Effects of Polarity on Defibrillation Thresholds Using a Biphasic Waveform in a Hot Can Electrode System

The polarity of a monophasic and biphasic shocks have been reported to influence DFTs in some studies. The purpose of this study was to evaluate the effect of the first phase polarity on the DFTofa biphasic shock utilizing a nonthoracotomy "hot can" electrode configuration which had a 90-μF capacitance. We tested the hypothesis that anodal first phase was more effective than cathodal ones for defibrillation using biphasic shocks in ten anesthetized pigs weighing 38.9 ± 3.9 kg. The lead system consisted of a right ventricular catheter electrode with a surface area of 2.7 cm² and a left pectoral "hot can" electrode with 92.9 cm² surface area. DFT was determined using a repeated "down-up" technique. A shock was tested 10 seconds after initiation of ventricular fibrillation. The mean delivered energy at DFT was 11.2 ± 1.7 J when using the right ventricular apex electrode as the cathode and 11.3 ± 1.2 J (P = NS) when using it as the anode. The peak voltage at DFT was also not significantly different (529.0 ± 41.3 and 531.8 ± 28.6 V, respectively). We concluded that the first phase polarity of a biphasic shock used with a nonthoracotomy "hot can" electrode configuration did not affect DFT.     

An institutional experience with epidural analgesia in children and young adults undergoing cardiac surgery

Background: Allowing spontaneous respiration after cardiac surgery eliminates complications related to mechanical ventilation and optimizes cardiopulmonary interaction. Epidural analgesia has been proposed to promote early extubation after cardiac surgery. Objective: To identify the characteristics of patients with epidural analgesia and safety profiles with respect to the timing of extubation following cardiac surgery. Design and method: A retrospective chart review of patients who underwent cardiac surgery during a 5‐year period. Demographic, procedural, and perioperative variables were analyzed to investigate factors that affect the timing of extubation. Results: A total of 750 records were reviewed. The patients’ median age was 12 months, and 52% were infants (<1 year). Seventy‐five percent of the patients utilized cardiopulmonary bypass. The study population was classified into three groups according to the timing of extubation: 66% were extubated in the operating room or upon arrival at the PICU (Immediate), 15% were extubated within 24 h (mean, 10.8 h; 95% CI, 9.0–12.6) (Early), and 19% were extubated after 24 h (Delayed). For the Immediate and Early groups, multivariate logistic regression identified young age, increased cross‐clamp time, and inotrope score as independent risk factors for the need for mechanical ventilation. Postextubation respiratory acidosis (mean P_aCO₂, 50 mmHg; 95% CI, 49–51) was well tolerated by all patients. There were no neurologic complications related to the epidural technique. Conclusion: Epidural analgesia in children undergoing cardiac surgery provides stable analgesia without complications in our experience.     

Ventricular fibrillation in an ex‐premature neonate following reperfusion of ischemic gut incarcerated within an inguinal hernia

We describe the case of a neonate who underwent surgery for bowel obstruction. The child was born at 25 weeks postconception, and at the time of surgery, he had a postconceptual age of 44 weeks. He had undergone two previous laparotomy procedures for necrotizing enterocolitis. At laparotomy, there was unexpected extensive compromise to gut perfusion. The child developed ventricular fibrillation following the reperfusion of a segment of ischemic gut found incarcerated in an inguinal hernial orifice. We discuss the pathophysiology of intestinal ischemia–reperfusion (I‐R) injury. We have reviewed the interventions that may be employed to minimize the systemic impact of I‐R.     

Advances in Catheter Ablation use of Unipolar Electrograms

Ventricular tachycardia in man can be eliminated by relatively small lesions in the reentrant circuit. This report includes a review of available energy sources, and methods for localizing arrhythmias. Methods to assure contact and prevent perforation using low frequency electrograms are presented including the new finding of reverse ST deflection with contact. Experience with laser energy in dogs showed discrete homogenous lesions. When compared with DC shock the animals showed far less arrhythmia and the lack of far field effect greatly reduced echo abnomalities in the post shock period. Studies with radiofrequency show ability to produce localized lesions similar to the laser but with a more flexible catheter. Localization requires a correlation of techniques including pacemapping, activation maps and pacing during tachycardia. Early activation (< −60 ms) at times 180–320 ms, with comparable pace to QRS during tachycardia with no change in morphology best localized the slow zone of the reentrant circuit. The low frequency unipolar electrogram from the tip and immediately proximal electrode revealed contact with ST deviation. The distal deviation was always greater than the proximal RV free wall and posterior basal produced depression rather than elevation of the electrogram. While the mechanism of ST reversal with contact is not understood and may relate to the type of indifferent reference used (Wilson central terminal), the ST depression reveals the same information about contact that elevation does in most other areas of the heart studied in our patients.     

Chasing, Arousal and Sensation Seeking in Off-course Gamblers

Off-course belling agency customers (N = 172) were assessed by a brief structured interview and by a questionnaire that included; the Sensation Seeking Scale (SSS Form V), a short form of the State portion of the State-Trait Anxiety questionnaire designed to assess subjective reports of levels of arousal after betting but prior to the race result, a question assessing the frequency of chasing and questions about other aspects of betting behaviour. Contrary to the hypothesis of Zuckerman (1979) the results showed that male bettors as a group were significantly lower on SSS scores than existing population norms. Despite the restricted range of these scores weak but significant relationships were shown between SSS subscales and level of involvement in betting. Chasing was shown to be a central feature of a group of out-of-control betting behaviours. Sensation Seeking scores were positively correlated with level of involvement and the relationship found between the Boredom Susceptibility subscale and arousal was tentatively highlighted as an individual difference that would predispose a person to greater loss of control and possible problematic levels of gambling.     

Utilization of screening mammography: comparison of different physician specialties

Data obtained on 426 consecutive patients referred to a breast center by 122 physicians, including family practitioners, general surgeons, and other specialists, showed that the obstetricians-gynecologists referred the greatest average number of patients per physician, with more than 50% of these referrals for screening mammography. Internists referred fewer patients by nearly a factor of ten, with only one-third of these patients referred for screening mammography. Internists may be the weakest link in the utilization of screening mammography.     

Treatment of Encainide Proarrhythmia with Hypertonic Saline

We report a case of successful treatment of encainide-induced ventricular tachycardia with 3% hypertonic saline. To our knowledge, no other report exists in the literature of this treatment for proarrhythmic ventricular tachycardia from a type 1C agent. Metabolic consequences of the treatment included severe hypernatremia, hyperosmolarity, hypocalcemia, and hypophosphatemia, which were reversible over 24 hours. In spite of the risks, treatment of incessant ventricular tachycardia induced by type 1C agents with hypertonic saline may be life saving.