The impact of severe obesity on image quality and ventricular function assessment in echocardiography and cardiac MRI.

This study sought to evaluate the impact of severe obesity on image quality and ventricular function assessment in cardiovascular magnetic resonance (MRI) and trans-thoracic echocardiography (TTE). We studied 100 consecutive patients who underwent clinically indicated cardiac MRI and TTE studies within 12 months between July 2017 and December 2020; 50 (28 females and 22 males; 54.5 ± 18.7 years) with normal body mass index (BMI) (18.5-25 kg/m2) and 50 (21 females and 29 males; 47.2 ± 13.3 years) with severe obesity (BMI ≥ 40 kg/m2). MRI and TTE image quality scores were compared within and across cohorts using a linear mixed model. Categorical left (LVF) and right (RVF) ventricular function were compared using Cohens Kappa statistic. Mean BMI for normal weight and obese cohorts were 22.2 ± 1.7 kg/m2 and 50.3 ± 5.9 kg/m2, respectively. Out of a possible 93 points, mean MRI image quality score was 91.5 ± 2.5 for patients with normal BMI, and 88.4 ± 5.5 for patients with severe obesity; least square (LS) mean difference 3.1, p = 0.460. TTE scores were 64.2 ± 13.6 for patients with normal BMI and 46.0 ± 12.9 for patients with severe obesity, LS mean difference 18.2, p < 0.001. Ventricular function agreement between modalities was worse in the obese cohort for both LVF (72% vs 80% agreement; kappa 0.53 vs 0.70, obese vs. normal BMI), and RVF (58% vs 72% agreement, kappa 0.18 vs 0.34, obese vs. normal BMI). Severe obesity had limited impact on cardiac MRI image quality, while obesity significantly degraded TTE image quality and ventricular function agreement with MRI.

Influence of maternal body mass index on interobserver variability of fetal ultrasound biometry and amniotic-fluid assessment in late pregnancy.

OBJECTIVE: To determine the interobserver reproducibility of fetal ultrasound biometric and amniotic-fluid measurements in the third trimester of pregnancy, according to maternal body mass index (BMI) category. METHODS: This was a prospective cohort study of women with a singleton gestation beyond 34 weeks, recruited into four groups according to BMI category: normal (18.0-24.9 kg/m2 ), overweight (25.0-29.9 kg/m2) , obese (30.0-39.9 kg/m2 ) and morbidly obese (≥ 40 kg/m2 ). Multiple pregnancies, women with diabetes and pregnancies with a fetal growth, structural or genetic abnormality were excluded. In each woman, fetal biometric (biparietal diameter (BPD), head circumference, abdominal circumference (AC), femur length (FL) and estimated fetal weight) and amniotic-fluid (amniotic-fluid index (AFI) and maximum vertical pocket (MVP)) measurements were obtained by two experienced sonographers or physicians, blinded to gestational age and each other's measurements. Differences in measurements between observers were expressed as gestational age-specific Z-scores. The interobserver intraclass correlation coefficient (ICC) and Cronbach's reliability coefficient (CRC) were calculated. Bland-Altman analysis was used to assess the degree of reproducibility. RESULTS: In total, 110 women were enrolled prospectively (including 1320 measurements obtained by 17 sonographers or physicians). Twenty (18.2%) women had normal BMI, 30 (27.3%) women were overweight, 30 (27.3%) women were obese and 30 (27.3%) women were morbidly obese. Except for AFI (ICC, 0.65; CRC, 0.78) and MVP (ICC, 0.49; CRC, 0.66), all parameters had a very high level of interobserver reproducibility (ICC, 0.72-0.87; CRC, 0.84-0.93). When assessing reproducibility according to BMI category, BPD measurements had a very high level of reproducibility (ICC ≥ 0.85; CRC > 0.90) in all groups. The reproducibility of AC and FL measurements increased with increasing BMI, while the reproducibility of MVP measurements decreased. Among the biometric parameters, the difference between the BMI categories in measurement-difference Z-score was significant only for FL. Interobserver differences for biometric measurements fell within the 95% limits of agreement. CONCLUSION: Obesity does not seem to impact negatively on the reproducibility of ultrasound measurements of fetal biometric parameters when undertaken by experienced sonographers or physicians who commonly assess overweight, obese and morbidly obese women. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Noninvasive assessment of hepatic steatosis and fibrosis in patients with severe obesity.

