Catheters In Pediatric Patients Research Articles

Old Versus New Needle-Retractable IV Catheters in Pediatric Patients: Are They Really Safer and Whom Are They Protecting?

Old Versus New Needle-Retractable IV Catheters in Pediatric Patients: Are They Really Safer and Whom Are They Protecting?

Central venous catheters in pediatric patients--subclavian venous approach as the first choice.

It is critical to establish a safe and functional i.v. access in severely sick patients. We evaluated the frequency of application and complications of central venous catheters in a pediatric intensive care unit. Pediatric patients in whom central venous catheters were inserted between March 1997 and May 1999 in the Pediatric Emergency Room and Intensive Care Unit were enrolled in this study. Patients were evaluated with respect to age, sex, weight, central venous catheter indication, site, duration of catheter stay and complications. During the study period a total of 156 central venous catheters were successfully inserted into 146 patients. Of the 156 central venous catheter attempts, 148 (94.9%) were placed into the subclavian vein, six were inserted into the femoral vein, and two into the jugular vein. In 156 attempts, arterial injuries occurred in 20 cases (12.8%). Pneumothorax developed in two patients on mechanical ventilation. Three catheters had to be removed due to catheter related infections. The mortality rate was 0%. We concluded that subclavian central venous catheterization is a safe procedure with minimal complications in pediatric patients. Arterial injury was the most frequent complication. In experienced hands, the success rate was 100%. Subclavian central venous catheter insertion may be considered as the first approach in critically ill patients.

Surgical intervention for complications caused by femoral artery catheterization in pediatric patients

Purpose: This study evaluated the risk factors and surgical management of complications caused by femoral artery catheterization in pediatric patients. Methods: From January 1986 to March 2001, the hospital records of all children who underwent operative repairs for complications caused by femoral artery catheterization were reviewed. A prospective cardiac data bank containing 1674 catheterization procedures during the study period was used as a means of determining risk factors associated with iatrogenic femoral artery injury. Results: Thirty-six operations were performed in 34 patients (age range, 1 week-17.4 years) in whom iatrogenic complications developed after either diagnostic or therapeutic femoral artery catheterizations during the study period. Non-ischemic complications included femoral artery pseudoaneurysms (n = 4), arteriovenous fistulae (n = 5), uncontrollable bleeding, and expanding hematoma (n = 4). Operative repairs were performed successfully in all patients with non-ischemic iatrogenic femoral artery injuries. In contrast, ischemic complications occurred in 21 patients. Among them, 14 patients had acute femoral ischemia and underwent surgical interventions including femoral artery thrombectomy with primary closure (n = 6), saphenous vein patch angioplasty (n = 6), and resection with primary anastomosis (n = 2). Chronic femoral artery occlusion (> 30 days) occurred in seven patients, with symptoms including either severe claudication (n = 4) or gait disturbance or limb growth impairment (n = 3). Operative treatments in these patients included ileofemoral bypass grafting (n = 5), femorofemoral bypass grafting (n = 1), and femoral artery patch angioplasty (n = 1). During a mean follow-up period of 38 months, no instances of limb loss occurred, and 84% of children with ischemic complications eventually gained normal circulation. Factors that correlated with an increased risk of iatrogenic groin complications that necessitated surgical intervention included age younger than 3 years, therapeutic intervention, number of catheterizations (≥ 3), and use of 6F or larger guiding catheter. Conclusion: Although excellent operative results can be achieved in cases of non-ischemic complications, acute femoral occlusion in children younger than 2 years often leads to less satisfactory outcomes. Operative intervention can provide successful outcome in children with claudication caused by chronic limb ischemia. Variables that correlated with significant iatrogenic groin complications included a young age, therapeutic intervention, earlier catheterization, and the use of a large guiding catheter. (J Vasc Surg 2001;33:1071-8.)

Tunneled epidural catheters for prolonged analgesia in pediatric patients. (Stanford University, Stanford, CA) Anesthesia and Analgesia 2001;92:1432–1438.

