What Can I Expect from Aortic Valve Replacement Surgery?

Aortic valve replacement is a thoracic and cardiovascular surgery that replaces the original lesion or abnormal heart valve with an artificial valve. The indication is aortic valve stenosis and aortic valve reflux.

Basic Information

English name

aortic valve replacement

Visiting department

Cardiac Surgery

Common locations

heart

Common causes

Aortic stenosis and aortic valve regurgitation

Indications for aortic valve replacement

Aortic stenosis

(1) Strong indications Patients with severe aortic stenosis. Patients with severe aortic valve stenosis undergoing coronary artery bypass surgery. Severe aortic valve stenosis patients undergo aortic valve and other leaflet surgery. In patients with severe aortic stenosis and left ventricular systolic dysfunction (ejection fraction <0.50).

(2) Reasons for aortic valve replacement: Patients with moderate aortic valve stenosis undergo coronary artery bypass surgery or aortic surgery or other valve surgery.

(3) Aortic valve replacement may be considered. Patients with asymptomatic aortic stenosis who have abnormal response to exercise (eg, developing symptoms, asymptomatic hypertension). Asymptomatic patients with severe aortic stenosis who have a high possibility of rapid disease development (such as age, calcification, coronary heart disease) or cannot be operated on in time when symptoms appear. For patients with mild aortic stenosis undergoing coronary artery bypass grafting, when there is evidence of rapid disease development (if moderate to severe valvular calcification). Patients with no symptoms but severe aortic stenosis (aortic valve area <0.6cm2, average gradient> 60mmHg, ejection speed> 5m / s), and the surgical mortality is expected to be less than 1%.

In patients with asymptomatic aortic valve stenosis, the aortic valve replacement does not prevent sudden death.

Aortic regurgitation

(1) Strong indications Patients with severe aortic regurgitation regardless of the status of left ventricular systolic function. Asymptomatic patients with chronic severe aortic regurgitation and resting left ventricular systolic dysfunction (ejection fraction <0.50). Patients with chronic severe aortic valve regurgitation when performing surgical coronary artery bypass surgery or aortic heart valve surgery. In patients with aortic valvular malformations, if the diameter of the aortic root or ascending aorta is> 5.0cm or the diameter increase rate is> 0.5cm / year, there is an indication to perform surgical repair of the aortic root or replace the ascending aorta. In patients with second-valvular deformity, reflux is caused by severe aortic stenosis or aortic regurgitation. If the diameter of the aortic root or ascending aorta is> 4.5cm, there are indications to repair the aortic root or replace the ascending aorta.

(2) There are reasons for aortic valve replacement. Asymptomatic, EF is normal, but there is left ventricular enlargement (left ventricular end-diastolic diameter> 75mm, or end-systolic diameter> 55mm) in patients with severe aortic valve reflux.

(3) Consider the case of aortic valve replacement. In patients with moderate aortic regurgitation who undergo coronary artery bypass surgery or ascending aortic surgery. Patients with severe EF at rest, severe aortic regurgitation with end-systolic diameter> 70mm, or end-systolic diameter> 50mm, but with further expansion of the left ventricle, decreased tolerance to exercise, or abnormal movement Hemodynamic Reflector.

Contraindications for aortic valve replacement

Aortic valve replacement is not suitable in the following cases: patients with mild, moderate and severe aortic valve regurgitation, when there is normal EF at rest and the degree of left ventricular enlargement is not moderate or severe (left ventricular end-diastole diameter <70mm, or End-systolic diameter <50mm).

Preoperative preparation for aortic valve replacement

1. Improve related preoperative tests, including routine hematuria, liver and kidney function, electrolytes, coagulation, eight items of preoperative immunity, BNP, cTnT, myocardial enzymes, and blood gas analysis.

2. Improve relevant preoperative examinations. Important examinations include: echocardiography, electrocardiogram, chest X-ray, and lung function. For patients with angina pectoris, as well as elderly patients, cardiac catheterization should be performed with the exception of coronary artery disease.

3. For patients with heart failure symptoms, strengthen diuretics, heart strengthening and other treatments to improve heart function.

4. Pay attention to electrolyte disorders in patients with symptoms, strictly control the amount of in and out to avoid heart failure caused by excessive fluid replacement.

5. Maintain the patient's blood pressure at normal levels. For patients with aortic stenosis, monitor blood pressure changes in the extremities. For patients with aortic regurgitation, attention should be paid to the difference in pulse pressure.

6. People with angina pectoris should be treated as much as possible to make it alleviate and maintain stability.

7. One week before the operation, the myocardium was protected with a static point of GIK solution.

8. The patient's cardiopulmonary function should be fully evaluated, and a breath-hold test should be performed before the physical examination. The normal value is 20 to 35 seconds. The holding time is shortened, which indicates respiratory insufficiency. Preoperatively exercise breathing function (blowing balloon) and expectoration.

