Negus & Anor v Guy's and St Thomas' NHS Foundation Trust

This is a clinical negligence claim relating to aortic valve replacement surgery performed on Mrs Tracy Ann Neill (“TN”), at St Thomas’ Hospital, London, on 5 March 2014. Proceedings were commenced by TN in 2017 but, after her death on 29

The Defendant is the NHS Trust responsible for the control and management of St

Subsequently, on 18 March 2015, TN underwent re-do surgery at King’s College Hospital, during which an ARE was undertaken and a larger, 23 mm, valve inserted. There were difficulties during the re-do operation and complications during TN’s postoperative recovery; after her discharge, TN’s condition continued to deteriorate and she died of heart failure on 29 January 2020. The Claimants say the re-do operation, and TN’s subsequent deterioration and death, would have been avoided had an ARE been performed on 5 March 2014 and a larger valve implanted.

Quantum has been agreed between the parties, subject to questions of breach of duty and causation, which remain in dispute. Specifically, the parties agree that the issues I have to determine are as follows:

Due to the continuing need to reduce transmission of the coronavirus, during the trial of this matter the in-person days were kept to a minimum, with the remainder of the hearing taking place remotely by MS Teams. Public access to the hearing, whether inperson or remote, was enabled by video-link and details for that access were published in the cause-list each day, thus securing the principle of open justice. No significant

In support of the Claimants’ case, I read the statements of TN and of her mother, Mrs Irene Lodge (adduced pursuant to Civil Evidence Act Notices as both had died since making their statements) and of Ms Lucy Neill, TN’s daughter, who was not required to attend for cross-examination. I also heard from the Claimants, Ms Tracy Negus and Ms Deborah Bambridge (both friends of TN and executors of her estate), and from TN’s husband, Mr Leslie Neill, and her son Mr Toby Neill; all confirmed their witness statements and were asked questions by counsel for the Defendant. For the Defendant, evidence was adduced from Mr Michael Sabetai, and from Mr Ian Cummings, Speciality Trainee in cardiothoracic surgery (who completed the consent form with TN prior to her 5 March 2014 operation), and Mr James Roxburgh, Consultant Cardiac Surgeon employed by the Defendant (now retired from clinical practice); each confirmed their written statements and answered questions by counsel for the Claimant.

Both sides also relied on expert opinion evidence. Although expert reports had been obtained from other specialisms, all agreed that the issues between the parties were to be determined by reference to the evidence of the cardiothoracic experts: for the Claimant, that evidence was adduced from Professor Wallwork, Emeritus Professor in Cardiothoracic Surgery and Chairman of Royal Papworth Hospital NHS Trust; for the Defendant, from Mr Lawrence, Consultant Cardiothoracic Surgeon, UCL Hospitals NHS Trust and St Barts NHS Trust. In advance of the hearing, I had read the reports from Professor Wallwork and Mr Lawrence, together with Professor Wallwork’s answers to CPR Part 35 questions, and their Joint Statement, and both experts attended to give oral evidence at trial.

The trial bundle comprised some 3,611 pages and additional documents were adduced by the experts during the course of the hearing (for which permission was given at the time).

At the time of the operation on 5 March 2014, TN, who was born on 6 December 1966, was 47. She was a qualified nurse but worked for Macmillan Cancer Support in a public information role. TN was married to Leslie Neill and they had two children, Lucy, then 19, and Toby, then 15. By all accounts, prior to the events with which I am concerned, TN was an active and sociable woman, who enjoyed life and had good relationships with her family and friends. Her later deterioration was plainly very difficult for both TN and for those close to her; on any view, TN’s death was very sad and I do not lose sight of the personal tragedy that lies behind this case.

In her teens, TN had suffered from Hodgkin’s Lymphoma and she underwent mediastinal radiotherapy for this when she was 17. This treatment had been successful in that TN had then been in remission, with no further relapses. In 2003, however, investigations revealed problems with her aortic valve, related to TN’s early radiotherapy, and she was thereafter monitored, having an echocardiogram every two years.

Between 2008 to early 2014, TN underwent various surgical procedures, including risk reducing mastectomies and subsequent breast reconstruction surgery, during which she had suffered an infection of her wound. TN had also had gastric band surgery and had later required re-do breast reconstruction surgery.