The charts of 25 patients with prolonged pain that was unresponsive to conventional opioid therapy and who received thoracic, lumbar, or caudal tunneled epidural catheters between 1995 and 1999 were reviewed for efficacy and catheter‐related complications. Tunneled epidural catheters were effective in providing extended analgesia in all subjects. In 14 patients with chronic pain, cumulative 48‐hour enteral and parenteral opioid requirements were reduced or eliminated after catheter insertion. Catheters remained in place for a median of 11 days until there was no further need for parenteral analgesia (n = 15), death because of the underlying disease (n = 6), accidental removal (n = 2), or possible infection (n = 2). No serious local or systemic complications occurred related to this technique. Five patients were discharged from the hospital with the catheter for home analgesic therapy. The use of a percutaneously inserted, subcutaneously tunneled epidural catheter is safe, effective, and provides pain relief in situations in which conventional analgesic therapy either fails or is impractical. The technique is one that may be of great value to children suffering from pain.Comment by Alan David Kaye, M.D., Ph.D., Amr Hegazi, M.D. This retrospective study assessed the safety, efficacy, complications, indications, and duration of use of subcutaneously tunneled lumbar, thoracic and caudal epidural catheters in pediatric patients with prolonged pain.The authors examined a total of 25 patients hospitalized for treatment of acute pain caused by trauma as well as chronic pain resulting from end‐stage cancer or cystic fibrosis. The catheters were introduced under either local anesthesia with sedation or general anesthesia after obtaining informed parental consent. Epidural catheters were inserted percutaneously, then tunneled subcutaneously away from the insertion site to bring the catheter exit site to the anterior abdominal and thoracic, posterior superior iliac crest to decrease the risk of potential infection and chance of catheter dislodgement. Tunneled catheters were effective in providing extended analgesia in all patients. None of the acutely ill patients required supplemental enteral or parenteral opioids while pediatric patients with chronic pain had dramatic decrease or elimination of opioid needs.Two of these patients had accidental removal of the catheter. One patient had postoperative fever with possible presence of infection and another patient developed cellulites at the catheter exit site. Both the catheter and wound site were sterile on bacterial cultures. The clinical relevance of routine microbiological culturing of epidural catheters in acute pain management has been evaluated by Simpson et al. It was concluded that a significant proportion of catheter tips can be positive. This suggests that colonization of the skin at the insertion site and subsequent contamination of the tip upon removal of the catheter is a concern and strict sterile aseptic techniques should be practiced by the anesthesiologist. This is an interesting article because at most institutions, pediatric pain and certainly critically ill children are clearly undermanaged. The small size of the study group, however, enables us to appropriately define the risk of infection for long‐term catheter placement (up to 240 days in this article). Also accidental catheter dislodgement especially on patients discharged home with an epidural catheter remains a concern.

Successful use of Tesio catheters in pediatric patients receiving chronic hemodialysis

Semipermanent venous catheters remain the most commonly used access for chronic hemodialysis (HD) in pediatric patients. The recent availability of Tesio catheters in 7 and 10 F has expanded available HD catheter options for children and adolescents. We report our experience with Tesio catheter survival, complications, and effect on dialysis adequacy in comparison to standard dual-lumen (DL) catheters in our pediatric HD patients. Demographic data were similar between the two groups. Overall actuarial survival was significantly longer for Tesio versus DL catheters (46% versus 0% at 1 year; P = 0.003). A comparison of smaller catheters (7 F Tesio catheter, 8 or 10 F DL catheter) showed that smaller Tesio catheters had a significantly longer survival (median survival, 244 versus 13 catheter-days; P < 0.01). Tesio 10 F catheters also survived significantly longer than the larger 11.5 and 12 F DL catheters ( P < 0.02). Catheter sepsis occurred less frequently with Tesio catheters (one episode/20 catheter-months) than DL catheters (one episode/5 catheter-months) despite the longer duration of Tesio catheters. Adequate dialysis (single-pool Kt/V > 1.2) was delivered with the same frequency, but for a longer duration with Tesio catheters (76% ± 32% over 100 monthly measurements versus DL catheter, 57% ± 45% over 54 monthly measurements). Our clinical practice was to replace cuffed catheters when adequate dialysis could not be delivered. We conclude that Tesio catheters provide superior performance compared with DL catheters in terms of catheter survival, infection rates, and duration of adequate performance. © 2001 by the National Kidney Foundation, Inc.

The semi-elective use of the pulmonary artery flotation catheter in children with progressive pulmonary hypertension or left ventricular dysfunction.

