Important Anatomical Factors Research Articles

Association between fat and fat-free body mass indices on shock attenuation during running

High amplitudes of shock during running have been thought to be associated with an increased injury risk. This study aimed to quantify the association between dual-energy X-ray absorptiometry (DEXA) quantified body composition, and shock attenuation across the time and frequency domains. Twenty-four active adults participated. A DEXA scan was performed to quantify the fat and fat-free mass of the whole-body, trunk, dominant leg, and viscera. Linear accelerations at the tibia, pelvis, and head were collected whilst participants ran on a treadmill at a fixed dimensionless speed 1.00 Fr. Shock attenuation indices in the time- and frequency-domain (lower frequencies: 3–8 Hz; higher frequencies: 9–20 Hz) were calculated. Pearson correlation analysis was performed for all combinations of DEXA and attenuation indices. Regularised regression was performed to predict shock attenuation indices using DEXA variables. A greater power attenuation between the head and pelvis within the higher frequency range was associated with a greater trunk fat-free mass (r = 0.411, p = 0.046), leg fat-free mass (r = 0.524, p = 0.009), and whole-body fat-free mass (r = 0.480, p = 0.018). For power attenuation of the high-frequency component between the pelvis and head, the strongest predictor was visceral fat mass (β = 48.79). Passive and active tissues could represent important anatomical factors aiding in shock attenuation during running. Depending on the type and location of these masses, an increase in mass may benefit injury risk reduction. Also, our findings could implicate the injury risk potential during weight loss programs.

Correlation between sagittal morphology of lower lumbar end plate and degenerative changes in patients with lumbar disc herniation.

As an important anatomic factor in the process of lumbar disc herniation (LDH), the correlation between end plate sagittal morphology and intervertebral disc degeneration (IDD) is unclear. Moreover, research on imaging data of lumbar end plate in patients with LDH is still insufficient. Our study aimed to observe the morphological change of the lower lumbar end plate (L3-S1) in patients with LDH on magnetic resonance imaging (MRI) and analyze its correlation with the degree of IDD. A total of 116 patients were included in the study. Based on their MRI, we divided end plates into three types (concave, flat, and irregular), assigned intervertebral discs with Grade I-V given 1-5 points successively according to the Pfirrmann system, and determined whether there was Modic change of each end plate. The correlation between the morphology of the end plate and the degree of IDD was analyzed. There was an excellent interobserver agreement for each item we analyzed (interclass correlation coefficient >0.75). Concave end plate appeared most frequently (187, 53.7%) and was mainly distributed in L3/4 and L4/5, whereas irregular end plate was the least common type (54, 15.5%) and mainly concentrated in L5/S1. The IDD degree of the corresponding disc increased gradually from concave (3.27 ± 0.81) to irregular end plates (4.25 ± 0.79) (P < 0.05). Irregular end plates were more likely to have Modic changes than concave and flat end plates (P < 0.05). The sagittal morphology of the lower lumbar end plate is related to modic changes and degree of IDD (based on the Pfirrmann grading system) in patients with LDH, and the concave end plate mostly reflects a lower degree of lumbar disc degeneration, which has substantial clinical significance.

C-Arm Guidance During Thin Flap Arthroscopic Trochleoplasty for Chronic Patellar Instability

The purpose of this paper is to provide a complete Technical Note for our treatment of choice for recurrent patellar dislocation in cases of trochlear dysplasia, especially in patients with types B and D trochlear dysplasia according to the Dejour classification. Different surgical procedures have been reported for the treatment of recurrent patellar instability. One of the most important anatomic factors to address when treating a recurrent patella dislocation is trochlear dysplasia. Few types of open trochleoplasty have been classically described to treat a dysplastic trochlea. However, in recent years, arthroscopic techniques have been reported to reduce invasiveness and complications as well as to improve accuracy and clinical outcomes. In this technique is described an arthroscopic thin-flap tracheoplasty with the use of C-arm guidance in order to precisely control the bone resection and to verify intraoperatively the disappearance of the radiologic landmarks used for diagnosis and classification of the dysplasia. The advantage of this technique is the precision in removal of the supratrochlear spur and bump, the accurate and delicate reshaping of the sulcus with preservation of cartilage vitality, combined with increased reproducibility and safety.