9. Patients with pulmonary insufficiency and patients with previous smoking history can be treated with nebulized inhalation before surgery.

10. Correct arrhythmia and control ventricular rate. If the patient's heart rate is too slow, consider placing a temporary pacemaker before surgery.

11. Strengthen education and education, strengthen patients' understanding of disease and surgery, and make psychological and physical preparations.

12. Preoperative blood distribution to ensure sufficient blood source

13. Combining other systemic diseases, actively contacting relevant departments for consultation, assessing surgical risks, and adjusting treatment strategies.

Selection criteria for aortic valve replacement

1. Class I

(1) In patients with mitral or tricuspid valve with mechanical valve, mechanical valve is recommended (level of evidence C).

(2) Biosynthetic flaps are recommended for patients of any age who are unwilling to take warfarin orally and have contraindications to warfarin treatment (level of evidence C).

2.IIa

(1) When choosing aortic valve surgery and prosthetic valve, the patient's wishes must be considered reasonably. For patients <65 years of age who have no contraindications to anticoagulation, mechanical valves can be used for aortic valve replacement. For patients <65 years of age, discuss the risks of anticoagulation in detail and may require a second aortic valve replacement in the future. Patients will consider biosynthetic valves as a way of life. Level C).

(2) Patients> 65 years of age with no risk of thromboembolism may perform aortic replacement with biosynthetic valves (level of evidence C).

(3) Patients with active prosthetic endocarditis can use the same graft for aortic valve replacement.

3.IIb

Aortic valve replacement with biosynthetic valves can be considered in women of childbearing age.

Aortic valve replacement procedure

The standard approach for aortic valve replacement is a midline chest incision. The aorta and right atrium were cannulated to establish extracorporeal circulation. After cardiopulmonary bypass, the aortic root was cannulated to drain and the left ventricle was drained to the right upper pulmonary vein. If the aortic closure function is good, the cardiac arrest fluid can be perfused antegrade to cardiac arrest, and then the cardiac muscle can be protected by retrograde perfusion. In addition, cardiac arrest fluid should be perfused retrogradely.

After the extracorporeal circulation is started, the space between the aorta and the pulmonary artery is separated, which is conducive to revealing the aorta and suture the aorta. The most important thing is to determine the anatomical location of the right coronary artery from the right Freund's sinus. The fat pad on the surface of the right Freund's sinus can be carefully separated for identification.

Cut the aorta transversely at a position about 3 to 4 cm above the right coronary artery, and observe the aortic valve through this incision. It is very important to extend the incision transversely in front of the aorta. The incision is 1 cm away from the apex of the valve junction. Extend the incision to the right to the midpoint of the non-coronary valve, turning downward to the aortic valve annulus. The incision stop should be at least 1 cm from the aortic annulus.

Adjusting the operating table to a low head and high foot position and tilting it slightly to the left can better expose the aortic valve. At the apex of each valve junction, the traction line is sutured and fixed on the surgical towel. The aortic valve is pulled upward toward the operator, and the aortic valve is cut. After the valve is removed, the left ventricle is filled with wet gauze to adhere small calcified debris. Bone forceps or other instruments can be used to carefully remove the calcified plaque on the annulus. During this process, the assistant can use external suction to suck out the calcified debris. . After the calcified plaques were completely removed, the gauze in the left ventricle was removed, and all small calcified debris in the left ventricle was washed out with cold saline, and the size of the annulus was measured.

According to the size of the annulus measured by the valve detector, a suitable artificial valve is selected. It is important not to implant an oversized artificial valve. An artificial valve that is smaller than the measured annulus value is usually selected. The aortic valve annulus is sutured with a horizontal mattress with a shim suture placed under the aortic valve annulus. After all the sutures are sewn, remove the artificial valve and sew the suture to the suture ring of the artificial valve. Note that the sutures must be evenly distributed and commensurate. The stitch pitch is generally 2mm. In order to be able to sew uniformly, the sewing ring of artificial valve can be divided into three quadrants.

After all the sutures have passed through the artificial valve suture ring, the artificial valve is pushed onto the aortic valve annulus to tie the suture. In order to reduce the difficulty of seating the artificial valve, the suture at the junction of the three valves can be knotted first, and then the suture at the midpoint of the junction can be knotted to ensure that the artificial valve is seated firmly in the annulus.

After the prosthetic valve is fixed, the aortic incision is sutured in two layers with 5-0 polypropylene thread, the first layer is horizontal mattress suture, and the second layer is continuous suture back and forth.

