Predicting ventricular tachyarrhythmia in patients with systolic heart failure based on texture features of the gray zone from contrast-enhanced magnetic resonance imaging.

BACKGROUND: Previous research showed that gray zone detected by late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) imaging could help identify high-risk patients. In this study, we investigated whether LGE-CMR gray zone heterogeneity measured by image texture features could predict cardiovascular events in patients with heart failure (HF). METHOD: This is a retrospective cohort study. Patients with systolic HF undergoing CMR imaging were enrolled. Cine and LGE images were analyzed to derive left ventricular (LV) function and scar characteristics. Entropy and uniformity of gray zones were derived by texture analysis. RESULTS: A total of 82 systolic HF patients were enrolled. After a median 1021 (25%-75% quartiles, 205-2066) days of follow-up, the entropy (0.60 ± 0.260 vs. 0.87 ± 0.28, p = 0.013) was significantly increased while the uniformity (0.68 ± 0.14 vs. 0.53±0.15, p = 0.016) was significantly decreased in patients with ventricular tachycardia or ventricular fibrillation (VT/VF). The percentage of core scar (21.9 ± 10.6 vs. 30.6 ± 10.4, p = 0.029) was higher in cardiac mortality group than survival group while the uniformity (0.55 ± 0.17 vs. 0.67 ± 0.14, p = 0.018) was lower in cardiac mortality group than survival group. A multivariate Cox regression model showed that higher percentage of gray zone area (HR = 8.805, 1.620-47.84, p = 0.045), higher entropy (>0.85) (HR = 1.391, 1.092-1.772, p = 0.024) and lower uniformity (≦0.54) (HR = 0.535, 0.340-0.842, p = 0.022) were associated with VT/VF attacks. Also, higher percentage of gray zone area (HR = 5.716, 1.379-23.68, p = 0.017), core scar zone (HR = 1.939, 1.056-3.561, p = 0.025), entropy (>0.85) (HR = 1.434, 1.076-1.911, p = 0.008) and lower uniformity (≦0.54) (HR = 0.513, 0.296-0.888, p = 0.009) were associated with cardiac mortality during follow-up. CONCLUSIONS: Gray zone heterogeneity by texture analysis method could provide additional prognostic value to traditional LGE-CMR substrate analysis method.

Probing age-related changes in cardio-respiratory dynamics by multimodal coupling assessment.

Quantifying respiratory sinus arrhythmia (RSA) can provide an index of parasympathetic function. Fourier spectral analysis, the most widely used approach, estimates the power of the heart rate variability in the frequency band of breathing. However, it neglects the time-varying characteristics of the transitions as well as the nonlinear properties of the cardio-respiratory coupling. Here, we propose a novel approach based on Hilbert-Huang transform, called the multimodal coupling analysis (MMCA) method, to assess cardio-respiratory dynamics by examining the instantaneous nonlinear phase interactions between two interconnected signals (i.e., heart rate and respiration) and compare with the counterparts derived from the wavelet-based method. We used an online database. The corresponding RSA components of the 90-min ECG and respiratory signals of 20 young and 20 elderly healthy subjects were extracted and quantified. A cycle-based analysis and a synchro-squeezed wavelet transform were also introduced to assess the amplitude or phase changes of each respiratory cycle. Our results demonstrated that the diminished mean and standard deviation of the derived dynamical RSA activities can better discriminate between elderly and young subjects. Moreover, the degree of nonlinearity of the cycle-by-cycle RSA waveform derived from the differences between the instantaneous frequency and the mean frequency of each respiratory cycle was significantly decreased in the elderly subjects by the MMCA method. The MMCA method in combination with the cycle-based analysis can potentially be a useful tool to depict the aging changes of the parasympathetic function as well as the waveform nonlinearity of RSA compared to the Fourier-based high-frequency power and the wavelet-based method.

A comprehensive model for sub-10 nm electron-beam patterning through the short-time and cold development.

In this study, we propose a set of single-spot experiment to construct a comprehensive model of electron-beam lithography to describe the relation among the incident electrons, resist, and the development conditions such as durations and temperatures. Through the experiments, small feature can be achieved by performing a short-time development due to the high acceleration voltage and large depth of focus of electron-beam system. The singular point in the beginning of the development is also observed in our model and supported by the experimental data. In addition, we verify the characteristic region of each incident spot induced by the point spread function of the electron-beam system. We further fabricate the single line with narrow groove width by utilizing the results from single-spot experiment at low developing temperatures. The line is formed by arranging a series of incident points with a distance close to the characteristic radius. This method can eliminate the proximity effect effectively and thus the groove width is scaled down to 8 nm. By adopting the successful experience in the single line formation, dense array with narrow linewidth is also demonstrated under well suppression of the proximity effect. The minimum groove width of 9 nm with 30 nm pitch is achieved with 5 s development time at -10 °C. Finally, the exceptional capability of pattern transfer is presented due to the high aspect ratio of the resist.

Sudden complete obstruction of breathing circuit during postural change upon completion of thoracic spinal surgery in a pediatric patient.

Positioning patients during the perioperative period is a common event to anesthesiologists. A variety of complications may arise during this cumbrous moment. We describe a rare circumstance that we came across immediately after changing the posture of a pediatric patient at the end of thoracic spinal surgery. A total occlusion of the combined heat-moisture exchanger (HME) and bacterial/viral filter was responsible for breathing circuit obstruction. The use of the combined HME and bacterial/viral filter is not entirely riskless during general anesthesia.

Inferior vena cava tear during posterior spinal fusion surgery.

Inferior vena cava tear is a rare but potentially lethal event associated with spinal surgery. Early recognition and repair are mandatory to minimize morbidity and mortality. Here we report a case of inferior vena cava tear which occurred during posterior spinal fusion surgery. Without marked bleeding from the surgical field, the patient was suddenly seized with a profound shock. Abdominal distension was found after resumption of the supine position from prone. Emergent exploratory laparotomy disclosed inferior vena cava tear. After repairing of the torn vessel, the patient was transferred to ICU. Unfortunately, patient expired two weeks later due to multiple-organ failure.

Fatal arrhythmia following intraoperative continuous hyperthermic peritoneal perfusion chemotherapy.

Continuous hyperthermic peritoneal perfusion chemotherapy (CHPPC) offers a safe alternative to manage peritoneal tumor seeding in advanced cancer patients. A 65-year-old male underwent exploratory laparotomy for advanced gastric cancer with intraabdominal carcinomatosis and massive ascites. Life-threatening dysrrhythmia of ventricular rhythm with a rate of 120 beats/min developed during the performance of intraoperative CHPPC following eradication of the main tumor. With timely cardiopulmonary resuscitation, appropriate fluid replacement, correction of electrolyte imbalance, and cooling of body temperature, the patient regained effective cardiopulmonary circulation without sequela.