15.4
승모판 역류증 I: 서론
승모판 역류증은 심장이 수축하여 심실에서 혈액을 내보내는 심장 주기의 한 단계인 수축기 동안 좌심실에서 좌심방으로 혈액이 역류하는 것을 특징으로 합니다. 이러한 비정상적인 흐름은 주로 승모판 또는 승모판막을 지지하는 구조물(승모판엽, 건삭, 고리, 유두근 포함)의 기능…
승모판 역류증(MR)은 수축기 중에 승모판막이 완전히 닫히지 않아 혈액이 좌심실에서 좌심방으로 역류하는 심장 질환입니다.
그 병인은 두 가지 유형으로 분류됩니다.
원발성 MR은 승모판 탈출증, 류마티스 열 및 퇴행성 변화를 포함한 직접적인 승모판 이상에서 비롯됩니다.
2차 MR은 허혈성 심장 질환 및 감염성 심내막염과 같은 간접적인 요인으로 인해 발생합니다.
MR의 병태생리학은 승모판 또는 첨판, 척삭 건대, 고리 또는 유두근을 포함한 지지 구조의 기능 장애와 관련이 있으며, 이는 역혈류 및 용적 과부하를 유발합니다.
이 과부하는 좌심방 비대와 좌심실 비대 및 확장을 유발합니다.
이러한 보상적 변화는 결국 수축기 기능 장애를 초래할 수 있습니다.
좌심방의 압력이 증가하면 폐막힘과 고혈압이 발생하여 우심실에 부담을 주고 심박출량 감소 및 심부전 증상을 유발할 수 있습니다.
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Q1: What happens to blood flow when the mitral valve fails to close properly?
When the mitral valve fails to close entirely during systole, blood leaks backward from the left ventricle into the left atrium instead of being pumped forward. This abnormal backward circulation reduces the efficiency of cardiac output and forces the heart to work harder to maintain adequate blood flow throughout the body.
Q2: What are the two main categories of mitral regurgitation causes?
Primary mitral regurgitation originates from direct valve abnormalities such as mitral valve prolapse, rheumatic fever, and degenerative changes affecting the leaflets and chordae tendineae. Secondary mitral regurgitation results from indirect factors like ischemic heart disease, myocardial infarction, and infective endocarditis that damage supporting structures or alter ventricular geometry.
Q3: How does mitral regurgitation affect the structure of the heart chambers?
The regurgitated blood creates volume overload in the left atrium and ventricle, causing them to enlarge and stretch. Initially, this adaptive response of hypertrophy and dilation helps maintain cardiac output, but chronic volume overload eventually leads to progressive ventricular dilation and systolic dysfunction.
Q4: What role do the mitral valve's supporting structures play in regurgitation?
The mitral valve's supporting structures include the leaflets, chordae tendineae, annulus, and papillary muscles. Dysfunction or damage to any of these components prevents complete valve closure during systole, leading to incomplete valve closure and blood regurgitation into the left atrium.
Q5: How does increased pressure in the left atrium affect the lungs and right heart?
Increased pressure in the left atrium due to regurgitated blood leads to pulmonary congestion and pulmonary hypertension. This back pressure strains the right ventricle, potentially causing right-sided heart failure and reducing overall cardiac output, which manifests as fatigue and exertional dyspnea.
Q6: What is the relationship between chronic mitral regurgitation and heart failure?
Chronic volume overload and increased atrial pressures result in progressive ventricular dilation and dysfunction, culminating in systolic heart failure. The heart's pumping efficiency decreases over time, reducing cardiac output and causing symptoms such as reduced exercise tolerance and breathing difficulties.
Q7: How do rheumatic fever and degenerative changes cause primary mitral regurgitation?
Rheumatic fever causes scarring and deformation of the mitral valve leaflets, while degenerative changes cause the leaflets and chordae tendineae to thicken and become fibrotic. Both conditions impair the valve's ability to close completely, resulting in blood leakage during systole.