With a clamp separating the perfusion cannula from the tiny root of the narrow aorta I made a transverse incision, carefully avoiding the orifices of the two main coronary arteries that emerge above the valve itself. Damage a main coronary artery in a small baby and it’s curtains – no coronary blood flow, no muscle contraction, no circulation. There’s absolutely no margin whatsoever for error. A normal infant aortic valve has three virtually transparent cusps. Those with congenital aortic stenosis often have two thickened and fused cusps. Cara had one rigid cusp – a rare volcano-like valve with an orifice so small I was surprised she survived birth as the thick left ventricular muscle could have easily fibrillated during the metabolic mayhem of delivery.
Now I needed to cut into it so that it would open as widely as possible. This required precise evaluation. Should I try to create three cusps like a normal aortic valve, or two cusps so that it would open like a bird’s beak? The thickened collagenous lump was so deformed that I decided to go for the latter. Two carefully judged cuts from the pinhole out to the perimeter of the valve ring and it was done. Now it opened like a puffin’s bill, but it was still thick and stiff. Although I knew we would be back to work on it again in time, this first step would provide better body blood flow and help the left ventricle to grow.
When I removed the cross clamp the heart began to wriggle and squirm in ventricular fibrillation. Then quite spontaneously it stopped and sat motionless in its fibrous cocoon. No problem – the bypass machine kept pumping warm blood around Cara’s little body and I knew it would start again. A poke to the empty right ventricle with the tip of my forceps and it contracted just once in response, as if to say piss off, I’m enjoying the rest. Keen to move on to the next scheduled case, I prodded it again and asked for the pacing wires. The heart got the message. It didn’t want the electrical shocks; it would rather get on and beat for itself. Blips on the monitor’s arterial trace showed that it was ejecting some blood, but the heart was still empty at that point. I told the perfusionist to leave some blood in, and the arterial trace got stronger. The heart looked happier with the blockage relieved, so we weaned Cara from the circuit.
As it so happened, Cara’s aortic valvotomy was the easy case for that day. The next baby was just two days old, with an aorta that literally stopped after the branches to his head and right arm – an interrupted aorta, as we call it – and a large ventricular septal defect between the two pumping chambers. After birth, babies with this condition can only survive as long as the ductus arteriosus, nature’s temporary connection between the main artery to the lungs and the disconnected distal aorta, remains open. As a result, the upper half of the body may be pink with well-oxygenated blood while the lower half looks blue with deoxygenated blood from the pulmonary artery. A harlequin baby.
If the ductus arteriosus closes soon after birth – as it is programmed to do – the whole lower half of the body is starved of blood flow and the baby dies. Only an infusion of hormones to fool the ductus that the baby is still in the uterus can keep it alive. My job was to dissect out and join up the tiny ascending and descending parts of the aorta, making sure that all the self-closing ductus arteriosus tissue was removed. These tubes are around the size of a child’s drinking straw, so the process is more easily described than done. It can only be achieved with the baby cooled down to 18°C and the circulation stopped altogether.
The cooling took around thirty minutes on the bypass machine, so I set about closing the hole in the heart with a patch of Dacron fabric, like sewing a button on a shirt but working inside a thimble. There is always a significant gap to span between the two ends of an interrupted aorta. The distal end begins way down in the back of the chest and has multiple branches to the chest wall. Consequently, it must be mobilised carefully and pulled forward. At the same time, it is important not to cut too many branches, as this can compromise the blood supply to the spinal cord.
Lots of technical considerations make this a complicated procedure, during which there is no blood flow to the brain or heart muscle. It’s a race against the clock. Once I had created the new aorta, we started up the heart–lung machine again and rewarmed the infant back to 37°C. It was then that the problems started. Blood began to well up from the dark recesses of the chest. Not torrential, but persistent.
Rewarming would normally take around another thirty minutes, giving me the chance to go out and relieve my aging bladder after I’d invited my assistant to stand in for me. But not this time. I needed to find the troublesome bleeding and stop it, not easy when it comes from way back against the vertebral column. Eventually I found the bleeding artery on the chest wall where a tiny titanium clip had fallen off. By then we had stopped and restarted the bypass machine on several occasions because we had difficulty in retracting the heart out of the way. Now it was objecting strongly, beating but not pumping. When three separate attempts to separate from bypass ended in failure, I thought the baby would not survive.
In those days as many as one in five of these babies would not get through surgery. So should I just give up and go home? It was now six in the evening, when everyone else was finishing work. The end of the day for me meant the end of the baby’s life – and the end of the world for the poor parents. So we battled on. Supportive drugs and more time on the machine did not make this heart any stronger, and a fifth of the left ventricular circumference now consisted of a Dacron patch, which, needless to say, didn’t contract. All of this, together with repeated muscle stunning through periods without blood flow, meant that the odds were stacked against us. Without mechanical circulatory support, death was inevitable.