PURPOSE: In morbid obesity nonalcoholic fatty liver disease (NAFLD) is endemic. Aim of this study is to evaluate the diagnostic accuracy of the most common noninvasive methods for identify NAFLD and fibrosis in a cohort of morbid obese population. METHODS: Ninety morbid obese patients undergoing bariatric surgery (BS) and intraoperative liver biopsy were evaluated preoperatively with Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and serum biomarkers for steatosis and fibrosis and liver stiffness measurement (LSM) using acoustic radiation force impulse (ARFI) elastography. All nondiabetic patient (n = 77) underwent OGTT and calculation of Oral Glucose Insulin Sensitivity index (OGIS). RESULTS: In the entire cohort prevalence of NAFLD was 77%, NASH 24%, moderate/severe steatosis 50%, and significant fibrosis 14%. New cut-offs were evaluated for all steatosis score assessed in this population. In all patients with moderate/severe steatosis HOMA IR was significantly greater than 3.5. ALT, GGT, Triglycerides, HOMA IR, and ARFI increased with fibrosis grade (p 0.03, p 0.008, p 0.04, p 0.05, respectively) and AST to Platelet ratio (APRI) was the only noninvasive fibrosis score significantly increased in significant fibrosis (p 0.04). A combination of 1/OGIS and VAI was able to discriminate NASH from simple steatosis (NAFL) (p 0.02). CONCLUSIONS: In morbid obese subjects, we calculated new cut-offs of the most common steatosis indexes and found that a score based on insulin resistance (1/OGIS) and abdominal obesity (VAI) could represent a way to identify morbid obese subjects at risk of NASH.

Ultrasound-based assessment of hyomental distances in neutral, ramped, and maximum hyperextended positions, and derived ratios, for the prediction of difficult airway in the obese population: a pilot diagnostic accuracy study.

BACKGROUND: Ultrasonography-assessed hyomental distance (HMD) ratio has been found to discriminate between obese patients with Cormack-Lehane grades 1 or 2 vs. those with grades 3 or 4. The aim of our study is to evaluate the performance of the HMD evaluated ultrasonographically in neutral, ramped, and maximum hyperextended positions, as well as for the ratios obtained by dividing the HMD in the ramped position to that in the neutral position (HMDR1) and by dividing the HMD in maximum hyperextension to that in the neutral position (HMDR2), in order to predict the occurrence of Cormack-Lehane grades 3 or 4 during direct laryngoscopy. METHODS: Ultrasound measurements were performed preoperatively in 25 patients with morbid obesity, measuring the HMD in the neutral, ramped, and maximum hyperextended positions. Pre-epyglotic soft tissue thickness, Mallampati and upper lip bite test scores were recorded. Cormack-Lehane grading was considered as an outcome variable in the Receiver Operating Characteristics curve analysis. RESULTS: HMD in the neutral, ramped and maximum hyperextended positions presented similar sensitivities, 100% [39.8-100.0]. For HMD, specificity was 42.86% [21.8-66.0] in the neutral position, 61.9% [38.4-81.9] in the ramped postion, and 71.4% [47.8-88.7] in the maximum hyperextended position. For HMDR1, the cut-off value was 1.12. This threshold provides 75% [19.4-99.4] sensitivity and 76.2% [52.8-91.8] specificity. For HMDR2, a cut-off value of 1.23 provides 100% [39.8-100.0] sensitivity and 90.5% [69.6-98.8] specificity. CONCLUSION: HMDR2 seems to have superior diagnostic accuracy in predicting difficult laryngoscopy in the obese population compared to HMDR1, as well as compared to the HMD in the neutral, ramped, and maximum hyperextended positions.