Orthodontic and Facial Characteristics of Craniofacial Syndromic Children with Obstructive Sleep Apnea.

Introduction: Obstructive sleep apnea (OSA) is a disorder in which ventilation becomes disrupted due to a complete or partial upper airway obstruction Altered craniofacial morphology is one of the most important anatomical factors associated with obstructive sleep apnea (OSA). Studies have assessed craniofacial features in the non-syndromic pediatric population. The aim of this study was to analyze the orthodontic and facial characteristic of craniofacial syndromic children referred for polysomnography (PSG) and to assess the correlation with the apnea-hypopnea index (AHI). Methods: In the current cross-sectional study, consecutive syndromic patients referred for PSG were invited to participate. A systematic clinical examination including extra- and intra-oral orthodontic examination was performed by calibrated orthodontists. Standardized frontal and profile photographs with reference points were taken and analyzed using ImageJ® software to study the craniofacial morphology. PSG data were analyzed for correlation with craniofacial features. STROBE guidelines were strictly adopted during the research presentation. Results: The sample included 52 syndromic patients (50% females, mean age 9.38 ± 3.36 years) diagnosed with 17 different syndromes, of which 24 patients had craniofacial photography analysis carried out. Most of the sample (40%) had severe OSA, while only 5.8% had no OSA. Down's syndrome (DS) was the most common syndrome (40%) followed by Goldenhar syndrome (5%), Pierre Robin Sequence (5%), and other syndromes. The severity of AHI was significantly correlated with decreased midfacial height. increased thyromental angle and cervicomental angle, decreased mandibular angle, and decreased upper facial height. All patients with DS were diagnosed with OSA (57% severe OSA), and their ODI was significantly correlated with increased intercanthal distance. Obesity was not correlated to the severity of AHI for syndromic patients. Conclusions: Decreased midfacial height and obtuse thyromental angle were correlated with increased AHI for syndromic patients. Increased intercanthal distance of DS patients could be a major predictor of OSA severity. Obesity does not seem to play a major role in the severity of OSA for syndromic patients. Further studies with larger samples are necessary to confirm these findings.

Novel Risk Score Calculator for Perioperative Mortality after EVAR with Incorporation of Anatomical Factors

Hostile proximal aortic neck anatomy has been associated with increased risk of perioperative mortality after endovascular aneurysm repair (EVAR). However, all available mortality risk prediction models after EVAR lack neck anatomic associations. The aim of this study is to develop a preoperative prediction model for perioperative mortality after EVAR incorporating important anatomic factors. Data were obtained from the Vascular Quality Initiative database on all patients who underwent elective EVAR between January 2015 and December 2018. Stepwise multivariable logistic regression analysis was implemented to identify independent predictors and develop a risk calculator for perioperative mortality after EVAR. Internal validation was done using bootstrap of 1000 reps. A total of 25,133 patients were included, of whom 1.1% (N=271) died within 30 days or before discharge. Significant preoperative predictors of perioperative mortality were age (odds ratio [OR], 1.053; 95% CI, 1.050-1.056; P<.001), female sex (OR, 1.46; 95% CI, 1.38-1.54; P<.001), chronic kidney disease (OR, 1.65; 95% CI, 1.57-1.73; P<.001), chronic obstructive pulmonary disease (OR, 1.86; 95% CI, 1.77-1.94; P<.001), congestive heart failure (OR, 2.02; 95% CI, 1.91-2.13, P<.001), aneurysm diameter ≥ 6.5cm (OR, 2.35; 95% CI, 2.24-2.47, P<.001), proximal neck length< 10mm (OR, 1.96; 95% CI, 1.81-2.12; P<.001), proximal neck diameter ≥30mm (OR, 1.41; 95% CI, 1.32-1.5; P<.001), infrarenal neck angulation ≥60° (OR, 1.27; 95% CI, 1.18-1.26; P<.001) and suprarenal neck angulation ≥60° (OR, 1.26; 95% CI, 1.16-1.37; P<.001). Significant protective factors included aspirin use (OR, 0.89; 95% CI, 0.85-0.93; P<.001) and statin intake (OR, 0.77; 95% CI, 0.73-0.81; P<.001), These predictors were incorporated to build an interactive risk calculator of perioperative mortality after EVAR (C-statistic=0.749) CONCLUSION: This study provides a prediction model for mortality following EVAR that incorporates aortic neck features. The risk calculator can be used to weigh risk/benefit ratio when counseling patients preoperatively. Prospective use of this risk calculator may show its benefit in long-term prediction of adverse outcomes.

