Question

The patient suffers from silent myocardial infarction, but there are other types of heart diseases. Consider these questions: Describe the heart valvular disorders and how they can produce cardiac failure. What is endocarditis, and what are the most common causes? How many types of shocks are there? Explain them

Answer 1

Valvular heart disease is characterized by damage to or a defect in one of the four heart valves: the mitral, aortic, tricuspid or pulmonary. Any of the four heart valves can become incompetent, causing hemodynamic changes long before symptoms are seen. Most often, valvular defect or damage occurs in isolation in individual valves, but multiple valvular disorders may coexist. Heart valve disorders include:

• Aortic regurgitation: Insufficiency of the aortic valve causing backflow of blood from the aorta into the left ventricle during diastole.
• Aortic stenosis: Narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole.
• Mitral regurgitation: Insufficiency of the mitral valve causing flow of blood from the left ventricle (LV) into the left atrium during ventricular systole.
• Mitral stenosis: Narrowing of the mitral orifice that impedes blood flow from the left atrium to the left ventricle.
• Mitral valve prolapse: Billowing of mitral valve leaflets into the left atrium during systole.
• Pulmonic regurgitation: Insufficiency of the pulmonic valve causing blood flow from the pulmonary artery into the right ventricle during diastole.
• Pulmonic stenosis: Narrowing of the pulmonary outflow tract causing obstruction of blood flow from the right ventricle to the pulmonary artery during systole.
• Tricuspid regurgitation: Insufficiency of the tricuspid valve causing blood flow from the right ventricle to the right atrium during systole.
• Tricuspid stenosis: Narrowing of the tricuspid orifice that obstructs blood flow from the right atrium to the right ventricle.

Endocarditis:

Endocarditis is an inflammation of the endocardium of the heart and usually involves the valves. It is a rare and potentially fatal infection caused by microorganisms. Endocarditis is characterized by vegetations, which is a mass of platelets, fibrin, colonies of microorganisms, and inflammatory cells. In the subacute form of infective endocarditis, the vegetation may also include a center of granulomatous tissue, which may fibrose or calcify. Since the valves of the heart do not receive any dedicated blood supply, defensive immune mechanisms cannot directly reach the valves via the bloodstream. Endocarditis can be caused by both bacteria and fungi.

Causes:

If the heart valves are damaged it is easier for microorganisms to take root and bypass the normal immune response to infection. Common ways, endocarditis is caused are:

• Mouth - Microorganisms can enter the bloodstream, when there is an injury during everyday activities, such as brushing and chewing food. When the teeth and gum conditions are bad, the risk is increased.

• Infection - Microorganisms can spread from the site of a pre-existing infection, such as a skin infection or a gum infection. Bacteria can also enter your body as a result of a sexually transmitted infection (STI), such as chlamydia or gonorrhoea.

• Needles and tubes - Any medical procedure that involves placing a medical instrument inside the body carries a small associated risk of introducing bacteria into your bloodstream. Instruments that have been linked to endocarditis include:syringes, catheters, the tubes used during dialysis and laparoscopes.

• Heart valve disease such as valvular stenosis and valvular regurgitation increase the ris of endocarditis.

• Rheumatic fever can also cause endocarditis.

• Prosthetic valves - Microorganisms sometimes can cause endocarditis in patients with prosthetic valves.

• Intravenous drug use - injecting illegal drugs into veins increases the risk of developing endocarditis due to the use of unsterilized needles.

Shock:

Shock or circulatory shock is a life-threatening condition in which delivery of oxygen to the organs is low, causing organ damage and sometimes death. Blood pressure is usually low. The presentation of shock is variable with some people having only minimal symptoms such as confusion and weakness. The types of Shock are:

Hypovolemia - It is a direct loss of effective circulating blood volume. This may lead to

• A rapid, weak, thready pulse due to decreased blood flow combined with tachycardia.
• Cool, clammy skin due to vasoconstriction and stimulation of vasoconstriction.
• Rapid and shallow breathing due to sympathetic nervous system stimulation and acidosis.
• Hypothermia due to decreased perfusion and evaporation of sweat.
• Thirst and dry mouth, due to fluid depletion.
• Cold and mottled skin (Livedo reticularis), especially extremities, due to insufficient perfusion of the skin.

Cardiogenic: Symptoms of cardiogenic shock include:

• Distended jugular veins due to increased jugular venous pressure.
• Weak or absent pulse.
• Arrhythmia, often tachycardia.
• Pulsus paradoxus in case of tamponade.
• Reduced blood pressure.

Distributive shock includes infectious, anaphylactic, endocrine, and neurogenic causes. The SIRS features typically occur in early septic shock. Distributive shock is different from the other three categories of shock in that it occurs even though the output of the heart is at or above a normal level.

Septic shock:

• Systemic leukocyte adhesion to endothelial tissue.
• Reduced contractility of the heart.
• Activation of the coagulation pathways, resulting in disseminated intravascular coagulation.
• Increased levels of neutrophils.

Obstructive shock is a form of shock associated with physical obstruction of the great vessels or the heart itself. Pulmonary embolism and cardiac tamponade are considered forms of obstructive shock.