Frequently Asked Questions
What is the material which gives the property of radiopacity to the leaflets? As Dr.Duarte said in the last meeting, the isotropic pyrolitic carbon does not have radiopacity, isn’t it?
Isotropic pyrocarbon has low radiopacity indeed. Pyrocarbon of which valves are made contains 10 % of boron. Due to presence of boron strength of the material rises significantly and low radiopacity appears on the considerable width of the material. The leaflets are visible with angiograph in profile but they are transparent full-face.
According to the brochure, the rotation of the leaflets is always clockwise direction. Do you have some article scientific which demonstrates this movement? In our demo, we have seen that depends of the flow direction, the pressure, …
In conditions of stable, non-turbulent laminar flow the leaflets rotate strictly clockwise. They make one full turn in 100 – 600 cycles. This characteristic is checked for each valve during a pulse-duplicator test. Video of a valve tested with a pulseduplicator is attached. Though in vivo when the blood flow is unstable, unstable rotation, no rotation, counterclockwise rotation or vibration is possible. This process can be observed using an angiograph.
Has the "sonority" of the prosthesis been analyzed? Why does it make less noise?
Loudness of the working valve depends on the myocardium condition and patients body weight. We did not carry out any research for reducing valve sonority.
Which is the real opening angle of the leaflets? 85 º?Dr. Duarte said that maybe the step of 90º to 85º of opening angle through the leaflets can have some good consequences. For example, maybe it can increase the blood flow. Do you have some information about it?
The real opening angle of the leaflets is 85 º, indeed. During the valve development process I carried out special hydrodynamic research to choose the optimal opening angle of the leaflets. When the angle is bigger than 85 º the gradient decreases not significantly but regurgitation rises a lot. Leaflets of “Cardiamed” valves have complex bent shape. At the valve entrance they are parallel to the flow and on the exit they aren’t. Thus gradient on the valve stays low and the flow force applied to the leaflets grows significantly. It speeds up opening and closing of the valve and stabilizes the opening angle. Many other valves with flat leaflets have a problem with leaflets hanging when the opening angle is approximately 80 º and autovibration (“flutter”) effect.
Why are there many types of suture rings: supra and anular? Why do we have intra-supra? As it is not so common.
There are three types of sewing rings according to ISO 5840: intra-, supra- and intra-supraannular. Prosthesis with intra-annular sewing ring takes place fully inside the fibrous ring of the operated valve. It causes significant constriction of hydraulic orifice and rise of gradient. These sewing rings are not popular among cardiac surgeons so we don’t produce them. Valve with supra-annular sewing ring takes place fully above the fibrous ring. Thus effective hydraulic orifice widens and pressure gradient decreases. We produce this type of sewing rings. But not all of the surgeons prefer this type of sewing ring. Most of the surgeons who use a method of sewing when fibrous ring is turned inside out (is everted) prefer intrasupra-annular cuff. In this case only a part of the sewing ring is inside the fibrous ring. Pressure gradient rises slightly but sewing becomes more hermetic, risk of fistula decreases and it’s much easier to change the suture thread with pledget if it breaks.
In the first study it is said that there is less hemolysis with the Cardiamed prostheses. Why did Cardiamed not show these results in the Indian congress? As we belive it may be interesting.
No event of hemolysis was revealed during the clinical investigation. This is mentioned in records and reports including Indian congress. Maybe it just was not accentuated. Hemolysis is not a problem for modern prostheses.
The pressure or compression that it can exert the mitral annulus on valve housing. Can it prevents the rotation of the leaflets ? Why?
Using of non-relevant prosthesis size can cause an odd irregular compression of the valve housing by the heart muscles. As a result housing deformation is possible; gap between hosing and leaflets changes and leaflets become impeded. It’s a common problem for all bileaflet pyrocarbon prostheses. Thus manufacturers recommend anti-anatomical position of the prosthesis because anatomical position can bring to locking the leaflets in the hinge or non-simultaneous closing when the valve is under compression.
Are we sure that the valve rotate inside human heart? How can we show this rotation? Do you have some xray video?
We have just started this research. First results confirm the leaflets rotation. We hope after the research is finished we will give the comprehensive answer.
Are there some cardiographic study analizing the different positions of the normal life (stand up, sitting, supine)?
I don’t know about this type of studies.
With the depth of the valve housing, is it possible to implant this valve preserving the valves, chordae tendinae and papillary muscles?
The significant depth of the valve housing gives a possibility of simplifying the operation and saving leaflets and chordae tendinae of the operated heart valve. “Cardiamed” valves are preferable in this kind of operations because the risk of leaflets blocking is reduced due to the high valve housing used as a protector.
Are there some scientific study about the possible alterations of the explanted valves?
We were given some explanted prosthetic valves after reoperations caused by endocarditis, pannus and thrombosis. The longest running time of a valve was 13 years. Reoperation was carried out due to the pannus growth in conditions of pregnancy. No signs of deterioration was revealed. A leaflet rotation was confirmed by weak traces all over the contact surface on housing. Investigation of the valve with a pulse-duplicator fully confirmed its functionality. Characteristics like pressure gradient and regurgitation did not change compared with the archive data for this valve.
Why does Cardiamed not insist on the few embolic issues, given the poor control of INR? A 40% in correct limits.
In the course of 7 year multi-center examination of 400 patients only 14.5% of patients had INR complied with international norms and this number did not change during the investigation period though anticoagulation therapy was updated for the patients every year to fulfill international norms for INR. It indicates that patients didn’t control their INR and didn’t get adequate anticoagulation therapy between annual follow-ups. In all registered cases of thromboembolic events we were not able to find out INR value in the nearest to the event period of time. The same situation was with thromboses. The only information we have from patients’ relatives that in some cases thrombosis appeared after a stop of anticoagulation therapy or after a prior disease. Thus we can’t confirm relation between INR value and probability of thrombolytic events. In our conclusion we say that even in condition of inadequate anticoagulation therapy the risk of thrombolytic events does not exceed values defined in international standards and is compared with publicated values for other bileaflet prosthetic valves.