Dose monitoring using the DICOM structured report: assessment of the relationship between cumulative radiation exposure and BMI in abdominal CT.

AIM: To perform a systematic, large-scale analysis using the Digital Imaging and Communication in Medicine structured report (DICOM-SR) to assess the relationship between body mass index (BMI) and radiation exposure in abdominal CT. MATERIALS AND METHODS: A retrospective analysis of DICOM-SR of 3121 abdominal CT examinations between April 2013 and March 2014 was performed. All examinations were conducted using a 128 row CT system. Patients (mean age 61 ± 15 years) were divided into five groups according to their BMI: group A <20 kg/m(2) (underweight), group B 20-25 kg/m(2) (normal weight), group C 25-30 kg/m(2) (overweight), group D 30-35 kg/m(2) (obese), and group E > 35 kg/m(2) (extremely obese). CT dose index (CTDIvol) and dose-length product (DLP) were compared between all groups and matched to national diagnostic reference values. RESULTS: The mean CTDIvol and DLP were 5.4 ± 2.9 mGy and 243 ± 153 mGy.cm in group A, 6 ± 3.6 mGy and 264 ± 179 mGy.cm in group B, 7 ± 3.6 mGy and 320 ± 180 mGy.cm in group C, 8.1 ± 5.2 mGy and 375 ± 306 mGy.cm in group D, and 10 ± 8 mGy and 476 ± 403 mGy.cm in group E, respectively. Except for group A versus group B, CTDIvol and DLP differed significantly between all groups (p<0.05). Significantly more CTDIvol values exceeded national diagnostic reference values in groups D and E (2.1% and 6.3%) compared to group B (0.5%, p<0.05). CONCLUSION: DICOM-SR is a comprehensive, fast, and reproducible way to analyse dose-related data at CT. It allows for automated evaluation of radiation dose in a large study population. Dose exposition is related to the patient's BMI and is increased by up to 96% for extremely obese patients undergoing abdominal CT.

The utility of routine postoperative upper gastrointestinal swallow studies following laparoscopic sleeve gastrectomy.

Laparoscopic sleeve gastrectomy (LSG) has grown in popularity in recent years for the treatment of morbid obesity. Controversy exists regarding the usefulness of upper gastrointestinal (UGI) swallow studies on the first postoperative day in detecting possible complications. The aim of our study was to determine the efficacy and cost benefit of routine UGI studies on the first postoperative day following LSG. We retrospectively reviewed the hospital's records to identify patients who underwent LSG between January 2012 and June 2013. All patients had iodine-based contrast swallow study on the first postoperative day. Reports from all imaging studies and medical files were retrospectively reviewed, and complications were recorded. The Institutional Review Board waived the requirement for informed consent. During the study period, 722 patients underwent LSG. Mean BMI was 43 kg/m(2) (range 25-70). Of the 722 UGI studies, 721 were normal. The 1 abnormal study showed complete obstruction due to an incarcerated hiatal hernia. Five patients presented with a leak (0.7%). UGI swallow studies failed to detect any of the leaks resulting in a sensitivity of 0%. All leaks were apparent on computed tomography (CT) scans on postoperative days 2, 5, 7, 23, and 90. The total cost of the UGI swallow studies was $180,500. Performing routine UGI studies on the first postoperative day following LSG is clearly not cost beneficial. UGI contrast studies are not efficient to screen for suture line leaks. We recommend obtaining a CT scan when there is clinical suspicion for a complication.

Feasibility and prognostic value of stress echocardiography in obese, morbidly obese, and super obese patients referred for bariatric surgery.