OBJECTIVE: To describe the experience with the semi-elective use of the pulmonary artery flotation catheter in pediatric patients with progressive pulmonary hypertension or left ventricular dysfunction. DESIGN: Prospective study. SETTING: Pediatric intensive care unit in a tertiary care center. PATIENTS: Seven consecutive children with pulmonary hypertension and ten children with left ventricular dysfunction. INTERVENTIONS: Drug-response studies were performed using a pulmonary artery flotation catheter. Cardiac index, systemic and pulmonary blood pressure, and occlusion pressure were measured during incremental doses of calcium channel blocker (diltiazem) that were administered to children with pulmonary hypertension and during incremental doses of nitroglycerine and angiotensin-converting enzyme-inhibitor (captopril) that were administered to patients with left ventricular dysfunction. MAIN RESULTS: Four patients (60%) with pulmonary hypertension were identified as responders to calcium channel blockers, resulting in maintenance therapy with high-dose diltiazem in three of them. Nine patients (90%) with left ventricular dysfunction showed a >15% increase in cardiac index with vasodilator therapy. Eleven patients (65%) developed fever during the procedure. Nine patients (53%) had a high probability of bacterial infection. Seven patients (40%) died within 3.5 months after the procedure. Fever, infection, and mortality appeared to occur more frequently in patients in New York Heart Association classes III and IV. CONCLUSIONS: The use of a pulmonary artery flotation catheter enables us to optimize medical treatment strategies in the individual child with progressive pulmonary hypertension or left ventricular dysfunction. Children with left ventricular dysfunction in poor clinical condition showed a high mortality rate post or propter the procedure. In our opinion, drug-response studies using pulmonary artery flotation catheters in patients with left ventricular dysfunction should be performed in a relatively early stage of the disease.

Transthoracic intracardiac catheters in pediatric patients recovering from congenital heart defect surgery: associated complications and outcomes.

To characterize transthoracic intracardiac catheter uses and associated morbidities in pediatric patients recovering from congenital heart defect surgery and to identify potential risk factors associated with their use. Prospective data collection and review. An 18-bed pediatric intensive care unit (PICU) in a tertiary care university hospital. All pediatric patients between October 1, 1996, and September 30, 1997, who were recovering from congenital heart defect surgery and had transthoracic intracardiac catheters in place. Catheter use, associated morbidity, necessary interventions, and risk factors for complications of catheter use were identified. During this period, 523 catheters (276 right atrial, 155 left atrial, 68 common atrial, and 24 right ventricular or pulmonary artery catheters) in 351 PICU patients were studied. Mean age was 23.1+/-45.1 months (median, 4.98 months); 138 patients (39.3%) were <3 months old. The rate of occurrence of bleeding with catheter removal (mediastinal output in the hour after removal that was more than twice the previous average hourly output) was 36.7%, and bleeding occurred more frequently with left atrial catheters (47%; odds ratio, 2.0; p < .05). However, interventions after catheter removal were required for only 8.3% (42/504) of catheters removed, and hemodynamic compromise occurred with the removal of only 2.6% (13/504) of catheters. Interventions included fluid resuscitation (35 cases), pleural drainage (three cases), catheter wiring for retention (one case), chest tube suctioning (two cases), and surgical removal (one case). No associated deaths occurred. In a multivariate logistic regression analysis, age <3 months (odds ratio, 4.74), catheter location (left atrial: odds ratio, 4.97; pulmonary artery: odds ratio, 12.48), and platelet count of <50,000 (odds ratio, 8.59) were identified as risk factors associated with a need for intervention after catheter removal (p < .05). Other complications included blood cultures positive for organisms (1.5%), thrombus (0.6%), and catheter nonfunction (10.9%). Prematurity was a risk factor for thrombus and nonfunction. Use of transthoracic intracardiac catheters in pediatric patients is safe. Young infants and pediatric patients with thrombocytopenia or with catheters in the left atrial or pulmonary artery position have a greater need for interventions after catheter removal, warranting added precautions.

