P1021Comparative efficacy of microfidelity technology vs standard ablation for atrioventricular nodal ablation

Background

Microfidelity Cateter Technology has proven efficacy in ablating atrial arrhythmias in multiple pilot studies. Closely spaced radial microelectrodes render a focused near-field electrogram. Case series suggest that this catheter design facilitates accurate ablations with fewer radiofrequency (RF) lesions. Atrioventricular junction (AVJ) ablation is regarded as a straightforward procedure, but case records show wide variance in procedure times and number of RF lesions required.

Methods

Twenty-four patients scheduled for AVJ ablation were randomized to treatment with either the Microfidelity technology or standard 8mm/8 French ablation catheter. Both groups located the AVJ by fluoroscopic landmarks and His electrograms, and the MiFi group used electroanatomical mapping to create the location of his electrograms. The primary endpoints were development of Junctional Rhythm (JR) or Complete Heart Block (CHB), and time from first RF lesion until rhythm change. Secondary endpoints included number of RF applications.

Results

Patients were randomized one-to-one to the MiFi arm or standard ablation arm. JR or CHB was achieved in all patients. Time from first RF lesion until JR/CHB was: (Median/IQR) 325 sec/250–1270 sec. vs 287 sec/101–406 sec. Number of RF applications was 5/3–15 applications vs 4.5/1–5 applications. Total procedure time in the lab was 134 min/73.5–172.5 min vs 58 min/52–146 min.

Microfidelity Technology vs Standard

Conclusion

Analysis suggests that the MiFi catheter is efficacious in ablating the AVJ, but requires greater RF duration and number of lesions, with wider case-by-case variability to achieve JR or CHB. Microfidelity technology and electroanatomical mapping did not result in faster time to completion than using fluoroscopic landmarks and His electrograms alone. Preoperative choice of sheath for catheter stability and contact may also play a role in a more efficient timely successful ablation of the AV node.

Acknowledgement/Funding

Boston Scientific

MRA of the skin: mapping for advanced breast reconstructive surgery

Autologous breast reconstruction using muscle-sparing free flaps are becoming increasingly popular, although microvascular free flap reconstruction has been utilised for autologous breast reconstructions for >20 years. This innovative microsurgical technique involves meticulous dissection of artery-vein bundle (perforators) responsible for perfusion of the subcutaneous fat and skin of the flap; however, due to unpredictable anatomical variations, preoperative imaging of the donor site to select appropriate perforators has become routine. Preoperative imaging also reduces operating time and enhances the surgeon's confidence in choosing the appropriate donor site for harvesting flaps. Although computed tomography angiography has been widely used for preoperative imaging, concerns over excessive exposure to ionising radiation and poor iodinated contrast agent enhancement of the intramuscular perforator course has made magnetic resonance angiography, the first choice imaging modality in our centre. Magnetic resonance angiography with specific post-processing of the images has established itself as a reliable method for mapping tiny perforator vessels. Multiple donor sites can be imaged in a single setting without concern for ionising radiation exposure. This provides anatomical information of more reconstruction donor site options, so that a surgeon can design a flap of tissue centralised around the best perforator, as well as a back-up perforator, and even a back-up flap option located on a different region of the body. This information is especially helpful in patients with a history of scar tissue from previous surgeries, where the primary choice perforator is found to be damaged or unsuitable intraoperatively. In addition, chest magnetic resonance angiography evaluates recipient site blood vessel suitability including vessel diameters, course, and branching patterns. In this article we provide a broad overview of various skin flaps, clinical indications, advantages and disadvantages of each of these flaps, basic imaging technique, along with advanced sequences for visualising tiny arteries in the groin and in the chest. Post-processing techniques, structure of the report and how automation of the reporting system improves workflow is described. We also describe applications of magnetic resonance angiography in postoperative imaging.

