Morpho-functional characterization of the heart of Gallus gallus domesticus with special reference to the right muscular atrioventricular valve

Abstract

In this work, we studied the structure and function of the adult chicken heart with a focus on the right muscular atrioventricular valve using anatomic and echocardiographic methods. We demonstrated that the free wall thickness of the right and left ventricles changes from the apex to the base of the heart. The right muscular atrioventricular valve (RAVV) is joined directly to both the parietal right ventricle free wall (one attachment) and the interventricular septum (two attachments: ventral and dorsal). This valve does not have chordae tendineae or papillary muscles. The quantitative morphological and functional characterization of the RAVV is given. In color Doppler echo, no regurgitation of blood flow in the RAVV was observed in any of the studied birds. The blood flow velocity in the RAVV is 56.2 ± 9.6 cm s^-1 . A contractile function of the RAVV is shown. Based on the findings obtained, we conclude that the RAVV has a sufficient barrier function. In addition, as this valve is an integral part of the right ventricle free wall, it contributes to the right ventricle pump function. An agreed nomenclature of the parts of the RAVV is required.

Keywords: Gallus gallus domesticus; anatomy; atrioventricular valve; echocardiography; heart; intracardiac hemodynamics.

Figure 1

Photographs of an adult chicken heart. The adipose tissue in the coronary sulcus is removed. (A) Ventral surface. (B) Dorsal surface. (C) Illustration of the measuring points for the postmortem evaluation of the myocardial thickness. (a–c) Left ventricular free wall: (a) basal, (b) middle, (c) apical. (d–f) Interventricular septum: (d) basal, (e) middle, (f) apical. (g –i) Right ventricular free wall: (g) basal, (h) middle, (i) apical. A, apex of the heart, A`, apex of the right ventricle; Ao, aorta; IVS, interventricular septum; LA, left atrium; LAVV, left atrioventricular valve; LBA, left brachiocephalic artery; LV, left ventricle; LVFW, left ventricular free wall; PA, pulmonary artery; PM, papillary muscle; RA, right atrium; RBA, right brachiocephalic artery; RV, right ventricle, RVFW, right ventricular free wall.

Figure 2

External view of the right muscular atrioventricular valve in the adult chicken heart. (A) Scheme explaining measurement of morphological parameters of the valve: A, valve length; B, valve width in the area d; C, thickness in the area d; D, thickness of the free edge of the valve; E, length of the a area; F, width of the large basis of the a area; G, width of the small basis of the a area; H, thickness of the a area. (B) Photograph of the endocardial surface of an adult chicken heart (a view of the base of the heart after some parts of the atria and the ventricles were removed). The black asterisk shows the place of the ventral septal attachment of the right muscular atrioventricular valve. Adapted and modified from Prosheva & Kaseva (2016). (C) Photograph of the ventricular surface of the right muscular atrioventricular valve; Ao, aorta; af, annulus fibrosus; cs, coronary sinus; ivs, interventricular septum; la, left atrium; ravv, right muscular atrioventricular valve; ra, right atrium; rv, right ventricle; a, part of the free edge of the valve, attached to the right ventricle free wall; b, area of the valve junction with the ventral side of the interventricular septum; c, base of the valve; d, area of the valve junction with the dorsal side of the interventricular septum; e, free edge of the valve.

Figure 3

Transverse diagram showing the connections of the chicken right muscular atrioventricular valve to the right ventricle free wall and to the interventricular septum (schematic section at the level of the atrioventricular junction). Adapted and modified from Prosheva & Kaseva (2016). Aov, aortic valve; ivs, interventricular septum; lavv, left atrioventricular valve; lv, left ventricle; ravv, right muscular atrioventricular valve; pav, pulmonary artery valve; rv, right ventricle; a, part of the free edge of the valve, attached to the right ventricle free wall; b, region of the valve junction with the ventral side of the interventricular septum; c, basis of the valve; d, region of the valve junction with the dorsal side of the interventricular septum; e, free edge of the valve.

Figure 4

The B‐mode echocardiographic image of a chicken heart obtained at the end of the systole. The marker on the limb lead II ECG shows the moment when the image was obtained. IVS, interventricular septum; LV, left ventricle; LVFW, left ventricular free wall; RAVV, right muscular atrioventricular valve; RV, right ventricle; RVFW, right ventricular free wall.

Figure 5

Sequential B‐mode echocardiographic images of the chicken right muscular atrioventricular valve excursion obtained in the course of the cardiac cycle. Arrows indicate the right muscular atrioventricular valve. The right muscular atrioventricular valve contour was outlined by hand and is shown by the red line. ED, end‐diastole; ES, end‐systole; IVS, interventricular septum; RAVV, right muscular atrioventricular valve; RV, right ventricle; RVFW, right ventricle free wall.

Figure 6

Pulsed‐wave Doppler echocardiographic image of a chicken heart. The pulsed Doppler sample volume is placed at the location of the right muscular atrioventricular valve.