In January 2014, TN suffered a heart attack. She was diagnosed as having significant aortic stenosis and was referred to St Thomas’ Hospital and to the care of Mr Sabetai.

Aortic stenosis describes the situation where the aortic valve does not function properly, leading to a narrowing of the valve and, thereby, reduced blood flow through the valve. It is common ground that, when aortic stenosis becomes symptomatic, there is a 2-year survival rate of below 50% and an aortic valve replacement is therefore indicated.

Mr Sabetai met with TN on 7 February 2014. As well as the information forwarded to him on referral and from an echocardiogram undertaken a few days earlier, he took a full history from TN. Mr Sabetai concluded that the aortic valve stenosis had progressed to a stage where it was necessary for TN to undergo aortic valve replacement surgery. This was because TN’s aortic valve had become fibrotic, as a result of the radiotherapy she had undergone in her teens, and had increasingly calcified over the years, such that the valve leaflets, which open and close during heart function to let blood flow through, were not functioning correctly. The result was that blood flow through the valve was impeded, which was reflected in a peak gradient (which reflects the amount of resistance there is to the blood flow through the valve) of 97mmHg; that showed that the pressure on the ventricular side of the valve was significantly higher than on the aortic side of the valve.

Mr Sabetai advised TN that if she did not undergo surgery she would continue to experience symptoms of shortness of breath and chest pain and would eventually suffer heart failure and death; the benefits of surgery would be to reduce her symptoms and prolong her life. Mr Sabetai also advised TN of various risks associated with aortic valve replacement surgery, in particular given her past medical history. Although his normal practice would be to quote a risk of mortality and morbidity for this procedure of between 1% and 2%, he considered TN’s history of mediastinal radiotherapy and previous experience of wound infection increased the risk of surgery in her case and therefore advised of a mortality risk of 2% and a morbidity risk of 2%.

Having been advised as to the risks and benefits of surgery, TN said that she wished to proceed with an aortic valve replacement. Mr Sabetai then discussed with her the type of valve he would insert.

In an aortic valve replacement, a surgeon removes a patient’s native valve and implants either a mechanical or a tissue prosthetic valve. Mechanical valves are made with synthetic materials and have a long lifespan but require the patient to take blood thinning medication for life, to prevent blood clotting. Tissue valves are made from animal tissue and do not require the patient to take blood thinning medication, but they have a shorter lifespan and are likely to require replacement if implanted in younger patients. In TN’s case, given her relatively young age, Mr Sabetai recommended that a mechanical valve be used. He recalled that TN, having been a nurse, had some knowledge of the different types of valve and agreed this recommendation.

Prosthetic valves come in different sizes; the smallest available for an adult is a 19mm, the largest 29mm. The size of valve that can be implanted depends, in principle, on the size of the annulus (the aperture at the root of the aorta). It is, however, possible to implant a larger valve by enlarging the aortic root. To perform an ARE, a surgeon would make an incision into the aortic root and then suture in a patch, resulting in an increase in the diameter of the annulus. An ARE is, however, a relatively rare procedure. As Mr Roxburgh – who was involved in the collection of national data for the Society for Cardiothoracic Surgery from 2003 to 2018 – explained, ARE surgery was not included in any of the datasets in which he was involved because it was so rarely performed.

The apparent rarity of an ARE is also evinced by the anecdotal evidence of the witnesses at trial. For example, in his 27 years’ of clinical experience, Mr Roxburgh had only performed one ARE (when the patient’s aortic root was too small for the smallest prosthesis), which would approximate to around 0.1% of the aortic valve replacement operations undertaken by Mr Roxburgh. For the Defendant, Mr Lawrence had looked at the figures for Barts Heart Centre over the past 10 years and had found only 8 ARE operations (of the type relevant to this case) had been performed, none of which had been carried out by surgeons under the age of 50. Given the number of aortic valve replacements carried out at Barts (for the years 2018 and 2019, there were an average of 251.5), this would equate to ARE operations being undertaken in only 0.32% of cases. Although the Claimant’s expert, Prof Wallwork, had more experience of undertaking AREs, over his entire clinical career he had only performed around 20. Given that Prof Wallwork can be estimated to have undertaken some 4,000 aortic valve replacements in his career, that would suggest AREs were limited to 0.5% of his cases.

