A transferable in-silico augmented ischemic model for virtual myocardial perfusion imaging and myocardial infarction detection.

This paper proposes an innovative approach to generate a generalized myocardial ischemia database by modeling the virtual electrophysiology of the heart and the 12-lead electrocardiography projected by the in-silico model can serve as a ready-to-use database for automatic myocardial infarction/ischemia (MI) localization and classification. Although the virtual heart can be created by an established technique combining the cell model with personalized heart geometry to observe the spatial propagation of depolarization and repolarization waves, we developed a strategy based on the clinical pathophysiology of MI to generate a heterogeneous database with a generic heart while maintaining clinical relevance and reduced computational complexity. First, the virtual heart is simplified into 11 regions that match the types and locations, which can be diagnosed by 12-lead ECG; the major arteries were divided into 3-5 segments from the upstream to the downstream based on the general anatomy. Second, the stenosis or infarction of the major or minor coronary artery branches can cause different perfusion drops and infarct sizes. We simulated the ischemic sites in different branches of the arteries by meandering the infarction location to elaborate on possible ECG representations, which alters the infraction's size and changes the transmembrane potential (TMP) of the myocytes associated with different levels of perfusion drop. A total of 8190 different case combinations of cardiac potentials with ischemia and MI were simulated, and the corresponding ECGs were generated by forward calculations. Finally, we trained and validated our in-silico database with a sparse representation classification (SRC) and tested the transferability of the model on the real-world Physikalisch Technische Bundesanstalt (PTB) database. The overall accuracies for localizing the MI region on the PTB data achieved 0.86, which is only 2% drop compared to that derived from the simulated database (0.88). In summary, we have shown a proof-of-concept for transferring an in-silico model to real-world database to compensate for insufficient data.

Long-Term Effect of Device-Guided Slow Breathing on Blood Pressure Regulation and Chronic Inflammation in Patients with Essential Hypertension Using a Wearable ECG Device.

BACKGROUND: Hypertension is related to autonomic nervous system (ANS) dysfunction, atherosclerosis and chronic inflammation. The stimulation of baroreflex regulation by slow-breathing exercise may improve the interplay among these systems. The objective of this study was to investigate the effect of device-guided slow breathing on ANS, cardiovascular system and chronic inflammation in hypertensive patients. METHODS: We prospectively collected 36 essential hypertension patients who were requested to practice slow-breathing exercise 5 times per day for 3 months. The breathing exercise was guided by a cellphone app with a wearable electrocardiography device and a rhythm of 6 cycles per minute. Cardiovascular indicators including heart rate variability (HRV), blood pressure, pulse wave velocity and baroreflex indexes were sampled 3 times: at the first visit, and 1 month and 3 months after the intervention. The levels of blood inflammatory biomarkers, including tumor necrosis factor-alpha (TNF-α), interleukin-6, interleukin-1 receptor antagonist and C-reactive protein were also collected at all 3 visits. The longitudinal differences in these variables and their correlations were tested. RESULTS: There was a significant decrease in blood pressure after 1 month of exercise. A significantly continuous decrease in TNF-α was also observed. The baroreflex indexes were significantly increased in the acute intervention of slow-breathing but not in the longitudinal effect. The HRV variables did not show differences with time. There were positive correlations between sympathetic index and TNF-α and galectin-3. CONCLUSIONS: The effect of slow-breathing exercise on blood pressure and chronic inflammation was significant. HRV indexes may also be used to assess chronic inflammation.

Echocardiography-guided balloon mitral valvotomy: transesophageal echocardiography versus intracardiac echocardiography.

BACKGROUND AND AIM OF THE STUDY: Although balloon mitral valvotomy (BMV) can be guided by on-line transesophageal echocardiography (TEE) or intracardiac echocardiography, few reports have been made comparing these methods. The study aim was to compare on-line TEE and on-line intracardiac echocardiography in the guidance of BMV. METHODS: Fifty-five consecutive patients with significant mitral stenosis (mitral area < or = 1.5 cm2), but without significant mitral regurgitation (< or = Sellers grade 2) or left atrial cavitary thrombus, underwent BMV. Patients were prospectively randomized to two groups: group A (n = 28) received on-line guidance by multiplane TEE, while group B (n = 27) received on-line guidance by intracardiac echocardiography. Pre-procedural and post-procedural data were compared between these groups. RESULTS: There were no significant differences in baseline data and procedural outcomes. On-line TEE was found to be of great help for septal puncture, immediate assessment of results, and the prevention and detection of complications. On-line intracardiac echocardiography also aided in septal puncture and was better tolerated by patients, but had less imaging capabilities, was more expensive, required a second venous access, and on occasion interfered with manipulation of the puncture and balloon catheters. CONCLUSION: Although both TEE and intracardiac echocardiography were safe and effective for on-line guidance of BMV, TEE provided better imaging capabilities.