Dual AV nodal non-reentrant tachycardia-induced cardiomyopathy.

Dual atrioventricular (AV) nodal non-reentrant tachycardia (DAVNNT) is rare phenomenon where dual AV nodal physiology allows a single P wave to conduct down both the slow and fast AV node extensions resulting in two ventricular beats. We present a case of DAVNNT manifest as incessant ventricular triplets resulting in tachycardia-inducted cardiomyopathy. We discuss the underlying electrophysiology for this rare phenomenon, how to diagnose this condition and the appropriate treatment for this syndrome.

Diagnosis and management of pharyngoesophageal stenosis: A comprehensive approach to prophylactic, endoscopic, and reconstructive treatment options.

BACKGROUND: Pharyngoesophageal stenosis (PES) is a serious complication that substantially impacts functional outcomes and quality of life (QOL) for up to a third of head and neck cancer patients who undergo radiotherapy. Dysphagia is often multifactorial in nature and is a devastating complication of treatment that impacts patients' QOL, general health and overall wellbeing. The authors detail the clinical presentation, risk factors, imaging characteristics, preventive measures, and multimodality treatment options for PES. METHODS: The authors present a comprehensive management algorithm for PES, including treatment by dilation, stenting, spray cryotherapy and dilation, and reconstructive treatment options utilizing different pedicled and free flaps. RESULTS: The authors advocate for a thorough assessment of the extent and degree of pharyngoesophageal involvement of PES to determine the optimal management strategy. CONCLUSIONS: The development of post treatment dysphagia requires appropriate imaging and biopsy, when indicated, to rule out the presence of persistent/recurrent cancer. Multidisciplinary management by a team of physicians well-versed in the range of diagnostic and therapeutic interventions available for PES is critical to its successful management.

Effect of Implantable vs Prolonged External Electrocardiographic Monitoring on Atrial Fibrillation Detection in Patients With Ischemic Stroke: The PER DIEM Randomized Clinical Trial.

Importance: The relative rates of detection of atrial fibrillation (AF) or atrial flutter from evaluating patients with prolonged electrocardiographic monitoring with an external loop recorder or implantable loop recorder after an ischemic stroke are unknown. Objective: To determine, in patients with a recent ischemic stroke, whether 12 months of implantable loop recorder monitoring detects more occurrences of AF compared with conventional external loop recorder monitoring for 30 days. Design, Setting, and Participants: Investigator-initiated, open-label, randomized clinical trial conducted at 2 university hospitals and 1 community hospital in Alberta, Canada, including 300 patients within 6 months of ischemic stroke and without known AF from May 2015 through November 2017; final follow-up was in December 2018. Interventions: Participants were randomly assigned 1:1 to prolonged electrocardiographic monitoring with either an implantable loop recorder (n = 150) or an external loop recorder (n = 150) with follow-up visits at 30 days, 6 months, and 12 months. Main Outcomes and Measures: The primary outcome was the development of definite AF or highly probable AF (adjudicated new AF lasting ≥2 minutes within 12 months of randomization). There were 8 prespecified secondary outcomes including time to event analysis of new AF, recurrent ischemic stroke, intracerebral hemorrhage, death, and device-related serious adverse events within 12 months. Results: Among the 300 patients who were randomized (median age, 64.1 years [interquartile range, 56.1 to 73.7 years]; 121 were women [40.3%]; and 66.3% had a stroke of undetermined etiology with a median CHA2DS2-VASc [congestive heart failure, hypertension, age ≥75 years, diabetes, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, sex category] score of 4 [interquartile range, 3 to 5]), 273 (91.0%) completed cardiac monitoring lasting 24 hours or longer and 259 (86.3%) completed both the assigned monitoring and 12-month follow-up visit. The primary outcome was observed in 15.3% (23/150) of patients in the implantable loop recorder group and 4.7% (7/150) of patients in the external loop recorder group (between-group difference, 10.7% [95% CI, 4.0% to 17.3%]; risk ratio, 3.29 [95% CI, 1.45 to 7.42]; P = .003). Of the 8 specified secondary outcomes, 6 were not significantly different. There were 5 patients (3.3%) in the implantable loop recorder group who had recurrent ischemic stroke vs 8 patients (5.3%) in the external loop recorder group (between-group difference, -2.0% [95% CI, -6.6% to 2.6%]), 1 (0.7%) vs 1 (0.7%), respectively, who had intracerebral hemorrhage (between-group difference, 0% [95% CI, -1.8% to 1.8%]), 3 (2.0%) vs 3 (2.0%) who died (between-group difference, 0% [95% CI, -3.2% to 3.2%]), and 1 (0.7%) vs 0 (0%) who had device-related serious adverse events. Conclusions and Relevance: Among patients with ischemic stroke and no prior evidence of AF, implantable electrocardiographic monitoring for 12 months, compared with prolonged external monitoring for 30 days, resulted in a significantly greater proportion of patients with AF detected over 12 months. Further research is needed to compare clinical outcomes associated with these monitoring strategies and relative cost-effectiveness. Trial Registration: ClinicalTrials.gov Identifier: NCT02428140.

