Coronary microvascular spasm in patients with vasospastic angina

A 75-year-old woman with chest pain and transient severe left ventricular systolic dysfunction

INTRODUCTION

Coronary spasm can cause myocardial ischemia and angina in both patients with and without obstructive coronary artery disease. However, provocation tests using intracoronary acetylcholine (ACh) have been rarely performed in the Western world.

CASE REPORT

We report a case of a 75-year-old woman with a history of hypertension and a mechanical aortic prosthesis who presented in the emergency room with acute-onset chest pain, widespread ST-segment depression and severe left ventricular systolic dysfunction, with no signs of prosthesis dysfunction. Emergent coronary angiography excluded obstructive coronary artery disease. Pain relief and normalization of ST segment and systolic function occurred within six hours. The patient was treated for a possible thromboembolic myocardial infarction and was discharged home asymptomatic. Two weeks later, cardiac magnetic resonance was performed showing inferoseptal transmural infarct scar, inferior and inferolateral subendocardial infarct and mid-basal ischemia in the anterior and anterolateral walls. She was readmitted with recurrence of chest pain and it was decided to perform a provocation test with ACh. After injection of ACh into the left anterior descending artery, chest pain, ST-segment depression, blood flow impairment (TIMI 1) and transient grade 3 atrioventricular (AV) block occurred. Intracoronary administration of nitrates reversed the coronary spasm and AV conduction disturbances. Twenty minutes later, chest pain and ischemic ST changes recurred; there was no response to vasodilators and the patient developed cardiac arrest with pulseless electrical activity. Advanced life support was maintained for 32 minutes without return of spontaneous circulation.

CONCLUSIONS

Provocation tests have a high sensitivity and specificity for the diagnosis of vasospastic angina. Although it is rare, these tests have the potential risk of irreversible spasm leading to arrhythmia and death.

A hypothesis for the cause of complex regional pain syndrome-type I (reflex sympathetic dystrophy): pain due to deep-tissue microvascular pathology

Complex regional pain syndrome-type I (CRPS-I; reflex sympathetic dystrophy) is a chronic pain condition that usually follows a deep-tissue injury such as fracture or sprain. The cause of the pain is unknown. We have developed an animal model (chronic post-ischemia pain) that creates CRPS-I-like symptomatology. The model is produced by occluding the blood flow to one hind paw for 3 hours under general anesthesia. Following reperfusion, the treated hind paw exhibits an initial phase of hyperemia and edema. This is followed by mechano-hyperalgesia, mechano-allodynia, and cold-allodynia that lasted for at least 1 month. Light microscopic analyses and electron microscopic analyses of the nerves at the site of the tourniquet show that the majority of these animals have no sign of injury to myelinated or unmyelinated axons. However, electron microscopy shows that the ischemia-reperfusion injury produces a microvascular injury, slow-flow/no-reflow, in the capillaries of the hind paw muscle and digital nerves. We propose that the slow-flow/no-reflow phenomenon initiates and maintains deep-tissue ischemia and inflammation, leading to the activation of muscle nociceptors, and the ectopic activation of sensory afferent axons due to endoneurial ischemia and inflammation. These data, and a large body of clinical evidence, suggest that in at least a subset of CRPS-I patients, the fundamental cause of the abnormal pain sensations is ischemia and inflammation due to microvascular pathology in deep tissues, leading to a combination of inflammatory and neuropathic pain processes. Moreover, we suggest a unifying idea that relates the pathogenesis of CRPS-I to that of CRPS-II. Lastly, our hypothesis suggests that the role of the sympathetic nervous system in CRPS-I is a factor that is not fundamentally causative, but may have an important contributory role in early-stage disease.