Risk Factors for Early Infection of Central Venous Catheters in Pediatric Patients

Background: In an effort to avoid infections that can lead to the premature removal of indwelling central venous catheters (CVCs), the surgical technique and host factors present in pediatric recipients of permanent CVCs were reviewed. Study Design: All patients receiving CVCs over a 17-month period were identified. Those patients with fever and positive blood cultures drawn through the CVC within 45 days of line placement were labeled as having early infection. A case-control design was used to select two control patients for each infected patient. Charts from both the infection and control groups were reviewed for several factors present at the time of CVC placement, including fever, neutropenia (absolute neutrophil count [ANC] < 500 and ANC < 1,000), use of perioperative antibiotics, diagnosis, CVC site, and type of CVC. Chi-square test with Yates correction was used to compare the groups. Odds ratios (ORs) and 95% confidence intervals were derived. Results: Among the 473 CVCs placed, early infections developed in 53 patients (12%). The control group consisted of 106 patients. Neutropenia was present in 16 of 53 infected patients versus 8 of 106 controls (p = 0.004, OR = 5.30). Perioperative antibiotics were given to 25 of 53 infected patients versus 72 of 106 controls (p = 0.02, OR = 0.42). Fever was present in 12 of 53 infected patients versus 14 of 106 controls (p = 0.19, OR = 1.92). Factors that were equally prevalent between the groups and that did not appear to influence the CVC infection rate included a diagnosis of malignancy, CVC type, and site of placement. Of the 53 infected catheters, 16 (30%) could not be cleared of infection and were removed. Conclusions: This study documents that neutropenia and failure to administer prophylactic antibiotics are risk factors for the development of early CVC infection in pediatric patients. To avoid early infection and possible premature CVC removal, we recommend that placement of permanent CVCs be postponed until the ANC is > 1,000. Perioperative antibiotics should be given. A trend toward higher infection rates was seen in patients with preoperative fever.

Accurate placement of central venous catheters in pediatric patients using endocavitary electrocardiography: Reassessment of a personal technique

To avoid the need for radiological control in the assessment of the proper location of central venous catheters (CVC), a particular use of endocavitary electrocardiography (EC-ECG) was proposed 10 years ago. The aim of this study is to reassess our experience with this method. EC-ECG assumes that the CVC, when filled with normosaline and connected to a standard electrocardiograph, behaves like an exploring electrode. The approach of the catheter tip to the right atrium is then detected by a slightly increasing negative P wave. When the tip reaches the exact level of the sinus node, the P wave suddenly deepens. After a preliminary test of the reliability of the technique versus the standard method in 50 CVC placements verified by both EC-ECG and chest x-ray, we have placed 807 CVCs in children using EC-ECG only. There have been no false-positive and one false-negative test result (lead connector misplacement). In 17 cases in which intrinsic deflection was not detected, the catheter tip was found to be wrongly positioned; all the remainder CVCs have been successfully positioned. For 10 years this technique has proved to be a simple, safe, quick, inexpensive and highly reliable method to assess the correct positioning of the CVC.

Device-specific sharps injury usage rates: An analysis by hospital department

Background: Whether universal precautions training has reduced percutaneous sharps injuries is questioned. Prevention programs directed to specific problem areas are required to further reduce injury. Our purpose was to identify target areas. Methods: Device-specific sharps injury rates per 100,000 devices purchased were determined by department at Yale New Haven Hospital (1993 to 1994). Usage per full-time equivalent was calculated by department. Rates were modelled using Poisson regression. Results: Three epidemiologic patterns resulted: (1) injury rates were independent of usage (butterfly needles); (2) injury rates varied directly with usage (lancets); (3) injury rates varied inversely with usage (intravenous catheters, sutures, and scalpels). Device-specific usage and injury rates varied by department. Devices used little (9/full-time equivalent) but under difficult circumstances, such as intravenous catheters in pediatric patients, were associated with high injury rates ( 67.7 100,000 ). Devices, sometimes disassembled, such as blood collecting tubes, caused significantly more injury in departments where health care professionals work under time constraints, such as in the emergency department and nursing. Unconventional use of devices (Luer-Lok syringes and scalpes) resulted in higher rates of injury (nursing and laboratories). Building services appeared to be at risk for injury. Conclusions: With device-specific injury and usage rates by department, injury prevention programs can now focus on specific devices and departments.

Reduced radiation during cardiac catheterization of infants using acquisition zoom technology

It has been estimated that for adults, each hour of fluoroscopic imaging exposure carries a lifetime risk of developing a fatal malignancy of 0.1% and a risk of a genetic defect of 20/million births.4 Chromosomal damage has been seen following catheterization in pediatric patients,5 although to date no increase in the incidence of malignancies in children who have undergone cardiac catheterization has been reported.6 As these patients age, close surveillance will enhance our knowledge of the precise effects of radiation exposure. In the meantime, AZ digital technology provides a method of reducing exposure to infants with a slight reduction in image quality. Future software advances in the technique should enhance the image quality and potentially broaden its application to older patients.