Dendrites of medial olivocochlear neurons in mouse

Stains for acetylcholinesterase (AChE) and retrograde labeling with Fluorogold (FG) were used to study olivocochlear neurons and their dendritic patterns in mice. The two methods gave similar results for location and number of somata. The total number of medial olivocochlear (MOC) neurons in the ventral nucleus of the trapezoid body (VNTB) is about 170 per side. An additional dozen large olivocochlear neurons are located in the dorsal periolivary nucleus (DPO). Dendrites of all of these neurons are long and extend in all directions from the cell bodies, a pattern that contrasts with the sharp frequency tuning of their responses. For VNTB neurons, there were greater numbers of dendrites directed medially than laterally and those directed medially were longer (on average, 25-50% longer). Dendrite extensions were most pronounced for neurons located in the rostral portion of the VNTB. When each dendrite from a single neuron was represented as a vector, and all the vectors summed, the result was also skewed toward the medial direction. DPO neurons, however, had more symmetric dendrites that projected into more dorsal parts of the trapezoid body, suggesting that this small group of olivocochlear neurons has very different physiological properties. Dendrites of both types of neurons were somewhat elongated rostrally, about 20% longer than those directed caudally. These results can be interpreted as extensions of dendrites of olivocochlear neurons toward their synaptic inputs: medially to meet crossing fibers from the cochlear nucleus that are part of the MOC reflex pathway, and rostrally to meet descending inputs from higher centers.

A recombinant rat regenerating protein is mitogenic to pancreatic derived cells

Pancreatic regenerating protein (reg I) is expressed in acinar cells and is mitogenic to beta- and ductal cells. Isolation of large amounts of endogenous reg I for in vivo and in vitro experiments has been difficult. The aim of this study was to develop a recombinant protein and determine its bioactivity on rat pancreatic derived cells. cDNA of the rat reg I coding region was created with unique BamHI flanking sequences using reverse transcriptase PCR. The coding region was then cloned into a bacterial expression vector in which expression is controlled by a T7 promoter. After transformation into the Escherichia coli strain B21(DE3) and induction by isopropyl-beta-d-thiogalactopyranoside, a fusion protein of 24 kDa in size, named reg-PET, was noted in the bacterial lysate. This protein contained a polyhistidine and S-peptide sequence to facilitate isolation and identification, respectively. This protein was purified using affinity chromatography, and identity was confirmed with gel electrophoresis and Western analysis. The reg-PET protein was mitogenic to both ARIP and RIN cells, rat pancreatic ductal and beta-cell lines, respectively. Antibodies raised to the protein reacted against rat reg I in pancreas. The purified recombinant reg I fusion protein, like endogenous reg I, is mitogenic to pancreatic derived cells. It is more potent than reg I isolated from pancreatic tissue. This protein can be isolated rapidly, easily, and with a high amount of purity.

Seat belt injury presenting as bilateral abdominal wall herniations in a child

The constellation of abdominal injuries caused by seat belts in automobile accidents usually consists of intraabdominal solid organ and hollow viscus injuries. We present a two-and-one-half-year-old patient with an unusual constellation of seat belt injuries that presented as bilateral abdominal herniations. We feel that an abdominal hernia caused by a seat belt injury should alert the clinician to the probability of other severe intraabdominal injuries. The uniqueness of this case is compounded by the way in which the seat belt was misused.

Comparison of Multi-Test device skin testing and modified RAST results

The initial purpose of this study was to determine the potential correlation between allergy test results obtained with the Multi-Test skin testing method and the radioallergosorbent test (RAST) blood test (used as a "standard"). Twenty patients with a history and physical examination findings suggestive of inhalant allergy underwent both a Multi-Test system screen (14 antigens plus histamine and glycerine controls) and RAST testing. The relationship between wheal size and Multi-Test system grade for each antigen and the corresponding RAST class was studied. The correlation between positive Multi-Test system and RAST results was poor, with an average agreement by antigen of 56.26% and overall agreement of 67.86%. However, the overall agreement between negative Multi-Test system results (< or =1+) and negative RAST results (< or =class 1) was 95.15%, with an average agreement by antigen of 83.99%. On the basis of results of this preliminary study, it appears that a negative Multi-Test system result indicates that significant inhalant allergy is unlikely, whereas a positive Multi-Test system result necessitates follow-up with more definitive testing by additional skin testing or RAST.