BACKGROUND: Stress echocardiography (SE) is clinically used in the risk stratification and prognosis of patients with coronary artery disease. Due to multiple comorbidities, obese patients have increased risk of adverse cardiovascular events perioperatively in noncardiac surgery. The aim of this study was to investigate the feasibility of SE in morbidly obese patients undergoing bariatric surgery. METHODS: Consecutive patients referred for SE for preoperative evaluation prior to bariatric surgery from January 2002 to July 2011 formed the study cohort. Contrast was used to define the endocardial border in patients with poor acoustic windows. All-cause mortality data were obtained from Social Security Death Index. RESULTS: Six hundred fifty-two patients (47 ± 10 years, 84% females) with the mean follow-up of 3.0 ± 2.7 years and mean body mass index (BMI) of 47 ± 9 kg/m² were included in this analysis. Dobutamine SE was performed in 65% of patients compared to exercise SE in 35%. Patients with higher BMI were more likely to undergo dobutamine SE (P < 0.0001). Similarly, incidence of poor acoustic windows and contrast use was higher in those with increased BMI (P < 0.001). Contrast use was higher in patients undergoing dobutamine SE (39%) versus exercise (25%), (P = 0.002). 19 patients (3%) had an abnormal SE and 8 patients (1.2%) died during the follow-up period. CONCLUSION: Stress echocardiography is feasible in the morbidly obese patients. Patients with higher BMI were more likely to undergo dobutamine SE and have higher incidence of poor acoustic windows and contrast use.

In vivo precision of the GE lunar iDXA for the assessment of lumbar spine, total hip, femoral neck, and total body bone mineral density in severely obese patients.

No study has evaluated the precision of the GE Lunar iDXATM (GE Healthcare) in measuring bone mineral density (BMD) among severely obese patients. The purpose of the study was to evaluate the precision of the GE Lunar iDXATM for assessing BMD, including the lumbar spine L1-L4, L2-L4, the total hip, femoral neck, and total body in a severely obese population (body mass index [BMI]>40 kg/m(2)). Sixty-four severely obese participants with a mean age of 46 ± 11 yr, BMI of 49 ± 6 kg/m(2), and a mean body mass of 136.8 ± 20.4 kg took part in this investigation. Two consecutive iDXA scans (with repositioning) of the total body (total body BMD [TBBMD]), lumbar spine (L1-L4 and L2-L4), total hip (total hip BMD [THBMD]), and femoral neck (femoral neck BMD [FNBMD]) were conducted for each participant. The coefficient of variation (CV), the root mean square (RMS) averages of standard deviations of repeated measurements, the corresponding 95% least significant change, and intraclass correlations (ICCs) were calculated. In addition, analysis of bias and coefficients of repeatability were calculated. The results showed a high level of precision for total body (TBBMD), lumbar spine (L1-L4), and total hip (THBMD) with values of RMS: 0.013, 0.014, and 0.011 g/cm(2); CV: 0.97%, 1.05%, and 0.99%, respectively. Precision error for the femoral neck was 2.34% (RMS: 0.025 g/cm(2)) but still represented high reproducibility. ICCs in all dual-energy X-ray absorptiometry measurements were 0.99 with FNBMD having the lowest at 0.98. Coefficients of repeatability for THBMD, FNBMD, L1-L4, L2-L4, and TBBMD were 0.0312, 0.0688, 0.0383, 0.0493, and 0.0312 g/cm(2), respectively. The Lunar iDXA demonstrated excellent precision for BMD measurements and is the first study to assess reproducibility of the GE Lunar iDXA with severely obese adults.

Assessment of abdominal fat compartments using DXA in premenopausal women from anorexia nervosa to morbid obesity.

