Protein signalling in heart development Protein signalling in heart development The heart is the first functional organ in a vertebrate embryo. There are 5 stages to heart development. Specification of cardiac precursor cells: The lateral plate mesoderm delaminates to form two layers: the dorsal somatic (parietal) mesoderm and the ventral splanchnic (visceral) mesoderm. The heart precursor cells come from the two regions of the splanchnic mesoderm called the cardiogenic mesoderm. These cells can differentiate into endocardium which lines the heart chamber and valves and the myocardium which forms the musculature of the ventricles and the atria. The heart cells are specified in anterior mesoderm by
Heart failure with preserved ejection fraction atrio-ventricular valves open (mitral valve at left side and tricuspid valve at right side) and the blood passes from the atria into the ventricles. First, ventricles are filled by a pressure gradient but near the end, atria contract (atrial kick) and force more blood to pass into ventricles. Atrial contraction is responsible for around 20% of the total filling blood volume. (In atrial fibrillation, this additional 20% filling volume is lost and the patient may experience systolic heart failure symptoms). Complete left ventricular filling is essential to maintain maximum cardiac output. Left ventricular filling is dependent upon ventricular relaxation and