Postnatal persistence of epidermoid rests in the human middle ear

It is widely believed that congenital cholesteatoma originates from epidermoid cell rests in the temporal bone. Congenital cholesteatomas of the anterior-superior middle ear may arise from such a rest, known as the epidermoid formation (EF), which has been described by Michaels and others. The EF is thought to disappear by 33 weeks' gestation in most cases; however, if it persists beyond fetal life, it may provide a nidus for cholesteatoma formation. The authors studied human temporal bones from individuals ranging from 20 weeks' gestation to 5 years of age to investigate pre- and postnatal occurrence of the EF. A total of 106 temporal bones were surveyed; 76 of these were fetal specimens and 30 were postnatal. EFs were present in 14 (18.4%) of the fetal specimens; they were identified in four (13.3%) of the postnatal temporal bones, with the oldest being 2 years, 7 months of age. Multiple EFs within a single temporal bone were also present in some cases. Although the EFs were composed of cells morphologically identical to those of the external ear canal epidermis, none of the specimens showed keratinization. These findings support the contention that EFs do occasionally persist into postnatal life and may be a source of cholesteatoma. However, a clear transition from epidermoid formation to unequivocal cholesteatoma has not yet been demonstrated.

Evaluation of patient, physician, nurse, and family attitudes toward do not resuscitate orders

We investigated attitudes toward resuscitation by interviewing 97 competent patients classified as do not resuscitate, 60 physicians, 80 family members, and 84 nurses. In addition, 58 family members of incompetent do not resuscitate patients were interviewed. Interview patients were generally elderly, female widows with a diagnosis of malignancy. The majority (66%) preferred that their medical decision making be shared with the physician and/or family. Only 38 patients (39%) could correctly define a "living will." After hearing the definition, 59 patients (61%) thought it was a good idea to ask noncritically ill patients at the time of hospital admission, if they had a living will. Fifty-six patients (58%) said they had discussed resuscitation with their physician, whereas 44 physicians (73%) said they had discussed it with the patient. Only 53 patients (55%) said that they thought their physician understood their wishes. Sixty-five patients (67%) wanted involvement in resuscitation decisions. Forty-eight patients (49%) offered "quality of life" reasons for not wanting to be resuscitated. Sixty-four patients (66%) did not think discussing resuscitation was cruel and insensitive. Eighteen physicians (30%) said they were uncomfortable discussing resuscitation with patients. We recommend introducing the topic of resuscitation early in the patient-physician relationship before diminished competency occurs.

Effect of cellular uncoupling by heptanol on conduction in infarcted myocardium

Experiments were performed in vitro on six normal thin ventricular epicardial tissue strips and 10 strips removed from the infarcted regions of dogs 21-60 days after experimental myocardial infarction. Conduction was evaluated by mapping activation sequences at 40-45 sites over an area of 1 x 2 cm during pacing at a basic cycle length of 2,000 msec. The amplitude and length of recorded electrograms were also determined at each site. After control recordings, heptanol, which increases gap junctional resistance, was added to the tissue bath at concentrations ranging between 0.2 and 1.0 mM. In contrast to its effect on normal tissues, heptanol caused 75 of 260 previously active sites in the infarcted tissues to become inactive. The affected sites were located in areas of very slow conduction and/or adjacent to areas of preexisting conduction block. In addition, heptanol decreased the length and degree of fractionation of electrograms recorded in slowly conducting regions of the infarcted tissues. The magnitude of the decrease in electrogram length following heptanol was related to the degree of electrogram abnormality during control as reflected in the ratio of electrogram length to amplitude. Heptanol shortened electrograms by causing local conduction block, which eliminated some components of the fractionated electrograms. In an additional eight epicardial strips removed from the infarcted region, 0.5 mM heptanol had only a slight effect (10.7% decrease) on the maximum rate of membrane depolarization. Thus, heptanol does not act primarily by way of depressing the fast inward current. We conclude from heptanol's effects on conduction and electrogram characteristics that slow and dissociated conduction in the infarcted region is due to an abnormality in gap junctional distribution between surviving cells and/or an abnormality in individual gap junctional function.

