Overview.
Ebstein’s deformity, also known as tricuspid valve downstroke deformity, is a condition in which the tricuspid septal and/or posterior valves occasionally move downstroke, along with the anterior valve, and attach to the right ventricular wall proximal to the apex of the heart. It accounts for 0.5% to 1.0% of congenital heart disease. It is a rare disease, first reported by Ebstein in 1866, so it is also called Ebstein’s malformation. The posterior and septal valves are positioned below normal, not at the level of the atrioventricular annulus but moved down to the right ventricular wall near the apex, and the anterior valves are usually positioned normally, but occasionally the attachment position is also moved downward, resulting in a larger-than-normal right atrium and a smaller-than-normal right ventricle, and tricuspid insufficiency may be present. These malformations are often associated with patent foramen ovale or atrial septal defects and pulmonary stenosis.
Etiology
The etiology of this disease is unclear. Occasionally, a family history has been reported, with the offspring of mothers who took lithium during early pregnancy being susceptible to the disease.
Symptoms
The most prominent symptoms of this malformation are cyanosis and right heart cardiac insufficiency.
(I) Main signs
1. There is no obvious pulsation in the precordial region on palpation and no sense of closure of the pulmonary artery on palpation.
2. The 1st heart sound and 2nd heart sound are obviously split, and there may be enhanced 3rd heart sound and 4th heart sound.
3. The second component of the split 1st heart sound is often characterized by a clicking sound, which is known as the “sail sign”.
4. A soft systolic murmur and a short mid-diastolic murmur may be heard in the tricuspid valve area, and there may be cyanosis, pestle-like fingers (toes), and positive systolic jugular vein pulsations.
(ii) According to the clinical manifestations and hemodynamic changes, it can be divided into the following 3 types
1. Mild
There is no or mild cyanosis, cardiac function class I-II, mild-moderate enlargement of the heart, intracardiac shunt mainly from left to right, there is no pressure difference between the right atrium and functional right ventricle, and there is no double-sphere sign on cardiovascular angiography; no surgery is needed or only closure of intracardiac defect is sufficient, and the prognosis is good.
2. Stenotic type
With obvious cyanosis, cardiac function class II or above, mild-moderate enlargement of the heart, reduced blood flow in the pulmonary circulation, right-to-left intracardiac shunt, and double-ball sign on cardiovascular angiography, surgery is required.
3. Atresia incomplete type
No or mild cyanosis, cardiac function grade II or above, severe enlargement of the heart, no pressure difference between the right atrium and the functional right ventricle, the intracardiac shunt may be left to right or right to left, the right atrium is extremely large with double ball sign on cardiovascular imaging, requiring surgical treatment.
Examination
1. Electrocardiogram
P-wave amplitude is increased and/or widened, and sometimes a tangent can be seen, most clearly in leads II, III, aVF and V1. P-R interval is often prolonged, and complete or incomplete right bundle branch block is common. Low voltage is often present in the limb leads and right thoracic leads. Right ventricular hypertrophy is occasionally seen, but there is never a pattern of left ventricular hypertrophy.
Pre-excitation syndrome (type B) is combined in 5% to 25% of patients with this malformation. In congenital heart disease combined with preexcitation syndrome, 30% of these patients have Ebstein’s anomaly. A variety of arrhythmias can occur with this malformation, with paroxysmal supraventricular tachycardia being common, even in the absence of preexcitation syndrome. Other arrhythmias such as atrial pre-systole, atrial flutter, or atrial fibrillation may be seen.
2. X-ray examination
In mild malformations, the heart enlargement is not obvious and the pulmonary blood is normal. In moderate and severe malformations, the heart is enlarged to both sides, mainly the right atrium. Under fluoroscopy, the beat of the heart edge is not obvious, and it is very disproportionate to the enlarged heart, similar to the X-ray sign of pericardial effusion or pulmonary stenosis with heart failure. Because of the enlarged right atrium and the displacement of the right ventricular outflow tract to the left, the cardiac shadow may be square-box or funnel-shaped, and a few lesions may be spherical. The pulmonary blood is reduced and the aortic node is normal or small.
3. Echocardiography
Echocardiography can be used to make a definitive diagnosis. Tricuspid septal and posterior valves are downwardly shifted and the anterior valve is closed late, the EF slope is decreased, the anterior tricuspid leaflet is redundant, the right atrium is enlarged, and the interventricular septum is paradoxically in motion. Color Doppler can confirm atrial level shunting and tricuspid insufficiency.
4. Selective right heart systemic imaging
The main basis for the diagnosis of this abnormality on angiography is tricuspid valve malformation, downward displacement, and atrialization of the right ventricle. Generally, two notches are seen at the lower edge of the right atrium, one near the midline of the spine, which is the intrinsic tricuspid annulus, and the second on the left side of the spine, which is the reaction of the downwardly shifted tricuspid valve. Between the two notches is the atrialized right ventricle. In addition, selective right ventriculography also reveals marked dilatation of the right atrium with slow passage of contrast; early visualization of the left atrium, left ventricle, and aorta (in the presence of atrioventricular traffic). Selective right ventriculography may also reveal tricuspid regurgitation, right ventricular outflow tract stenosis or dilatation.
Diagnosis
Clinical symptoms and signs may be important in the diagnosis of Ebstein’s anomaly, but an accurate diagnosis depends on the following ancillary tests, mainly echocardiography.
Treatment
This congenital malformation should be treated mainly by surgery, supplemented by relevant symptomatic drug therapy.
(I) Surgery
1. Indications for surgery
Except for some patients who cannot bear surgery due to peripheral diseases, all other patients, including those with mild symptoms or no symptoms at all, should be considered for surgical treatment.
2. Timing of surgery
In general, the patient’s symptoms and heart size should be taken into consideration. Surgery should be avoided in infancy and childhood, and should be considered after 15 years of age.
3. Surgical approach
According to the development of the tricuspid valve, there are two types of surgery: palliative surgery and radical surgery, and the current tendency is to favor radical surgery. Patients with Ebstein’s anomaly, especially infants and young children, should be treated with plasty, which has good immediate and long-term results.
(ii) Drug therapy
If there is heart failure, cardiac drugs, diuretics or vasodilators should be given; if there is arrhythmia, appropriate drug therapy or radiofrequency ablation should be given according to the type of arrhythmia; if there are complications such as embolism and infection, they should also be treated accordingly.
Prognosis
The prognosis of Ebstein’s anomaly varies depending on the degree of tricuspid valve subluxation and the development of the tricuspid valve. Some patients may die shortly after birth or remain asymptomatic until adulthood. In general, the earlier the onset of cyanosis and congestive heart failure, the worse the prognosis; the larger the heart, especially if it is progressively enlarged over a short period of time, the worse the prognosis; the more severe the tricuspid valve malformation, the worse the prognosis; and the worse the prognosis if there are severe complications.