Etiologies of valve diseases

There are several causes that can cause dysfunction, or improper functioning of a heart valve. In our country, as it is still predominantly low-income and with inadequate access to health, the main cause is still rheumatic disease, but we are following the emergence of many patients with senile and even congenital origin.

Rheumatic valve disease

Rheumatic fever is an autoimmune disease secondary to infection of the oropharynx by a certain strain of bacteria called lancefield group B streptococcus. After infection, the human immune system begins to form antibodies against these bacteria, but at a certain point, they confuse the antigens of the heart with the antigens of the bacteria leading to an attack on several cardiac structures, including the valves.

Acutely, when a valve is affected, it develops dysfunction predominantly due to regurgitation, due to local edema and inflammation. Over the years, this aggression generates a process of fibrosis and shortening of the affected structures, with retraction and the pathognomonic involvement of commissural fusion.

The free edges of the valves touch one another when they are closed. At this point, an inflammatory healing process occurs, leading to the fusion of adjacent structures. We call this a commissural fusion that occurs only in rheumatic involvement in heart valve diseases.

In general, the rheumatic lesion remains silent, that is, not causing symptoms for years and near the fourth decade of life, more severe repercussions occur with the appearance of cardiovascular symptoms such as dyspnea (shortness of breath), tiredness, palpitations and chest pain.

Rarely does an individual present isolated involvement of only one valve disease when the etiology is rheumatic. In this case, patients have multivalvar involvement, but to different degrees. For example, we can find an individual with significant aortic stenosis, but with mild mitral regurgitation.

Therefore, we say that the individual has multivalvular disease, but the one that has significant hemodynamic repercussions and could cause symptoms is only the involvement of the aortic valve, due to its graduation.

It is not uncommon to find individuals with mitro-aortic-tricuspid involvement, but in different degrees of severity. The pulmonary valve of all has a lower incidence of rheumatic involvement, but it is not exempt from being affected.

When the mitral valve is affected, we have a special configuration due to commissural fusion, fish-mouth appearance, because it resembles the shape of a catfish’s mouth. Echocardiographically, we have the specific description of rheumatic involvement, which is the opening of the anterior leaflet in a dome, or hockey stick, while the anterior leaflet behaves as described, the posterior leaflet has reduced mobility, being described as fixed.

The reason for this, basically, is the commissural fusion due to the peculiar anatomy of the mitral valve. The anterior leaflet has a large surface and a small perimeter of implantation in the annulus. The posterior leaflet has a small surface, but a large perimeter of implantation in the annulus. When the blood encounters a difficulty in passage due to the reduction of the valve area (stenosis), the anterior leaflet bulges, which is not seen in the posterior leaflet.

When another heart valve is affected, we do not find these spatial changes, as the other valves do not present this specific conformation between the leaflets, but in all cases we find commissural fusion.

Anticipating what we will see in other posts, when we have an individual with rheumatic valve involvement, we have the indication of secondary prophylaxis using intramuscular benzathine benzathine penicillin every 21 days.

Suggested literature:

1 – Braunwald, Eugene. Tratado de medicina cardiovascular. 10ª ed. São Paulo: roca, 2017. v.1 e v.2.

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