Prevalence of undiagnosed atrial fibrillation in elderly individuals and potential cost-effectiveness of non-invasive ambulatory electrocardiographic screening: The ASSERT-III study.

BACKGROUND: In approximately 10% of patients with implanted pacemakers or defibrillators, previously unrecognized atrial fibrillation (AF) is detected within 3 months. It is unknown whether elderly patients without implanted devices have a similar prevalence of undiagnosed AF using non-invasive ECG monitoring, and if this approach to screening in this population is cost-effective. METHODS: Individuals ≥80 years old attending outpatient clinics without a history of AF and with hypertension and one additional risk factor underwent 30 days of continuous ECG monitoring with an option for an additional 30 days of monitoring if no AF was detected. The primary outcome was AF ≥ 6 min. Cost-effectiveness to prevent stroke was estimated using a Markov model based on observed AF detection rates and data from the published literature. RESULTS: Among 129 patients enrolled, 100 initiated monitoring for an average duration of 36 ±â€¯21 days. The proportion of patients that completed at least 30 days of monitoring was 59%. Average age was 84 ±â€¯3 years and mean CHA2DS2-VASc score was 4.5 ±â€¯1.2. AF ≥ 6 min was documented in 14%, ≥6 h in 8%, and ≥24 h in 3%. One week of monitoring costed $50,000 per quality-adjusted life-year-gained, 30 days and 60 days of monitoring costed $70,000 and $84,000, respectively. CONCLUSIONS: Continuous non-invasive ECG monitoring is feasible in elderly patients. Undiagnosed AF is present in many elderly individuals, with 1 in 7 having episodes lasting ≥6 min. One week of monitoring may be cost-effective for stroke prevention in this population.

The use of negative pressure wound therapy in the primary setting for high-risk head and neck surgery.

BACKGROUND: In head and neck surgery, dead space is typically managed by transferring a secondary pedicled flap or harvesting a larger composite flap with a muscular component. We demonstrate the novel use of prophylactic negative pressure wound therapy (NPWT) to obliterate dead space and reduce possible communication between the upper aerodigestive tract and the contents of the neck. METHODS: We present a single-institutional case series of five patients with high-risk head and neck cancer treated with NPWT after ablative and reconstructive surgery to eliminate dead space following surgical resection. RESULTS: All patients achieved successful wound closure following NPWT, which was applied in the secondary setting to combat infection in one patient and the primary setting to prophylactically eliminate dead space in four patients. CONCLUSION: NPWT can be used to treat unfilled dead space in the primary setting of head and neck ablative and reconstructive surgery and help to avoid wound healing problems as well as the need for secondary flap transfers.

Estimated stroke risk, yield, and number needed to screen for atrial fibrillation detected through single time screening: a multicountry patient-level meta-analysis of 141,220 screened individuals.

