Bookshelf

Fate map of pacemaker field. (a) At early somite stages, heart precursors occupy bilateral fields within the lateral plate mesoderm. The primary heart field is indicated in yellow, the secondary heart field is indicated in pink, and the posterior tertiary heart field [5] is indicated in blue. Fate mapping studies indicate the progenitors of the SAN pacemaker cells reside within the tertiary heart field (asterisk). (b) At heart tube stages, the primary heart fields have fused along the midline, while the secondary and tertiary heart fields have not yet been incorporated into the heart. The pacemaker precursors maintain their position within the tertiary heart field mesoderm (blue). (c) At looping stages, the pacemaker cells have incorporated into/can be seen attaching the right inflow of the heart and begin to pace the heartbeat. at atria, avj atrioventricular junction, ht heart tube, vt ventricle, a anterior, p posterior, r right, l left

Heart tumors are rare tumors that form in the tissues of the heart, including muscle tissue, connective tissue, and tissues that line the blood vessels, control heart rhythm, and cover the nerves of the heart. They may also form in the pericardium (the sac around the heart). Most heart tumors are benign (not cancer), but some may be malignant (cancer).

These graphics represent the normal cardiac pulsations and heart sounds. The jugular venous pulsation normally has 3 positive waves—the a, c, and v waves and 2 negative troughs—x and y troughs. The "a" wave is approximately synchronous with the first heart sound and just precedes the carotid upstroke. The "v" wave coincides approximately with the second heart sound. The normal carotid artery pulsation has a single positive wave during systole, followed by the dicrotic notch (about the time of the second heart sound). The apex impulse represents the normal brief, palpable systolic impulse occurring at the time of the first heart sound. In young normal individuals there may be a palpable early diastolic filling wave representing the rapid filling phase of ventricular diastole and corresponding to the normal third heart sound. Auscultation at the aortic area reveals a normal first heart sound (S₁) and second heart sound (S₂). S₂ is normally louder than S₁ in this area. At the pulmonary area there is normal inspiratory (physiologic) splitting of the second sound due to asynchronous aortic and pulmonic closure. The aortic component of the second heart sound (A₂) normally precedes the pulmonic component (P₂). At the tricuspid area there is normal splitting of the first heart sound due to asynchronous mitral and tricuspid closure. The mitral component of the first sound (M₁) normally precedes the tricuspid component (T₁). At this area, physiologic splitting of the second sound may also be appreciated. At the mitral area, the first and second heart sounds are normal. The first sound is normally louder than the second heart sound and only the aortic component of the second heart sound is normally appreciated. Occasionally a third heart sound is normal, reflecting deceleration of blood into the left ventricle during the rapid filling phase of early diastole. Children and young adults often have normal or physiologic third heart sounds.

Coronary heart disease and diabetes status are self-reported.