A Novel Electrocardiogram Algorithm Utilizing ST-Segment Instability for Detection of Cardiopulmonary Arrest in Single Ventricle Physiology: A Retrospective Study.

OBJECTIVE: We evaluated ST-segment monitoring to detect clinical decompensation in infants with single ventricle anatomy. We proposed a signal processing algorithm for ST-segment instability and hypothesized that instability is associated with cardiopulmonary arrests. DESIGN: Retrospective, observational study. SETTING: Tertiary children's hospital 21-bed cardiovascular ICU and 36-bed step-down unit. PATIENTS: Twenty single ventricle infants who received stage 1 palliation surgery between January 2013 and January 2014. Twenty rapid response events resulting in cardiopulmonary arrests (arrest group) were recorded in 13 subjects, and nine subjects had no interstage cardiopulmonary arrest (control group). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arrest data were collected over the 4-hour time window prior to cardiopulmonary arrest. Control data were collected from subjects with no interstage arrest using the 4-hour time window prior to cardiovascular ICU discharge. A paired subgroup analysis was performed comparing subject 4-hour windows prior to arrest (prearrest group) with 4-hour windows prior to discharge (postarrest group). Raw values of ST segments were compared between groups. A 3D ST-segment vector was created using three quasi-orthogonal leads (II, aVL, and V5). Magnitude and instability of this continuous vector were compared between groups. There was no significant difference in mean unprocessed ST-segment values in the arrest and control groups. Utilizing signal processing, there was an increase in the ST-vector magnitude (p = 0.02) and instability (p = 0.008) in the arrest group. In the paired subgroup analysis, there was an increase in the ST-vector magnitude (p = 0.05) and instability (p = 0.05) in the prearrest state compared with the postarrest state prior to discharge. CONCLUSIONS: In single ventricle patients, increased ST instability and magnitude were associated with rapid response events that required intervention for cardiopulmonary arrest, whereas conventional ST-segment monitoring did not differentiate an arrest from control state.

Continuous cerebral hemodynamic measurement during deep hypothermic circulatory arrest.

While survival of children with complex congenital heart defects has improved in recent years, roughly half suffer neurological deficits suspected to be related to cerebral ischemia. Here we report the first demonstration of optical diffuse correlation spectroscopy (DCS) for continuous and non-invasive monitoring of cerebral microvascular blood flow during complex human neonatal or cardiac surgery. Comparison between DCS and Doppler ultrasound flow measurements during deep hypothermia, circulatory arrest, and rewarming were in good agreement. Looking forward, DCS instrumentation, alone and with NIRS, could provide access to flow and metabolic biomarkers needed by clinicians to adjust neuroprotective therapy during surgery.

Cerebral blood flow autoregulation is preserved after continuous-flow left ventricular assist device implantation.

OBJECTIVE: To compare cerebral blood flow (CBF) autoregulation in patients undergoing continuous-flow left ventricular assist device (LVAD) implantation with that in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Prospective, observational, controlled study. SETTING: Academic medical center. PARTICIPANTS: Fifteen patients undergoing LVAD insertion and 10 patients undergoing CABG. MEASUREMENTS AND MAIN RESULTS: Cerebral autoregulation was monitored with transcranial Doppler and near-infrared spectroscopy. A continuous Pearson correlation coefficient was calculated between mean arterial pressure (MAP) and CBF velocity and between MAP and near-infrared spectroscopic data, rendering the variables mean velocity index (Mx) and cerebral oximetry index (COx), respectively. Mx and COx approach 0 when autoregulation is intact (no correlation between CBF and MAP), but approach 1 when autoregulation is impaired. Mx was lower during and immediately after cardiopulmonary bypass in the LVAD group than in the CABG group, indicating better-preserved autoregulation. Based on COx monitoring, autoregulation tended to be better preserved in the LVAD group than in the CABG group immediately after surgery (p = 0.0906). On postoperative day 1, COx was lower in the LVAD group than in the CABG group, indicating preserved CBF autoregulation (p = 0.0410). Based on COx monitoring, 3 patients (30%) in the CABG group had abnormal autoregulation (COx ≥0.3) on the first postoperative day but no patient in the LVAD group had this abnormality (p = 0.037). CONCLUSIONS: These data suggest that CBF autoregulation is preserved during and immediately after surgery in patients undergoing LVAD insertion.

Use of an optimized transient occlusion of the middle cerebral artery protocol for the mouse stroke model.

Intraluminal occlusion of the middle cerebral artery in rodents is widely used for investigating cerebral ischemia and reperfusion injury. Two types of filaments used for occlusion were tested in terms of surgical success, incidence of subarachnoid hemorrhage, and mortality: a standard 6-0 monofilament coated with methyl methacrylate glue (rigid probe) and an 8-0 monofilament coated with silicone (flexible probe). In 98 wild-type (WT) mice, the flexible probe produced significantly (P < .05) more successful strokes (73.5%) than the rigid probe (46.6%). The incidences of subarachnoid hemorrhage (3.7%) and mortality (5.6%) with the flexible probe were significantly lower than those with the rigid probe (26.6% and 11.1%, respectively). Rigid and flexible probes were also compared in heme oxygenase 1 knockout (n = 17) and WT littermates (n = 17), because knockout mice have been suggested to have more fragile blood vessels. All mice receiving the flexible probe had successful strokes, with no cases of subarachnoid hemorrhage or mortality; however, with the rigid probe, the success rate was only 80% in the WT mice and 60% in the knockout mice. The rates of subarachnoid hemorrhage and mortality were also significantly higher with the rigid probe in both genotypes, but the infarct volumes produced by each type of probe did not differ significantly between the 2 groups. We conclude that the flexible silicone-coated 8-0 probe is superior to the more rigid glue-coated probe, because it produces infarct volumes of equal size with a higher success rate and lower risk of subarachnoid hemorrhage and mortality.