SONOWORLD : Fetal Spongiform Myocardium
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Obstetrics » Obstetrics 2nd And 3rd Trimester
Fetal Spongiform Myocardium
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Author(s) :
Manjiri Dighe, MD
Presentation A 32 year old gravida 1, para 1 female came for her 1st ultrasound at 28 weeks of gestation. The fetus had a normal anatomic survey except for the appearance of the heart.
Caption: 4 chamber fetal heart in an apical orientation
Description: Ultrasound of the 4 chamber fetal heart showing thickened apices of the ventricles (LV, RV) with anechoic areas within it (LV - left of screen and RV - right of the screen).
Caption: Lateral 4 chamber fetal heart
Description: Lateral 4 chamber fetal heart showing the thickened apices of the ventricles with anechoic areas within it.
Caption: Oblique transverse through the fetal heart
Description: Color Doppler ultrasound showing high velocity flow into the anechoic spaces in the thickened ventricular apices
Differential Diagnosis
  • fetal spongiform myocardium or isolated noncompaction of the fetal myocardium
  • normal appearance of the septomarginal trabecula or moderator band in the right ventricle
  • cardiac tumors like teratomas, rhabdomyomas
Final Diagnosis Fetal spongiform myocardium or isolated noncompaction of the fetal myocardium
Discussion Congenital isolated noncompaction of the ventricular myocardium or fetal spongiform myocardium is a rare disorder of endomyocardial morphogenesis characterized by numerous, excessively prominent ventricular trabeculations and deep intertrabecular recesses (1).
In the early embryo the heart is a loose interwoven mesh of muscle fibers. The developing myocardium gradually condenses, and the large spaces within the trabecular meshwork flatten or disappear (2, 3). Trabecular compaction is normally more complete in left ventricular than in right ventricular myocardium. Therefore noncompaction of the ventricular myocardium is more common on the right than on the left. Noncompaction of ventricular myocardium (sometimes referred to as “spongy myocardium”) is believed to represent an arrest in endomyocardial morphogenesis (4, 5). There is an arrest of the normal process of compaction of the loose interwoven mesh of myocardial fibers in the embryo.

The gross anatomical appearance is characterised by numerous, excessively prominent trabeculations and deep intertrabecular recesses (4, 5). Histological examination reveals that the deep intertrabecular recesses are lined with endothelium that is continuous with the endocardial endothelium. This indicates that the “spongy” appearance of noncompaction is due to the deep intertrabecular recesses per se and not to intramyocardial sinusoids. Furthermore ischemic lesions are sometimes found in the thickened endocardium as well as in the prominent trabeculae surrounded by deep intertrabecular recesses.

Three major cardiac risks are associated with noncompaction; these are 1) depressed systolic function of the noncompacted ventricle, 2) endocardial clot with systemic embolisation and 3) ventricular arrythmias, sometimes fatal. Congenital fetal spongy myocardium or noncompacted myocardium is a rare disorder with poor prognosis (6). In our case the patient underwent a therapeutic abortion and the findings were confirmed on histopathology.

Isolated noncompaction of ventricular myocardium is a rare disorder. Both sexes are affected. Distinct morphological features can be diagnosed on two- dimensional echocardiography; these features correspond to the gross endomyocardial morphology at necropsy. Early diagnosis of fetal spongiform myocardium and correct management of such patients are crucial as the clinical manifestation is characterized by important morbidity and mortality caused by early heart failure, life threatening ventricular arrythmias and systemic emboli events (5).

The differential diagnoses in this case also include normal appearance of the septomarginal trabecula or moderator band in the right ventricle, cardiac tumors like teratomas and rhabdomyomas and noncompacted myocardium.

Cardiac rhabdomyomas appear solid and echogenic and and typically arise from interventricular septum. Teratomas appear cystic or solid but do not have flow within the cystic spaces (7).
The septomarginal trabecula of the right ventricle, originally termed the moderator band, is a muscular thickening extending from the interventricular septum to the base of the anterior papillary muscle (8). The left ventricle has a relatively smooth inner wall, hence appearance of apical wall thickening with vascular flow within it is most suggestive of a noncompacted or spongiform myocardium.

Case References 1. Chin TK, Perloff JK, Williams RG, et al. Isolated Noncompaction of the left
ventricular myocardium: a study of eight cases. Circulation 1990; 82: 507-13.

2. Patten BM: Development of the heart, in Gould SE (ed): Pathology of the Heart. Springfield, Ill, Charles C. Thomas, 1968.

3. Volodaver Z, Neufeld HN, Edwards JE: Coronary Arterial Variations in the Normal Heart and in Congenital Heart Disease. New York, Academic Press, 1975.

4. Chenard J, Samson M, Beaulieu M: Embryonal sinusoids in the myocardium: Report of a case successfully treated surgically. Can Med Assoc J 1965; 92: 1356 - 57.

5. Jenni R, Goebel N, Tartini R, Schneider J, Arbenz U, Oswald O: Persisting sinusoids of both ventricles as an isolated anomaly. Echocardiographic, angiographic, and pathologic anatomical findings. Cardiovasc Intervent Radiol
1986;9: 127-131

6. Guntheroth W, Komamiski C, Atkinson W, Fligner CL. Criterion for fetal primary spongiform Cardiomyopathy: restrictive pathophysiology. Obstet Gynecol 2002 May; 99 (5 pt 2); 882-5.

7. Stamm E and Drose J. The Fetal Heart, in Rumack C, Wilson S, Charboneau J. Diagnostic Ultrasound. 2nd edition. Mosby-Year Book Inc. 1998 1124-1159.

8. Hosseinpour A. R., Anderson R.H., and Ho S.Y.  The anatomy of the septal perforating arteries in normal and congenitally malformed hearts. J. Thorac. Cardiovasc. Surg., June 1, 2001; 121(6): 1046 - 1052.

Follow Up The patient underwent a therapeutic abortion and the ultrasound findings were confirmed on histopathology.
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