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The first-line evaluation of aortic stenosis severity is Doppler echocardiography. However, in up to 40% of patients, resting echocardiographic assessment of aortic stenosis severity is discordant, leading to clinical uncertainty. Interest has therefore grown in aortic valve calcium scoring by multidetector computed tomography (CT-AVC) as an alternative load independent assessment of aortic stenosis severity. This paper will briefly review the pathophysiology of aortic stenosis and the crucial role that calcification plays in driving progressive obstruction of the valve. Subsequently, it will describe published reports that have investigated CT-AVC, validating this parameter against histology, and establishing its diagnostic accuracy versus echocardiography as well as its powerful independent prognostic capability. Finally, this review seeks to provide a practical guide about how best to acquire and interpret CT-AVC with a close focus on potential pitfalls and how these might be best avoided as this technique becomes more widely adopted in to clinical practice.

Pulmonary arterial hypertension, although not common in children, has a poor prognosis. The definition, modern classification, causes and pathogenesis are discussed. Although the pathogenesis is complex and not completely understood, we now have a better understanding of it. The mechanisms and structural alterations underlying vasoconstriction of the pulmonary vasculature, remodelling of the pulmonary vessel wall and progressive obstruction and obliteration of the vascular bed with thrombosis are set out with the different mediators involved. Diagnosis can be difficult and a high level of suspicion is necessary to achieve an early diagnosis. The approach to management includes a methodical workup. The medication options discussed are based on an understanding of the pathophysiology.

Left ventricular outflow tract obstruction after neonatal repair of interrupted aortic arch with ventricular septal defect may warrant reintervention. We sought to identify clinical and preoperative echocardiographic predictors of reintervention for postoperative left ventricular outflow tract obstruction.Retrospective data were collected on neonates with interrupted aortic arch with ventricular septal defect who underwent single-stage repair from 1995 to 2009. Univariate and multivariate analyses were performed to identify predictors of reintervention.Seventy patients underwent repair, with 16 patients requiring reintervention: 8 underwent surgical reintervention, 5 underwent percutaneous reintervention, and 3 underwent both. The median time to reintervention was 1.2 years (range, 0.2 to 7.7). All surgical reoperations involved subaortic resection, and all percutaneous reinterventions included balloon aortic valve dilation. Several preoperative echocardiographic measurements were significant by univariate analysis; however, smaller preoperative aortic root size was an independent predictor (p = 0.02) by multivariate analysis. Patients with an aortic root size less than 6.5 mm were at greater risk for reintervention compared with patients with a root size greater than 6.5 mm (reintervention rate 44% and 12%, respectively; p0.001). Postoperative left ventricular outflow tract gradient by echocardiogram before discharge was significantly higher in the reintervention group.Preoperative aortic root size predicts reintervention for postoperative left ventricular outflow tract obstruction after single-stage repair of interrupted aortic arch with ventricular septal defect. Patients with elevated left ventricular outflow tract gradients at discharge are at higher risk of having progressive obstruction and require closer follow-up to ensure early identification and management.

Atherosclerosis is a systemic and multifocal disease, which starts early in life, and that usually takes decades before overt disease eventually appears as a consequence of progressive obstruction or abrupt thrombotic occlusion. This silent course makes necessary to develop predictors of disease long before symptomatic lesions develop. Besides several classical risk factors and new emerging humoral risk predictors, imaging may constitute a formidable diagnostic and prognostic tool in order to identify presence, extension, progression (or regression) of disease as well as vulnerability of atherosclerotic lesions. This review summarizes the rapidly growing clinical and research field in imaging atherosclerosis from different perspectives opening important opportunities for timely detection and treatment of atherosclerosis.