There was only one circulatory support device suitable for small children. This was the Berlin Heart, an external air-driven pumping system that I had once used to keep a boy with a heart muscle disease alive until we transplanted him in Oxford. I had paid for that apparatus and the Lear jet from Germany from my own research funds. But the NHS would not pick up the tab for this equipment, so I didn’t have a device for the baby dying on my operating table.
What I did have was an adult circulatory support system that had been sent from the US for us to test. This Levitronix centrifugal pump was the last of five donated free of charge, and every one of the others had saved a patient in shock who would otherwise have died. Could I adapt this adult system for a newborn baby? It had certainly never been done before, we didn’t have regulatory approval to use it in children and there were several worrying technical issues to overcome.
As with the heart–lung machine, the Levitronix circuit contained more volume of fluid than a child’s whole circulation, so we would have to fill the tubing with blood to avoid excessive dilution. Next, this pump normally provided between five to seven litres of blood flow per minute, more than enough for a 70 kg man but far too much for a 1.7 kg baby. We’d need to switch the flow rate way down and compensate by increasing the level of anticoagulation to prevent clot formation. The flip side was that this would increase the risk of bleeding into the chest or brain. Finally, the nurses in paediatric intensive care had no experience of the device, so an adult team would have to be called in to help.
Every time I did something unconventional like this, someone complained to the management and I was threatened with the sack. Did that ever impact on my thought processes? No. We have an NHS that publishes surgeons’ death rates but fails to provide the equipment necessary for rescuing lives. Where is the morality in that? My perfusion team were up for the challenge, as no one wants to see a waxen dead newborn washed clean and placed in a shroud at the end of a long operation, least of all the nurses who have to deal with the body long after the bean counters have gone to the pub to celebrate their cost savings.
To connect the Levitronix circuit I simply left the small aortic perfusion cannula in place but switched the venous drainage pipe from right to left atrium. After trying one last time to separate from bypass but failing miserably, we stopped the heart–lung machine
and I swiftly made the adjustments. At this point, the baby hovered between life and death for one minute, two minutes, then three minutes. Any more time spent at normal body temperature without circulation and his brain would have suffered irreversible damage.
The circulatory support system was connected in less than four minutes and the spinning rotor switched on to provide one litre of blood flow per minute. We still had a live baby, albeit one with low blood pressure and lacking a pulse. Unlike the pulsatile Berlin Heart, the Levitronix pump provides continuous blood flow. Managing pulseless people in the intensive care unit is fraught with difficulties, but my adult circulatory support nurses were on their way back to the hospital. As we closed the tiny chest over the pipes, I had no real expectation that we could win this one. Many things could still go wrong, yet in my mind any chance of recovery was worth the effort. The alternative was an interminably miserable interview with bereaved parents in the dingy relatives’ room, trying to convey something I didn’t fully understand myself. I had been there before, often on behalf of less robust bosses who couldn’t face the prospect themselves.
I sat with the nurses beside the cot, watching the sun go down, then long into the night. None of those alongside me were ‘on duty’. We were simply doing our best for this family and taking the usual crap for it. ‘Should you really be using this pump in a baby?’ I’d be asked. Answer: ‘Would you prefer for the child to be in the mortuary? If so, you’re in the wrong job.’ My brain followed on with, ‘So go shit yourself,’ but I wouldn’t verbalise that. Cara was in the cot next door, with her anxious parents each holding a tiny hand. She was still sleeping in drug-induced La La Land, but was doing fine.
It took three days of circulatory support with the Levitronix system for the boy’s tiny heart to recover. As soon as we were convinced it was strong enough, we took him back to the operating theatre and removed all the intimidating machinery. Two weeks later he left hospital with happy parents. Had we not had that last freebie from the company in the States, there would have been a funeral not a happy homecoming. It was charity-shop healthcare.
I remember the day that Cara left hospital for one curious reason – I repaired atrial septal defects in the hearts of three siblings that day. Why? Because their mother was so distraught at the prospect of her kids being operated on that she couldn’t decide who should go first or last. To limit her suffering, the children’s intensive care unit agreed to take all three on the same day and brought in extra nurses to assist.
It was four years before I saw Cara again. During that time Dr Wilson kept her under close surveillance, with echocardiography every six months. At first she made great progress. The heart failure disappeared, her feeding improved immeasurably, and she blossomed and grew into an active toddler. Her left ventricle grew too. Then gradually things started to slow down again. The murmur directly behind the breast-bone grew louder once more, with the echo pictures showing the aortic valve to be stiff and narrow as the muscle became thicker. There were long faces in the clinic, and it was time for another procedure. Wilson decided against the less invasive balloon dilatation, so I took her back to the operating theatre to do the best I could before she started school.
When I exposed the valve it had grown to some extent, but the orifice was tight again. As before, I cut outward from the restricted hole with a sharp scalpel blade to mobilise the two thickened cusps. Under the valve itself the muscle was thick and obstructive, so I cut away a channel to enlarge the outflow from the ventricle. It looked better but didn’t give me much cause for optimism, and I remember thinking that it would only last a couple more years. Cara bounced back and skipped happily out of the hospital, although her parents knew she would have to return. She had been born with a self-destruct mechanism and next time there would be no alternative but to replace the valve.
