Biomedical subjects
Publications and source records attributed to L Wexler.
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BACKGROUND: Theophylline has been used to treat central apnea associated with Cheyne-Stokes respiration (periodic breathing). We studied the effect of short-term oral theophylline therapy on periodic breathing associated with stable heart failure due to systolic dysfunction. METHODS: Fifteen men with compensated heart failure (left ventricular ejection fraction, 45 percent or less) participated in the study. Their base-line polysomnograms showed periodic breathing, with more than 10 episodes of apnea and hypopnea per hour. In a double-blind crossover study, the patients received theophylline or placebo orally twice daily for five days, with one week of washout between the two periods. RESULTS: After five days of treatment, the mean (+/-SD) plasma theophylline concentration was 11 +/- 2 microgram per milliliter. Theophylline therapy resulted in significant decreases in the number of episodes of apnea and hypopnea per hour (18 +/- 17, vs. 37 +/- 23 with placebo and 47 +/- 21 at base line; P<0.001), the number of episodes of central apnea per hour (6 +/- 14, vs. 26 +/- 21 and 26 +/- 20, respectively; P<0.001), and the percentage of total sleep time during which the arterial oxyhemoglobin saturation was less than 90 percent (6 +/- 11 percent, vs., 23 +/- 37 and 14 +/- 14 percent, respectively; P<0.04). There were no significant differences in the characteristics of sleep, the frequency of ventricular arrhythmias, daytime arterial-blood gas values, or the left ventricular ejection fraction during the base-line, placebo, and theophylline phases of the study. CONCLUSIONS: In patients with stable heart failure, oral theophylline therapy reduced the number of episodes of apnea and hypopnea and the duration of arterial oxyhemoglobin desaturation during sleep.
OBJECTIVE: To determine the prevalence and effect of sleep-disordered breathing in ambulatory patients with stable, optimally treated congestive heart failure. DESIGN: A prospective, longitudinal study. SETTING: Referral sleep laboratory of a Department of Veterans Affairs medical center. PATIENTS: 42 of the 48 eligible patients with stable congestive heart failure and left ventricular systolic dysfunction (left ventricular ejection fraction < or = 45%). MEASUREMENTS: After an adaptation night, polysomnography and Holter monitoring were done in the sleep laboratory. Arterial blood gases and pH were measured, and cardiac radionuclide ventriculography and pulmonary, renal, and thyroid function tests were done. RESULTS: Patients were divided into two groups. Group I (n = 23) had an hourly rate of apnea and hypopnea (apnea-hypopnea index) of 20 episodes per hour or less; group II (n = 19 [45%; CI, 30% to 60%]) had an index of more than 20 episodes per hour. In group II, the index varied from 26.5 to 82.2 episodes per hour (mean +/- SD, 44 +/- 13 episodes per hour; CI, 38 to 51 episodes per hour). Group II had significantly more arousals (24 +/- 12 compared with 3 +/- 3 in group I) that were directly attributable to episodes of apnea and hypopnea, longer periods of time with an arterial oxyhemoglobin saturation of less than 90% (23% +/- 24% of total sleep time compared with 2% +/- 4%), lower arterial oxyhemoglobin saturation during sleep (74% +/- 13% compared with 87% +/- 4%), lower left ventricular ejection fraction (22% +/- 9% compared with 30% +/- 10%), and a significantly increased number of episodes of nocturnal ventricular arrhythmias. Multiple regression analyses showed that left ventricular systolic dysfunction was an independent risk factor for sleep apnea in patients with congestive heart failure. CONCLUSIONS: The prevalence of severe occult sleep-disordered breathing is high in ambulatory patients with stable, optimally treated chronic congestive heart failure. The breathing episodes are associated with severe nocturnal arterial blood oxyhemoglobin desaturation and excessive arousals. Severe untreated sleep-disordered breathing may adversely affect left ventricular function, resulting in a vicious cycle that could contribute to death in patients with congestive heart failure. Prospective, longitudinal studies on survival are needed.