La enfermedad pulmonar obstructiva crónica (EPOC) es una enfermedad de las vías aéreas inferiores, la cual resulta en el remodelado de las vías aéreas y culmina con su estrechamiento provocando obstrucción progresiva. Esta enfermedad afecta principalmente a animales de mediana edad y de edad avanzada y en la mayoría de los casos se desconoce su causa. El presente trabajo de revisión tiene como objetivo mostrar la importancia clínica, las herramientas diagnósticas, las principales diferencias entre el diagnóstico de asma y bronquitis, y las alternativas terapéuticas que ofrecen mejores resultados y menores efectos secundarios para los pacientes. Chronic obstructive pulmonary disease (COPD) is a disease of the lower airways, which result in remodelling of the pulmonary tract and culminates with narrowing airway causing progressive obstruction. The disease mainly affects elderly animals and the cause is generally unknown. This review aims to describe the clinical significance, diagnostic tools, main differences between the diagnosis of asthma and bronchitis, as well as therapeutic alternatives that offer better results and fewer side effects for patients.

If peak inspiratory airway pressure (Ppeak) is used to monitor airway patency, progressive obstruction of the endotracheal tube (ETT) resulting from secretions can go undetected for a prolonged period. The reason is that any increase in Ppeak depends not only on the degree of narrowing but also on the inspiratory flow () rate. Although the impact of narrowing on low inspiratory is small, its decelerating effect on the high expiratory is pronounced and, hence, easily detectable. Dividing the volume-flow curve of a passive expiration into five consecutive segments (slices) and calculating the time constants (tau(Epsilon)) of these slices allows for analyzing whether and how expiratory is impeded by a partial obstruction. In nine piglets, during volume-controlled ventilation, three grades of ETT obstruction were created with an external clamp. In all animals the tau(E) increased with ETT obstruction (mean for the first slice: 550 ms with unobstructed ETT; grade 1: 661; grade 2: 877; and grade 3: 1563 ms, respectively) and this increase was significant with grade 2 and 3 obstruction. Ppeak, by contrast, did not increase significantly (base: 13, grade 1: 14, grade 2: 15 cm H(2)O) until the most severe (grade 3: 20 cm H(2)O) obstruction was created. We conclude that partial obstruction of the ETT can be reliably monitored with the expiratory V signal and has the potential of monitoring ETT narrowing in ventilator-dependent patients independent of the inspiratory pattern applied.

Background We report a case of Ex-PRESS miniature glaucoma shunt obstruction resulting from progressive iris synechial formation after transient anterior chamber shallowing. Case presentation A 68-year-old woman with pseudoexfoliation glaucoma in her right eye underwent filtration surgery with implantation of the Ex-PPESS shunt (model P-50, Alcon Japan, Tokyo, Japan) in combination with intra-surgical 0.04% mitomycin C use. After the anterior chamber injection of viscoelastic material and 100% sulfur hexafluoride gas for treatment of early postoperative over filtration, the intraocular pressure (IOP) was controlled between 9 and 12 mmHg. On postoperative day 121, gonioscopy showed that synechial formation around the shunt obstructed the axial port leaving the relief port opened. On postoperative day 274, the intraocular pressure increased to 40 mmHg and synechiae obstructed both the axial and relief ports. Dispersion of iris tissue by neodymium:yttrium-aluminium-garnet (Nd:YAG) laser (2 mJ, one shot to each port) opened both ports and immediately lowered the IOP, leaving peripheral anterior synechiae around the shunt. Up to postoperative day 400, the IOP was controlled between 13 and 15 mmHg, and the cystic bleb was maintained. Conclusion The synechiae formed gradually extends around the shunt’s shaft and can result in later external obstruction of the relief port. The current case requires further follow-up since synechiae remaining around the shaft can cause future obstruction. We emphasize the fact that, if the iris synechiae to the shunt once formed, it can progress and obstruct the shunt ports later.

Chronic obstructive pulmonary disease (COPD) is the fourth-leading cause of death in the United States. Although many other diseases have seen a gradual decline in their associated mortality, COPD rates have increased nearly 33% from 1979 to 1991. The disease is defined as a slowly progressive obstruction of airflow that is predominantly irreversible. COPD usually begins in the fifth decade of life as an increased cough. Dyspnea on exertion is frequently observed in the sixth or seventh decade.

