Cardiac conduction: fish vs. mammals

Back to: cardiac conduction

Birds:

Many avian species develop an AV-ring which plays a role similar to that of the mammalian AV-node (Szabo et al. Anat Rec. 1986 May;215(1):1-9. PubMed PMID:3706789.) [[1]]

Steps in CCS develoment in zebrafish:

From Genetic and physiologic dissection of the vertebrate cardiac conduction system. PLoS Biol. 2008 May 13;6(5):e109. PubMed PMID: 18479184; PubMed Central PMCID: PMC2430899. [[2]]

1. Initially, a linear conduction travels across the heart tube from the sinus venosus to the OFT (20–24 hours postfertilization (hpf)).
2. next, a significant AV conduction delay develops during cardiac chamber formation (36–48 hpf)
3. as the heart loops and develops ventricular trabeculations (72–96 hpf), an immature fast conduction network develops within the ventricle
4. finally, this fast conduction network fully matures to an apex-to-base activation pattern when the ventricular apex has

formed.

Notable bits from PMC:2323757 [3]

Automaticity of heart rhythm can be neurogenic or myogenic depending on the organism "Invertebrates have been proven to be outside the general concept of the myogenic origin of the heartbeat; pacemaking of a primitive heart originating from a neural ganglion placed behind the dorsal heart wall was documented in some tiny crustaceans ranked among stomatopods – Stomatopoda – for example, Squilla mantis or Squilla oratoria (9). Immediate heart arrest was demonstrated after the neural connection between the ganglion cordis and the heart muscle was cut (10). On the other hand, there was no heart innervation found in other primitive crustaceans – Branchiopoda (eg, Daphnia) – and their heart automaticity is considered to be myogenic"