OBJECTIVE: To test a newly developed dual energy X-ray absorptiometry (DXA) method for abdominal fat depot quantification in subjects with anorexia nervosa (AN), normal weight, and obesity using CT as a gold standard. DESIGN AND METHODS: 135 premenopausal women (overweight/obese: n = 89, normal-weight: n = 27, AN: n = 19); abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT) areas determined on CT and DXA. RESULTS: There were strong correlations between DXA and CT measurements of abdominal fat compartments in all groups with the strongest correlation coefficients in the normal-weight and overweight/obese groups. Correlations of DXA and CT VAT measurements were strongest in the obese group and weakest in the AN group. DXA abdominal fat depots were higher in all groups compared to CT, with the largest % mean difference in the AN group and smallest in the obese group. CONCLUSION: A new DXA technique is able to assess abdominal fat compartments including VAT in premenopausal women across a large weight spectrum. However, DXA measurements of abdominal fat were higher than CT, and this percent bias was most pronounced in the AN subjects and decreased with increasing weight, suggesting that this technique may be more useful in obese individuals.

Validation of ultrasound examination for assessment of the abdominal visceral fat in clinically serious obese patient.

BACKGROUND: Computerized tomography is the gold-standard for measurement of abdominal visceral fat. However, it is costly and involves submitting patients to ionizing radiation. AIM: To validate the use of ultrasonography in assessing abdominal visceral fat among clinically serious obese patients of both genders. METHODS: The sample included adult patients with clinically serious obesity with body mass index of 40 kg/m2 or from 35 kg/m(2) to 40 kg/m2 with co-morbidities. Abdominal visceral fat thickness was measured using ultrasound and tomography. Two ultrasonographic exams were conducted to assess the interobserver reproducibility among a patient subsample. Validation was done by comparing these results with the tomographic findings. RESULTS: The study included 13 patients (61.54% female) with an average BMI of 38.82 kg/m2. In terms of validation, the result obtained from applying the Pearson correlation coefficient was equal to 0.94 (p = 0.0005), showing a strong positive correlation between the two measurements. As for the results for reproducibility, the interobserver was equal to 0.822, with a confidence interval of 95% (-0.076 to 0.980), revealing good interobserver agreement. The average difference between the two ultrasound interobserver examination was equal to 0.10 ± 1.51 (p=0.8898) and so not significant. Interobserver bias was also not significant. CONCLUSION: The validation of ultrasonographic examination to replace tomographic method in assessing abdominal visceral fat among clinically serious obese patients was effective. The ultrasound measurement is independent of the examiner.

Submandibular sonography: assessment of hyomental distances and ratio, tongue size, and floor of the mouth musculature using portable sonography.

OBJECTIVES: The aim of this study was to evaluate the feasibility of sonography as a tool to measure the hyomental distance ratio and tongue size in obese patients with a large neck circumference. The hyomental distance ratio is a predictor of difficult laryngoscopy that may result in difficult intubation. METHODS: Five obese and 7 morbidly obese adult patients with a history of either difficult or easy intubation had a submandibular sonographic examination performed in the supine position. The hyomental distance was measured while the head was placed in the neutral position and then in a hyperextended position, and the ratio of two distances (hyomental distance ratio) was calculated. Their tongue volumes were derived from multiplication of the midsagittal cross-sectional area of the tongue by its width obtained from transverse sonograms. RESULTS: The mean hyomental distance ratios ± SD in 6 patients with difficult intubation and 6 with easy intubation were 1.02 ± 0.01 and 1.14 ± 0.02 (P < .002), respectively. Tongue volumes did not differ statistically between the two groups: 137 ± 29 cm(3) (difficult intubation) and 168 ± 34 cm(3) (easy intubation). The mean body mass indices were 36.3 ± 6.0 and 43.2 ± 7.2 kg/m(2) in the difficult and easy intubation groups. The mean neck circumferences were 44.5 ± 7.4 and 46.8 ± 7.0 cm in the difficult and easy intubation groups. CONCLUSIONS: Sonography allows bedside measurements of the hyomental distance ratio and tongue size in morbidly obese patients. Preoperative assessment of the hyomental distance ratio may predict difficult laryngoscopy resulting in difficult intubation.

Imaging in bariatric surgery: service set-up, post-operative anatomy and complications.