BACKGROUND: The precise age distribution and calculated stroke risk of screen-detected atrial fibrillation (AF) is not known. Therefore, it is not possible to determine the number needed to screen (NNS) to identify one treatable new AF case (NNS-Rx) (i.e., Class-1 oral anticoagulation [OAC] treatment recommendation) in each age stratum. If the NNS-Rx is known for each age stratum, precise cost-effectiveness and sensitivity simulations can be performed based on the age distribution of the population/region to be screened. Such calculations are required by national authorities and organisations responsible for health system budgets to determine the best age cutoffs for screening programs and decide whether programs of screening should be funded. Therefore, we aimed to determine the exact yield and calculated stroke-risk profile of screen-detected AF and NNS-Rx in 5-year age strata. METHODS AND FINDINGS: A systematic review of Medline, Pubmed, and Embase was performed (January 2007 to February 2018), and AF-SCREEN international collaboration members were contacted to identify additional studies. Twenty-four eligible studies were identified that performed a single time point screen for AF in a general ambulant population, including people ≥65 years. Authors from eligible studies were invited to collaborate and share patient-level data. Statistical analysis was performed using random effects logistic regression for AF detection rate, and Poisson regression modelling for CHA2DS2-VASc scores. Nineteen studies (14 countries from a mix of low- to middle- and high-income countries) collaborated, with 141,220 participants screened and 1,539 new AF cases. Pooled yield of screening was greater in males across all age strata. The age/sex-adjusted detection rate for screen-detected AF in ≥65-year-olds was 1.44% (95% CI, 1.13%-1.82%) and 0.41% (95% CI, 0.31%-0.53%) for <65-year-olds. New AF detection rate increased progressively with age from 0.34% (<60 years) to 2.73% (≥85 years). Neither the choice of screening methodology or device, the geographical region, nor the screening setting influenced the detection rate of AF. Mean CHA2DS2-VASc scores (n = 1,369) increased with age from 1.1 (<60 years) to 3.9 (≥85 years); 72% of ≥65 years had ≥1 additional stroke risk factor other than age/sex. All new AF ≥75 years and 66% between 65 and 74 years had a Class-1 OAC recommendation. The NNS-Rx is 83 for ≥65 years, 926 for 60-64 years; and 1,089 for <60 years. The main limitation of this study is there are insufficient data on sociodemographic variables of the populations and possible ascertainment biases to explain the variance in the samples. CONCLUSIONS: People with screen-detected AF are at elevated calculated stroke risk: above age 65, the majority have a Class-1 OAC recommendation for stroke prevention, and >70% have ≥1 additional stroke risk factor other than age/sex. Our data, based on the largest number of screen-detected AF collected to date, show the precise relationship between yield and estimated stroke risk profile with age, and strong dependence for NNS-RX on the age distribution of the population to be screened: essential information for precise cost-effectiveness calculations.

A novel radial forearm free flap design to treat pharyngoesophageal stenosis in combination with the posterior wall of the trachea.

Pharyngoesophageal stenosis (PES) is a common and serious complication of head and neck cancer treatments such as radiation therapy, chemotherapy, tracheoesophageal puncture placement, and total laryngectomy surgery. Dilation-resistant stenosis requires surgical reconstruction, often with a radial forearm free flap (RFFF). With the present technique, the authors refine their previous bipaddled free flap design used to reconstruct a persistent tracheoesophageal fistulae (TEF) in combination with PES. Accordingly, we present a novel bipaddled triangular RFFF design ideally suited to address the shape of the defect in the posterior tracheal wall that results when the TEF is opened and the esophageal and tracheal components are restored.

Screening for undiagnosed atrial fibrillation in the community.

PURPOSE OF REVIEW: Recent years have seen significant advances in knowledge about the prevalence of 'silent' atrial fibrillation and the morbidity associated with this condition. Data are emerging on improved strategies for screening, and new technologies for detecting atrial fibrillation are becoming available, making a review of this field timely. RECENT FINDINGS: Studies suggest that, when screening is performed, undiagnosed atrial fibrillation is present in around 1% of the screened population, rising to 1.4% for those aged at least 65 years. The prevalence of silent atrial fibrillation is even higher in patients with additional risk factors (e.g. those aged 75 years, patients with heart failure). Prolonged monitoring of patients with hypertension and an implanted cardiac device showed subclinical atrial arrhythmias in at least 10% and these patients had a 2.5-fold increased risk of stroke or systemic embolism. The feasibility of screening for silent atrial fibrillation has been demonstrated in a number of populations and many new technologies for atrial fibrillation detection exist, which could improve the efficiency and cost-effectiveness of this process. SUMMARY: Increased attention is being directed towards screening for silent atrial fibrillation and our 'toolbox' for detecting it is expanding. Whether this will translate into improved outcomes for patients remains to be proven.

Development of mycosis fungoides after bone marrow transplantation for chronic myeloid leukaemia: transmission from an allogeneic donor.

We report on a patient who developed donor-derived cutaneous T-cell lymphoma (CTCL) 4 years after successful treatment of chronic myeloid leukaemia with an allogeneic bone marrow transplant. The patient developed an eczematous rash unresponsive to topical therapy and immunosuppression. When CTCL was diagnosed in the recipient, his sibling donor had been attending his local dermatology unit with a maculosquamous rash, which proved subsequently to be mycosis fungoides. An identical pattern of donor and recipient clonality assessment and T-cell receptor gene sequencing indicated that the CTCL was probably transmitted in the bone marrow harvest. This suggests that CTCL cells circulate in the marrow at an early subclinical stage in this disease. This is the second case of donor-derived CTCL reported to date.

