Kaden, from Auckland's North Shore, is likely to become New Zealand's youngest heart transplant recipient. The youngest so far, since Greenlane Hospital introduced the surgery to New Zealand in 1987, was 8.
‘‘He's got the best chance of growing from a transplant,'' said Kaden's father, Darren, ‘‘putting on weight, getting involved in sport, being able to do things he's never been able to do before would be just amazing - being able to get up the slide [on his own].''
Kaden was born with what Auckland Hospital transplant cardiologist Dr Peter Ruygrok describes as a ‘‘twisted, scrambled heart''.
He has had three operations to correct the congenital abnormalities, and other procedures to rectify faulty heart rhythms, including the installation of a pacemaker device.
That has improved the life of the fairhaired youngster, who says he wants to be a Formula One racing driver when he grows up. But Kaden's weak, enlarged heart has caused numerous medical emergencies, has left him severely undersized, and is now nearly worn out.
He is on heart medications and without a transplant he is expected to gradually deteriorate and eventually die.
‘‘They talked about having around 12 months' expectancy from here, give or take six or 12 months,'' said Mr Probst, an IT manager who has taken leave without pay to spend several weeks at home with his son, and his daughters aged 2 and 4 and wife Jody.
Dr Ruygrok said how long people waited for a heart transplant varied, partly because the organs had to be matched by blood group and patient weight.
‘‘It depends on an appropriate donor and the donor always dies under tragic and sudden circumstances. It could be a wait of two days or up to a year. It's a random, tragic event.''
‘‘I'm guessing that Kaden may have to wait three to six months.''
He said a child lighter than 15kg needing a transplant would require a child's heart and would be referred to the Royal Children's Hospital in Melbourne because New Zealand had few child organ donors. Patients weighing 15kg or more could receive the heart of a light adult.
Even with a successful transplant, Kaden's life expectancy is severely limited.
Dr Ruygrok said most recipients were expected to live more than 12 years and with modern anti-rejection treatment could live significantly longer.
Kaden is tiny for his age, little taller than 2-year-old sister Hannah, and slightly shorter than 4-year-old Aalia. He weighs a little over 15kg - 8kg less than the average for his age.
He has little appetite, sometimes can't keep food down and lacks energy.
His failure to thrive is because his heart pumps only one-third the amount of a normal heart, causing the blood pressure to rise in veins draining into the heart.
Paediatric cardiologist Dr Tom Gentles explains: ‘‘ . . . the ‘back pressure', if you like, gets distributed to all the veins in the liver and your tummy and that makes you feel a bit uncomfortable and interferes with your appetite, and your general sense of wellbeing.''
When The New Zealand Herald visited the Probsts, Kaden was sipping a liquid breakfast for morning tea, but pushed aside creamed biscuits.
He nipped off to fossick in the vegetable garden with his sisters and called out: ‘‘Where are all the carrots?'' leading his father to gently discourage them from pulling them out.
Mr Probst said Kaden now led a ‘‘relatively normal'' life. He rarely missed a day at school and he loved practising his swing at the Pupuke Golf Club.
Until he was nearly 4, when he had a treatment to control his rapid heart rhythms, life was hectic. Kaden's parents sometimes had to dunk him in ice to shock his heart back to a normal rhythm and when that didn't work, rush him to hospital.
In October, while in Starship children's hospital's heart unit having a procedure to measure his heart for a transplant, Kaden had a cardiac arrest.
‘‘They said there was no heart-beat for 10 or 15 minutes. They did a hell of a job resuscitating him. They say he had a good response,'' Mr Probst said, adding that Kaden had always received fantastic care at the hospital.
Mr Probst urged families to discuss organ donation, because family members' wishes are considered crucial by health authorities in deciding on donation following a death.