Obesity is an increasingly prevalent and costly problem faced by the healthcare system. The role of bariatric surgery in managing obesity has also increased with evidence showing a reduction in long-term morbidity and mortality. There are unique challenges faced by the radiology department in providing an imaging service for this population of patients, from technical and staffing requirements through to the interpretation of challenging post-surgical images. We describe these challenges and provide an overview of the most frequently performed procedures, normal post-operative imaging findings and the appearance of common complications.

Virtual three-dimensional computed tomography assessment of the gastric pouch following laparoscopic Roux-Y gastric bypass.

BACKGROUND: The construction of the gastric pouch during surgery is largely based on the prevailing dogma of Roux-Y gastric bypass (RYGB) surgery. The scarce data that exist suggest that the smaller the gastric pouch, the greater the weight loss after surgery. Current estimations of pouch volume have inherent limitations. We describe the use of virtual three-dimensional computed tomography (3D CT) to assess pouch volume in the immediate postoperative period. METHODS: We performed 3D CT on three patients 1 day after laparoscopic RYGB using a 16-channel multidetector CT scan. Effervescent granules were administered, along with 1 oz of water, orally to achieve gastric pouch distension. Transaxial images were transferred to the 3D workstation (Vitrea, Vital Images, Inc.) and endoluminal views of the gastric pouch were generated with perspective volume rendering. Pouch area was also measured from the standard postoperative upper gastrointestinal (UGI) contrast study. RESULTS: All three patients were female, with a mean preoperative body mass index (BMI) of 43.7 kg/m(2) and a mean age of 44.3 years. Mean pouch height was 4.07 cm, mean pouch width was 3.79 cm, and mean pouch depth was 2.1 cm. The mean calculated pouch volume was 31.6 cm(3). The calculated pouch area using 3D CT was statistically indistinct from the pouch area calculated using the UGI study (15.2 cm(2) vs 16.9 cm(2); p = 0.549.) CONCLUSION: For the first time, we describe the use of 3D CT to accurately measure postoperative pouch volume. In addition, we were able to confirm the utility of area (postoperative UGI) as an accurate surrogate for pouch volume.

SPECT myocardial perfusion imaging in morbidly obese patients: image quality, hemodynamic response to pharmacologic stress, and diagnostic and prognostic value.

BACKGROUND: Obesity is a growing epidemic in the United States, and little is known about the characteristics of the morbidly obese population (body mass index [BMI] > or = 40 kg/m2) undergoing stress myocardial perfusion imaging (MPI). METHODS AND RESULTS: We retrospectively reviewed all consecutive morbidly obese patients without known coronary artery disease presenting for a clinically indicated technetium 99m (Tc-99m) gated stress single photon emission computed tomography imaging study over a 42-month period. Studies were analyzed for image quality, for the contribution of attenuation correction to image interpretation, and for the hemodynamic response to pharmacologic stress. In patients who subsequently had cardiac catheterization, the results were compared with those from the initial MPI study, and the Social Security Death Index and hospital medical records were searched to the assess survival rate in the entire cohort. A total of 433 patients were identified with a mean BMI of 47.3 +/- 8 kg/m2 and a mean Tc-99m stress dose of 35.6 +/- 5.4 mCi. Image quality was good in 61% of the patients, adequate in 37%, and poor in 2%. It was found to be dependent on the stressor used (better with exercise) but did not correlate with increasing weight or BMI. Attenuation correction was used in 95% of the studies reviewed and was helpful for image interpretation in 60%. The heart rate response to dipyridamole and adenosine was more pronounced and the blood pressure response to dipyridamole was less pronounced in morbidly obese patients compared with nonobese control patients. In the 43 patients who underwent catheterization, stress MPI had a sensitivity of 95% and negative predictive value of 80%. Kaplan-Meier survival analysis at 1 year showed a significant difference in survival rate of 98.3% for normal MPI studies and 94.0% for abnormal MPI studies (P = .02). CONCLUSION: Diagnostic-quality single photon emission computed tomography imaging is feasible in the majority (98%) of morbidly obese patients with the use of a dual-head camera, attenuation correction, and high stress Tc-99m tracer doses. Exercise stress was associated with better image quality. The prognostic value of a normal MPI study in this population appears to be less favorable than in non-morbidly obese patients.

