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Laterality defect of the heart in non-teleost fish
Myrte M Huijskes1, José M Icardo2, Bram F Coolen3
1Department of Medical Biology, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands.
Insights
A rare heart malformation, dextrocardia, was found in a wild spiny dogfish and farmed sturgeon. This mirrored heart condition, similar to human dextrocardia, highlights congenital heart anomalies in non-teleost fish.
Area of Science:
- Cardiovascular anatomy
- Comparative embryology
- Ichthyology
Background:
- Dextrocardia, a congenital condition where the heart is on the right side, is rare in humans.
- Atypical cardiac chamber positions have been noted in farmed teleost fish.
- Congenital heart malformations are less studied in non-teleost fish.
Purpose of the Study:
- To report the finding of a left-right mirrored heart in a wild spiny dogfish (Squalus acanthias).
- To investigate the incidence of similar cardiac malformations in farmed Adriatic sturgeon (Acipenser naccarii).
- To compare dextrocardia-like conditions in non-teleost fish with human cases.
Main Methods:
- Macroscopic and internal anatomical examination of a wild-caught spiny dogfish.
- Magnetic Resonance Imaging (MRI) and 3D modeling of the shark's heart.
- Re-examination of previously collected data on farmed Adriatic sturgeon, including larvae and adults.
Main Results:
- A wild spiny dogfish exhibited a left-right mirrored heart with an outflow tract from the left ventricle and a rightward atrioventricular canal.
- Approximately 1%-2% of farmed Adriatic sturgeon alevins showed inverted (left-loop) hearts.
- An adult sturgeon displayed abnormal cardiac chamber topology, distinct from abdominal organ positioning.
Conclusions:
- Left-right mirrored hearts, analogous to human dextrocardia, occur in wild and farmed non-teleost fish.
- This finding expands the understanding of congenital heart malformations in diverse fish species.
- The study suggests non-teleost fish can serve as models for studying cardiac development and anomalies.
Abstract:
Dextrocardia is a rare congenital malformation in humans in which most of the heart mass is positioned in the right hemithorax rather than on the left. The heart itself may be normal and dextrocardia is sometimes diagnosed during non-related explorations. A few reports have documented atypical positions of the cardiac chambers in farmed teleost fish. Here, we report the casual finding of a left-right mirrored heart in an 85 cm long wild-caught spiny dogfish (Squalus acanthias) with several organ malformations. Macroscopic observations showed an outflow tract originating from the left side of the ventricular mass, rather than from the right. Internal inspection revealed the expected structures and a looped cavity. The inner curvature of the loop comprised a large trabeculation, the bulboventricular fold, as expected. The junction between the sinus venosus and the atrium appeared normal, only mirrored. MRI data acquired at 0.7 mm isotropic resolution and subsequent 3D-modeling revealed the atrioventricular canal was to the right of the bulboventricular fold, rather than on the left. Spurred by the finding of dextrocardia in the shark, we revisit our previously published material on farmed Adriatic sturgeon (Acipenser naccarii), a non-teleost bony fish. We found several alevins with inverted (left-loop) hearts, amounting to an approximate incidence of 1%-2%. Additionally, an adult sturgeon measuring 90 cm in length showed abnormal topology of the cardiac chambers, but normal position of the abdominal organs. In conclusion, left-right mirrored hearts, a setting that resembles human dextrocardia, can occur in both farmed and wild non-teleost fish.
