Aortic valve replacement

Aortic valve replacement is a procedure whereby the failing aortic valve of a patient's heart is replaced with an artificial heart valve. The aortic valve may need to be replaced because: Aortic valve replacement is a procedure whereby the failing aortic valve of a patient's heart is replaced with an artificial heart valve. The aortic valve may need to be replaced because: Current methods for aortic valve replacement include open heart surgery, minimally invasive cardiac surgery (MICS) and transcatheter aortic valve replacement (TAVR). During the late 1940s and early 1950s, the first surgical approaches towards treating aortic valve stenosis had limited success. The first attempts were valvotomies, (i.e. cutting the valve while the heart is pumping). A ball valve prosthesis placed on the descending thoracic aorta (heterotopically) was developed by Hufnagel, Harvey and others to address aortic stenosis, but had disastrous complications. Later, with the innovation of cardiopulmonary bypass, the ball valve prosthesis was placed orthotopically (i.e. in same place as the original aortic valve). This first generation of prosthetic valves was durable, but needed intense anti-coagulation, and cardiac hemodynamics were compromised. During the mid-1950s, a single-leaflet prosthesis was developed by Bahnson et al. In early 1960, Ross and Barratt-Boyes used allografts. Tissue prosthetic valves were introduced in 1965 by Binet in Paris, but they degenerated quickly because the tissue was insufficiently preserved. Carpentier solved this problem by introducing glutaraldehyde-preserved stent-mounted porcine valves. The aortic valve is semilunar (half-moon shaped) with three cusps. It separates the heart from the aorta. Each cusp is attached to the aortic wall creating a sinus; a Valsalva sinus. The origins of the two coronary arteries are sited in two Valsalva sinuses, each named after the coronary artery they supply. Leaflets are separated by commissures. The posterior leaflet is in continuation with the anterior leaflet of the mitral valve (the tissue is called the aorto-mitral curtain). The aortic valve is opened during systole, the driving force for it to open is the difference in pressure between the contracting left ventricle of the heart and the aorta. During cardiac diastole (when the heart chamber gets bigger) the aortic valve closes. Aortic stenosis most commonly is the result of calcification of the cusps. Other reasons for stenosis are the bicuspid valve (some patients have only two cusps at the aortic valve instead of the usual three) and rheumatic aortic stenosis (now rare in the West). Obstruction at the level of the aortic valve causes increased pressure within the heart's left ventricle. This can lead to hypertrophy and ultimately dysfunction of the heart. While x-ray and ECG might indicate aortic stenosis, echocardiography is the diagnostic procedure of choice. US findings also help in grading the severity of the disease. In cases of symptomatic severe aortic stenosis, AVR is warranted. In cases of asymptomatic but severe aortic stenosis, more factors should be taken into consideration. Aortic regurgitation, on the other hand, has many causes: degeneration of the cusps, endocarditis, bicuspid aortic valve, aortic root dilatation, trauma, connective tissue disorders such as Marfan syndrome or Ehlers-Danlos lead to imperfect closure of the valve during diastole, hence the blood is returning from the aorta towards the left ventricle of the heart. Acute aortic regurgitation (caused by endocarditis, aortic dissection or trauma) ends up in pulmonary edema, because of the acute increase in left ventricle (LVEDP) that does not have time to adjust to the regurgitation. Chronic regurgitation, by contrast, gives the heart time to change shape, resulting in eccentric hypertrophy, which has disastrous effects on the myocardium. Ultrasound is here also the best diagnostic mobility, either it is transthoracic or transesophageal. As long-term data on the survival and quality of life of people following valve replacement have become available, evidence-based guidelines for aortic valve replacement have been developed. These help healthcare professionals decide when aortic valve replacement is the best option for a patient. Two widely accepted sets of guidelines used by surgeons and cardiologists are the American Heart Association and American College of Cardiology Guidelines for the Management of Patients with Valvular Heart Disease, and the European Society of Cardiology and the European Association for Cardio‑Thoracic Surgery Guidelines for the management of valvular heart disease. Aortic stenosis is treated with aortic valve replacement in order to avoid angina, syncope, or congestive heart failure. Individuals with severe aortic stenosis are candidates for aortic valve replacement once they develop symptoms or when their heart function is impacted. Some people with asymptomatic aortic stenosis may also be candidates for aortic valve replacement, especially if symptoms appear during exercise testing. Patients with moderate aortic valve stenosis who need another type of cardiac surgery (i.e. coronary artery bypass surgery) should also have their valve addressed by the surgical team if echocardiography unveils significant heart problems. Low gradient aortic stenosis with concomitant left ventricular dysfunction poses a significant question to the surgeon and the patient. Stress echocardiography (i.e. with dobutamine infusion) can help determine if the ventricle is dysfunctional because of aortic stenosis, or because the myocardium lost its ability to contract.