Hongbo Lin

Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram

BACKGROUND Sympathetic nerve activity is important to cardiac arrhythmogenesis. OBJECTIVE The purpose of this study was to develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. This method (neuECG) can be used to adequately estimate sympathetic tone. METHODS We recorded neuECG signals from the skin of 56 human subjects. The signals were low-pass filtered to show the ECG and high-pass filtered to show nerve activity. Protocol 1 included 12 healthy volunteers who underwent cold water pressor test and Valsalva maneuver. Protocol 2 included 19 inpatients with epilepsy but without known heart diseases monitored for 24 hours. Protocol 3 included 22 patients admitted with electrical storm and monitored for 39.0 ± 28.2 hours. Protocol 4 included 3 patients who underwent bilateral stellate ganglion blockade with lidocaine injection. RESULTS In patients without heart diseases, spontaneous nerve discharges were frequently observed at baseline and were associated with heart rate acceleration. SKNA recorded from chest leads (V1-V6) during cold water pressor test and Valsalva maneuver (protocol 1) was invariably higher than during baseline and recovery periods (P < .001). In protocol 2, the average SKNA correlated with heart rate acceleration (r = 0.73 ± 0.14, P < .05) and shortening of QT interval (P < .001). Among 146 spontaneous ventricular tachycardia episodes recorded in 9 patients of protocol 3, 106 episodes (73%) were preceded by SKNA within 30 seconds of onset. Protocol 4 showed that bilateral stellate ganglia blockade by lidocaine inhibited SKNA. CONCLUSION SKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating sympathetic tone.

Subcutaneous nerve activity and spontaneous ventricular arrhythmias in ambulatory dogs

BACKGROUND Stellate ganglion nerve activity (SGNA) is important in ventricular arrhythmogenesis. However, because thoracotomy is needed to access the stellate ganglion, it is difficult to use SGNA for risk stratification. OBJECTIVE The purpose of this study was to test the hypothesis that subcutaneous nerve activity (SCNA) in canines can be used to estimate SGNA and predict ventricular arrhythmia. METHODS We implanted radiotransmitters to continuously monitor left stellate ganglion and subcutaneous electrical activities in 7 ambulatory dogs with myocardial infarction, complete heart block, and nerve growth factor infusion to the left stellate ganglion. RESULTS Spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) was documented in each dog. SCNA preceded a combined 61 episodes of VT and VF, 61 frequent bigeminy or couplets, and 61 premature ventricular contractions within 15 seconds in 70%, 59%, and 61% of arrhythmias, respectively. Similar incidence of 75%, 69%, and 62% was noted for SGNA. Progressive increase in SCNA [48.9 (95% confidence interval [CI] 39.3-58.5) vs 61.8 (95% CI 45.9-77.6) vs 75.1 (95% CI 57.5-92.7) mV-s] and SGNA [48.6 (95% CI 40.9-56.3) vs 58.5 (95% CI 47.5-69.4) vs 69.0 (95% CI 53.8-84.2) mV-s] integrated over 20-second intervals was demonstrated 60 seconds, 40 seconds, and 20 seconds before VT/VF (P <.05), respectively. The Pearson correlation coefficient for integrated SCNA and SGNA was 0.73 ± 0.18 (P <.0001 for all dogs, n = 5). Both SCNA and SGNA exhibited circadian variation. CONCLUSION SCNA can be used as an estimate of SGNA to predict susceptibility to VT and VF in a canine model of ventricular arrhythmia and sudden cardiac death.

Facial Fracture in the Setting of Whole-Body CT for Trauma: Incidence and Clinical Predictors

