Heart Murmurs - Stenosis & Regurgitation

Review Heart Anatomy In present times, echocardiography is used to visualize the valvular disease but auscultation of a murmur is a quick, important way to identify whether pathology is present. Heart murmurs are abnormal sounds created by turbulent blood flow across defective cardiac valves. Endocarditis, an infection of the endocardium (inner heart lining) commonly affects the valvular leaflets and causes murmur. Calcification deposits on the valve leaflets create an audible murmur. Rheumatic fever, which is an autoimmune disease (typically associated with Group A streptococcal infection) affects the leaflets and causes murmur. Congenital defects of the valves can also be heard on heart auscultation. Pressure graphs illustrate changes in aortic, left ventricular, and left atrial pressures during a cardiac cycle; if you are unfamiliar with these graphs, you may want to review our tutorial on the Wigger's diagram. Normal blood flow and pressures in the left side of the heart: – The left atrium is characterized by low blood pressure, approximately 10 mmHg; this allows passive blood flow to the ventricle. – Blood pressure in the left ventricle is 120 mmHg during systole, 10 during diastole. – Aortic pressure is 120/80. Notice that aortic and ventricular pressures during systole are the same. Valvular insufficiency occurs when the valve doesn't completely seal and allows blood to flow "backwards" across the valve; for example, regurgitation occurs when scarring of the valve leaflets prevents closure. Mitral valve regurgitation produces a murmur during systole. Be aware that tricuspid valve regurgitation produces the similar effects on the right side of the heart, and that ventricular septal defects produce similar holosystolic heart murmurs. Anatomical and physiological effects of mitral valve regurgitation: During ventricular contraction, the faulty mitral valve allows blood to "backflow" from the ventricle to the atria, increasing both atrial blood volume and pressure. In chronic conditions, the left atrium responds by dilating to increase its compliance to mitigate the increase in pressure. The blood that was pushed into the atrium combines with blood returning from the pulmonary circulation. Thus, a greater volume of blood drains to the ventricle during diastole, increasing its preload; like the atrium, the ventricle accommodates by dilating. Because only a portion of the stroke volume enters the aorta, aortic pressure is decreased. In graphical form: Mitral valve regurgitation raises left atrial pressure, most notably during ventricular systole, and is indicated by the higher v-wave; high left atrial pressure can lead to pulmonary congestion and edema. Aortic pressure is reduced. Left ventricular pressure is elevated during diastole. Characterized by a high-pitched holosystolic murmur that lasts from S1 to S2. Aortic valve regurgitation produces a murmur during ventricular diastole. Faulty aortic valve allows "backflow" of blood to the left ventricle. Because only a portion of blood remains in the aorta, its diastolic pressure falls. The blood that "backflows" into the ventricle combines with blood from the atria, increasing ventricular preload. Thus, stroke volume and systolic aortic pressures increase. Furthermore, increased ventricular filling and pressure causes blood to "back up" and raise pressure in the left atrium and pulmonary veins. As in mitral valve insufficiency, chronic overload leads to atrial and ventricular dilation to increase compliance and mitigate pressure changes. Atrial and ventricular pressures increase. Systolic aortic pressure is increased, but diastolic pressure is reduced (and, therefore, aortic pulse pressure is increased). Characterized by high-pitched murmur is heard after S2. Aortic valve insufficiency can lead to heart failure, and is characterized clinically by "head bobbing," aka, Corrigan's Sign, aka, dancing carotids, in which carotid pulsation is easily visible in the neck. Stenosis occurs when a narrowed valve opening causes an elevated pressure gradient across valve, resulting in increased blood flow velocity, and, therefore, turbulence. For example, calcification causes hardening and thickening of the valves, preventing their opening. Produces a murmur during diastole. Stiffened mitral valve raises the pressure gradient between the atrium and ventricle and creates blood flow turbulence. To effectively move blood into the ventricle across the valve, the atrial muscle must generate additional force; it hypertrophies to meet this demand, and pressure is increased. The opposite occurs in the ventricle, where filling and pressure are reduced. Consequently, stroke volume, aortic pressure, and, in the absence of compensatory mechanisms, cardiac output, are reduced. Ventricular and aortic pressure are reduced. Left atrial pressure is increased We shade the area between the atrial and ventricular pressure curves to highlight the unusually high pressure gradient between them. The weak diastolic murmur occurs after the opening snap; notice that this delay after S2 distinguishes the diastolic murmur of mitral valve stenosis from that of aortic valve regurgitation. Produces a loud, harsh murmur during systole. Stiffened aortic valve obstructs blood flow into the aorta, creating turbulence and low aortic pressure. The left ventricle hypertrophies to meet the demand for increased pressure generation, which can reach as high as 300 mmHg. As a result of increased ventricular pressure, atrial pressure may also increase; in turn, the atrium will need to generate additional contractile force, so it, too, hypertrophies. Pressure in both chambers is elevated. Aortic pressure is drastically reduced during systole, which increases the pressure gradient between the aorta and the left ventricle. Very loud systolic murmur with a crescendo-decrescendo pattern. Notice that this differentiates it from the murmur heard in mitral valve regurgitation, which is steadier. Systolic murmurs are present with mitral valve regurgitation and aortic valve stenosis. Diastolic murmurs are present with mitral valve stenosis and aortic valve regurgitation. Be aware that patent ductus arteriosus, a congenital disorder, produces a continuous murmur that gets loudest at S2. Heart failure and pulmonary edema; enlargement of the atria can cause atrial fibrillation when cardiac electrical signals have to travel increased distances through the atrial wall.