Heart- surgical anatomy
- The largest mediastinal organ.
- Extends from the third rib to the caudal border of the sixth rib; however, variations have been noted among breeds and between individuals.
- The heart base (i.e., the craniodorsal aspect [from where the great vessels originate(vascular system)) faces dorsocranially, whereas the apex (i.e., formed by muscles of the left ventricle) points caudoventrally.
- Except for a portion of the right side of the heart (cardiac notch), most of its surface is covered by lung.
- The right ventricular wall accounts for approximately 22% of the total heart weight; the left ventricular wall accounts for nearly 40%.
- The pericardium is a thick, two-layer sac composed of outer fibrous and inner serous layers.
- The pericardial cavity is located between two layers (visceral and parietal) of serous pericardium and normally contains a small amount of fluid.
- Phrenic nerves lie in a narrow plica of pleura adjacent to the pericardium at the heart base.
- The vagus nerves lie dorsal to the phrenic nerve.
- The left recurrent laryngeal nerve leaves the vagus and loops around the aortic arch distal to the ligamentum arteriosum to run cranially along the ventrolateral tracheal surface.
Conditions related to cardiovascular system are;
- Patent ductus arteriosus:
- The ductus arteriosus is a fetal vessel that connects the main pulmonary artery and the descending aorta. During development, it shunts blood away from collapsed fetal lungs.
- Normally, it closes shortly after birth during the transition from fetal to extrauterine life.
- Continued patency of the ductus arteriosus for longer than a few days after birth is called patent ductus arteriosus (PDA).
- Mitral regurgitation:
- Occurs when blood leaks retrograde across the mitral valve into the left atrium during contraction of the left ventricle.
- Synonyms – mitral valve disease and mitral insufficiency.
- Pulmonic stenosis:
- Pulmonic stenosis (PS) is a congenital narrowing of the pulmonic valve, pulmonary artery, or right ventricular outflow tract. Synonyms include pulmonic valve dysplasia and right ventricular outflow tract obstruction.
- Aortic stenosis:
- It is a congenital narrowing of the aortic valve, aorta, or left ventricular outflow tract. The stenosis may be supravalvular, valvular, or subvalvular.
- Ventricular septal defect:
- It is a congenital defect that results from failure or incomplete development of the membranous or muscular interventricular septum.
- Atrial septal defect:
- Atrial septal defect (ASD) is a congenital defect that results from failure or incomplete development of the atrial septum.
- Tetralogy of fallot:
- Tetralogy of Fallot is a complex congenital heart defect that consists of PS(Pulmonic stenosis), VSD (ventricular septal defect),a dextropositioned overriding aorta, and right ventricular hypertrophy.
- Pericardial effusion and Pericardial constriction:
- It is an abnormal accumulation of fluid within the pericardial sac.
- Pericardial constriction results from restrictive fibrosis of the parietal and/or visceral pericardium that interferes with diastolic function of the heart.
- Cardiac neoplasia:
- Cardiac neoplasia includes any neoplastic condition involving the heart, great vessels, or pericardium.
- Synonyms for hemangiosarcomas include angiosarcomas and malignant hemangioendotheliomas.
- Bradycardia:
- Bradycardia is a heart rate that is slower than normal.
- Bradycardia can be physiologic (i.e., sinus bradycardia) or can result from a variety of pathologic disorders, including sick sinus syndrome, atrial standstill, or AV block with ventricular escape.
- Cor triatriatum:
- It is an uncommon congenital defect in companion animals that results from persistence of an embryonic membrane that divides the atrium into two chambers.
- The separation can occur in either the right atrium (cor triatriatum dexter) or left atrium (cor triatriatum sinister).
For more details please download the attachment- PPT.