In TN’s case, the pre-operative echocardiogram indicated that she had a small aortic annulus, with a diameter of around 18mm, and that the valve surface area was 0.7cm². Mr Sabetai also noted that TN was of short stature (1.56m) but had a body mass index of 32.9 and a body surface area (“BSA”) of 1.8m².

As was common ground before me, the size of prosthetic valve to be used is not something that can be determined prior to surgery. As Mr Sabetai explained (and it was not in dispute), it is standard practice to ascertain the size of valve which can be inserted in the aortic root once it has been decalcified and is ready to take the replacement valve. The surgeon will then use a sizer to find the size of valve which fits the aortic root at the level of the annulus, and try the next size up, and the next size down, to see which is the best possible fit. As was volunteered by Mr Sabetai, and agreed by both Prof Wallwork and Mr Lawrence, it is also standard practice to insert the largest size of valve which can safely be inserted at operation.

There are, further, different brands of mechanical valves and different designs. Relevant for present purposes is the distinction between valves that are placed just above the annulus in the aortic root – so called “top hat” or “supra-annular” valves – and valves that are placed within the annulus – “intra-annular” valves. An important difference is that, owing to their positioning, where the ostia are situated close to the annulus, top hat valves can entail an increased risk of blocking the beginning of the coronary arteries (the coronary ostia) and thus causing a heart attack.

I accept Mr Sabetai’s evidence that, pre-operatively, he considered it most likely that he would be able to implant a 21mm valve in TN’s case. This was because, although

I have already described how the surgeon uses a sizer to determine the best fit, but regard would also be had to the effective orifice area (“the EOA”) produced by the particular prosthetic valve under consideration. Mr Sabetai described the EOA as “a complex calculation based on the geometric orifice area and the blood flow patterns through the valve” (the geometric orifice area being the space provided by the leaflets of the valve when open). That calculation was detailed by Mr Lawrence, who explained that to calculate the EOA of a valve, one has to measure three things: the radius of the channel of the left ventricle leading to the aortic annulus (the left ventricular outflow tract or “LVOT” – thus the “LVOT Radius”); the velocity of the blood passing through the LVOT (“LVOT Velocity”); and the velocity of the blood passing through the aortic valve (“Valve Velocity”). The EOA of a valve is then calculated as follows:

In practice, as Mr Sabetai explained, there are sources of information to which a surgeon can (and will) refer to check the EOA achieved by a particular valve. In 2014, it was Mr Sabetai’s practice to use an application (or “app”) on his ‘phone called Cardiovalve.

In any event, prior to the operation, Mr Sabetai did not discuss with TN the size, particular brand or design of the valve to be implanted. As he explained, he would not do so as the decision as to the particular size and make of valve would have to be determined intra-operatively.

Mr Sabetai agrees that, prior to surgery, he did not discuss with TN the possibility of undertaking an ARE to permit the insertion of a larger prosthetic valve. I accept his evidence that this was not because he was incapable of performing such a procedure but, whilst he had in mind the possibility that he might need to undertake an ARE, this would only be something he would do if he found it was necessary intra-operatively. In making this finding, I note that whilst Mr Sabetai had been appointed to his

Following the discussion on 7 February 2014, Mr Sabetai referred TN for a cardiac CT scan, which took place on 10 February 2014. The results of the CT scan did not cause Mr Sabetai to change his advice and TN was duly booked in for surgery on 5 March 2014.

On 4 March 2014, Mr Cummings, working at St Thomas’ hospital as a Specialist Registrar, completed the consent form with TN. This recorded the advice as to risks as previously communicated by Mr Sabetai, and included the following statements:

“I understand that any procedure in addition to those described on this form will only be carried out if it is necessary to save my life or to prevent serious harm to my health.

I have been told about additional procedures which may become necessary during my treatment.”

TN raised no concerns and signed the consent form.

