Chapter 2138: Chapter 2138: Decided by the Body Itself
Given this, it’s impossible to say that the doctor didn’t consider the preoperative factors of the patient’s own physical needs.
The first time the doctor used a mechanical valve for this patient, there was only one reason left: no other choice.
Biological valves are more expensive, and while the patient could afford it, unfortunately, the patient’s body might not accept it. It’s like buying an expensive piece of clothing; if it doesn’t fit, it doesn’t fit, no matter how expensive it is. Once again, it shows that illness does not differentiate between the rich and the poor.
The compatibility of biological valves is much better than mechanical valves, and the post-operative anticoagulant medication only needs to be taken for six months, which is an advantage over mechanical valves. They are more friendly to women who want to get pregnant. The problem is that the manufacturing process of biological valves is subjected to material science and other physical constraints, resulting in finished products that often aren’t as good as mechanical valves, limiting their usage conditions.
The simplest example is when the aortic root of the current patient is so narrow that it’s less than 19 millimeters in diameter, only mechanical valves can achieve such a fit for small-caliber valves. If a biological valve could be made to the same diameter of less than 19 millimeters, there are few manufacturers with such manufacturing processes, reducing the range of the best products that patients and doctors can choose from. Moreover, even if they could make a size just under 19 millimeters that perfectly fits the original mitral valve caliber, the effective valve area of biological valves is much smaller than that of mechanical valves.
The crucial role of a valve in the human heart is determined by the effective valve area rather than anything else. To be specific, it refers to the valve leaf area apart from the opening and closing hinge.
What’s the benefit of a large effective valve area? The leaflets’ daily job is to continuously endure the blood flow impact from the heart and major blood vessels.
When the leaflets close, they face the surging blood flow; a larger leaflet closes tightly, just like a solid, massive dam that withstands enormous blood flow pressure.
The hemodynamics when the leaflets open are even more important because it’s at this moment that the blood flows out of the heart to nourish other organs. The best effect needed is like the dam gates releasing water. A large effective valve area means the gates are wide open, allowing the blood stored in the heart to gush out, avoiding residual blood within the heart which would increase the cardiac burden, while also ensuring adequate blood flow to nourish other body organs.
What happens if the effective valve area isn’t large enough? From the above principles, one can deduce the clinical symptoms of valve insufficiency and stenosis.
The human heart has a total of four valves.
Among them, the mitral valve and the aortic valve are on the Left Atrium and Left Ventricle side, bearing the hemodynamic pressure of systemic circulation, which is quite overwhelming, compared to the pulmonary valve and tricuspid valve of the Pulmonary circulation, which bear slightly less workload, and thus their importance is somewhat lessened.
The mitral valve is relatively more crucial and prone to issues compared to the aortic valve because of its position between the Left Atrium and Left Ventricle, located at the root of the aorta. Its position is quite tricky, and many patients’ calibers here are smaller than the aortic valve’s position, leading to fewer options for valve models.
The current statement by the Chief Surgeon seems to suggest, in conjunction with Student Zhang’s words, that upon opening the patient’s heart during surgery, the doctor might have discovered: Oh dear, this patient’s physiological structure isn’t quite right, likely necessitating another mechanical valve replacement.