The incidence of nephrotoxicity occurring with the nonionic contrast agent, iohexol, and the ionic contrast agent, meglumine/sodium diatrizoate, was compared in 1196 patients undergoing cardiac angiography in a prospective, randomized, double-blind multicenter trial. Patients were stratified into four groups: renal insufficiency (RI), diabetes mellitus (DM) both absent (N = 364); RI absent, DM present (N = 318); RI present, DM absent (N = 298); and RI and DM both present (N = 216). Serum creatinine levels were measured at -18 to 24, 0, and 24, 48, and 72 hours following contrast administration. Prophylactic hydration was administered pre- and post-angiography. Acute nephrotoxicity (increase in serum creatinine of > or = 1 mg/dl 48 to 72 hours post-contrast) was observed in 42 (7%) patients receiving diatrizoate compared to 19 (3%) patients receiving iohexol, P < 0.002. Differences in nephrotoxicity between the two contrast groups were confined to patients with RI alone or combined with DM. In a multivariate analysis, baseline serum creatinine, male gender, DM, volume of contrast agent, and RI were independently related to the risk of nephrotoxicity. Patients with RI receiving diatrizoate were 3.3 times as likely to develop acute nephrotoxicity compared to those receiving iohexol. Clinically severe adverse renal events were uncommon (N = 15) and did not differ in incidence between contrast groups (iohexol N = 6; diatrizoate N = 9). In conclusion, in patients undergoing cardiac angiography, only those with pre-existing RI alone or combined with DM are at higher risk for acute contrast nephrotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
Magnetic resonance (MR) imaging techniques have evolved sufficiently to produce clinically relevant studies that depict the anatomy and physiology of the heart. Applications to congenital cardiac disease in adult patients are numerous. MR imaging is particularly useful for noninvasive evaluation of the aorta in patients with aortic arch anomalies and coarctations and to study the results of palliative and corrective surgery for transposition of the great arteries and for reconstructive procedures that restore sufficient pulmonary blood flow. MR imaging is superior to transthoracic echocardiography in defining the anatomy of the central pulmonary arteries. Recent technological advances permit motion studies acquired during a single breath-hold and can be used to accurately measure stroke volume, ejection fraction, regional wall motion, and wall thickening from both ventricles. Functional parameters, such as the velocity and volume of blood flow in vessels, valve gradients, regurgitant flow, shunt flow, and pulmonary artery blood flow into each lung are readily performed. This review article documents the value of MR imaging in adult patients with congenital disorders of the heart, pulmonary arteries, and aorta, and includes illustrations of typical examples.
Palliative and corrective operations for the treatment of cyanotic congenital heart disease frequently involve or potentially influence the size of the pulmonary arteries. Echocardiography and magnetic resonance imaging (MRI) are two noninvasive imaging techniques currently used to assess morphologic abnormalities of the pulmonary arteries. The purpose of this study was to evaluate the role of MRI in comparison with echocardiography for defining morphologic changes of the pulmonary arteries after congenital heart surgery. The MRI scans and echocardiograms of 33 patients with surgery involving or affecting the pulmonary arteries were compared. The pulmonary outflow tract, pulmonary confluence, right and left pulmonary arteries, and surgical shunts were separately evaluated. Cineangiography and surgical reports were used to confirm findings. MRI and echocardiography were equivalent for demonstrating abnormalities of the right ventricular outflow tract, main pulmonary artery, and a variety of pulmonary shunts. MRI was superior to echocardiography in demonstrating abnormalities of the right and left pulmonary arterial branches (p < 0.001). MRI is effective for monitoring pulmonary arterial status after surgery and is superior to echocardiography for the evaluation of the right and left pulmonary arteries.
