1, Etiology.
Atrial septal defect (ASD) is a residual unclosed defect between the left and right atria due to abnormal occurrence, resorption and fusion of the atrial septum during embryonic development. It accounts for 10% of all congenital heart diseases, is more common in females, and is common in the secondary foramen ovale type. The majority of ASDs can be cured by interventional methods. Echocardiography can clearly diagnose and accurately measure the location and size of the defect.
2. Clinical manifestations.
Most children with ASD are generally asymptomatic and do not affect their activities, and most patients do not develop symptoms until after puberty. Congestive heart failure and pulmonary hypertension will occur at the age of 20-30 years in large and medium-sized ASD, especially after the age of 35 years. If no intervention is taken, patients may have increased right ventricular volume and pressure load due to pulmonary hypertension and then right heart failure, and atrial arrhythmias (atrial flutter or atrial fibrillation) may develop after surgery with or without surgical treatment. In addition, some patients can develop cerebrovascular embolism due to paradoxical thrombosis. For the prognosis of surgical intervention, Murphy reported that patients without preoperative pulmonary hypertension, heart failure, and atrial fibrillation who underwent early closure had the same survival rate as normal subjects. Follow-up revealed that those who underwent surgery before the age of 24 had the same long-term survival rate as normal controls of the same age and sex. those who underwent surgery after the age of 40 had a significantly higher incidence of atrial fibrillation. Therefore, in adult patients with ASD, the defect should be closed as early as possible whenever there is evidence of increased right ventricular volume load on ultrasound. In addition, although it is traditionally believed that small ASDs smaller than 10 mm without cardiac enlargement and symptoms can be treated without surgery, considering that small ASDs may be complicated by paradoxical thrombosis and brain abscess, and these two complications are more likely to occur in adults, especially after 60 years of age, interventional treatment is also recommended for small ASDs in adults.
3. Indications for interventional occlusion therapy.
Usually age ≥ 3 years. ASD with a secondary orifice ≥5 mm in diameter, with increased right heart volume load and left-to-right shunt ASD ≤36 mm. distance from the edge of the defect to the coronary sinus, superior and inferior vena cava and pulmonary veins ≥5 mm; distance to the atrioventricular valve ≥7 mm.
4.Interventional device selection.
At present, only the Amplatzer double-disc blocker produced by the American AGA is used in China, and the domestic ASD blocker has been widely used in the clinic, and the price is only about 1/3 of the imported similar products.
5.Operation methods.
(1) Pre-operative examination: routine laboratory tests such as cardiac X-ray, electrocardiogram, echocardiogram, blood routine, liver and kidney function and blood electrolytes, bleeding and clotting time and infectious disease indicators. The purpose of the examination is to comprehensively evaluate the function of the patient’s heart and other organs, and add relevant items if necessary according to the condition.
(2) Preoperative transthoracic (TTE) or (and) transesophageal echocardiography (TEE), with the following key observations: TTE views are usually monitored in the following three views, and the size of the ASD is measured: (1) short-axis views of the aorta to observe the anterior and posterior walls of the aorta and its contralateral septal stumps, and the length and thickness of the septal stumps at the top of the atria; (2) four-chamber views of the heart to observe the distance between the ASD and the left and right TEE views were taken. Usually two-chamber atrial, short-axis aortic and four-chamber heart views are chosen, which are mainly helpful to observe the images of the septum and surrounding tissue edges that cannot be clearly displayed by TTE, especially the two-chamber atrial view can fully observe the length and thickness of the ASD stump at the superior and inferior vena cava.
6. Preoperative preparation.
Routinely sign a written consent form, and explain the possible complications in the intervention with the patient and his family or guardian, and obtain consent before proceeding with the procedure.
7.Operation procedure.
(1) Local anesthesia is available for adults and older children who cooperate with the operation.
(2) Routinely puncture the femoral vein, deliver the arterial sheath, and push 100u/kg of heparin intravenously, and then add 1/4 to 1/3 of the loading dose every 1h.
(3) Exchange the guidewire to enter the left atrium and left upper pulmonary vein through the ASD, and exchange the 0.035 English 260 cm long stiffened guidewire into the left upper pulmonary vein.
(4) Blocker selection: Currently, most hospitals select blockers based on the maximum defect diameter of ASD measured by TTE, plus 4-6 mm for adults and 2-4 mm for pediatric patients, and also measure the total septal length in order to determine whether the blocker can be fully deployed. The blocker may be increased to 8-10 mm for large ASD, and the selected blocker will be flushed with saline and inserted into a short delivery sheath.
(5) Deliver the delivery sheath. Depending on the size of the blocker, different delivery sheaths are selected and placed in the left atrium or at the opening of the left superior pulmonary vein under the guidance of a stiffened guidewire. 7.5 Blocker placement. The blocker is delivered along the sheath to the left atrium under X-ray and echocardiographic monitoring. The right atrial lateral umbrella of the blocker was opened, and the blocker was fixed at an angle of 20°-30° in the left anterior oblique position of 45°-60° plus the head to the angle, and the blocker was seen to unfold in an “I” shape under X-ray. In the echocardiographic four-chamber view, the blocker was clamped on both sides of the interatrial septum; in the case of aortic margin without stump, the blocker formed a “Y” shape with the aorta in the short-axis view; in the subxiphoid two-atrial view, the blocker was clamped on the stump of ASD without residual shunt; there was no adverse effect on the peripheral structures including left atrium, right atrium and coronary sinus. No adverse effects on peripheral structures including left atrium, right atrium and coronary sinus; no AV block on ECG monitoring. If the above conditions are met, the blocker can be released by rotating the push rod, the sheath can be withdrawn, and the local pressure bandage can be applied.
(6) Postoperative local compression sandbag for 4-6h and bed rest for 20h; intravenous antibiotics are given for 3 d to prevent infection.
(7) Postoperative heparin anticoagulation for 48 h. Normal heparin 100u/(kg?d), divided into 4 intravenous injections, and low molecular heparin 100u/kg each time, subcutaneous injection, once every 12 hours. Aspirin can be taken at a dose of 3-5mg?kg for 6 months in both pediatric and adult; clopidogrel 75mg/d can be added as appropriate in adults with blocker diameter ≥30mm, and warfarin should be taken for a long time in those with atrial fibrillation.