...the images had to be striking and intriguing, but they also had to tell a story.
Arterial health
Most of us are familiar with the dire consequences of ischemia when it leads to a stroke or heart attack; many of us have family members who have suffered such events. The two are closely related, and due in large part to atherosclerosis, the thickening of the arterial wall. When the wall thickens, the passageway for blood narrows. As the narrowing progresses, it becomes more and more likely that a blood clot might get lodged, greatly reducing or cutting off blood flow. This results in ischemia – a lack of blood supply to a given part of the body.
If the clot doesn't dissolve quickly the result is an infarct, or the death of tissue. In the heart this is commonly called a heart attack; in the brain a stroke.
These illustrations were part of a series that featured various aspects of the human body, including strokes and heart attacks. As disturbing as these topics are by nature, the illustrations were required to be engaging, attractive and informative.
An embolus in the heart leads to a heart attack.
Keeping it clean
This was an image-based book targeted toward a general audience, so the primary goals were twofold: the illustrations had to be striking and intriguing, but they also had to tell a story: the story was the embolus and the concept that blood flow to various organs can be blocked. The less pleasant, further consequences (ischemia and tissue death) were conveyed with diagrams.
The general audience for the book also dictated the amount of detail presented. My favorite phrase for this approach is "simple but not simplistic" – the astonishing beauty and complexity of our human form has to still shine through.