Partial outlet obstruction has been used for a considerable period of time as an animal model for the urodynamic changes that occur with the progressive obstruction of benign prostatic hyperplasia (BPH). Although there are many models of partial outlet obstruction, one common feature is that the degree of obstruction produced is inconsistent. The current study evaluates the responses of the bladder to a partial outlet obstruction created using an autologous fascial collar from harvested rectus fascia. The results demonstrate that although there was a moderate and variable increase in bladder mass, the alterations in the contractile responses to field stimulation (FS), carbamyl choline (carbachol), KCl, and adenosine 5'-triphosphate (ATP) were less severe than other models of partial outlet obstruction. Specifically, there was an approximate 40% decrease in the magnitude of the contractile response to FS but no significant changes in the magnitude of the contractile responses to carbachol, KCl, or ATP. Further analysis of the contractile responses demonstrated that there was a greater decrease in the rate of tension generation than in the magnitude of response for FS, and a significant increase in the time to maximal tension. Although there were no decreases in the magnitude of the responses to carbachol, KCl, or ATP, there were significant reductions in the rate of tension generation for carbachol and KCl and significant increases in the time to maximal tension for carbachol and ATP. Applying less tension over a wider area, the fascial collar provided a consistent and reproducible mild partial outlet obstruction.

Marine evaporites such as the Zechstein (Permian, NW Europe) consist of thinning-upward sulphate- halite-potash cycles whose origin is poorly understood. An intra-basinal mechanism presented here explains well their mineral composition and cycle development. It involves the progressive obstruction of ocean connections by sulphate-platform progradation, causing a chain reaction of outflow reduction and subsequent accelerated sulphate precipitation. Numerical modelling shows this to be a self-accelerating process that ultimately triggers halite and potash precipitation. Isostatic compensation of the salt load explains the formation of accommodation space for subsequent cycles, each about half the thickness of the previous cycle.

Echocardiography has changed the prognosis of cardiac tumors which was in the past poor not only for malignant, but also for benignant lesions. In fact, cardiac masses could not be suspected until progressive obstruction of cardiac chambers and/or embolic events occurred. The ultrasound diagnosis of cardiac tumors depends on the technological level of the instrumentation and on the operator’s skill and experience, which is particularly true for small and unusual lesions. The cardiologist performing the examination should know the clinical history of the patient and should be expert on the wide spectrum of cardiac masses which may be occasionally encountered during a routine examination.

The ventricular septal defect (VSD) can rarely be associated with other malformations such as double-chambered right ventricle (DCRV) in which hypertrophied muscle bundles divide the right ventricle into two chambers causing progressive obstruction (Mao et al., Asia Pac J Thorac Cardiovasc Surg 5:14–17, 1996). Most VSDs close spontaneously by apposition of the tricuspid leaflets, but the process is rarely disrupted, resulting in communication between left ventricle and right atrium called Gerbode defect [Cho et al., J Cardiovasc Ultrasound 19(3):148–151, 2011]. Hence, the Gerbode defect involves potential misinterpretation of its high-velocity shunt as pulmonary hypertension. Here we present a case with DCRV and Gerbode defect initially misdiagnosed to have Eisenmenger syndrome.

Publisher Summary This chapter explores the various new drugs now in development for asthma and chronic obstructive pulmonary disease (COPD). Current asthma therapy is highly effective and majority of patients can be well controlled with inhaled corticosteroids and short- and longacting β2-agonists. These treatments are not only effective, but also safe and relatively inexpensive. This poses a challenge for the development of new treatments, since they will need to be safer or more effective than existing treatments, or offer some other advantage in long-term disease management. In sharp contrast to asthma there are few effective therapies in COPD, despite the fact that it is a common disease that is increasing worldwide. None of the treatments currently available prevents the progression of the disease, and yet the disease is associated with an active inflammatory process that results in progressive obstruction of small airways and destruction of lung parenchyma. Blocking the receptors or synthesis of inflammatory mediators is a logical approach to the development of new treatments for asthma and COPD. Several mediator antagonists have now been tested in asthma and COPD. Proteases are involved in the pathophysiology of asthma and COPD and are therefore a logical target for inhibition. However, it has proved very difficult to find drugs that effectively block specific proteases without side effects. New drugs for the treatment of severe asthma and COPD are greatly needed and there has been an enormous effort now invested by the pharmaceutical industry to find such treatments.

