A governing equation for rotor and wavelet number in human clinical ventricular fibrillation: Implications for sudden cardiac death.

BACKGROUND: Ventricular fibrillation (VF) is characterized by multiple wavelets and rotors. No equation to predict the number of rotors and wavelets observed during fibrillation has been validated in human VF. OBJECTIVE: The purpose of this study was to test the hypothesis that a single equation derived from a Markov M/M/∞ birth-death process could predict the number of rotors and wavelets occurring in human clinical VF. METHODS: Epicardial induced VF (256-electrode) recordings obtained from patients undergoing cardiac surgery were studied (12 patients; 62 epochs). Rate constants for phase singularity (PS) (which occur at the pivot points of rotors) and wavefront (WF) formation and destruction were derived by fitting distributions to PS and WF interformation and lifetimes. These rate constants were combined in an M/M/∞ governing equation to predict the number of PS and WF in VF episodes. Observed distributions were compared to those predicted by the M/M/∞ equation. RESULTS: The M/M/∞ equation accurately predicted average PS and WF number and population distribution, demonstrated in all epochs. Self-terminating episodes of VF were distinguished from VF episodes requiring termination by a trend toward slower PS destruction, slower rates of PS formation, and a slower mixing rate of the VF process, indicated by larger values of the second largest eigenvalue modulus of the M/M/∞ birth-death matrix. The longest-lasting PS (associated with rotors) had shorter interactivation time intervals compared to shorter-lasting PS lasting <150 ms (∼1 PS rotation in human VF). CONCLUSION: The M/M/∞ equation explains the number of wavelets and rotors observed, supporting a paradigm of VF based on statistical fibrillatory dynamics.

Endobronchial ultrasound-guided transbronchial needle aspiration prevents mediastinoscopies in the diagnosis of isolated mediastinal lymphadenopathy: a prospective trial.

RATIONALE: Patients with isolated mediastinal lymphadenopathy (IML) are a common presentation to physicians, and mediastinoscopy is traditionally considered the "gold standard" investigation when a pathological diagnosis is required. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is established as an alternative to mediastinoscopy in patients with lung cancer. OBJECTIVE: To determine the efficacy and health care costs of EBUS-TBNA as an alternative initial investigation to mediastinoscopy in patients with isolated IML. METHODS: Prospective multicenter single-arm clinical trial of 77 consecutive patients with IML from 5 centers between April 2009 and March 2011. All patients underwent EBUS-TBNA. If EBUS-TBNA did not provide a diagnosis, then participants underwent mediastinoscopy. MEASUREMENTS AND MAIN RESULTS: EBUS-TBNA prevented 87% of mediastinoscopies (95% confidence interval [CI], 77-94%; P < 0.001) but failed to provide a diagnosis in 10 patients (13%), all of whom underwent mediastinoscopy. The sensitivity and negative predictive value of EBUS-TBNA in patients with IML were 92% (95% CI, 83-95%) and 40% (95% CI, 12-74%), respectively. One patient developed a lower respiratory tract infection after EBUS-TBNA, requiring inpatient admission. The cost of the EBUS-TBNA procedure per patient was £1,382 ($2,190). The mean cost of the EBUS-TBNA strategy was £1,892 ($2,998) per patient, whereas a strategy of mediastinoscopy alone was significantly more costly at £3,228 ($5,115) per patient (P < 0.001). The EBUS-TBNA strategy is less costly than mediastinoscopy if the cost per EBUS-TBNA procedure is less than £2,718 ($4,307) per patient. CONCLUSIONS: EBUS-TBNA is a safe, highly sensitive, and cost-saving initial investigation in patients with IML. Clinical trial registered with ClinicalTrials.gov (NCT00932854).

Heparin-bonded circuits versus nonheparin-bonded circuits: an evaluation of their effect on clinical outcomes.

Heparinization of the blood contact surface in cardiopulmonary bypass circuits has been promoted as an important step in the development of open heart surgery. As it decreases the inflammatory response resulting from the extracorporeal circulation, it may have a positive effect on clinical outcomes. This meta-analysis was carried out to examine if heparin-bonded circuits (HBCs) reduce the need for blood products and improve overall clinical outcome. A systematic literature search was performed to identify randomized controlled trials reporting outcomes of HBCs compared with non-HBCs. Primary outcomes assessed were postoperative blood/blood-product transfusion and blood loss. Secondary outcomes included all-cause mortality, acute postoperative myocardial infarction, stroke, re-sternotomy for postoperative bleeding, wound infection, atrial fibrillation, duration of ventilation, intensive care unit (ICU) and hospital-length of stay (LOS). Random effects meta-analytical techniques were applied to identify differences in outcomes between the two groups. Quality of the included studies and heterogeneity were assessed. From an initial review of 762-published studies, 41-randomized trials fulfilled the inclusion criteria, leaving 3434-patients' data for analysis. HBCs significantly decreased the incidence of blood transfusion required (OR=0.8; 95% CI=0.6:0.9, P=0.004). It also significantly decreased re-sternotomy (OR=0.6; 95% CI=0.4:0.8, P=0.002), duration of ventilation (WMD= -1.3h; 95% CI= -1.9:-0.6, P<0.001), ICU-LOS (WMD= -9.3h; 95% CI=-14.7:-3.9, P<0.001) and hospital-LOS (WMD= -0.5 day; 95% CI= -0.9:-0.1, P=0.02). HBCs had no effect on other adverse events evaluated. Although HBCs showed a positive effect on some of the clinical outcomes, we identified only marginal differences for other outcomes. Further evaluation of the cost-effectiveness of this technology is required.