Dr. Juan Carlos Kaski, Head of the Cardiovascular Sciences Research Centre, St. George’s University of London in the U.K., explains an unusual cardiac diagnosis that I happen to share: Inoperable Coronary Microvascular Disease (MVD).
When I was at Mayo Clinic five months after my heart attack, cardiologists there referred to MVD as a “trash basket diagnosis” – not because the condition doesn’t exist, but because this disorder of the tiniest blood vessels in the heart is so often missed entirely. A correct diagnosis usually happens only after all other possible diagnoses are thrown out. It’s far more common in women and in people who have diabetes. It’s treatable, but can be very difficult to detect.
Traditional cardiac tests – even coronary angiography, widely considered the ‘gold standard’ diagnostic tool in identifying potential heart attacks – usually miss MVD entirely.
Dr. Kaski explains that 40% of patients suffering the severe chest pain of MVD have “normal” angiograms. Unless a cardiologist has experience with cases like mine, these patients can be misdiagnosed – often over and over again – and sent home despite truly debilitating cardiac symptoms similar to your basic Hollywood Heart Attack.
According to Mayo Clinic experts:
“The narrowing of these very small blood vessels in the heart means they can’t expand properly when you’re active. As a result, you don’t get an adequate supply of oxygen-rich blood to the heart muscle.
“This inability to expand is called endothelial dysfunction.
“This problem may cause your small vessels to actually become smaller when you’re active or under emotional stress. The reduced blood flow through the small vessels causes chest pain and other symptoms similar to those you’d have if you were having angina or a heart attack.”
On his video, Dr. Kaski discussed the difference (and possible similarity) between another non-obstructive diagnosis, Prinzmetal’s Variant Angina (a spasm disorder of the coronary arteries) and MVD.
What triggers coronary microvascular disease is not known, but cardiologist Dr. Noel Bairey Merz of Cedars-Sinai Medical Center in Los Angles suggests that high blood pressure during pregnancy might predispose some women to the condition.
(Not coincidentally, I too was diagnosed with pre-eclampsia during my first pregnancy – typified by spiking high blood pressure. And we now know that women with pre-eclampsia are up to five times more likely to develop heart disease compared to women whose pregnancies are uneventful).
Typically, the narrowings in small blood vessels are caused by fatty plaque, the same stuff that clogs bigger vessels where most heart attacks begin, explains Dr. Bairey Merz. But in MVD, plaque doesn’t form a mound or bulge. Instead, it uniformly coats the inside of these tiny vessels.
This reduces the space for blood flow and makes the arteries stiff and less able to expand in response to exercise or emotional stress. She explains:
“Women are relatively more like to suffer from plaque erosion and distal coronary embolism, compared to relatively higher rates of plaque rupture and proximal thrombosis in men.”
Currently, Dr. Bairey Merz believes that the best diagnostic test for detecting MVD may be something called coronary reactivity testing. This angiogram-like test lasts 60-90 minutes and allows doctors to see how very small vessels supplying the heart respond to different “challenges” from medications.
She recently added this comment to an article called “Myocardial Infarction Re-Defined“ in the American College of Cardiology’s In Touch blog:
“A majority of patients with microvascular coronary dysfunction also have atherosclerosis evidenced by intra-coronary vascular ultrasound (IVUS).”
UPDATE November 2019: Diagnostic tools used to identify coronary microvascular dysfunction
My Love-Hate Relationship with my Little Black Box (how wearing a portable TENS unit has reduced my use of nitroglycerin for MVD chest pain)
Small Vessel or Coronary Microvascular Disease – from Mayo Clinic
Watch this 5-minute video about Joan Jahnke of South Carolina who went to Emory Heart & Vascular Center to have her MVD appropriately diagnosed and treated.