Multilumen central venous catheters in children: relative potential to perforate vessels. An in vitro study.

Because cardiovascular perforation by a central venous catheter (CVC) is a serious complication of catheterization in pediatric patients, we conducted an in vitro study of the relative potential for perforation of a standard material by the tips of multilumen pediatric catheters. Since we could not simulate vessel tissue, we hypothesized that testing catheters on a standard material would show whether catheters varied in tendency to perforate such a material and thus indicate a "relative potential for perforation." Each CVC protruding from a support tube was suspended in a water-filled Plexiglas chamber at a 90 degrees incident angle to a polyethylene film, which was made to bulge 6 mm into the CVC tip 120 times per minute by hydropressure. Perforation of the polyetheylene film was documented on a time-based, strip-chart recording of pressure change on the opposite side of the film. We recorded the number of pulsations required for the following catheters to perforate the polyethylene: Arrow flex tip, Cook polyurethane, Viggo hydrocath polyurethane, and Cook silicone CVCs of 4- and 5-Fr size with 2 or 3 lumens (n = 5 catheters of each type, each catheter being tested 5 times). The number of pulsations to perforation ranged from 1 +/- 0.4 SD to > 7000. This in vitro study of the worst-case condition (90 degrees incident angle between CVC tip and polyethylene film) indicates that pediatric multilumen CVCs vary significantly in their relative potential to perforate a standard material. We suggest that, when central venous catheterization is contemplated in children, in addition to insertion site, catheter length, and depth of insertion, the type of catheter is another variable to consider in order to minimize the chance of cardiovascular perforation by the CVC tip.

Central venous catheterization in pediatric patients affected by hematological malignancies.

The objective of this retrospective study was to evaluate the significance and complications of percutaneous central venous catheterization in pediatric patients affected by hematologic malignancies. One hundred and fifty-eight central venous catheters were inserted in 125 pediatric patients (male/female 67/58; median age: 4 years; range 10 m - 6 y.) affected by hematological malignancies. Venous access was obtained by means of a tunnelled silicone rubber Groshong catheter inserted percutaneously in the subclavian vein (91.1%), the internal jugular vein or in the femoral vein. The medial duration of catheterization was 231.8 days (range 8-1014 days). The total number of catheter days was 33,792 (92.6 years). There were no complications related to catheter insertion. Only one patient developed significant post-operative bleeding. One hundred and nine catheters (68.9%) were removed when they were no longer needed and 49 (31.1%) were removed due to complications: 6 catheter occlusions (12.2%), 7 were accidentally withdrawn (14.3%), 3 for local infections (6.1%) and 33 for catheter-related infection (67.3%). A Groshong catheter seems to provide good access to the blood stream for a long period of time with a low incidence of complications in children with acute hematological malignancies.

The internal mammary vein: An alternate route for central venous access with an implantable port

Central venous catheterization in pediatric patients has, among other risks, flebitis and thrombosis, and finally occlusion of the superior and inferior venae cavae, making long-term catheterization and multiple venous cutdown more difficult. Use of the internal mammary vein might be an alternative procedure to provide sure and easy access to the central venous circulation. The authors report on a patient with multiple venous cutdown and thrombosis of the inferior vena cava, in whom the internal mammary vein was used for placement of a vascular device. The procedure is technically easy, and no special positioning of the patient is required.

Optimal Depth of Placement of Central Venous Pressure Catheter in Pediatric Patients with Congenital Heart Disease

Optimal Depth of Placement of Central Venous Pressure Catheter in Pediatric Patients with Congenital Heart Disease

Double-blind, randomized, controlled trial of papaverine-containing infusions to prevent failure of arterial catheters in pediatric patients