Surgery took place on 5 March 2014. Having excised TN’s native valve, Mr Sabetai was able to de-calcify the aortic root, which he found to be small and heavily fibrotic. The pericardium (the sac containing the heart and the roots of the great vessels supplying the heart) was also fibrotic and the calcification extended into the coronary ostia, which were very close to the aortic valve annulus. Given the position of the coronary ostia, Mr Sabetai took the view that he could not insert a top hat valve but would need to use an intra-annular valve. Having used a sizer, he further concluded that he would be unable to fit a 21mm valve but would, instead, have to implant a 19mm valve. Mr Sabetai considered that the best option would be a 19mm CarbomedicsReduced valve, which is what he proceeded to fit.

It was Mr Sabetai’s evidence that he would have considered, intra-operatively, whether it was appropriate to perform an ARE in these circumstances. Had he concluded this was necessary, he would have taken the view that – for consent purposes - it amounted to a procedure necessary to save a patient’s life or prevent serious harm to their health. Mr Sabetai stated, however, that he did not consider it would be appropriate to undertake an ARE in TN’s case, explaining (I take these passages from his witness statement but his responses in cross-examination were to similar effect):

“77.

… the small size of the aortic annulus and the fact that the calcification extended in and around the rather small coronary ostia were both contra-indications to performing aortic root enlargement, rendering the enlargement very challenging and of high risk. In order to enlarge the aortic root I would need to use a segment of pericardium to bridge the gap where incisions had been made in the aortic root to widen it, to allow it to take a larger valve. Where the aortic root is densely fibrotic it makes it very difficult to safely enlarge the root, because the tissue is not supple and accepting of a large valve.

78.

In addition, the closeness of the origin of both the coronary arteries to the annulus would have created an additional risk factor. A large valve sitting close to the origin of the coronary arteries creates a risk of blocking the coronary arteries causing a heart attack. Attempting to insert a large size aortic valve into a small size aortic root also creates a risk that the aorta could tear, which could cause a risk of substantial damage to the aorta and bleeding as a result.

79.

Taking into account all these factors, it was necessary to weigh the risk of performing aortic root enlargement, set against a risk of PPM resulting from having to insert a 19mm valve which was smaller than I had expected to be able to insert. Taking into account the risks identified both pre and intraoperatively in connection with aortic root enlargement, and taking into account the fact that I expected Tracy Neill to have a good outcome with a 19mm Carbomedics Reduced prosthesis, I

concluded that this was the safest and most appropriate option. The 19mm Carbomedics Reduced prosthesis represented a significant improvement in EOA compared to Tracy Neill's native valve and was the largest valve I could safely insert.”

The reference to “PPM” is to a concept known as “patient-prosthesis mismatch”. While there was a dispute between the parties as to its clinical relevance, it was not in dispute that there exists in the literature the concept of PPM. PPM refers to the situation where the prosthetic valve used is too small for the patient’s size. As mechanical prosthetic valves include a case that has to be inserted into the annulus (the actual operative part of the valve will thus tend to be smaller than the native valve), PPM is not uncommon (in studies its prevalence ranges from 8% to 80%, but an estimated overall prevalence of 44% has been cited, based on a meta-analysis of 34 observational studies in 2012; see R. Bilkhu et al ‘Patient-prosthesis mismatch following aortic valve replacement’ Heart 2019;105:s28-s33). PPM is defined by what is known as the indexed effective orifice area of a valve (the “iEOA”), which is determined by dividing the EOA of the valve (in cm²) by the BSA of the patient (in m²). In the literature, PPM is standardly described as severe where a valve has an iEOA below 0.65; as moderate where a valve has an iEOA between 0.65 and 0.85; and as absent where a valve has an iEOA greater than 0.85.

There is a dispute between the parties as to what extent the presence of PPM is relevant to clinical outcomes and, therefore, whether the additional risk of an ARE (in order to be able to insert a larger valve) ought to be taken to avoid at least severe PPM (and whether this should be discussed with a patient pre-operatively). At this stage, however, I am concerned with the circumstances facing Mr Sabetai on 5 March 2014, and the factors that informed the decisions he made.