The workup for bariatric surgery does not require a routine upper gastrointestinal series.

BACKGROUND: Morbid obesity is a serious disease that afflicts over five million Americans, threatening their health with such co-morbidities as diabetes, arthritis, pulmonary failure and stroke. Surgery is the only effective therapy, providing long-term control of weight, diabetes, pulmonary failure, and hypertension for as long as 14 years. Because the operation presents a major expense, this study examined whether X-ray examination of the gut could be omitted safely as a cost-saving measure. METHODS: The records of 814 consecutive morbidly obese patients who underwent gastric bypass were reviewed to determine: (1) whether these individuals had undergone an upper gastro-intestinal (GI) series, and (2) if these studies influenced therapy or caused cancellation or postponement of surgery. RESULTS: Of the 814 patients, 657 (80.7%) underwent a preoperative GI radiography. Of these examinations, 393 (59.8%) were normal, with the following abnormalities in the remaining 264: hiatal hernia, 164; esophageal reflux, 39; Schatzki's ring, 18; small bowel diverticula, four; renal stones, four; malrotation, three; gall stones, two; pyloric ulcer, one; possible pelvic mass, one; calcified leiomyoma, one; and dysphagial lusoria, one. None of these findings resulted in cancellation or a delay in surgery. CONCLUSIONS: The upper GI series can be safely omitted from the routine preoperative evaluation of patients undergoing gastric bypass. At a cost of $741.00 per examination, this change represents significant potential savings. Similar evaluations of other routine preoperative tests may well provide a better basis for the evaluation of these complex patients.

Assessment of cardiac function in patients who were morbidly obese.

Cardiac function of 30 patients who were morbidly obese was studied before bariatric surgery. Twelve patients were studied 13 +/- 4 months after surgery. These patients had a mean age of 37.1 +/- 2.9 years and a body mass index of 50.0 +/- 1.4 kg/m2. Cardiac function was measured by echocardiography, radionuclide angiography scanning, and right heart catheterization. To determine the degree of cardiac dysfunction, the patients were studied with exercise and intravenous fluid challenges. Ultrasonography produced evidence of myocardial thickening with an increased interventricular septum in eight patients (32%) and increased left ventricular mass in 17 patients (53%). The radionuclide scan suggested that morbid obesity was associated with a significantly (p less than 0.05) increased end-diastolic volume and decreased left ventricular ejection fraction as compared with patients who were of normal weight. With exercise the patient who was of normal weight had an increase in the end-diastolic volume, stroke volume, and heart rate, but the patient who was morbidly obese only increased heart rate to produce the necessary increase in cardiac output. Right heart catheterization indicated that the relationship of the pulmonary wedge pressure and the left ventricular stroke work index was abnormal in 14 of 29 patients (48.3%) and depressed in six of 29 patients (20.7%) with exercise. One liter of fluid caused an abnormal relationship of the pulmonary wedge pressure and the left ventricular stroke work index in 12 of 30 patients (40%) and a depressed response in 10 of 30 patients (33.3%). Cardiac studies were repeated in 12 patients after a 54.8 +/- 1.9 kg weight loss. Echocardiography indicated a decrease in dilatation (27.3% to 9.1%) and a significant (p less than 0.05) decrease in hypertrophy (45.5% to 0%). After the weight loss, radionuclide and right heart catheterization studies indicated improved cardiac function with reduced filling pressures and increased left ventricular work during fluid and exercise challenges. These results support the presence of obesity-related cardiomyopathy with ventricular dysfunction, which appears to be caused by a noncompliant ventricle. Significant weight loss achieved with gastroplasty results in increased ventricular compliance and improved cardiac function.