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RATIONALE AND OBJECTIVES: Low-osmolality contrast agents, ionic and nonionic, are being used more frequently in coronary arteriography. A new nonionic contrast agent, iopromide, has recently become available for use in clinical trials. The purpose of this phase II-phase III Food and Drug Administration (FDA) trial was to compare the side effects and diagnostic quality of iopromide with iohexol and iopamidol for coronary arteriography and left ventriculography. METHODS: Two separate double-blind trials were performed using iopromide and comparison nonionic contrast agents. In the first trial, 41 patients were randomized to receive iopromide or iopamidol. The second trial was a three-center trial involving 120 patients, of whom half received iopromide (370 mg I/mL) and the other half received iohexol (350 mg I/mL). In a third study, 26 patients received iopromide (370 mg I/mL) according to an open-label design. RESULTS: Comparison of iopromide with the other agents revealed that there were no significant differences in adverse events between iopromide and the comparison agents. Most adverse reactions were mild or moderate in severity in all patient groups. There was no difference in the patients' perceptions of heat and pain and no statistically significant difference in systolic or diastolic blood pressure at baseline, at 30 to 60 minutes, or at 24 hours after the procedure. No difference was found in the biochemical or hematologic analysis at baseline or at 24-hour follow-up. No difference between the contrast media groups in terms of the quality of the left ventriculogram or the quality of the coronary arteriography was noted. CONCLUSION: Compared to the other nonionic agents, iopromide showed no statistically significant differences in terms of safety or efficacy.
Some patients with congenital cardiac anomalies develop their first symptoms as adults, and many more will survive to adulthood with congenital lesions that have been treated surgically. Magnetic resonance imaging (MRI) currently provides sufficient morphological information to allow the anatomical diagnosis of congenital abnormalities involving the heart and the great arteries. Newer MR techniques have also been developed that provide functional information such as measurements of valve gradients, stroke volumes, regurgitant volumes, and shunt volumes. Cardiac evaluation utilizing MR techniques may soon replace cardiac catheterization for the preoperative diagnosis of congenital heart disease and its long-term follow-up.
PURPOSE: To evaluate the accuracy of computed tomographic (CT) angiography in the detection of renal artery stenosis (RAS). MATERIALS AND METHODS: CT angiography was performed in 31 patients undergoing conventional renal arteriography. CT angiographic data were reconstructed with shaded surface display (SSD) and maximum-intensity projection (MIP). Stenosis was graded with a four-point scale (grades 0-3). The presence of mural calcification, poststenotic dilatation, and nephrographic abnormalities was also noted. RESULTS: CT angiography depicted all main (n = 62) and accessory (n = 11) renal arteries that were seen at conventional arteriography. MIP CT angiography was 92% sensitive and 83% specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). SSD CT angiography was 59% sensitive and 82% specific for the detection of grade 2-3 stenoses. The accuracy of stenosis grading was 80% with MIP and 55% with SSD CT angiography. Poststenotic dilatation and the presence of an abnormal nephrogram were 85% and 98% specific, respectively. CONCLUSION: CT angiography shows promise in the diagnosis of RAS. The accuracy of CT angiography varies with the three-dimensional rendering technique employed.
Contrast agents used for cardiac angiography are different in regard to ionicity, osmolality and physiologic effects. The nonionic contrast media have been shown to have less toxic effects and a better safety profile than do higher osmolar agents. To better assess this risk, clinically stable patients undergoing cardiac angiography were stratified according to the presence of diabetes mellitus, and level of serum creatinine, and then randomized to receive either iohexol (Omnipaque 350) or sodium meglumine diatrizoate (Renografin 76). All adverse events that occurred during and immediately after angiography were tabulated. A multivariate model was used to identify patients at increased risk for adverse outcome. The 1,390 patients were randomized to iohexol (n = 696) or diatrizoate (n = 694). Significant differences were found in the number of patients with contrast media-related adverse (iohexol vs diatrizoate: 10.2 vs 31.6%; p < 0.001) and cardiac adverse (7.2 vs 24.5%; p < 0.001) events. Severe reactions and the need for treatment were more frequent with diatrizoate than with iohexol, but there was no difference in the incidence of death. The presence of New York Heart Association classification 3 or 4 and serum creatinine > or = 1.5 mg/dl predicted a higher incidence of adverse events as a result of contrast media alone. Use of iohexol is associated with a lower incidence of all types of adverse events during cardiac angiography than is diatrizoate.
