Two patients with COVID-19 and a fever-induced Brugada-like electrocardiographic pattern.

Febrile states may unmask certain Brugada syndrome patients and precipitate ventricular arrhythmias. Here we describe two patients with COVID-19 who developed a fever-induced type 1 Brugada electrocardiographic pattern. Both patients did not show any ventricular arrhythmias during admission. These and previously published cases suggest that the threshold to run an ECG should be low in febrile patients with suspected COVID-19, because these patients are potentially at risk for developing proarrhythmic complications.

Postural orthostatic tachycardia syndrome (POTS): a common but unfamiliar syndrome.

Postural orthostatic tachycardia syndrome (POTS) is a condition in which a change from a supine to an upright position causes an abnormally large increase in heart rate which may be accompanied by a variety of physical complaints. We report two cases illustrating the heterogeneity of this syndrome. We give an update on the etiology of POTS, which is still poorly understood, and its overlap with other syndromes such as chronic fatigue syndrome. Clinicians should be aware of POTS, a fairly common clinical entity, that can result in significant impairments to a patient's quality of life. Lifestyle measures (under which adequate fluid and salt intake, exercise) are a first line of treatment; if insufficient, pharmacotherapy can be considered to improve quality of life.

On-line detection of cholesterol and calcification by catheter based Raman spectroscopy in human atherosclerotic plaque ex vivo.

BACKGROUND: Raman spectroscopy has the unique potential to detect and quantify cholesterol and calcification in an atherosclerotic plaque in vivo. OBJECTIVE: To evaluate the sensitivity and specificity of this technique for detecting cholesterol or calcification in human coronary artery and aorta specimens ex vivo, using a compact clinical fibreoptic based Raman system developed for in vivo applications. DESIGN: From nine coronary arteries and four aorta specimens, 114 sites were evaluated for the presence of cholesterol and calcification by Raman spectroscopy and standard histology. Raman spectra were acquired and evaluated on-line in around five seconds. RESULTS: The correlation between Raman spectroscopy and histology was r = 0.68 for cholesterol and r = 0.71 calcification in the plaque (p < 0.0001). Sensitivity and specificity for detecting cholesterol and calcification were excellent: receiver operating characteristic (ROC) analysis for each of the components revealed areas under the curves of > 0.92 (p < 0.0001). At the optimal cut-off values determined by ROC analysis, positive predictive values of > 80% and negative predictive values of > 90% were obtained. CONCLUSIONS: On-line real time catheter based Raman spectroscopy detects accumulation of cholesterol and calcification in atherosclerotic plaque with high sensitivity and specificity.

Raman spectroscopic evaluation of the effects of diet and lipid-lowering therapy on atherosclerotic plaque development in mice.

Quantitative characterization of atherosclerotic plaque composition with standard histopathological methods remains limited to sectioned plaques. Raman spectroscopy enables nondestructive quantification of atherosclerotic plaque composition. We used Raman spectroscopy to study the effects of diet and lipid-lowering therapy on plaque development in apolipoprotein (APO) E*3-Leiden transgenic mice. Raman spectra were obtained over the full width and entire length of the ascending aorta and aortic arch. Spectra were modeled to calculate the relative dry weights of cholesterol and calcium salts, and quantitative maps of their distribution were created. In male mice (n=20) that received a high-fat/high-cholesterol (HFC) diet for 0, 2, 4, or 6 months, Raman spectroscopy showed good correlation between cholesterol accumulation and total serum cholesterol exposure (r approximately 0.87, P<0.001). In female mice (n=10) that were assigned to an HFC diet, with or without 0.01% atorvastatin, a strong reduction in cholesterol accumulation (57%) and calcium salts (97%) (P<0.01) was demonstrated in the atorvastatin-treated group. In conclusion, Raman spectroscopy can be used to quantitatively study the size and distribution of depositions of cholesterol and calcification in APOE*3-Leiden transgenic mice. This study encourages Raman spectroscopy for the quantitative investigation of atherosclerosis and lipid-lowering therapy in larger animals or humans in vivo.

Fluorescence spectroscopy of endomyocardial tissue post-human heart transplantation: does it correlate with histopathology?

BACKGROUND: A significant correlation between autofluorescence spectroscopy and heart allograft rejection has been described in the rat heterotropic allograft model. However, the use of this technique in human heart transplants has not been validate. METHODS: We obtained fluorescence and reflectance spectra on 37 human endomyocardial biopsy specimens and correlated the spectra with International Society Heart and Lung Transplantation grade for histologic rejection. RESULTS: Using different excitation wavelengths (ultraviolet, lambda = 337 nm; blue, lambda = 440 nm, and green, lambda = 486 nm), we found no significant difference in the fluorescence spectra among the different grades of rejection. CONCLUSIONS: Fluorescence spectroscopy is not a sensitive method for detecting rejection in human heart transplant recipients.