Presentation of Case A 62-year-old woman was admitted to the hospital because of progressive obstruction of the left nasal cavity by a mass. There was a 14-year history of seasonal allergic rhinitis associated with intermittent nasal obstruction; evaluation elsewhere was reported to show allergy to wheat, other grains, dusts, and grasses. During the two years before admission the obstructive symptoms worsened. Two months before entry the left nasal obstruction was constant, and the patient became aware of the sensation of a left nasal mass. Two weeks before entry a physician confirmed the presence of a left nasal mass. A computed . . .

Accessory mitral valve tissue is a rare anomaly of embryologic development of the endocardial cushion and may cause substantial and progressive obstruction of the left ventricular outflow tract. Subaortic obstruction resulting from accessory mitral tissue is most likely due to systolic ballooning of the tissue into the outflow tract. The obstruction can occur in the early period of life as a result of mass effect or it can develop gradually due to the continued deposition of fibrous tissues within the left ventricular outflow tract. In patients with accessory mitral valve tissue, surgery is mandatory if there is a significant obstruction in the left ventricular outflow tract. We report two cases with accessory mitral valve tissue causing mild subaortic stenoses which did not require surgery.

We describe an unusual right atrial aneurysm, occurring with progressive obstruction of the right ventricular outflow tract and increasing cyanosis, in a nine-month-old boy with chromosome 8(p23.1) deletion. Surgical resection of the diverticulum, and relief of the right ventricular obstruction, was successful, although impairment of right ventricular compliance persists after 19 months follow-up.

A critical evaluation of the literature concerning experiments on the development of an alloplastic tracheal prosthesis shows that infection and progressive obstruction of the prosthesis are among others important causes for failures.

Purpose Surgery for post-natal persistence of clinically significant hydronephrosis is poorly predicted by the anteroposterior diameter of prenatal pyelectasis. We sought to determine if the timing of pyelectasis in either the second or third trimester could better predict the need for surgery. Material and methods A database query for fetal pyelectasis in our maternal-fetal registry for all fetuses with pyelectasis. Utilizing >7mm in 2nd trimester and >10mm in 3rd trimester, patients were then selected for review of post-natal imaging and clinical outcome (Fisher's exact test). Results 59 children with 116 involved kidneys were identified. Second trimester pyelectasis correlated with the degree of post-natal hydronephrosis (Grade 3 or 4; p=0.03), but not the need for surgery (p=0.61). Third trimester pyelectasis also correlated with pos-natal hydronephrosis (p=0.0005), and predicted those requiring surgical intervention (p=0.0001). Eleven children (18%)came to surgery during the 5 year follow-up. Surgery was for progressive obstruction, ectopia, and one child with VUR with recurrent pyelonephritis. Conclusions A third trimester ultrasound for fetal pyelectasis is a better predictor of post-natal outcome than the second trimester.

The relationship of exercise-induced electrocardiographic changes to severity of obstruction in congenital aortic stenosis was studied in 44 children. Twelve subjects, with ST segment depression of 1 mm or more lasting 0.08 seconds after the J Point, had left ventricular-aortic peak systolic pressure differences (gradients) ranging from 54 to 112 mm Hg. The remaining 32 children had less than 1 mm or no ST segment depression. Thirty-one of these had gradients ranging from 10 to 48 mm Hg and one had a gradient of 52 mm Hg. Vectorcardiograms, electrocardiograms, and chest roentgenograms were not useful in the identification of the severity of the lesion. The study suggests that children with severe gradients develop electrocardiographic ST segment changes with exercise, thereby helping to select those patients who should have catheterization studies to delineate the severity of the lesion. In those with a normal exercise test, cardiac catheterization may be safely delayed, but the exercise test should be repeated to identify those who develop progressive obstruction.