Rotator Cuff Tears Are Related to the Side Sleeping Position.

Purpose: To determine whether there was a relationship between sleep position and symptomatic partial- and full-thickness rotator cuff tears. Methods: A consecutive series of patients that met the inclusion/exclusion criteria (n = 58) were in seen in clinic between July 2019 and December 2019. All of these individuals had a significant partial-thickness (> 50%) or full-thickness rotator cuff tear determined by either ultrasound, magnetic resonance imaging, or both. All patients in this series either had an insidious onset of shoulder pain or their symptoms were related to the basic wear and tear of daily activities. Traumatic rotator cuff tears (those associated with a significant traumatic event such as shoulder instability, motor vehicle accidents, sports related injuries, etc.) were excluded. Previous shoulder surgery, recurrent rotator cuff tears, and worker's compensation cases also were excluded from this series. As part of the history-taking process, the patients were asked what was their preferred sleeping position-side sleeper, back sleeper, or stomach sleeper. A χ2 test was conducted to determine the relationship between rotator cuff pathology and sleep position. Results: Of the 58 subjects, 52 of the patients were side sleepers, 4 were stomach sleepers, 1 was a back sleeper, and 1 preferred all 3 positions. Statistical analysis, using the χ2 test (P < .0001), demonstrated that rotator cuff tears were most often seen in side sleepers. Conclusions: In our study, there appeared to be a relationship between the preference of being a side sleeper and the presence of a rotator cuff tear. Level of Evidence: Level IV, prognostic case series.

Assessing Postoperative Phosphate and Calcium/Phosphate Ratio as Surrogates for Parathyroid Hormone Following Total Thyroidectomy.

OBJECTIVE: Evaluate utility of postoperative phosphate and calcium/phosphate ratio (Ca/P) as surrogates for parathyroid hormone (PTH) following total thyroidectomy. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care hospital. METHODS: We retrospectively reviewed patients 18 years or older who underwent total thyroidectomy in a tertiary care hospital by a single surgeon from 2015 through 2021. Patients with incomplete data, pre-existing hypoparathyroidism, vitamin D deficiency, or renal failure were excluded. All patients had PTH drawn within 4 hours of surgery and serum calcium, albumin, and phosphate levels on postoperative Day 1. Corrected calcium was used to calculate a Ca/P. Receiver operating characteristic (ROC) curves were generated to compare phosphate level or Ca/P with PTH. Each possible surrogate was assessed relative to PTH cutoffs of less than 5, 10, 15, and 20 pg/mL. A good screening test was defined as having an area under the curve (AUC) greater than 0.8. RESULTS: A total of 185 patients underwent total thyroidectomy with 1 fellowship-trained otolaryngologist. Most patients were female (62%), median age 48 years. Most surgeries were performed for cancer (68%). Six (3.2%) patients required IV calcium supplementation and 2 (1.1%) required readmission for symptomatic hypocalcemia. ROC curves comparing phosphate and Ca/P to PTH at the listed cutoffs demonstrated AUC ranging from 0.55 to 0.66 and 0.61 to 0.79, respectively. None met the threshold for a good screening test. CONCLUSION: Postoperative phosphate and Ca/P ratio are not surrogates for PTH levels following total thyroidectomy. More research is needed to identify cost-effective strategies for postoperative calcium monitoring in patients undergoing total thyroidectomy. LEVEL OF EVIDENCE: Retrospective cohort study.

High-density mapping improves detection of conduction gaps after pulmonary vein isolation ablation with a circular mapping catheter.

BACKGROUND: High-density (HD) mapping of the pulmonary vein (PVs) has been hypothesized to improve the detection of conduction gaps in the radiofrequency ablation lesions set after pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). We aimed to compare the incidence of gaps after PVI with a standard 20-pole circumferential mapping catheter (CMC-20) and an HD mapping catheter (HD Grid). METHODS: This prospective study included patients scheduled for high-power short-duration PVI. Acute PVI was defined as an entrance and exit block using the CMC-20 after ≥ 20 min waiting period. The left atrium was then remapped using the HD Grid high-density mapping catheter to identify residual conduction gaps in the PVI lines by voltage and activation criteria. The primary endpoint was the number of gaps identified per patient by the HD Grid catheter. RESULTS: A total of 20 patients were included (mean age 59.9 ± 10.8 years, 15% female, 70% paroxysmal AF). The new map with the HD Grid identified 6 gaps in 4 patients (20%) or 0.3 ± 0.7 gaps per patient (p = 0.055 when compared to CMC-20). Five gaps (83%) were located at the right PVs. There was no difference in mapping time (CMC-20 12.2 ± 2.6 min vs HD Grid 11.7 ± 3.4 min, p = 0.452); however, the number of points was significantly higher in the HD Grid map (1662.7 ± 366.1 vs 1171.6 ± 313.6, p < 0.001). CONCLUSIONS: HD mapping during AF ablation identified PVI gaps in 1 out of 5 patients. Therefore, HD mapping may have the potential to improve AF ablation success rates in the long term. TRIAL REGISTRATION: ClinicalTrials.gov NCT04850508 on April 20, 2021.