For the reasons I have already explained, I again accept Mr Sabetai’s evidence that he had in mind the possibility of undertaking an ARE during TN’s surgery: although AREs are rarely performed, he had experience of the procedure and had previously demonstrated that he could, and would, undertake an ARE if he considered it necessary. The fact that he had not raised this possibility with TN does not undermine my conclusion in this regard; I accept Mr Sabetai’s evidence that he did not see this as an elective procedure but one that would need to be undertaken if necessary to save life or prevent harm, and thus covered by the general consent given by TN. As for his decision not to undertake an ARE, I find that Mr Sabetai was particularly concerned about the potential uncertainties of embarking upon this procedure in TN’s case, given the fibrotic nature the aortic root, and was unconvinced that an ARE would actually allow for a larger valve, explaining as follows:

I also accept Mr Sabetai’s evidence that he considered that the 19mm CarbomedicsReduced valve achieved a significant improvement over TN’s natural valve. Using the Cardiovalve app, he understood the valve could achieve an EOA of 1.2cm², which he calculated to be an improvement on TN’s natural valve of 71%. Moreover, if that was correct then, given his calculation of TN’s BSA, the iEOA would be 0.67cm²/m² (falling within the moderate category of PPM). I further accept Mr Sabetai’s evidence that he saw this in the context of the more general benefit provided by the prosthetic valve: whilst the stenosis afflicting TN’s natural valve would only get worse, the leaflets in the prosthesis should allow for an unimpeded flow of blood through the valve.

There is a dispute between the parties as to whether, in fact, Mr Sabetai should have taken the EOA of the 19mm CarbomedicsReduced valve to be 1.2cm². Although initially accepting this figure in the joint statement, shortly before trial, Prof Wallwork drew attention to the manufacturer’s own literature, which gave an EOA for this model of only 1cm² and questioned the reliability of the figure of 1.2cm². Some time was spent during the hearing, tracing through the sources cited for these figures. What is, however, clear to me is that it was entirely reasonable for Mr Sabetai to work on the basis that he was implanting a valve that gave an EOA of 1.2cm². That was the figure given on the entirely reputable app he was using; it was also the figure cited in the publication Echopedia and was based on a reputable study published in 2003. An EOA of 1.2cm² for the 19mm CarbomedicsReduced valve was also given by another app – Echocalc – which was developed on behalf of the British Society of Echocardiography. There was a competent and reasonable body of opinion that supported Mr Sabetai’s understanding in this regard.

The 19mm valve having been successfully implanted, TN’s surgery was uneventful; she made an uncomplicated recovery and was discharged home on 11 March 2014.

On 28 March 2014, TN was admitted to her local hospital with an episode of atrial fibrillation. An echocardiogram was performed, which showed a peak gradient across the aortic valve of 72mmHg. Mr Sabetai did not consider this was of particular concern as atrial fibrillation is not uncommon after surgery (and could explain the peak gradient) and generally resolves with time.

In any event, TN was referred back to St Thomas’ and a further echocardiogram was undertaken on 6 May 2014. At that time, TN was not experiencing any symptoms and the echocardiogram showed a peak gradient of 61mmHg and a mean gradient of 39mmHg; an EOA of 0.8 was also noted. Mr Sabetai saw TN again on 10 June 2014, noting that, although she had gained almost 3kg in weight, she was entirely asymptomatic and seemed to have recovered well. Referring to the results of the May echocardiogram, Mr Sabetai considered the 39mmHg mean gradient was consistent with a 19mm mechanical prosthesis and the peak gradient of 61mmHg was a significant improvement on the 97mmHg recorded on the pre-operative echocardiogram of February 2014. Happy with TN’s progress, Mr Sabetai discharged her from his clinic and had no further involvement in TN’s treatment.

Towards the end of the summer of 2014, however, TN began to again suffer from shortness of breath. In her statement, TN explained that her renewed symptoms had started after a walking holiday in September; in her Particulars of Claim, her difficulties were attributed to climbing the stairs (albeit, also in September 2014). Although TN had returned to work in early June 2014, her job was largely sedentary in nature and I accept she may have been less active for some time after her surgery. TN would, however, have had to climb the stairs in her home since her discharge from hospital and it is apparent that she was largely symptom-free for the spring and summer after her operation.

On 1 October 2014, TN was reviewed at King’s College Hospital and a further echocardiogram was performed, which showed a peak gradient of 83mmHg and a mean gradient of 49mmHg; a significant deterioration from May. In his witness statement, Mr Sabetai hypothesised that something must have occurred since he had met with TN on 10 June 2014 to cause the functioning of the aortic valve to deteriorate:

“I consider this was possibly due to either tissue beginning to grow across the valve, which can happen from three months post-operatively. Alternatively it is possible that the valve leaflets were not opening properly, which was impeding blood flow across the valve.”