There are no artificial heart valves small enough to use in young children, but there is one valve replacement operation that can be done, a complex, intimidating procedure that few surgeons ever attempt. I learned it from its originator, my old boss Donald Ross at the National Heart Hospital. Ross came up with the ingenious idea of removing the patient’s pulmonary valve and transposing it to the aortic position, then replacing the pulmonary valve on the low-pressure side of the heart with a pulmonary valve taken from a dead donor. The procedure worked well in adults, but even Ross had never attempted it in a small child.
After learning the steps and pitfalls from Ross, in 1995 I was the first surgeon to perform the procedure in a baby. This boy was found to have a heart murmur following an emergency caesarean section. Within hours the struggling left ventricle had failed and he was turning blue with low blood flow, so I rushed him to theatre to do exactly what I had done for Cara – put him on a heart–lung machine, then cut into the valve to relieve the obstruction. Just like Cara, he was one day old. The echo pictures the following day showed an improvement in flow, and after several days in intensive care the family were allowed home.
Six weeks later the valve seemed tighter than ever and the left ventricle contracted poorly. The boy was going to die if nothing could be done. Faced with that prospect, I decided to take the bull by the horns and risk Mr Ross’s operation, although he would probably have thought me bloody mad to attempt it in such a tiny heart. Then there was the added issue of sourcing the spare part, an infant pulmonary valve from the autopsy room.
We didn’t know whether the switched valve would grow in its new position, yet we were certain that the dead donor pulmonary valve wouldn’t. So I needed to oversize it, but we were never going to be offered a row of dead babies to choose from. We were lucky to obtain the valve from a three-year-old accident victim – misery for its poor parents, although the knowledge that their lost child had saved another baby’s life provided a small crumb of comfort. The valve would wear out one day, but at least it would take the boy through to his teenage years.
It was an intensely worrying case right from the start. The left ventricle was so poor that the stiff little lungs were floating in a pool of straw-coloured fluid. There was more heart failure fluid within the pericardial sac, which spurted out as soon as I made a hole in it. Then the aorta was so narrow that the smallest perfusion cannula almost blocked it. My first attempt to insert it missed the tiny incision altogether and we were sprayed with blood. It went in on the second attempt, then I put the baby on bypass and stopped the heart with cold cardioplegia solution. What followed was just about the most nerve-wracking heart operation in the book, miniaturised and without precedent. But it was still the Ross procedure, not mine.
I cut across the aorta below the perfusion cannula and proceeded to mobilise the vital coronary artery buttons, which were no larger than pinheads. These had to be re-implanted into the baby’s own floppy pulmonary autograft without kinking or tension. Life depended on that. There was no music in theatre and no one spoke unnecessarily. Every so often my anaesthetic colleague Mike Sinclair would put his head over the drapes and ask how it was going. ‘Slowly. It’s bloody difficult,’ was my automatic response. Yet we were desperately working against the clock. The longer the cardiopulmonary bypass time and the longer the period without blood flow to the heart muscle, the greater the risk of death.
The step that made my adrenaline levels surge was the dissection of the pulmonary valve root out from the ventricular septum in proximity to one of the main branches of the left coronary artery. This required sharp dissection with a glistening scalpel blade less than a millimetre from a vital vessel buried in muscle – a bit like hanging a picture while trying to avoid a high-voltage electric cable hidden under the plaster. I knew where it should be but couldn’t be certain. I almost lost my first adult Ross patient – a young mother of two small children – by occluding that invisible coronary artery with a stitch. Had she died, when instead she could have had a straightforward valve replacement at low risk, I would never have attempted another Ross operation.
Aft
er the agony comes ecstasy, at least it did in this case. I enlarged the outflow tract of the left ventricle and switched the valves, finally re-implanting the origins of the tiny coronary arteries back into the new aortic root. The donor valve then filled the gap created by removing the pulmonary root. Magic. We had succeeded within a reasonable time frame. What’s more, the new valves didn’t leak. Although I was a surgeon, when we took off the clamp to let blood back into the heart I felt more like a painter who had just put the finishing touches to his masterpiece. This remodelling of the whole outflow of the heart was a voyage of discovery. Ross had anticipated that the patient’s own pulmonary valve would remain alive in the blood stream, giving it the potential for growth in children. Now we would find out. Could this at last be the solution for lethal aortic stenosis in babies?
The Ross procedure was the only operation I was consistently apprehensive about performing – and it’s not difficult to understand why. Indeed many other surgeons found it far too intimidating in comparison with straightforward, low-risk aortic valve replacement for adult patients using a commercially produced valve off the shelf. Others who had a go sometimes made errors that proved fatal. But for small children, the only other option was to use an aortic valve from a dead donor, and this doesn’t grow as they got older because it imbibes calcium and soon turns into a tube of chalk. On the few occasions when I backed away from the Ross operation and used an aortic homograft in a child, I usually regretted it.
The Knife's Edge Page 16