• Thirty-seven patients with severe head injury underwent radionuclide cisternography to detect early and late effects of trauma on cerebrospinal fluid (CSF) circulation. Thirty-one patients had subdural hematomas or hygromas and six had cerebral contusions without extracerebral masses. Cisternographic results were abnormal in 23 patients with subdural masses and normal in five who had only cerebral contusions. Of eight patients undergoing serial studies, one had persistent partial obstruction, five had partial resolution of abnormalities, and the two with progressive obstruction had their conditions improved by shunting. Angiography suggested transtentorial herniation in 11 patients with cisternal block, six of whom had clinical signs of herniation on the same side.

From 1950 to 1973, 169 patients received irradiation for esophageal squamous cell carcinoma. The average survival time was 10 months, with 7% of the patients living 2 years or more. The median survival time was 7 months; palliation averaged 6 months. Most completing therapy (89%) achieved some palliation: 66% had significant relief of dysphagia for 2 months or longer. The anatomical location of the malignant obstruction did not influence therapeutic response; there was similar response in cases of upper, middle, and lower esophageal lesions. Thirty patients with progressive obstruction underwent endoesophageal intubation with Celestin tube placement; this procedure provided symptomatic relief with minimal morbidity.

Of two patients with type 5 hyperlipoproteinemia, one exhibited lipemia retinalis with multiple retinal hemorrhages and intraretinal lipid extravasations. Postmortem examination showed hemorrhages in the inner retinal layers and lipid deposits largely in the outer plexiform layer. Lipid within the walls of the retinal vessels was demonstrated by light and electron microscopy. The second patient exhibited visual loss due to progressive obstruction of retinal vessels with white material presumed to be lipid. Findings were confined to one eye.

Summary— Bladder outflow obstruction was produced in 18 young male pigs using either a silver ring or a silk ligature placed around the proximal urethra. Normal growth of the animals resulted in progressive obstruction. This was monitored by urodynamic studies in conscious animals, using either long-term indwelling bladder cannulae or by intermittent suprapubic catheterisation. At urodynamic assessment 3 to 5 months later, the obstructed pigs voided at an elevated pressure and with a diminished flow rate compared with control animals. Sixty-four per cent of the obstructed pigs developed detrusor instability, with spontaneous contractions exceeding 15 cm H2O during bladder filling; another 14% had decreased bladder compliance. In control animals the filling cystometrogram was stable, with little pressure rise during filling and no spontaneous contractions. This animal model provides the opportunity to study the physiological changes responsible for the development of detrusor instability in the obstructed bladder. It may also be useful for evaluating new treatment regimes for detrusor instability.

A sensitive rheometer was used to obtain pressure drop-velocity data for erythrocyte suspensions in the capillary pores of Nuclepore filters. Earlier, nonlinear resistance-velocity behaviour was described for 7-μm pores at cell velocities below 0.8 mm · sec −1 . Similar behaviour is now described for cells in narrower pores (diameter of 5 μm). Two-limbed, straight-line, pressure-velocity relations are again found, which indicate a constant maximum resistance below a critical velocity and a region of decreasing resistance beyond. As previously reported, the findings occur in both the cell velocity (0–1 mm · sec −1 ) and the capillary diameter (5–7 μm) ranges for which Lighthill (1969, In “Circulatory and Respiratory Mass Transport,” Churchill, London) and Fitz-Gerald (1969, Proc. Roy. Soc. Ser. B 174, 193–227) predicted elasto-hydrodynamic resistance effects. The finding of similar behaviour in narrower pores, with a higher critical driving pressure drop, reinforces the preliminary conclusion of behaviour resulting from elastic cell distortion. The present paper examines the resistance data using simple models, showing that the resistance values are consistent with lubrication by a very thin (∼0.1 μm) fluid film, which surrounds the cells and increases in width with velocity beyond the critical point. The findings indicate tight-fitting conditions for the cells, and the changes in film width (and hence resistance) are such as might be expected from elastic bending of the cell membrane, with previously reported estimates for its Young's elastic modulus. The data are compared with hydrodynamic theory, and related experiments are discussed.