Data on disease severity, co-morbidity, and process of care were obtained from the medical records of 356 patients without rheumatoid arthritis undergoing a first unilateral total hip replacement at four teaching hospitals in California and Massachusetts. Socio-demographic characteristics, functional status prior and subsequent to hospitalization, and improvement in health status were measured with a patient questionnaire 12 months after discharge. Completed questionnaires were received from 284 patients, a response rate of 79.8%. The questionnaire was acceptable to patients, reliable, and had good construct validity. The data indicate substantial benefits from hip arthroplasty. As expected, pre-surgical functioning was a strong predictor of outcomes 1 year after surgery. Controlling for pre-surgical functioning, age was not related to outcomes.
Each trainee in vascular medicine must be eligible for the board certification examination of the American Board of Internal Medicine or its equivalent. Training faculty, preferably at least two members, should meet the qualifications and training requirements described in this report. They must be dedicated, effective teachers and should spend most of their time in research, education and patient care related to peripheral vascular diseases. A curriculum of training should be established. Faculty experts in related specialties and in the related basic sciences should be available for teaching. The institution should have a fully equipped noninvasive vascular laboratory and areas where catheter revascularization techniques and vascular surgery are performed. The period of training should not be less than 1 year, preferably continuous.
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RATIONALE AND OBJECTIVES: A number of pressures have taken their toll on cardiovascular (CV) imaging in radiology. We conducted a survey to develop accurate information about the current status of cardiac radiology (CR) that might guide future responses and initiatives. METHODS: To assess the current status of CR, a survey form was sent to all 117 active radiologist members of the North American Society for Cardiac Imaging (N = 72) and/or the Council on Cardiovascular Radiology of the American Heart Association (N = 98). The topics of inquiry included 1) present CR staffing; 2) specific adult and pediatric CR activities (cardiac plain-film interpretation, cardio-angiography (CA), echocardiography, nuclear cardiology (NC), and CV magnetic resonance imaging (MRI); 3) CR instruction of radiology residents; and 4) CR fellowship activities. RESULTS: The survey was concluded with 64 (55%) individual responses from 58 (67%) different centers with CR groups. An overall need for CR staff (average unfilled positions/center = 0.4) was indicated. Regarding CR activities, the following were reported: 1) universal cardiac plain-film interpretation by radiologists, with most CR groups involved (adult, 64%; pediatric, 64%); 2) moderate CR contributions to CA (adult, 62%; pediatric, 57%), of which cine interpretation was the most common form (79% and 85%, respectively); 3) rare CR involvement in echocardiography (adult, 9%; pediatric, 6%); 4) low-level CR involvement in NC (adult, 16%; pediatric, 17%), but high level when combined with that of nuclear medicine (93% and 91%, respectively); and 5) almost universal radiology responsibility for CV MRI (adult, 96%; pediatric, 96%), with extensive CR involvement (77% and 82%, respectively). Of 46 reporting academic centers, most (76%) required CR training of residents; a smaller proportion (33%) of all centers offered CR fellowships. CONCLUSIONS: Because of the insights gained from this survey, recommendations can be better made to strengthen CR based on a foundation in plain-film interpretation, computed tomography, NC, and MRI.
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Cardiac catheterization and angiography is a safe procedure performed on patients with suspected or potentially serious cardiovascular disorders. Complications of the procedure are related both to heart disease itself and to elements of the procedure. For a variety of social and financial reasons, the performance of cardiac catheterization and coronary angiography on an outpatient basis has increased recently. The purpose of this paper is to state the guidelines of The Society for Cardiac Angiography and Interventions regarding the performance of outpatient catheterization in a hospital setting.
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