enhancement of vessels and parenchymal organs and the signi&#64257;cantly increased abdominal aorta diameter that were seen in our patient on the CT scan obtained 4 minutes after contrast administration would be the improvement of his hemodynamic status. Although vigorous &#64258;uid resuscitation is likely needed to have a signi&#64257;cant effect on central venous pressure, the relatively small volume of &#64258;uid that was administered during the CT examination probably would have made a signi&#64257;cant difference in the hemodynamic status in this patient. </<span class="end-tag" />P
><p><B>CONCLUSION </<span class="end-tag" />B></<span class="end-tag" />p><P

>This case illustrates that the presence of contrast material pooling in the dependent parts of the right side of the body in patients with serious tran</<span class="end-tag" />P
><P

>sient hemodynamic abnormalities during a CT scan should be considered a sign of transient cardiac arrest or of the imminent development of cardiac arrest. </<span class="end-tag" />P <OL
type="1"
><LI

>Luterman A. Burns and metabolism. J Am Coll Surg. 2000;190:104-114. </<span class="end-tag" />LI
><LI

>Shin MS, Berland LL, Ho KJ. Small aorta: CT detection and clinical signi&#64257;cance. J Comput Assist Tomogr. 1990;14:102-103. </<span class="end-tag" />LI
><LI

>Rotondo A, Catalano O, Grassi R, et al. Thoracic CT &#64257;ndings at hypovolemic shock.Acta Radiol. 1998;39:400-404. </<span class="end-tag" />LI
><LI

>Stoger A, Munsterer B, Schinnerl A. Acute heart arrest in spiral CT [in German]. Rofo. 2000;172:490-491. </<span class="end-tag" />LI
><LI

>Tsai PP, Chen JH, Huang JL, Shen WC. Dependent pooling: A contrast-enhanced sign of cardiac arrest during CT. AJR Am J Roentgenol. 2002;178:1095-1099. </<span class="end-tag" />LI
><LI

>Ko SF, Ng SH, Chen MC, et al. Sudden cardiac arrest during computed tomography examination: Clinical &#64257;ndings and &ldquo;dense abdominal veins&rdquo; on computed tomography. J Comput Assist Tomogr.2003; 27: 93-97. </<span class="end-tag" />LI
><LI

>Meiner E, Rosioreanu A, Katz DS. CT &#64257;ndings of impeding cardiac arrest.Am J Emerg Med.2004; 22: 504-505. </<span class="end-tag" />LI
><LI

>Roth C, Sneider M, Bogot N, et al. Dependent venous contrast pooling and layering. A sign of imminent cardiogenic shock. AJR Am J Roentgenol.2006;186: 1116-1119