Palatoradicular groove and periodontal disease- A case report

Palatoradicular groove is an important anatomic factor that presents accessibility problems and worsens the prognosis of periodontal disease. Palato-radicular groove is a rare developmental anomaly with prevalence rate of 2.8-8.5%. Most commonly affected tooth is the maxillary lateral incisor (93.8%). Palatoradicular groove may present as a radiolucent para pulpal line, radiographically. Treatment of radicular groove presents a clinical challenge to the operator. Removal of local predisposing factor is of prime importance. This case report presents the management of the periodontal defect associated with palatoradicular groove incorporating periodontal flap surgery with bone graft and GTR.

Age-Related Changes in the Anatomy of the Triangle of Koch: Implications for Catheter Ablation of Atrioventricular Nodal Re-entry Tachycardia

BackgroundAtrioventricular nodal re-entrant tachycardia is the most common type of paroxysmal supraventricular tachycardia. We sought to assess whether important anatomic factors, such as the location of the slow pathway, proximity to the bundle of His, and coronary sinus ostium dimensions, varied with patient age, and whether these factors had an impact on procedural duration, acute success, and complications. MethodsBaseline demographic and procedural data were collected, and the maps were analyzed. Linear regression models were performed to evaluate the associations between age and these anatomic variations. Associations were also assessed, with age categorized as being ≥ 60 years or < 60 years. ResultsThe slow pathway was more commonly located in a superior location relative to the coronary sinus ostium in older patients. The location of the slow pathway moved in a superior direction by 1 mm for every increase in 2 years from the mean estimate of age. Additionally the slow pathway tended to be closer to the coronary sinus ostium in older patients, and the diameter of the ostium was larger in older patients. This resulted in longer procedure time, longer ablation times, and a greater need for long sheaths for stability. ConclusionsThe location of the slow pathway becomes more superior and closer to the coronary sinus ostium with increasing age. Additionally, the coronary sinus diameter increases with age. These factors result in longer ablation and procedural times in older patients.

The Association Between Rotator Cuff Muscle Fatty Infiltration and Glenoid Morphology in Glenohumeral Osteoarthritis

Glenoid morphology and rotator cuff muscle quality are important anatomic factors that can impact longevity of the glenoid component following total shoulder arthroplasty (TSA). We hypothesized that rotator cuff muscle fatty infiltration is associated with increased pathologic glenoid bone loss in glenohumeral osteoarthritis (OA). We retrospectively reviewed 190 preoperative computed tomography (CT) scans of 175 patients (mean age, 66 years; range, 44 to 90 years) who underwent TSA for the treatment of primary glenohumeral OA. Two-dimensional orthogonal CT images were reformatted in the plane of the scapula from 3-dimensional images. Pathologic joint-line medialization was defined with use of the glenoid vault model. Pathologic glenoid version was measured directly. Glenoid morphology was graded according to a modified Walch classification (subtypes A1, A2, B1, B2, B3, C1, and C2). Rotator cuff muscle fatty infiltration was assessed and assigned a Goutallier score on the sagittal CT slice just medial to the spinoglenoid notch for each muscle. There was a significant difference in the Goutallier score for the supraspinatus, infraspinatus, and teres minor muscles between Walch subtypes (p ≤ 0.05). High-grade posterior rotator cuff muscle fatty infiltration was present in 55% (21) of 38 B3 glenoids compared with 8% (3) of 39 A1 glenoids. Increasing joint-line medialization was associated with increasing fatty infiltration of all rotator cuff muscles (p ≤ 0.05). Higher fatty infiltration of the infraspinatus, teres minor, and combined posterior rotator cuff muscles was associated with increasing glenoid retroversion (p ≤ 0.05). After controlling for joint-line medialization and retroversion, B3 glenoids were more likely to have fatty infiltration of the supraspinatus and infraspinatus muscles than B2 glenoids were. High-grade rotator cuff muscle fatty infiltration is associated with B3 glenoids, increased pathologic glenoid retroversion, and increased joint-line medialization. Additional studies are needed to determine the causal relationship between these muscle changes and glenoid wear, whether these muscle changes independently affect clinical and radiographic outcomes in anatomic TSA, and whether fatty infiltration can improve postoperatively with correction of pathologic version and/or joint-line restoration. This study investigates the association between different patterns of glenoid bone loss and rotator cuff muscle fatty infiltration. Both factors have been shown to affect clinical outcome following TSA.

