Disruption of coronary vasomotor function: the coronary spasm syndrome

Intracoronary injection of nitroglycerine can prevent unnecessary percutaneous coronary intervention

Background

Despite the recommendation of the current guidelines, intracoronary administration of nitroglycerine during coronary angiography is often neglected. We investigated the effect of intra-coronary nitroglycerin on the relief of coronary artery stenosis in the candidates for percutaneous coronary intervention (PCI).

Methods

We included patients with angina pectoris or myocardial infarction who were candidates for PCI. In the coronary angiography, the culprit vessel involved was evaluated, and bolus nitroglycerin at a dose of 25–200 mcg was injected into the affected coronary artery. A significant change in the percentage of coronary artery stenosis was considered a positive response, and these patients were then compared with patients who did not have a substantial change in the percentage of stenosis at the same time. Univariate analysis and then multivariate logistic regression analysis was performed to determine the predictors of response to intracoronary nitroglycerin.

Results

Among 360 patients, 27 (7.5%) responded to nitroglycerine, and 333 (92.5%) were non-responsive. The mean age of patients was 60.2 ± 11.6 years, ranging from 23 to 93 years, and 265 (73.6%) were men. The study groups were not significantly different in the baseline demographic characteristics. The presence of multivessel disease (Odds ratio (OR) = 16.26, 95% confidence interval (CI):2.07–127.6; P = 0.008) and stenosis in the left circumflex artery (OR = 3.62, 95% CI: 1.03–12.70; P = 0.044) were the independent predictors for nonresponse to nitroglycerine, leading to PCI.

Conclusion

In some cases, especially those without multivessel diseases, intracoronary nitroglycerine administration can efficiently relieve coronary stenosis and prevent unnecessary PCI.

Centipedes subdue giant prey by blocking KCNQ channels

The work showed that centipede venom can cause disorders in cardiovascular, respiratory, and nervous systems. The cardiovascular toxicity of the venom comes mostly from a peptide toxin SsTx, which blocks the KCNQ family of potassium channels. Retigabine, a KCNQ channel opener, neutralizes centipede venom toxicity, and thus could be used to treat centipede envenomation.

Centipedes can subdue giant prey by using venom, which is metabolically expensive to synthesize and thus used frugally through efficiently disrupting essential physiological systems. Here, we show that a centipede (Scolopendra subspinipes mutilans, ∼3 g) can subdue a mouse (∼45 g) within 30 seconds. We found that this observation is largely due to a peptide toxin in the venom, SsTx, and further established that SsTx blocks KCNQ potassium channels to exert the lethal toxicity. We also demonstrated that a KCNQ opener, retigabine, neutralizes the toxicity of a centipede’s venom. The study indicates that centipedes’ venom has evolved to simultaneously disrupt cardiovascular, respiratory, muscular, and nervous systems by targeting the broadly distributed KCNQ channels, thus providing a therapeutic strategy for centipede envenomation.

Deep Vein Thrombosis, Raynaud's Phenomenon, and Prinzmetal Angina in a Patient with Glanzmann Thrombasthenia

Patients with Glanzmann thrombasthenia fail to form large platelet thrombi due to mutations that affect the biosynthesis and/or function of the αIIbβ3 integrin. The result is a moderate to severe bleeding syndrome. We now report unusual vascular behaviour in a 55-year-old woman with classic type I disease (with no platelet αIIbβ3 expression) and a homozygous ITGA2B missense mutation (E324K) affecting the terminal β-propeller domain of αIIb. While exhibiting classic bleeding symptoms as a child, in later life this woman first developed deep vein thrombosis after a long air flight then showed vascular problems characteristic of Raynaud's phenomenon, and finally this year she presented with chest pains suggestive of coronary heart disease. Yet while coronary angiography first showed a stenosis, this was not seen on a second examination when she was diagnosed with coronary spastic angina and Prinzmetal phenomenon. It is significant that the absence of platelet aggregation with physiologic agonists had not prevented any of the above cardiovascular or vascular diseases.