Low temperature increases capillary blood refill time following mechanical fingertip compression of healthy volunteers: prospective cohort study.

Capillary refill time has been accepted as a method to manually assess a patient's peripheral blood perfusion. Recently, temperature has been reported to affect capillary refill time and therefore temperature may interfere with accurate bedside peripheral blood perfusion evaluation. We applied a new method of analysis that uses standard hospital pulse oximetry equipment and measured blood refill time in order to test whether lowered fingertip temperature alters peripheral blood perfusion. Thirty adult healthy volunteers of differing races (skin colors) and age (young: 18-49 years and old: ≥ 50 years) groups were recruited. We created a high fidelity mechanical device to compress and release the fingertip and measure changes in blood volume using infrared light (940 nm). Capillary refill times were measured at the fingertip at three different temperature settings: ROOM TEMPERATURE, COLD by 15 °C cold water, and REWARM by 38 °C warm water. The COLD group has decreased fingertip temperature (23.6 ± 3.6 °C) and increased blood refill time (4.67 s [95% CI 3.57-5.76], p < 0.001). This was significantly longer than ROOM TEMPERATURE (1.96 [1.60-2.33]) and REWARM (1.96 [1.73-2.19]). Blood refill time in older subjects tended to be longer than in younger subjects (2.28 [1.61-2.94] vs. 1.65 [1.36-1.95], p = 0.077). There was a negative correlation (r = - 0.471, p = 0.009) between age and temperature. A generalized linear mixed-effects model revealed that lower temperature (OR 0.63 [95% CI 0.61-0.65], p < 0.001) rather than age (OR 1.00 [0.99-1.01], p = 0.395) was the independent factor most associated with increased blood refill time. Lowered fingertip temperatures significantly increase blood refill time which then returns to baseline when the fingertip is rewarmed. In our limited number of population, we did not find an association with age after the adjustment for the fingertip temperature.

Mavacamten: A Novel Disease-Specific Treatment for Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is characterized by an abnormal thickening of the myocardium, leading to left ventricular outflow tract obstruction. Current treatments for HCM include non-disease-specific medications such as beta blockers or invasive interventions. Mavacamten has been studied for its effects on adenosine triphosphatase, myocardial-specific sarcomeric proteins, and myocardial tissue calcium sensitivity. Given these properties, mavacamten could be used as a disease-specific treatment for HCM. Clinical trials of mavacamten have shown improvements in left ventricular outflow tract obstruction among other favorable improvements in biochemical markers and the clinical symptoms of the disease. While trials to date have been relatively small, mavacamten shows promise as a future disease-specific treatment for HCM.

Vagus Nerve Stimulation and the Cardiovascular System.

The vagus nerve plays an important role in maintaining physiological homeostasis, which includes reflex pathways that regulate cardiac function. The link between vagus nerve activity and the high-frequency component of heart rate variability (HRV) has been well established, correlating with vagal tone. Recently, vagus nerve stimulation (VNS) has been investigated as a therapeutic for a multitude of diseases, such as treatment-resistant epilepsy, rheumatoid arthritis, Crohn's disease, and asthma. Because of the vagus nerve's innervation of the heart, VNS has been identified as a potential therapy for cardiovascular disorders, such as cardiac arrest, acute myocardial infarction, and stroke. Here, we review the current state of preclinical and clinical studies, as well as the potential application of VNS in relation to the cardiovascular system.