Diagnostic pacing maneuvers for supraventricular tachycardias: part 2.

The approach to supraventricular tachycardia (SVT) diagnosis can be complex because it involves synthesizing baseline electrophysiologic features, features of the SVT, and the response(s) to pacing maneuvers. In this two-part review, we will mainly explore the latter while recognizing that neither of the former can be ignored, for they provide the context in which diagnostic pacing maneuvers must be correctly chosen and interpreted. Part 1 involved a detailed consideration of ventricular overdrive pacing, since this pacing maneuver provides the diagnosis in the majority of cases. In Part 2, other diagnostic pacing maneuvers that might be helpful when ventricular overdrive pacing is not diagnostic or appropriate, including attempts to reset SVT with single atrial or ventricular beats, para-Hisian pacing, apex versus base pacing, and atrial overdrive pacing, are discussed, as are some specific diagnostic SVT challenges encountered in the electrophysiology lab. There is considerable literature on this topic, and this review is by no means meant to be all-encompassing. Rather, we hope to clearly explain and illustrate the physiology, strengths, and weaknesses of what we consider to be the most important and commonly employed diagnostic pacing maneuvers, that is, those that trainees in cardiac electrophysiology should be well familiar with at a minimum.

Genomic Degeneration and Reduction in the Fish Pathogen Mycobacterium shottsii.

Mycobacterium shottsii is a dysgonic, nonpigmented mycobacterium originally isolated from diseased striped bass (Morone saxatilis) in the Chesapeake Bay, USA. Genomic analysis reveals that M. shottsii is a Mycobacterium ulcerans/Mycobacterium marinum clade (MuMC) member, but unlike the superficially similar M. pseudoshottsii, also isolated from striped bass, it is not an M. ulcerans ecovar, instead belonging to a transitional group of strains basal to proposed "Aronson" and "M" lineages. Although phylogenetically distinct from the human pathogen M. ulcerans, the M. shottsii genome shows parallel but nonhomologous genomic degeneration, including massive accumulation of pseudogenes accompanied by proliferation of unique insertion sequences (ISMysh01, ISMysh03), large-scale deletions, and genomic reorganization relative to typical M. marinum strains. Coupled with its observed ecological characteristics and loss of chromogenicity, the genomic structure of M. shottsii is suggestive of evolution toward a state of obligate pathogenicity, as observed for other Mycobacterium spp., including M. ulcerans, M. tuberculosis, and M. leprae. IMPORTANCE Morone saxatilis (striped bass) is an ecologically and economically important finfish species on the United States east coast. Mycobacterium shottsii and Mycobacterium pseudoshottsii were originally described in the early 2000s as novel species from outbreaks of visceral and dermal mycobacteriosis in this species. Biochemical and genetic characterization place these species within the Mycobacterium ulcerans/M. marinum clade (MuMC), and M. pseudoshottsii has been proposed as an ecovar of M. ulcerans. Here, we describe the complete genome of M. shottsii, demonstrating that it is clearly not an M. ulcerans ecovar; however, it has undergone parallel genomic modification suggestive of a transition to obligate pathogenicity. As in M. ulcerans, the M. shottsii genome demonstrates widespread pseudogene formation driven by proliferation of insertion sequences, as well as genomic reorganization. This work clarifies the phylogenetic position of M. shottsii relative to other MuMC members and provides insight into processes shaping its genomic structure.

Influence of Sex-Based Differences in Cardiac Phenotype on Atrial Fibrillation Recurrence in Patients Undergoing Pulmonary Vein Isolation.