Using skin and fascial sheath of preputial sac; A new technique for surgery for congenital buried penis

Congenital buried penis (CBP) is a rare condition characterized by penis with normal length obscured under penopubic and penoscrotal skin and subcutaneous tissue. Though rare, this condition causes great parental anxiety because of abnormal shape and appearance of penis, dribbling of urine and poor hygiene. Abnormal distal attachment of fundiform ligament on penile shaft, large, redundant preputial sac, and severe paucity of nonpigmented penile skin are important anatomical factors responsible for CBP. We here describe a different approach for degloving of penis and achieving penile skin cover using skin and fascial sheath of preputial sac. This method is simple and easy to learn, teach and reproduce.

The anatomic study and clinical application of the premasseter space

Through the anatomy study of the premasseter space, further improved the anatomic knowledge of the premasseter space and explored its application in rhytidectomy, in order to reduce the risk of facial nerve injury. To further improve the anatomic knowledge of the premasseter space and to determine its application in rhytidectomy. The anatomy of the premasseter region was investigated in 12 fresh cadaver (24 hemi-faces) dissections;810 patients of SMAS rhytidectomy procedures were observed. ①There were several soft tissue spaces superficial to the masseter muscle, and the boundaries were strengthened by retaining ligaments. Adjacent spaces were separated by numerous weak fiber membranes connecting the SMAS and masseter fascia.② The space was further divided into two parts; one part was located under the platysma and another part was under the aponeurosis of SMAS. The former part was easier to identify and dissect. ③ The relaxation, expansion, and sliding of the space is an important reason in the face sags with aging, which is referred to as the layered ptosis theory. The soft tissue space superficial to the masseter muscle have two different characteristics. The different nature of the two parts of the space can easily mislead dissection to the wrong layer, which is the important anatomical factors for the risk of facial nerve damage in rhytidectomy. The layered ptosis theory seem to better explain the process of aging. The primary treatment of aged face was facial space dissection and tighten.

Cardiac Assist Devices and Hemodialysis Catheter Procedures - What Do the Nephrologists Need to Know?

The use of ventricular assist devices (VAD) and total artificial heart (TAH) is increasing rapidly, and a large proportion of these device recipients already have or will develop severe renal dysfunction at the time of device implantation. As a consequence, nephrologists are becoming more and more involved in the care of this challenging population. As nephrologists take upon themselves many aspects of dialysis vascular access care, they need to be familiar with the special circumstances of performing hemodialysis catheter procedures in these patients. This review describes the important characteristics of these devices that have serious implications for the technique of placing or replacing dialysis catheters. These implications apply for both tunneled and nontunneled dialysis catheters and so concern all nephrologists, not only the interventionalists. We describe the important anatomical factors, anticoagulation management, device management, vascular access management and technical considerations of placing or replacing tunneled and nontunneled hemodialysis catheters from the perspective of a nephrologist establishing and maintaining lifesaving dialysis vascular access. Without a good understanding of these devices, serious consequences such as VAD rotor damage or blockage, or artificial heart valve blockage or damage can occur. These artificial devices are lifesaving, and any such complication is unacceptable. This review describes steps to minimize the risks.