In any event, TN was referred to Prof Olaf Wendler, Professor of Cardiothoracic

TN was seen by Prof Wendler in clinic on 16 January 2015; he considered she was suffering patient-prosthetic mismatch and needed a re-do aortic valve replacement, as a larger valve was required for her heart to function properly. In his post-clinic letter, Prof Wendler advised:

“I totally agree that this lady suffers from symptoms of prosthetic-patient mismatch. I have discussed this with her today and explained that the aim of the next time surgery will be to implant a larger heart valve. This may only be possible by enlarging the aortic root or even replacing the aortic root using a mechanical composite. I quoted her a risk of 2-3% for this operation and she is keen to go ahead with surgery.”

On 18 March 2015, Prof Wendler performed the re-do operation. He explanted the valve Mr Sabetai had inserted and then decalcified the annulus and performed an ARE. Prof Wendler first sought to insert a 23mm top hat mechanical valve but, whilst her coronary ostia had appeared not to be obstructed, it was not possible to successfully wean TN off bypass and Prof Wendler therefore decided to replace the 23mm top hat valve with a 23mm tissue valve. TN was then taken off bypass but her left ventricular function was severely reduced and she had to be placed on a life support machine.

TN was unconscious and in intensive care for around four weeks. During that time she had to have further open heart surgery; first to remove a large amount of blood that had collected around her heart, second to resuscitate her following cardiac arrest. TN was discharged from King’s College Hospital on 8 May 2015 and admitted to a local hospital for rehabilitation. She eventually returned home on 28 August 2015.

TN’s progress after her return home was very slow and she had a number of further admissions to hospital and continued to experience serious health problems. TN ultimately developed progressive heart failure and died on 29 January 2020.

In determining the issues that arise in this case, there is no dispute as to the approach I am to take as a matter of law. Where treatment of a patient by a medical practitioner is in question, the test is as expressed by McNair J in Bolam v Friern Hospital Management Committee [1957] 1 W.L.R. 582 at p. 587 (“the Bolam test”):

“… [a medical practitioner] is not guilty of negligence if he has acted in accordance with a practice accepted as proper by a responsible body of medical men skilled in that particular art. …. Putting it the other way round, a man is not negligent, if he is acting in accordance with such a practice, merely because there is a body of opinion who would take a contrary view. …”

At p. 589, McNair J summarised the question to be asked as being whether the practitioner had:

“… fallen below a standard of practice recognised as proper by a competent reasonable body of opinion?”

In Bolitho v City and Hackney Health Authority [1998] A.C. 232, however, Lord Browne-Wilkinson highlighted the references in the Bolam test to “a responsible body of medical men” and “a competent reasonable body of medical opinion” (emphases added), making clear that it would not be sufficient merely to show there was a genuine belief amongst experts that the practitioner had acted in accordance with respectable medical practice:

“… the court has to be satisfied that the exponents of the body of opinion relied upon can demonstrate that such opinion has a logical basis. In particular in cases involving, as they so often do, the weighing of risks against benefits, the judge before accepting a body of opinion as being responsible, reasonable or respectable, will need to be satisfied that, in forming their views, the experts have directed their minds to the question of comparative risks and benefits and have reached a defensible conclusion on the matter.” (see pp. 241-242)

Thus, whilst respect is to be afforded to the views of experts in a particular field, the determination of breach of duty in clinical negligence cases remains firmly a matter for the court. Negligence will only be established if the treatment undertaken was outside the range of professional opinion, but that is subject to the court being satisfied that the views within that range are capable of withstanding logical analysis.

The Bolam test does not apply to the issue of consent, where a different approach is adopted. Where a medical practitioner is advising a patient as to the risks or benefits of a form of treatment, the test is as articulated by the Supreme Court in Montgomery v Lanarkshire Health Board [2015] UKSC 11; [2015] A.C. 1430, see the Judgment of Lords Kerr and Reid (with whom Lords Neuberger, Clarke, Wilson and Hodge agreed), at paragraph 87:

“An adult person of sound mind is entitled to decide which, if any, of the available forms of treatment to undergo, and her consent must be obtained before treatment interfering with her bodily integrity is undertaken. The doctor is therefore under a duty to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments. The test of materiality is whether, in the circumstances of the particular case, a reasonable person in the patient’s position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it.”

