There were lots of things I didn’t know about the human heart in 1987.

I knew it sat more centrally in the chest than I might have guessed. I knew it didn’t look anything like the cherry red valentine’s symbol you might find tattooed on a sailor’s arm. My knowledge, aged 22, had been gleaned from biology textbooks. I’d poured over diagrams of pumps, valves and branching vessels rendered in blue and red. The elegant plumbing of our circulatory system stripped out and laid bare in an intricate map of hand drawn pipework with a cross section of the heart at its hub. I knew the heart had four chambers. A left and a right. A lub and a dub. Lub dub. Lub dub. Lub dub.

My own heart thudded quietly as I climbed the stairs at the west end of the infirmary on my first day as a physiological technician trainee. I was ushered into a changing room where, for the next year, Monday to Friday, I would don a clean set of blue scrubs, slip on a pair of white clogs, pull my hair under a polyester cap, tie a mask round my neck and begin a shift in the wards and theatres of the cardiothoracic unit.

I was part of a team responsible for setting up the systems used to monitor patients undergoing open heart surgery. Each day would begin with the construction of unwieldy looping networks of tubing. Bags of sterile saline solution and all the widgets required to connect patients to the monitoring setup were unpacked and prepared. These systems would help us provide the medical team with essential information about patients’ physiology during surgery.

We were able to watch the surgeons’ work from the viewing step beside the anaesthetist. My textbook knowledge didn’t correspond to the feisty meatiness of the hearts I witnessed beating in those opened chests. The tussle of it surprised me. The breastbone would be sawn down the middle and retractors used to prise open the thoracic cavity, a process that seemed more akin to carpentry than medicine. The heart would eventually become becalmed as the perfusionist, sitting at a heart-lung machine, kept the circulation going. Blood would flow, a dark maroon, into the tubes and chambers of the perfusionist’s kit, shifting to a bright oxygenated pillar box red before it snaked its way back into the dreamless sleep of the patient swaddled under green drapes on the operating table.

It was extraordinary to observe the skill and care of those theatre staff day after day; from the nurses with their arsenal of surgical instruments and quick wits to the surgeons with their uncanny ability to navigate the morass of tissues at the core of a patient and repair broken hearts with precise needlework. The experience of working in the infirmary has proved unforgettable.  Almost four decades have passed since then. How many heartbeats ago? Billions. Lub dub. Lub dub. Lub dub.