Cognitive therapy and pharmacotherapy for depression. Sustained improvement over one year

Seventy patients with nonbipolar affective disorder who completed a 12-week course of either cognitive therapy (CT), pharmacotherapy, CT plus active placebo, or CT plus pharmacotherapy were assessed one month, six months, and one year after termination of active treatment. Of the 44 patients who had originally responded to treatment, 16 relapsed as defined by reentry into treatment or by self-reported depression scores in the moderately depressed range. Twenty-eight patients remained well during the one-year follow-up. Patients with relatively high levels of remaining depressive symptoms on completion of treatment relapsed more often than those who had little or no residual depression. Further, at treatment termination, patients who relapsed had significantly higher scores on a measure of dysfunctional attitudes. Patients who had received CT (with or without tricyclic antidepressants) were less likely to relapse in the one-year follow-up period than patients who received pharmacotherapy.

Hypnosis and its effects on left and right hemisphere activity

Recent research suggests a relationship between hypnosis and the right cerebral hemisphere in man. With several major modifications in the 1978 study of Frumkin, Ripley, and Cox, the following hypothesis was investigated: Hypnosis creates a shift towards relatively greater left ear accuracy, suggesting greater participation of the right hemisphere during a trance. Two studies were undertaken with 36 right-handed male volunteers in each; 12 of low susceptibility to hypnosis, 12 of medium susceptibility, and 12 of high susceptibility. Study 1 investigated the affect hypnosis had on the processing of musical stimuli while Study 2 investigated its affects on verbal stimuli. Study 1 found that the more susceptible an individual was to hypnosis the greater the shift towards the left ear. Study 2 found no such relationship. Possible differences in stimulus characteristics which might have caused these different results were discussed.

Patient attrition in a comparative outcome study of depression. A follow-up report

Eighty-seven moderately to severely depressed psychiatric outpatients were randomly assigned to 12 weeks of cognitive therapy (n = 24), pharmacotherapy (n = 24), cognitive therapy plus pharmacotherapy (n = 22) or cognitive therapy plus active placebo (n = 17). Seventy patients completed the treatment protocol; 17 dropped out before the end of the treatment period. Completers and dropouts did not differ at pretreatment on demographic variables, measures of depression, cognitive functioning or social adjustment. Sixteen of the 17 patients who dropped out were followed up and interviewed to assess their clinical status and reasons for discontinuing treatment. Neither group remained depressed at follow-up. Practical matters and issues related to the type of treatment received seemed to contribute most to patients' decision to drop out. Patients assigned to the combination therapies were more likely to complete the research protocol than those assigned to single treatment modalities. These findings are discussed in terms of their implications for clinical practice and outcome research.

Performance of an eyetracker for office use

The design, construction and performance of an eyetracker is discussed. The device provides real-time signals giving the direction of a user's gaze, with a precision of 0.3 degrees of arc and an update time of 17 ms. It is usable by a wide range of subjects in normal office-type conditions.

Effect of anatomical location on prognosis in patients with clinical stage I melanoma

A study of the influence of the anatomical location of malignant melanoma on the prognosis of 971 patients with stage I disease disclosed specific high-, intermediate-, and low-risk sites. High-risk sites included scalp, mandibular area, midline of trunk (anterior and posterior), upper medial thighs, hands, feet (except the arches), popliteal fossae, and genitalia. The life-table-adjusted five-year disease-free survival was 54% in the high-risk locations, 79% in intermediate-risk locations, and 93% in low-risk sites. A Cox proportional hazards analysis demonstrated that the grouping of lesions by their anatomical risk location had prognostic value that was significant in a model of eight other known predictive variables (thickness, sex, age, type, level, mitotic index, ulceration, and presence of preexistent nevus). The results indicate that anatomical location of the primary melanoma is significantly associated with five-year disease-free survival.