Submental Ultrasound Measurement of Dynamic Tongue Base Thickness in Patients with Obstructive Sleep Apnea

Dynamic tongue base thickness (TBT) may be an important anatomic factor in airway narrowing in patients with obstructive sleep apnea (OSA). The development of an accurate clinical assessment of the retroglossal airway in patients with OSA is still evolving. Submental ultrasound was used to investigate the association between measurements of TBT in response to negative airway pressure and the existence of OSA. Twenty OSA patients and 20 control participants underwent ultrasound measurement of TBT on eupneic breathing and with the Mueller maneuver, as well as clinical and polysomnographic assessments. Logistic regression analyses indicated that after adjustment for confounding factors, independent predictors of OSA included TBT in response to negative airway pressure, as measured by submental ultrasound with the Mueller maneuver (odds ratio: 2.11, 95% confidence interval: 1.15–3.87, p < 0.05), and the difference between TBT with the Muller maneuver and that without the Mueller maneuver (odds ratio: 2.47, 95% confidence interval: 1.09–5.58, p < 0.05). Ultrasound measurement of TBT during the Mueller maneuver provides a quantitative assessment of the retroglossal airway in OSA patients with minimal invasiveness and easy accessibility.

Renal Denervation – A Flight of Icarus?

Since its introduction in 2008 Renal Denervation (RDN) has garnered enthusiasts among physicians, patients and the medical device industry. In December 2013 a research and consulting firm predicted a growth of the global renal denervation market in the next 6 years from approximately 3,000 procedures in 2012 up to nearly 40,000 by 2019 (representing a value of over $170 million). Even though the optimism was toned down after 5 years of trial applications of RDN (initial expectations mentioned a market on the order of a billion dollars by 2020), the hype surrounding this invasive therapy method for patients with treatment-resistant hypertension was still on the rise. This all changed in January 2014 when Medtronic announced that its pivotal SYMPLICITY HTN-3 trial failed to meet its primary efficacy endpoint. After promising data obtained from SYMPLICITY HTN-2 Medtronic’s this next trial, that included a sham-control group, was supposed to strengthen the position of RDN as an emerging leading therapy in patients with treatment resistant hypertension. Putting aside the discussions about the necessity and usefulness of a control sham treatment (according to some experts the pain caused in a number of patients by denervation reduced the validity of blinding) and differences between using ambulatory BP monitoring, home electronic BP monitoring and repeated office electronic measurement as an endpoint, SYMPLICITY HTN-3’s failure has been widely received as a major blow to the potential future worldwide deployment of RDN in the treatment of hypertension. SYMPLICITY HTN 4, HTN-India und HTN-Japan trials have been consequently called off, while previously, at the end of 2013, the EnligHTN II trial was stopped (apparently due to recruitment difficulties). Many have spelled the demise of RDN at this point even though the actual data from the SYMPLICITY HTN-3 trial still needs to be fully analysed. Some are trying to look at the bright side of recent developments now is the time to take a step back and analyse the underlying principle of this treatment method – interruption of signal transmission in the renal sympathetic nervous system. There are still some contradictory views on the longitudinal distribution of renal sympathetic nerves along renal arteries which may affect the currently advised course of RDN procedure (distal to proximal) [1]. Furthermore the radial distribution of nerves in renal artery walls, which seems to be the most important anatomic factor for intravascular RDN, has only been studied in small groups both in animal models and human cadavers [1-3]. It is widely accepted that most (up to 90%) nerves are situated within 2 mm of the lumen-intima interface [2,3]. To obtain a successful result an ablation depth of 4 mm is targeted but it is well known that some ablation related changes might extend to a depth of up to 6 mm [4], thus introducing a potential risk of irreversible injury to the artery itself. Dissections and vasospasm during ablation have been reported and well documented but there are some new reports of delayed renal artery stenosis related to RDN [5,6]. Templin et al used Optical Coherence Tomography (OCT) to document wall oedema after RDN Procedures but they have also admitted to a limitation of their results as a consequence of limited imaging depth of OCT (0.5 to 2.0 mm) [7]. In vivo monitoring of acute RDN related changes in arterial walls remains challenging. In conclusion transcatheter renal radiofrequency ablation is still not yet ready to be widely introduced into clinical practice and must be further investigated. On the other hand different methods of RDN might come into limelight, such as an intravascular ultrasound based technique, chemical trancatheter denervation with ethanol, MR-based or CT-based perirenal denevation with ethanol or an extracorporal high-intensity focused ultrasound. Despite many concerns, the future of RDN seems to be bright.