At paragraph 89, Lords Kerr and Reid further explained that the materiality of a particular risk will not be something that can be reduced to percentages:

“…The significance of a given risk is likely to reflect a variety of factors besides its magnitude: for example, the nature of the risk, the effect which its occurrence would have upon the life of the patient, the importance to the patient of the benefits sought to be achieved by the treatment, the alternatives available, and the risks involved in those alternatives. The assessment is therefore fact-sensitive, and sensitive also to the characteristics of the patient.”

At paragraph 90, Lords Kerr and Reid also reflected upon the nature of the dialogue between doctor and patient as part of the doctor's advisory role:

“… the aim of which is to ensure that the patient understands the seriousness of her condition, and the anticipated benefits and risks of the proposed treatment and any reasonable alternatives, so that she is then in a position to make an informed decision. This role will only be performed effectively if the information provided is comprehensible. The doctor's duty is not therefore fulfilled by bombarding the patient with technical information which she cannot reasonably be expected to grasp, let alone by routinely demanding her signature on a consent form.”

Turning to causation, where allegedly negligent medical treatment is concerned, standard principles apply and the starting position will be the ordinary “but for” test: the claimant must establish on balance of probability that but for the defendant’s negligence, she would not have suffered the loss complained of. As Lord Bingham observed in Chester v Afshar [2004] UKHL 41; [2005] 1 A.C. 134:

“8.

… in the ordinary run of cases, satisfying the "but for" test is a necessary if not a sufficient condition of establishing causation.”

The more difficult cases are those in which there are multiple causes for the injury; as Lord Toulson JSC observed in Williams v Bermuda Hospitals Board [2016] UKPC 4; [2016] A.C. 888:

“40.

A claim will fail if the most that can be said is that the claimant's injury is likely to have been caused by one or more of a number of disparate factors, one of which was attributable to a wrongful act or omission of the defendant: Wilsher v Essex Area Health Authority [1988] AC 1074. In such a case the claimant will not have shown as a matter of probability that the factor attributable to the defendant caused the injury, or was one of two or more factors which operated cumulatively to cause it. …”

Where, however, a claimant can establish that the act of negligence contributed to her injury in a manner that was more than negligible – where it is found to be a material contribution to the injury – the but for test will be satisfied (see per Lord Toulson JSC in Williams at paragraph 47).

Where alleged negligent medical advice is concerned, the law has recognised a narrow departure from standard causation principles. The case of Chester v Afshar concerned the question whether causation was made out where a claimant would have delayed a procedure, had they received the appropriate advice; the House of Lords held that causation was made out in such a situation, even though the likelihood of the harm occurring at a later stage was no different (see paragraph 87 in the speech of Lord Hope). The ratio of Chester v Afshar was explained by Simon LJ in Correia v University Hospital of North Staffordshire NHS Trust [2017] EWCA Civ 356, as follows:

“24.

... If there has been a negligent failure to warn of a particular risk from an operation and the injury is intimately connected to the duty to warn, then the injury is to be regarded as being caused by the breach of the duty to warn; and this to be regarded as a

modest departure from established principle of causation.”

Chester v Afshar will not apply where the court concludes, on the facts, that it is probable that, even if warned about the risks, the claimant would have proceeded with the operation as and when she did, see Duce v Worcestershire Acute Hospitals NHS Trust [2018] EWCA Civ 1307; [2018] P.I.Q.R. P18. Moreover, as Simon LJ went on to observe in Correia:

“28.

… The crucial finding in Chester v. Afshar was that, if warned of the risk, the claimant would have deferred the operation. In contrast, in the present case, it was not the appellant’s case that she would not have had the operation, or would have deferred it or have gone to another surgeon. There was no such contention in either her Protocol Letter, the appellant’s pleading or her witness statement. Nor was it part of her evidence. To some extent, the reason for this omission is the artificial nature of the appellant’s argument on this part of the case. Nevertheless, it seems to me that if a claimant is to rely on the exceptional principle of causation established by Chester v. Afshar, it is necessary to plead the point and support it by evidence. In the event, the material evidence, such as it was, did not support the appellant’s case on this aspect of the causation argument. … the appellant did not say she would not have had the surgery if advised differently.”