Prior to opening the ascending aorta, warm blood was routinely perfused retrogradely. The purpose is to expel the gas in the coronary arteries before cardiac resuscitation and increase the level of myocardial metabolism. During this period, the venous drainage tube should be partially clamped, and the exhaust tube of the aortic root and the left ventricle continues to attract air to help exhaust the left ventricle. After retrograde perfusion of 500ml warm blood, aortic blocking forceps were opened.

After cardiac resuscitation, transesophageal ultrasound can be used to check whether the ventilation measures are effective. After confirming that the gas in the left ventricle has been completely exhausted, pull out the ventricle of the left ventricle to make the heart beat without load for a period of time, then open the superior and inferior vena cava blocking bands and enter the parallel circulation. After a period of auxiliary circulation, if the shutdown conditions are met, the machine should be shut down in time.

Precautions during aortic valve replacement

1. When removing calcified tissue, prevent damage to the annulus and aortic wall.

2. The choice of artificial valve should not be too large.

3. The aortic incision must not be too close to the coronary artery opening, otherwise the left and right coronary artery openings will be blocked after the artificial valve implantation and knotting.

4. When the whole body is cooled, ventricular fibrillation may occur. At this time, the aorta should be blocked and the cardiac arrest fluid should be perfused. During the entire aortic occlusion period, cold blood cardioplegic solution was perfused every 20 minutes. Pay attention to the application of ice to reduce the temperature of the cardiac surface. The interventricular septal temperature should be kept below 10 ° C.

5. When inserting the left ventricle exhaust pipe through the right upper pulmonary vein, prevent air from entering the left atrium. This is crucial because the venous drainage tube can be briefly clamped to fill the left atrium. Conventionally, a drainage needle is inserted at the root of the aorta before the left heart drainage tube is placed to expel any gas that may enter the heart.

6. The ascending aortic wall of patients with aortic valve replacement may be very weak due to dilatation after stenosis, dilated aortic annulus, etc. Therefore, care must be taken when suture the aortic purse to prevent tearing of the aorta. Gastric sutures can usually be used to suture the aortic cannula to reduce this complication.

7. In aortic reflux surgery, ventricular fibrillation can occur after extracorporeal circulation. Once ventricular fibrillation occurs, left ventricular decompression must be performed immediately. Sometimes this situation is fatal. To avoid this, the whole body is usually cooled after the left ventricular drainage tube is placed. Ventricular fibrillation will soon occur after cooling. At this time, the ascending aorta should be blocked immediately and the cardiac arrest fluid should be perfused retrogradely.

8. Enlargement of the annulus: When the inside diameter of the aortic annulus is too small and valve replacement is unavoidable, the annulus can be enlarged to implant a suitable type of artificial heart valve.

Postoperative management of aortic valve replacement

Blood volume supplement

Appropriate whole blood and plasma should be replenished after surgery, and the crystal fluid should be appropriately restricted. Proper fluid negative balance should be maintained within 2 to 3 days after surgery.

2. Management of heart rhythm disorders and hypokalemia

Postoperative cardiac rhythm disorders are mainly due to hypokalemia, so potassium supplementation should be actively postoperatively.

3. Application of vasodilators and positive drugs

Most patients with valve replacement have left ventricular dysfunction, so vasodilators should be used routinely after surgery. Low blood pressure is not contraindicated. It can be used in combination with dopamine or dobutamine to achieve a balance.

4. Artificial respiration

Routine use of artificial respiration to reduce heart load. The average patient uses it for 6 to 12 hours; the severe patient can extend the use time until the condition is stable.

5. Anticoagulation therapy

Those who use mechanical valves are routinely anticoagulated after surgery, and generally start after the thoracic drainage is significantly reduced, that is, oral warfarin is started 24 to 48 hours after surgery, and heparin is used at the same time. Need for latency.

Aortic valve replacement complications

1. Patients with heart valve bleeding after valve replacement.

2. Severe low cardiac output syndrome.

3. Malignant arrhythmia.

4. Respiratory failure.

5. Severe renal damage and multiple organ failure.

6. Perivalval leakage.

7. Hemolysis and hemolytic anemia.

8. Acute respiratory failure.

9. Mediastinal infection.

10. Artificial valve thrombosis and thromboembolism.

11. Secondary bleeding and pericardial tamponade after prosthetic valve replacement [1-3].

References

1. Johns Hopkins Hospital Cardiac Surgery Manual (Second Edition); Author JVConteW.A. Baumgartner

2. Essentials of Cardiothoracic Surgery, 2nd Edition, edited by LarryR.Kaiser, IrvingL.Kron, ThomasL.Spray

3. Yan Hongbing compiled. American Heart Valve Disease Treatment Guidelines: China Environmental Science Press, 2006 Revised Edition: 50-200.