Is it permissible to do an operation on the heart valves using pigskin?
Question

One of my female relatives suffers from narrowing of the valves, and it has been decided that she should have an operation in a western country. There are two options with regard to implanting a tube in the valve: it may be made from either metal, which will result in the blood clotting around it, which means that she will have to have drugs all her life to dissolve these clots, or the tube may be made of pigskin, which will not have the same consequences as the metal tube. Is it permissible for her to choose the pigskin to make this tube?.
Praise be to Allah.Firstly: 
The fuqaha’ differed with regard to whether pigskin is purified by means of tanning. The Shaafa’is are of the view that tanning purifies all kinds of skin, whether the animal is one that is permissible to eat or not, apart from (the skin of) dogs and pigs. Abu Haneefah was of the view that an exception is made in the case of pigs only. Imam Ahmad and Maalik were of the view that no skins of dead meat can be purified by means of tanning, including pigskin. There is a report from Ahmad which says that the skin of that which was pure in life may be purified by means of tanning, even if the meat of the animal is not permissible to eat, and there is another report which says that nothing can be purified by means of tanning except only the skin of animals whose meat is permissible to eat. 
Dawood al-Zaahiri and Ibn Hazm were of the view – and it was narrated from Abu Yoosuf, the companion of Abu Haneefah, and some of the Maalikis such as Sahnoon, Ibn ‘Abd al-Hakam and ‘Abd al-Mun’im ibn al-Faras, and al-Shawkaani among later scholars – that all kinds of skins may be purified by means of tanning, including the skins of dogs and pigs. 
Secondly: 
The scholars differed concerning the ruling on making use of pigskin after it has been tanned. As for those who were of the view that it is pure after tanning, they have no doubt that it is permissible to use it for all kinds of purposes. Some of those who said that tanning does not make pigskin pure said that it is permissible to make use of it in dry circumstances but not in wet circumstances. This was narrated from the Hanbalis. What that means is that it may be used as a container for grains, and it may also be used in clothing such as shoes and the like.  
In al-Mawsoo’ah al-Fiqhiyyah (20/34) it says:  
The fuqaha’ are unanimously agreed that pigskin cannot be purified by tanning and it is not permissible to use it because it is impure in and of itself and tanning is like life, because being alive does not make it pure, and the same applies to tanning. 
It was narrated from Abu Yoosuf that pigskin does become pure by means of tanning. 
There is another report which differs from the well-known Maaliki view; It was narrated from ‘Abd al-Mun’im ibn al-Faras, that pigskin is like any other kind of skin, and it is permissible to use it in dry and wet circumstances once it has been tanned, whether it was slaughtered in the proper manner or not. End quote. 
In the answer to question no. 1695 we have stated that pigskin is impure and does not become pure by means of tanning. In the answer to question no. 13213 we quoted Shaykh Ibn Baz (may Allah have mercy on him) as saying that in order to be on the safe side it is better not to use it even if it has been tanned, because of the difference of opinion concerning it. 
Thirdly: 
From the above it is clear that the issue of whether pigskin is purified by means of tanning is the matter of ijtihaad, and it is not like the ruling on pig meat (pork etc). The prohibition on pig meat is a matter on which there is unanimous agreement and it is not permissible to dispute that. 
Based on the view that pigskin becomes pure by means of tanning, there is no doubt that it is permissible to use it. 
Based on the view that it does not become pure by means of tanning, there is no doubt that it is permissible to use it if that is necessary. If there is consensus that it is permissible to eat pig meat in cases of necessity, even though it is unanimously agreed that it is haraam, then it is more likely that it is permissible to use the skin after tanning, concerning which there is a difference of opinion. 
Fourthly: 
With regard to the specific issue of using pigskin to make valves for the heart, if it is not possible to make the valve from pure (taahir) skin, then it is permissible to make it from pigskin out of necessity, and it should be used in preference to the metal which would require one to take medicines permanently, which may lead to many side-effects. 
Al-Nawawi (may Allah have mercy on him) said: 
If a person breaks a bone, it should be set using a pure bone. Our companions – i.e., the Shaafa’is – said: it is not permissible to set it using something impure, when one is able to use something pure instead. If he sets it using something impure the matter is subject to further discussion.  If it needs to be set and he could not find anything pure to use instead, then he is excused. But if that was not necessary and there was something pure that could be used instead, then he has sinned and it must be removed if there is no fear that he may die or the limb may be damaged as a result. End quote. 
Al-Majmoo’ (3/145). 
Shaykh Muhammad al-Mukhtaar al-Shanqeeti (may Allah have mercy on him) said, commenting on the words of al-Nawawi: 
He (may Allah have mercy on him) explained that the basic principle is that it is haraam to use impure bones for medical treatment, and pure bones should be given preference. If there are none available then it may be set using an impure bone, but in that case two conditions must be met: 
1-There should be a need to set the bone
2-There should be nothing pure available that could be used instead
If one of these two conditions is not met, then it is not permissible to set it using something impure, and he is regarded as sinning if he does so, and it must be removed, so long as there is no fear that he may die or one of his limbs may be damaged as a result. 
Based on this discussion, medical treatment by means of transplanting an animal organ of this type [i.e., from an impure animal] should meet two conditions: 
1-The sick person should be in need of the transplant from the impure animal. This condition is met when specialist doctors testify that there is indeed such a need.
2-No pure organ is available that could be used instead.
If these two conditions are met, then there is nothing wrong with the surgeon transplanting this impure organ or part of it, and the presence of this impure organ in the patient’s body is not regarded as having any effect on his prayer or acts of worship for which purification is required, since there is a reason for which a concession is granted allowing it. End quote. 
Ahkaam al-Jaraahah al-Tibbiyyah (p. 268). 
Hence the Islamic Fiqh Council stated that it is permissible, with no reservations, to take an organ from an animal whose meat is permissible to eat and that has been slaughtered properly, or from another animal in the case of necessity, and transplant it into the person who is in need of that. 
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allah have mercy on him) was asked: The heart doctors may put in a vein made of metal or they may put in a vein that they have taken from a pig. But the metal vein may deteriorate and the veins from the pig may be better, as they may be accepted (by the body) and become like part of the person’s body. What is the ruling on that? 
He replied: 
There is nothing wrong with it, i.e., there is nothing wrong with putting veins from another animal into a person’s heart, and it should be based on what is most suitable for his heart, because this is not the matter of eating, and Allah has only forbidden eating pigs, and this is not eating. Once we know that nothing else will help him except this, then it becomes the matter of necessity and Allah says with regard to eating pig meat, i.e., putting it directly in the mouth (interpretation of the meaning): 
“while He has explained to you in detail what is forbidden to you, except under compulsion of necessity” [al-An’aam 6:119]
End quote. 
Liqaa’aat al-Baab il-Maftooh (106/question no. 2). 
And Allah knows best.