Mild and clinically silent ureteropelvic junction obstruction was observed to progress in severity in 2 infants. Diuretic renography was useful in serial evaluation and documentation of progression. The possible mechanism for such progression of obstruction is proposed. Although mild obstruction in the older child and adult can be followed successfully without surgery, it appears that close follow-up of mild obstruction during the first year of life is necessary to detect and assure treatment of progressive obstruction at an optimum age.

Summary Three cases of primary circumferential ulceration of the small intestine are reported, two leading to frank perforation and one to chronic progressive obstruction. All three patients had received thiazide-potassium chloride therapy, and it must be concluded that all three cases fall into the newly described syndrome of small bowel ulcer associated therewith. The patients reported on do not conform to the usual category of elderly persons with cardiorenal disease, and they reinforce the concept that healthy and reasonably young persons exposed to this pharmacologic regimen may suffer the consequence of small bowel ulceration from thiazide-potassium chloride medication.

Sarcoidosis of the larynx is an uncommon manifestation but can be potentially life threatening when progressive obstruction of the upper airway develops. A patient presented with sarcoid infiltration involving successively the skin, palate, nose, lymph glands, bones and finally the larynx. Local irradiation was instrumental in relieving a progressive airway closure.

Renal cysts usually are asymptomatic, produce no harm to the kidney and require no treatment once diagnosed. However, an occasional expanding cyst causes progressive obstruction to caliceal or pelvic outflow. Herein is reported observations on 4 patients in whom cysts produced significant obstruction to the pelvic or major caliceal outflow. In 3 cases treatment was by decompression, with resolution of the obstruction.Two requirements must be met for a cyst to obstruct: 1) it must lie at or near the hilus and 2) it must have turgor sufficient to overcome the pressure of the intrapelvic urine. In contrast to most renal cysts those producing significant obstruction require operation.

Necrosis due to an electrical injury extends by progressive obstruction of blood vessels. Means of inhibiting expansion of necrosis and predicting early the demarcation line after an electric injury were studied in the local electric injury of a rabbit ear produced by application of an electric current of 50 Hz. 1 800 V for 1 sec between the right ear and the right posterior leg. Although no effective method of inhibiting expansion of necrosis was obtained, a method of predicting a demarcation line of necrosis was obtained by inducing ischemia of the ear early after the application of an electric current. From three hours to three days after the application of the electric current, ischemia of the ear was induced by compressing it between a pair of blood pressure cuffs at a pressure of 300 mmHg. As a result, the area proximal to the expected demarcation line of necrosis became white by ischemia. while the peripheral part remained dark red because of thrombi, and the expected demarcation line was clearly o...

Fetal screening during maternal ultrasonography has changed the mode and age of presentation of congenital uropathies, particularly congenital obstructed megaureter. We studied 47 infants less than 8 months old with primary obstructed megaureter. Surgical correction in 42 patients with moderate to severe obstruction was performed at a mean age of 1.8 months in those detected prenatally and 3.8 months in those presenting after birth. All infants showed functional and structural urographic improvement with a mean followup of 2.3 years. Reflux was seen postoperatively in 8 patients, which subsided spontaneously in 3, continues to be followed in 2 and resulted in repeat reimplantation in 3. Five infants had mild obstruction, which was managed nonoperatively and 2 showed progressive obstruction, which required repair at ages 20 and 28 months. Repair of obstructed megaureters in early infancy improves renal drainage and offers the potential for preventing renal damage before the development of symptoms or infection. With proper attention to detail, excellent results may be achieved.

