8.11. Applying Anatomy
The main symptom of angina is chest pain during exertion, but not rest. During exercise the heart rate and force of contraction increases. However, in the patient with coronary artery atherosclerosis (narrowed arteries), an insufficient volume of blood reaches the respiring myocardium and the death of some cardiac myocytes occurs, leading to pain. After rest, the pain reduces and disappears.
The medical event that is commonly referred to as a heart attack. Atherosclerosis is well-developed in the coronary arteries and the fatty plaques bulge into the lumen of the arteries. A fatty plaque then ruptures due to the turbulent blood flow. An infarct (blood clot) develops at the site of the ruptured plaque. The infarct can block a large proportion of the lumen of the artery, which means the myocardium does not receive blood (and thus oxygen and glucose) for respiration. Cardiac myocytes quickly die / undergo necrosis. The location of the infarct will determine the effects on the heart. For example, a block in the right coronary artery, proximal to the atrial branches that supply the SA node, could cause serious electrical conduction problems.
Transposition of the great arteries
This is a congenital defect where the pulmonary trunk and aorta are connected to the wrong ventricles of the heart (i.e. the aorta leaves from the right ventricle and the pulmonary trunk leaves from the left ventricle). Surgery is performed to correct the situation and thereby prevent excess strain on the heart.
This can present in some patients after a stab wound to the heart. Blood leaks from the heart's chambers into the pericardial cavity. The build-up of blood limits the expansion of the ventricles, which do not fill fully. The cardiac output (the volume of blood pumped out of the heart in one minute) is reduced.