 Pathology of cardiac disease. In this activity, you will identify the symptoms of cardiac conditions. Valvular disease. Heart valves can become damaged with disease or infection. Two complications result from valvular disease. Volume overload and pressure overload. Both of these conditions can lead to shortness of breath with fluid accumulation in the lungs and the potential for irregular and ineffective contractions in both atria. Consequently, blood flow through the heart slows and blood clots may develop in the ventricles. Cerebral vascular accidents are caused when emboli are ejected from the heart into the circulatory system of the brain. Let's look at some examples of blood flow. With a normal valve, blood flow is freely forward. There is no back flow of blood. With stenosis, less blood flows through a smaller opening, there is no back flow of blood. With an incompetent valve, blood flows freely forward, but blood leaks backward through the valve. Valve problems increase the workload of the heart and require the heart to pump harder to force blood through a stenosed valve or to maintain adequate flow if blood is seeping back into an insufficient valve. Most defects are detected by the presence of heart murmurs. All significant defects result in a decreased oxygen supply to the tissues unless compensation is available. As these conditions progress, symptoms of heart failure develop. Here we see decreased cardiac output, incomplete atrial emptying, narrowing of the aortic valve limits blood leaving the ventricle and left ventricular hypertrophy. Myocardial infarction In the case of an MI or heart attack, a coronary artery is partially or completely blocked and the heart muscle does not get enough oxygen. During an MI, part of the heart muscle dies. If a substantial section of the heart is damaged, the heart will stop and the person may die. Here is the area of necrosis or infarction. Coronary artery disease CAD develops over a period of years. The internal wall of an artery can become injured by years of smoking or high blood pressure. Once damaged, the wall becomes prone to collecting plaque. The artery narrows and allows less blood to pass through it. The disease process is called atherosclerosis. Coronary artery disease Here we see a normal artery. Intimal layer is damaged by atherosclerosis. Fatty streak lipoproteins penetrate smooth muscle cell. Fibrous plaque composed of lipoprotein filled smooth muscle cells and collagen decreases blood flow in the artery. Platelets adhere to rough damaged surface of the arterial wall. Necrosis or calcification weakens the arterial wall. Congestive heart failure Congestive heart failure results when the heart is unable to pump effectively and fluid backs up into the lungs or other parts of the body. Fluid overload is serious because it puts a greater workload on the heart. CHF usually occurs as a complication secondary to another heart condition such as an infarction or valve defect. CHF may also be caused by increased cardiac output due to hypertension or lung disease. Left-sided congestive heart failure High pressure in pulmonary capillaries leads to pulmonary congestion or edema. Blood backs up into the pulmonary vein. The left ventricle weakens and cannot empty. Cardiac output to the system is decreased. Decreased renal blood flow stimulates renin angiotensin and aldosterone secretion. This results in vasoconstriction and increased blood volume and increases the heart's workload. Right-sided congestive heart failure Very high venous pressure causes a distended neck vein and cerebral edema. Blood backs up into the systemic circulation. Increased venous pressure results in edema in the legs, liver, and abdominal organs. The right ventricle weakens and cannot empty. Cardiac output to the system is decreased. Decreased renal blood flow stimulates renin angiotensin and aldosterone secretion. This results in vasoconstriction and increased blood volume and increases the heart's workload. You have completed this activity Pathology of Cardiac Disease.