Ureteroarterial fistulas are rare. A case is presented of a fistula between the distal right limb of an aorto-bifemoral graft and the right ureter that was treated with preservation of the kidney. Some of the reported fistulas were associated with complex pelvic cancer procedures, some with difficult distal ureteral stone procedures, or represent old reports from the days when long-term ureteral stents were used often to treat pyelonephritis of pregnancy. The remainder are associated with vascular lesions. Since ureteral obstruction predated all of the fistulas reported, a high index of suspicion and an aggressive approach to progressive obstruction is indicated. Symptoms of a ureteroarterial fistula vary from mild hematuria and flank pain to vascular collapse. The retrograde pyelogram is the most useful diagnostic study.

Acute retention of urine in the patient with benign prostatic hypertrophy (BPH) probably occurs for a number of reasons. In some cases it is the culminating event in a steadily progressive obstruction due to increasing enlargement of the prostate. In other cases, however, the condition may develop suddenly in a patient who has had relatively little antecedent trouble and in whom no prior progress of obstruction had been detectable. Some of these cases may be due to an episode of prostatitis superimposed on the already enlarged gland, and others may be due to infarction in the enlarged prostate; some authors believe this to be a common cause.5,12

We encountered an unusual case of carcinoid tumor of the terminal ileum with intermittent recurrent small bowel obstruction of seven years' duration rather than the usual presentation of chronic progressive obstruction. ( JAMA 239:2686-2687, 1978)

OBJECTIVE--The aim was to define the long term prognosis of isolated ventricular septal defect (VSD) with anteriorly malaligned outlet septum. DESIGN--Cohort study. SETTING--University hospital, tertiary medical care centre. PATIENTS--Between July 1986 and June 1993, 63 patients were studied with an isolated VSD and anteriorly malaligned outlet septum (59 perimembranous; 4 muscular outlet). MAIN OUTCOME MEASURES--The diagnosis of septal malalignment, aneurysmal transformation, right ventricular obstruction, subaortic ridge, and aortic valve prolapse was based on echocardiographic criteria, then confirmed by angiography in 33 patients and by surgery in 28. An actuarial curve for each event was obtained by Kaplan-Meier non-parametric analysis and the significance was examined by log-rank test. RESULTS--Aneurysmal transformation decreased the size of the VSD in 52% of the patients, but was also associated with the appearance of subaortic ridge (p < 0.05). Progressive obstruction in the right ventricle was observed in 51%, more often in those without aneurysmal transformation (p < 0.05). Aortic valve prolapse was quite common whether or not aneurysmal transformation occurred (33% and 23%, respectively). This was attributed to the location of the VSD and the anterior malalignment of the outlet septum. Surgery was performed in 28 patients at a median age of 50 months because of significant left to right shunt (n = 5), or the development of obstruction in right ventricle (n = 9), aortic valve prolapse (n = 3), or combinations (n = 11). The presence of subaortic ridge per se was not considered to be a surgical indication. CONCLUSIONS--Anteriorly malaligned VSDs have variable presentation. Careful echocardiographic evaluation is needed to identify various combinations of progressive right ventricular obstruction, aneurysmal transformation, subaortic ridge, or aortic valve prolapse. In extreme cases a patient may have a pathology complex comprising right ventricular outflow obstruction, subaortic ridge, aortic valve prolapse, and anteriorly malaligned VSD.

To the Editor .—In the article by Dr. Yanagisawa and me in the February 1968Archives( 87 :165) entitled "Carbon Dioxide Narcosis," we described an unusual complication of postnasal packing. It has been brought to our attention that this is a clinical impression and that further evidence by blood gas studies should be used to substantiate our opinions. Recently we have treated another patient with a clinical history similar to the one reported in the paper. This patient was a 74-year-old man with a metastatic renal cell carcinoma in the nasopharynx which required bilateral posterior nasal packing to control hemorrhage. Thirty-six hours postpacking, the patient developed marked edema and progressive obstruction of the upper airway. It was elected to do a tracheotomy for relief of this obstruction, but prior to and following tracheotomy arterial blood gas studies were obtained. The preoperative values were: PO 2 , 132; O 2 saturation, 96.6%