Given the nature of the allegations made in this claim and the legal tests I am to apply, it is unsurprising that the parties’ focus was on the expert cardiothoracic evidence. Before turning to the detail, I make the following observations relating to the testimony of the expert witnesses in this case.

First, both Prof Wallwork (for the Claimant) and Mr Lawrence (for the Defendant) are acknowledged experts, who have enjoyed considerable success in their careers and are to be afforded due respect. Although Prof Wallwork retired from clinical practice as a Consultant Cardiothoracic Surgeon in 2011 (and last performed an aortic valve replacement in June 2011), I have no doubt that he continues to be aware of the standards appropriate to his specialism, not least given his role as Chairman of the Royal Papworth Hospital. And, whilst Mr Lawrence does not recall having personally undertaken an ARE, I have no doubt as to his understanding of that procedure, still less as to his skill and experience relating to aortic valve replacement surgery more generally.

It was, furthermore, apparent that both experts hold themselves to very high standards and are (not without justification) confident as to the professional judgements they make. At times, however, this was a characteristic that was unhelpful in this case, leading the expert witnesses to lose sight of the test that is to be applied in these proceedings.

For instance, at paragraph 5.1 of his report, Mr Lawrence spoke of ARE as a “procedure now relegated to the history books”, a view that I do not find is shared by all reasonable bodies of opinion (as demonstrated not only by the evidence of Prof Wallwork, but also by the view plainly taken by Prof Wendler and by the testimony of Mr Sabetai in these proceedings). ARE may be a relative rarity, and there may be competing views as to the risks and benefits of the procedure, but I do not find that it can properly be characterised as “relegated to the history books”. Similarly, in stating (at paragraph 6.2 of his report) that “The issue of PPM was effectively resolved in a landmark paper by Tirone David (Is Prosthesis-Patient Mismatch a Clinically Relevant Entity? Tirone E. David. Circulation. 2005;111 :3186-3187, Originally published June 20, 2005 (Reference 2))”, Mr Lawrence may have been stating his own opinion on the subject, but the literature does not suggest that all reasonable bodies of opinion in this area would agree (see, e.g., Philippe Pibarot and Jean G. Dumesnil ‘The Relevance of Prosthesis-patient Mismatch After Aortic Valve Replacement’ Nat Clin Pract Cardiovasc Med. 2008;5(12):764-765; and R. Bilkhu et al ‘Patient-prosthesis mismatch following aortic valve replacement’ Heart 2019;105:s28-s33).

More significantly, however, the Claimant’s case was founded upon a number of allegations of negligence that, upon exploration with Prof Wallwork in crossexamination, were demonstrated to be based upon a particular opinion as to how things should be done, rather than allowing for possible alternative views that might still be recognised as proper by a competent, reasonable body of opinion. Whilst experts should, of course, make concessions where it is appropriate to do so, the concern in this case is that so many of the allegations levied against Mr Sabetai appear to have been based on the application of the wrong test. I have already referred to the challenge taken (late in the day) to Mr Sabetai’s reliance on the EOA figure given for the 19mm CarbomedicsReduced valve by an entirely reputable app regularly used by surgeons undertaking aortic valve replacements. Prof Wallwork had, however, initially also criticised the suturing technique used by Mr Sabetai (in the pre-action protocol letter of 22 July 2016 this was characterised as giving rise to a breach of duty in the failure to recognise this as “likely to constrict the valve area for insertion of the prosthetic valve.”), explaining (in cross-examination, see transcript day 3/203-204) that this was because it was not a technique that he would use, albeit that he acknowledged it was “perfectly acceptable”. Whilst this was not a point pursued in the Particulars of Claim, this was an allegation of breach of duty that should never properly have been made.

Having sought to provide a general insight into the expert testimony in this case, I will return to that evidence in my discussion of the issues I am required to determine, below. Ultimately, however, the testing of the expert evidence at trial has made my task easier in that it has demonstrated that the real issues between the parties were far narrower than originally appeared to be the case.