Background: Pulmonary vein isolation (PVI) is a commonly engaged therapy for symptomatic atrial fibrillation (AF). Prior studies have documented elevated AF recurrence rates among females vs. males. Sex-specific mechanisms underlying this phenomenon are poorly understood. This prospective cohort study aimed to evaluate the sex-based differences in cardiac phenotype and their influence on (AF) recurrence following first-time PVI. Methods: A total of 204 consecutive patients referred for first-time PVI and 101 healthy subjects were prospectively studied by cardiovascular magnetic resonance (CMR) imaging. Multi-chamber volumetric and functional measures were assessed by sex-corrected Z-score analyses vs. healthy subjects. Patients were followed for a median of 2.6 years for the primary outcome of clinical AF recurrence. Multivariable analyses adjusting for age and comorbidities were performed to identify independent predictors of AF recurrence. Results: AF recurrence following first PVI occurred in 41% of males and 59% of females (p = 0.03). Females were older with higher prevalence of hypertension and thyroid disorders. Z-score-based analyses revealed significantly reduced ventricular volumes, greater left atrial (LA) volumes, and reduced LA contractility in females vs. males. Multivariable analysis revealed each of LA minimum and pre-systolic volumes and booster EF Z-scores to be independently associated with AF recurrence, providing respective hazard ratios of 1.10, 1.19, and 0.89 (p = 0.001, 0.03, and 0.01). Conclusion: Among patients referred for first time PVI, females were older and demonstrated significantly poorer LA contractile health vs. males, the latter independently associated with AF recurrence. Assessment of LA contractile health may therefore be of value to identify female patients at elevated risk of AF recurrence. Factors influencing female patient referral for PVI at more advanced stages of atrial disease warrant focused investigation.

Novel technique to prevent or correct open-mouth deformity after bilateral mandibular resection: Use of tensor fascia lata slings.

Open-mouth deformity after mandibular resection presents a challenge for surgeons and patients, contributing to significant functional and cosmetic morbidity. We present an innovative surgical technique to prevent or correct open-mouth deformity. Tensor fascia lata slings were utilized in combination with maxillomandibular fixation to surgically correct or prevent open-mouth deformity in four patients who had previously undergone mandibulectomy or at the time of a contralateral mandibulectomy following prior hemimandibulectomy and reconstruction. Two patients achieved favorable outcomes, including oral competence and improved resting jaw position, while open-mouth deformity could not be corrected for one patient. Another patient remains in the early postoperative period following a secondary procedure to correct open-mouth deformity. Open-mouth deformity is a functional/aesthetic problem that has not been addressed in the literature. Use of tensor fascia lata slings to suspend the mandible is a novel approach to the surgical management of open-mouth deformity.

Diagnostic pacing maneuvers for supraventricular tachycardia: part 1.

This two-part manuscript reviews diagnostic pacing maneuvers for supraventricular tachycardia (SVT). Part one will involve a detailed consideration of ventricular overdrive pacing (VOP), since this pacing maneuver provides the diagnosis in the majority of cases. This will include a review of the post-VOP response, fusion during entrainment, the importance of the VOP site, quantitative results of entrainment such as the postpacing interval, differential entrainment, and new criteria derived from features found at the beginning of the VOP train. There is a considerable literature on this topic, and this review is by no means meant to be all-encompassing. Rather, we hope to clearly explain and illustrate the physiology, strengths, and weaknesses of what we consider to be the most important and commonly employed diagnostic pacing maneuvers, that is, those that trainees in cardiac electrophysiology should be well familiar with at a minimum. \

Maxillary anterior tooth dimensions and proportions in an Irish young adult population.

This study was undertaken in a young Irish population to determine the dimensions and ratios of the six maxillary anterior teeth. One hundred and nine Irish subjects (age 18-25 inclusive) had irreversible hydrocolloid impressions made of their maxillary dentition poured in type V stone. Clinical crown dimensions were measured with a digital calliper. The stone casts were digitally photographed in a standardised manner enabling calculation of various ratios between the maxillary anterior teeth. Sexual dimorphism existed for various tooth dimensions; most notably canine teeth were in the region of 0·8 mm longer and 0·6 mm wider in males. Central and lateral incisors were found to be 0·5 mm wider in males. It is, therefore, recommended that dimensional tooth guidelines should be given for each of the sexes and not on a population basis. With regard to tooth proportion ratios, no significant differences were found between genders or the left and right sides for any of the measurements or ratios measured. The digitally recorded tooth proportions were similar for both sexes, and the Golden Proportion guidelines could only be applied to the lateral incisor/central incisor widths (0·618). Identified width proportions for the canine/central incisor were 0·58 and for canine/lateral incisor 0·89.