Vertebral body integrity: a review of various anatomical factors involved in the lumbar region

The body of the vertebra can be affected in the majority of the conditions involving the lumbar spine. Multiple references, both books and periodicals, have been reviewed, and the anatomical factors responsible for the vertebral body integrity in the lumbar spine have been included under the following important areas, namely, morphology, development, genetics, microscopic examination using histology, structural architecture, blood supply, neuromuscular control, and biomechanics. The anatomy provides a three-dimensional frame work to support the interaction between the physiological and pathological alterations. The body of the vertebra can be affected in a majority of acute or chronic conditions involving the lumbar spine. The etiology of these conditions is multifactorial, which has been dealt with in previous studies sporadically. This study aims to review and incorporate the important anatomical factors which can influence the integrity of vertebral bodies in the lumbar region and manifest as low back pain. Multiple references, both books and periodicals, have been reviewed for the literature. Electronic databases, including Medline and PubMed, were used to collect the latest information. They were finally arranged in an anatomical framework for the article. An attempt has been made to cover these relevant issues in an integrated way in the article and have been structured into introduction, morphology, development, genetics, microscopic examination using histology, structural architecture, blood supply, neuromuscular control, biomechanics, and conclusion. The aforementioned anatomical aspects, some of which have received less attention in the literature, may be helpful to clinicians for restoring the mobility, stability, and load bearing capacity of the lumbar spine as well as planning better management strategies, especially for the chronic low back pain. In our article all the anatomical factors affecting the integrity of vertebral body, including the morphology, development, genetics, growth and ossification, blood supply, specifically in the lumbar region, have been described, which were not covered earlier. The limitations of this review is its wide dimensions; hence, there are fair scopes of missing many relevant facts, as all of them cannot be compiled in a single article. We have attempted to confine our views to different anatomical domains only, this is our second limitation. Additional studies are required to incorporate and discuss the uncovered relevant scientific details. The integrity of the body of the lumbar vertebra is multifactorial (Fig. 8). The vast spectrum of the anatomical domain influencing it has been summarized. The evolution of erect posture is a landmark in the morphology of human beings and the lumbar lordosis, which has also contributed to the gross design of the vertebral body, is one of the most important adaptations for axial loading and bipedal movements. The role of metamerism in the evolution of vertebrate morphology is repeated in the development of spine. The body of the vertebra is intersegmental in origin, which results in dual vascular and nerve supply, both from superior and inferior aspects of the body of the lumbar vertebrae. The vertebral body ossifies from three primary centers, one for centrum, which will form the major portion of body, and the other two for neural arches. The cartilaginous growth plate is mainly responsible for the longitudinal vertebral growth. Regional differentiation of the vertebral column, and the definite pattern of the structure of the different vertebra, is regulated by a large number of genetic factors, including the Hox genes. The vertebral body design therefore provides the requirements for optimal load transfer by maximal strength with minimal weight. Bone mineral density (BMD), bone quality, microarchitecture, and material properties are the important factors that contribute to bone strength. BMD is highly heritable; bone mineral distribution and architecture are also shown to be under strong genetic influence. All the aforementioned factors finally integrate to ensure mainly the mobility, stability, and load bearing capacity of the lumbar spine.

Isolated deep peroneal (fibular) nerve palsy in association with primary total hip arthroplasty

We present two patients suffering isolated deep peroneal (fibular) nerve (DPN) palsies post primary total hip arthroplasty. The consistent factor in both patients was difficulty with initial dislocation and subsequent relocation. Both developed immediate isolated DPN palsies, with loss of dorsiflexion and paraesthesia over the first web space. The superficial peroneal nerve was intact in both. Despite intensive physiotherapy neither patient regained a return to pre-morbid motor or sensory function. Common peroneal nerve (CPN) palsy is common than due to a number of important anatomical factors. It is thought that the deep and superficial branches of this nerve also exist as discrete fascicles and these same factors make the deep division more frequently affected. Recovery is prolonged and incomplete despite intensive physiotherapy, thus putting emphasis on prevention.

