A case of fetal cardiac rupture diagnosed by postmortem magnetic resonance image

Introduction

Cardiac rupture is generally caused by myocardial infarction, cardiac aneurysm, cardiac diverticulum or trauma. Fetal cardiac rupture is very rare and has been scarcely reported [1–4]. Therefore, prenatal image diagnosis of fetal cardiac rupture is not well characterized. We described a case of fetal cardiac rupture diagnosed by postmortem magnetic resonance image (MRI).

Presentation of the case

A 37-year-old healthy woman (gravida 1, para 1) had a natural pregnancy with an unremarkable medical and family history. Fetal bilateral pleural effusion was suspected after ultrasonography at 15 weeks of gestation at a private clinic. Amniocentesis was performed, and the chromosomal karyotype was normal (46, XX). She was referred to our hospital for further examination at 18+6 weeks of gestation. Prenatal ultrasonography revealed a high echogenic mass on the anterior surface of the heart (Figure 1, white star), free echogenic fluid around the mass (Figure 1, white arrowhead), insufficient heart motion and bilateral dorsally compressed lungs. A pulse wave Doppler image revealed a reverse flow of ductus venosus. No hydrops fetalis or other structural abnormalities were found. We diagnosed fetal cardiac tamponade caused by pericardial tumor and effusion. We planned pericardiocentesis for definitive diagnosis and relief of compression of the heart and lungs. Fetal death at 19+3 weeks of gestation was confirmed before we attempted pericardiocentesis. The female stillborn weighed 365 g.

Figure 1:

Prenatal ultrasonographic findings at 18 weeks’ gestation.

(A) Four-chamber view, (B) sagittal view of chest. High echogenic mass (white star) is on the anterior surface of the heart, free echogenic fluid around the mass (white arrowhead).

Postmortem MRI at 3.0 Tesla revealed massive abnormal content surrounding the heart and showed very low signal on a T2-weighted image (Figure 2B, C and D, white star). The mass lesion was surrounded by another space that showed iso- to high-signal on the T2-weighted image (Figure 2B, C and D, white arrowhead). These characteristic signal patterns suggested hemopericardium.

Figure 2:

Postmortem magnetic resonance images.

(A) Coronal T1-weighted image of the chest, (B) coronal T2-weighted image of the chest, (C) axial T2-weighted image of the chest, (D) sagittal T2-weighted image of the chest. High-signal content on T1-weighted image and very low signal content on T2-weighted image on the anterior surface of the heart (white star). The mass lesion indicates hemopericardium in subacute stage and is surrounded by another space with iso-signal content on T1-weighted image and iso- to high-signal content on T2-weighted image (white arrowhead). This indicates hemopericardium from subacute to chronic stage.

Macroscopic examination showed 10 mL of pericardial dark, bloody fluid and hematoma surrounding the heart (Figure 3A, white arrowhead). We did not find a malformation or tumor lesion. Microscopic examination showed disruption of the posterior wall in the right atrium (Figure 3B, black star) and a calcification of hematoma near the cardiac apex, which indicated residual cardiac rupture. Idiopathic cardiac rupture was suspected to have resulted in cardiac tamponade causing eventual fetal demise.

Figure 3:

Pathological findings. (A) Macroscopic view (opening of thorax, pericardium and peritoneal cavity) that shows a hematoma that is covering the heart (white arrowhead). (B) Microscopic view of cardiac horizontal section that shows disruption of the posterior wall of the right atrium (black star). RA=right atrium, RV=right ventricle.

Discussion

Prenatal image diagnosis of fetal cardiac rupture is not well characterized. We show prenatal ultrasound and postmortem MRI images of a fetal cardiac rupture. Cardiac rupture accompanies hemopericardium and cardiac tamponade. In the present case, prenatal ultrasonography revealed a high pericardial echogenic mass and free echogenic fluid. A high echogenic mass around the heart is usually suspected to be a tumor such as a teratoma or hemangioma [5]. As a hematoma can display either high or low echogenicity in ultrasonography [6], it is sometimes difficult to distinguish between tumor and hematoma. Postmortem MRI showed a uniform signal void on T2-weighted images as a characteristic of subacute hematoma. MRI is useful in distinguishing between tumor and hematoma. Furthermore, MRI is applicable for the identification of fluid or solid structures and comprehensive delineation of hemopericardium [7]. Our case indicated the effectiveness of postmortem MRI for accurate diagnose of cardiac rupture. Although prenatal MRI at 1.5 Tesla is likely to reveal lower resolution images compared to those of postmortem MRI at 3.0 Tesla, prenatal MRI may aid in obtaining an accurate diagnosis. Hence, fetal MRI can be used for differential diagnosis of a fetal pericardial mass.

To our knowledge, this is only the fifth case report of fetal cardiac rupture [1–4]. We show a summary of all five cases in Table 1. The diagnostic procedure of fetal cardiac rupture was predominantly either autopsy or pericardiocentesis. Fetal demise occurred in four out of the five cases, with gestational age of diagnosis and fetal demise occurring earliest in the present case. In general, the etiology of cardiac rupture is myocardial infarction, cardiac aneurysm, cardiac diverticulum or trauma. We did not detect any findings that correspond to cardiac aneurysm or diverticulum. Moreover, due to the maceration, we were unable to evaluate myocardial infarction and to discuss the etiology of cardiac rupture and the relatively early fetal demise.

It is important to distinguish between cardiac rupture and a pericardial tumor for appropriate prenatal management. The prognosis of fetal cardiac rupture is very poor. However, a fetal pericardial tumor, such as teratoma or hemangioma, is mostly benign, and survival has been reported [5, 8]. A literature review stated that 15 out of 17 cases of fetal pericardial teratoma with fetal therapy achieved survival [8]. The release of cardiac tamponade by pericardiocentesis and resection of tumor are considered to result in good outcome.

In conclusion, we described the image findings of fetal cardiac rupture. Prenatal ultrasonographic finding of a pericardial hematoma is sometimes similar to a pericardial tumor. Postmortem MRI was useful for the accurate diagnosis of fetal cardiac rupture, which suggests the applicability of MRI for prenatal diagnosis.