To test the efficacy of the continuous infusion of papaverine-containing fluids into peripheral arterial catheters for reducing the risk of catheter failure. Prospective, double-blind, randomized, controlled trial. Pediatric intensive care unit in a children's hospital. A total of 239 children, aged 3 wks to 18 yrs who had an arterial catheter inserted for clinical purposes. Patients were randomized to receive either papaverine (60 mg/500 mL) or no additive, within the infused fluids. Data about patient demographics and potential risk factors for arterial catheter failure were collected at the time of catheter insertion, throughout the life of the catheter, and at the time of catheter removal. Catheter failure was defined as an inability to draw blood from the catheter or loss of the arterial waveform. Overall, 35 (15%) subjects had catheter failure. The risk of catheter failure was lower in patients randomized to receive papaverine (eight [7%] of 115 vs. 27 [22%] of 124; chi-square = 5.2; p = .02), and the time until failure of the catheter was longer in the papaverine group (p = .02, log-rank test). This difference persisted when controlling for potentially confounding factors. In critically ill children, infusion of papaverine-containing fluids reduces the risk of failure of peripheral arterial catheters.

Chronic Peritoneal Dialysis Catheters in Pediatric Patients: Experience of the Italian Registry of Pediatric Chronic Peritoneal Dialysis

During the period 1986-1991, 140 pediatric patients [age < or = 15 years at the start of chronic peritoneal dialysis (CPD)], belonging to 15 dialysis centers, were enrolled in the Italian Registry of Pediatric Chronic Peritoneal Dialysis. Data on 188 peritoneal catheters were collected: 161 catheters were Tenckhoff (144 double-cuff, 17 single-cuff), and 27 were two-cuff Valli-type catheters. All catheters were surgically inserted; the entry site was in the midline in 84 cases and paramedian in 104. An omentectomy was performed in 78.8% of the cases. Apart from peritonitis, there were 161 catheter-related complications (103 exit-site infections, 17 leakages, 15 obstructions, 15 outer-cuff extrusions, 5 hemoperitoneum, 6 others) observed during 2687.5 dialysis-months, with an incidence of one complication every 16.7 dialysis-months. Fifty-five catheters (29.2%) were removed; infection (39 cases) was the main cause for removal, followed by obstruction (9 cases), dislocation, and outer-cuff extrusion (2 cases each). Actuarial survival of all catheters was 79.7% at 1 year, 66.6% at 2 years, 42.8% at 3 years, and 39.8% at 4 years. No difference in catheter survival was observed according to the entry site. When considering the age of the patients at catheter insertion, a difference close to statistical significance was found (p = 0.06).

Complications of central venous catheters in pediatric patients with acquired immunodeficiency syndrome.

Medical records of 18 pediatric acquired immunodeficiency syndrome patients with 24 central venous catheters (CVCs) were reviewed to determine the rates and types of CVC complications and to evaluate the influence of selected social factors, absolute granulocyte counts and CD4+ T cell counts on the rate of CVC infections. CVCs were in place for a total of 4233 days. CVCs were used for blood sampling, administration of blood products and infusions of intravenous immune globulin, parenteral nutrition and medications. Complications included catheter-related infections (8 episodes; with a rate of 1.9/1000 CVC days), occlusions (15 episodes) and unplanned catheter removals (9 episodes). Reduced CD4+ T cell counts were not predictive of CVC infection. The CVC infection rate in our pediatric acquired immunodeficiency syndrome patients was similar to rates reported in children with cancer and adults with cancer and acquired immunodeficiency syndrome.

Allometric determination of the distance from the central venous pressure port to wedge position of balloon-tip catheters in pediatric patients.

Position of the CVP port on a flow-directed balloon-tip pulmonary arterial catheter affects the accuracy of both thermodilution cardiac output determinations and CVP measurements. Systemic allometry (the study of the growth of a part in relation to the total organism) has been used to determine an easily measured independent variable that would predict this position. Sixty-one pediatric patients (aged 0 to 165 months) were studied either at autopsy or at the time of cardiac catheterization. The distance from the central venous port to the wedge position was best predicted by nonlinear manipulation of age.

Echographic application of the Gorlin formula for assessment of aortic stenosis: Correlation with cardiac catheterization in pediatric patients

We have investigated the use of M-mode echocardiography for the diagnosis of aortic valve stenosis by application of the Gorlin formula. The hemodynamic parameters which enter this formula are shown to derive wholly from noninvasive measurements. The predicted valve areas correspond with those derived by classical catheterization studies at a level of r = 0.89, SE = 0.11 cm 2 n = 10. These results suggest that the Gorlin formula for aortic stenosis may have application in a noninvasive context.