Esophageal Temperature During Radiofrequency‐Catheter Ablation of Left Atrium: A Three‐Dimensional Computer Modeling Study

There is current interest in finding a way to minimize thermal injury in the esophagus during radiofrequency-catheter ablation of the left atrium. Despite the fact that the esophageal temperature is now being monitored during ablation, the influence of different anatomic and technical factors on the temperature rise remains unknown. We implemented a three-dimensional computational model that included atrial tissue, epicardial fat, esophagus, aorta, and lung, all linked by connective tissue. The finite-element method was used to calculate the esophageal temperature distribution during a procedure of constant-temperature ablation with an 8-mm electrode, under different tissue conditions. Results showed that the distance between electrode and esophagus was the most important anatomic factor in predicting the esophageal temperature rise, the composition of the different tissues being of lesser importance. The measurement of the esophageal temperature in different sites of the lumen offered differences up to 3.7 degrees C, especially for a short electrode-esophagus distance (5 mm). The difference in the convective cooling by circulating blood around electrode and endocardium did not show a significant influence on the esophageal temperature rise. Computer results suggest that (1) the electrode-esophagus distance is the most important anatomic factor; (2) the incorrect positioning of an esophageal temperature probe could give a low reading for the maximum temperature reached in the esophagus; and (3) the different cooling effect of the circulating blood flow at different atrial sites has little impact on the esophageal temperature rise.

The Anatomic Matrix as a Factor in Susceptibility to Lethal Arrhythmias in a Canine Model of Sudden Cardiac Death

In a previously reported canine model of sudden cardiac death, its authors heavily weighted the role of the autonomic nervous system in determining whether or not a combined stress of submaximal exercise and ischemia would produced a fatal arrhythmia the setting of a healed anterior wall myocardial infarction. This morphologic study of that model reveals that anatomic factors are also relevant to vulnerability to sudden death: dogs who developed ventricular fibrillation in response to such a stress (susceptible) had significantly more of the left ventricle (LV) infarcted than dogs who survived the stress (resistant): 13.14% (± 2.67 S.E.M) as compared with 4.01% (± 2.11 S.E.M.). Moreover, areas of fibrosis were spread more widely throughout the ventricle and septum in susceptible as compared with resistant animals, which consistently showed more homogeneous areas of infarct largely confined to the apical portion of the LV. While the autonomic nervous system may well be relevant to survival to stress in an animal which has survived a myocardial infarction, we conclude that there are important anatomic factors which determine vulnerability.

THE ROLE OF UPPER AIRWAY ANATOMY AND PHYSIOLOGY IN OBSTRUCTIVE SLEEP APNEA

Research efforts to date have determined that both anatomic and physiologic variables may contribute to the pathophysiology of OSA. Whether specific factors within either of these two categories will be shown to predominate remains to be seen. Surely, experience with sleep apnea patients teaches us that different variables are important in different OSA patients. However, even those patients who initially appear to have predominantly an anatomic or physiologic cause of their OSA often fail to respond to specific treatment. Treatment failure implies the following: (1) The initial impression of the importance of a given variable was wrong. This may happen in the patient who has a narrow transpalatal airway and fails to respond to uvulopalatopharyngoplasty. In this individual, physiologic variables such as pharyngeal collapsibility or periodic breathing may need to be addressed. Of course, the reverse may occur; patients may be treated pharmacologically for an assumed physiologic mechanism and important anatomic factors may have been overlooked. Our ability to differentiate the importance of these different variables is poor. Therefore, our diagnostic acumen needs further refinement. (2) Of course, it is likely that the proper diagnosis was made, but the therapy chosen was imperfect. In the area of anatomy, investigators are just beginning to try surgical approaches designed specifically for the pharyngeal site of obstruction. In other words, uvulopalatopharyngoplasty is not the best approach for everyone. In physiology, treatments beyond continuous positive airway pressure will be needed. It is hoped that advances in the pharmacology of sleep disorders will establish more convenient and successful therapies. It is likely that OSA is a heterogenous disease process. We must realize that a treatment that helps one patient may not be applicable to the next individual. Through a better understanding of the pathophysiology of OSA, better treatment modalities should be developed, resulting in improved quality of life for OSA patients.