OBJECTIVE The objective of our study was to identify the incidence and clinical predictors of facial fracture in the setting of whole-body MDCT for trauma. MATERIALS AND METHODS The clinical data from the electronic medical records, including the final radiology reports, of 486 consecutive patients who underwent MDCT for trauma (head, cervical spine, chest, abdomen, and pelvis examinations) with dedicated maxillofacial reconstructions from October 1, 2011, to July 31, 2013, were studied. The clinical variables were compared between cohorts of patients with and those without facial fracture. The two-sample t test was used to compare continuous variables, and the Fisher exact test was used to compare categoric variables. RESULTS Two hundred sixteen (44.4%) patients had at least one fracture on the dedicated maxillofacial CT examinations, 215 of whom had facial physical examination findings (sensitivity = 99.5%). Of the 28 patients without documented physical examination findings, 27 did not have a facial fracture (negative predictive value = 96.4%). Statistically significant differences were found between positive and negative cases of facial fracture in patients with a Glasgow coma scale (GCS) score of 8 or less (p < 0.0001), an injury severity score of 16 or greater (p < 0.0001), acute alcohol intoxication according to blood alcohol concentration (BAC) (p = 0.0387), intubation at presentation (p < 0.0001), positive physical examination findings (p < 0.0001), and loss of consciousness (p = 0.0364). Falls from a height greater than standing height and open-vehicle collisions had the highest fracture rates (80.0% and 58.3%, respectively). CONCLUSION A negative finding at facial physical examination reliably excluded fracture. Clinical variables positively associated with facial fracture included the following: GCS score of 8 or less, ISS of 16 or greater, alcohol intoxication according to BAC, intubation at presentation, loss of consciousness, and the presence of abnormal facial findings at physical examination.

B-Type Natriuretic Peptide-Guided Therapy and Length of Hospital Stay Post Left Ventricular Assist Device Implantation

B-type natriuretic peptide (BNP)-guided therapy during the early postoperative period following left ventricular assist device (LVAD) implantation has not been well described in the literature. We conducted a retrospective cohort study consisting of consecutive patients who underwent LVAD implantation at our institution during May 2009 to March 2013. The study was limited to patients receiving HeartMate II (Thoratec) or HVAD (HeartWare) LVADs. Patients with acute myocardial infarction were excluded. We compared between patients with multiple postoperative BNP tests (BNP-guided therapy) and earlier period patients who typically had only a baseline BNP measurement (non-BNP-guided therapy). A total of 85 patients underwent LVAD implantation during the study period. Eight patients were excluded (five acute myocardial infarction, three without BNP measurements). The only differences in the baseline characteristics of BNP versus non-BNP-guided therapy included age and female gender. The postoperative length of hospital stay (LOS) in the BNP-guided therapy group was 5 days shorter when compared with the non-BNP-guided therapy group. In multivariate analysis, BNP-guided therapy remained a significant predictor of reduced LOS. The use of repeated BNP measurements during the early postoperative period was associated with a significantly lower LOS post LVAD implantation.

B‐Type Natriuretic Peptide Levels Predict Ventricular Arrhythmia Post Left Ventricular Assist Device Implantation

B-type natriuretic peptide (BNP) levels have been shown to predict ventricular arrhythmia (VA) and sudden death in patients with heart failure. We sought to determine whether BNP levels before left ventricular assist device (LVAD) implantation can predict VA post LVAD implantation in advanced heart failure patients. We conducted a retrospective study consisting of patients who underwent LVAD implantation in our institution during the period of May 2009-March 2013. The study was limited to patients receiving a HeartMate II or HeartWare LVAD. Acute myocardial infarction patients were excluded. We compared between the patients who developed VA within 15 days post LVAD implantation to the patients without VA. A total of 85 patients underwent LVAD implantation during the study period. Eleven patients were excluded (five acute MI, four without BNP measurements, and two discharged earlier than 13 days post LVAD implantation). The incidence of VA was 31%, with 91% ventricular tachycardia (VT) and 9% ventricular fibrillation. BNP remained the single most powerful predictor of VA even after adjustment for other borderline significant factors in a multivariate logistic regression model (P < 0.05). BNP levels are a strong predictor of VA post LVAD implantation, surpassing previously described risk factors such as age and VT in the past.

B-TYPE NATRIURETIC PEPTIDE LEVELS PREDICT VENTRICULAR ARRHYTHMIA POST LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION

B Type Natriuretic Peptide (BNP) levels have been shown to predict Ventricular Arrhythmia (VA) and sudden death in heart failure. We sought to determine whether BNP can predict VA post Left Ventricular Assist Device (LVAD) implantation. We conducted a retrospective nested case-control study