aortic valve replacement

Surgical treatment of aortic regurgitation is the same as aortic stenosis: valvuloplasty and valve replacement. Valvuloplasty has a long history with the development of cardiac surgery. Before the advent of extracorporeal circulation, there are two surgical methods for the treatment of aortic regurgitation: one is circumflexion and the other is valvuloplasty. In 1958, Lillehei et al used extracorporeal circulation for bilobal incision or Ivalon sponge for single-valve enlargement aortic valvuloplasty. In 1960, Mulder et al. reported different types of valve formation methods. Valve suspension, annuloplasty, and valve repair are commonly used. Treatment of diseases: aortic regurgitation aortic stenosis Indication Aortic valve replacement is applicable to: 1. Patients with aortic regurgitation have symptoms such as palpitations, shortness of breath, chest pain, etc. The pulse pressure is wider than 1/2 of the systolic blood pressure, and there are typical water splashing sounds and water impulses. The chest radiograph showed enlargement of the left ventricle, and the electrocardiogram showed left ventricular hypertrophy and strain, and surgery should be performed. 2. Patients with aortic regurgitation and stenosis should be operated promptly when the left ventricular end-diastolic pressure is >12 mmHg. 3. Due to acute aortic regurgitation caused by infective endocarditis, surgery should be performed after infection control, improvement and stabilization of cardiac function. However, if recurrent arterial embolism occurs, echocardiography should be performed as soon as possible. 4. Acute aortic regurgitation caused by closed thoracic trauma, because the normal left ventricle can not withstand a sudden increase in capacity load, heart failure can occur in a short period of time. Therefore, surgery should be sought in the short term. 5. Patients with aortic regurgitation have mild clinical symptoms, but during systemic follow-up, the heart expands progressively, left ventricular radionuclide angiography, cardiac color Doppler measurement of progressive decline in cardiac function, and surgery should also be performed. 6. In asymptomatic patients, when the proportion of cardiothoracic exceeds 55%, echocardiography shows left ventricular end-systolic diameter >55mm or diastolic diameter >75mm, surgery should be performed; when left ventricular end-systolic diameter is equal to 50mm or EF< 40% and average ring fiber shortening rate <0.6/s should also be operated. 7. Aortic stenosis. Contraindications 1. When heart failure occurs repeatedly, the aortic valve area is weakened, the pulse pressure is not widened, the electrocardiogram axis is obviously shifted to the left (-30°), and the anterior lateral wall myocardial infarction occurs. High, surgery should be carefully considered. 2. Cardiac function grade IV, X-ray showed extreme enlargement of left ventricle, echocardiography showed left ventricular end-systolic diameter >6.0cm, left ventricular short-axis shortening rate <25%, indicating that myocardial function has reached irreversible degree, indicating surgery Poor effect. Should be listed as a relative contraindication. Preoperative preparation In addition to general open heart surgery, the medical history should be carefully analyzed and a comprehensive examination should be carried out. Patients over 40 years of age should be treated with retrograde aortic retrograde angiography, left ventricular angiography and Coronary angiography, detailed understanding of left ventricular function, aortic valve disease, and the presence of coronary lesions to design a surgical plan. Smokers should quit smoking for at least 10 to 14 days before surgery. Myocardial inhibitory drugs should be discontinued 3 days before surgery. Antiarrhythmic drugs and coronary dilatation drugs can be used until the day before surgery. Surgical procedure 1. Incision and establishment of extracorporeal circulation. 2. Aortic incision: After the extracorporeal circulation, when the body temperature drops to 30 °C, the ascending aorta is blocked, the cold heart cardioplegia is poured, and the heart surface is cooled. After the cardiac arrest, the transverse or oblique incision of the aorta is performed, and the lower end of the incision is about 1 to 1.5 cm from the opening of the right coronary artery. Observe the position of the left and right coronary artery openings and confirm that the aortic valve disease needs to be replaced. 3. Sewage traction line: a traction line is laid at each of the three junctions of the aortic valve. 4. Resection of the valve: first remove the three leaflets, leave 2mm edge, then remove the calcified tissue on the annulus, measure the annulus with the valve to determine the artificial valve number. 5. Stitching: Use 2-0 nylon suture with support pad double-ended needle, suture from top to bottom, suture the suture ring immediately after suturing the annulus, pay attention to the suture in the annulus The stitching circle of the artificial heart valve should be evenly distributed and commensurate, and the stitch length is generally 2 mm. 6. Implantation: Straighten all the sutures, push the artificial flap under the annulus, confirm that the bed is in place, and prove that the artificial flap does not block the opening of the left and right coronary arteries and knot them one by one. Finally, check again to make sure the left and right coronary arteries are open. 7. Flush: Thoroughly flush the aorta and left ventricle above and below the artificial valve, and fill the aorta and left chamber with saline. 8. Suture incision: suture the aortic incision continuously with 4-0 or 5-0 sutures, and the last needle should be vented before tightening. 9. Exhaust and resuscitation: After the left heart and ascending aorta are vented, open the ascending aorta blocking forceps. At this point, care should be taken to keep the left heart from flowing smoothly and to avoid swelling of the left heart. If you do not automatically jump, you can use electric shock to defibrillation and recovery. 10. Auxiliary circulation and shutdown: After resuscitation, the heart is beaten for no load for a period of time, then the upper and lower vena cava blocking bands are opened and enter the parallel cycle. After the auxiliary cycle has been in use for a period of time, if it meets the shutdown conditions, it should be stopped in time. complication Important complications after aortic regurgitation include: 1. Ventricular arrhythmia: In patients with severe hypertrophy of the left ventricle, myocardial thickening can exceed 2 to 3 times of normal. Due to the pathological changes of the myocardium, especially the ischemic hypoxia damage and myocardial edema in the intraoperative myocardium, multiple premature ventricular contractions can occur suddenly in the early postoperative period, and can be converted to ventricular tachycardia or ventricular fibrillation in a short time. Causes paroxysmal fainting, occasionally and can appear multiple times in succession. The urgent treatment is rapid intravenous bolus injection of lidocaine, and continuous intravenous infusion, if it is not effective, should be cardioversion. This condition is different from electrolyte disorder, low potassium or low magnesium-induced arrhythmia, and is difficult to treat and has a tendency to recur. The intra-aortic balloon counterpulsation pump can also be applied immediately to increase myocardial perfusion blood flow, so that the myocardial work is reduced, and the heart rhythm disorder can often be effectively controlled. 2. Acute renal failure: In patients with severe aortic regurgitation, renal blood flow is reduced, glomerular filtration rate is reduced, tubular bacteria and protein may appear in the urine, and urea nitrogen is increased. Intraoperative hypoperfusion may result in oliguria or even no urine. Early renal vascular tolerance to hypoxia is poor, especially in the case of low cardiac output syndrome, renal vasoconstriction, decreased urine output. Some patients have stable cardiopulmonary function, but after stopping mechanically assisted breathing, even if the blood pressure and arterial oxygen partial pressure are normal, the first thing that appears is oliguria or even intravenous furosemide. The effect is not significant. If the re-assisted breathing is fully oxygenated, the amount of urine can be significantly increased. Acute renal failure can occur if this secondary effect causes the renal vascular ischemia and hypoxia to be too long.