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Biomedical subjects

W K Freeman

Publications and source records attributed to W K Freeman.

33 records · Page 2Linked to original sources
PubMed1991

Cardiac surgery in the octogenarian: perioperative outcome and clinical follow-up.

The perioperative and follow-up results of cardiac operations employing extracorporeal circulation and cold cardioplegic arrest were examined in 191 consecutive patients greater than or equal to 80 years of age having surgery over a 5 year period (1982 to 1986). Most patients had severe preoperative symptoms with functional class III (39.8%) or IV (57.1%) limitation. The overall 30 day postoperative cardiac mortality rate was 15.7%. The total in-hospital mortality rate was 18.8%; the mean postoperative hospital stay was 16.4 +/- 13.3 days. The perioperative mortality rate for elective operations was as follows: coronary artery bypass (5.6%), aortic valve replacement (9.6%), aortic valve replacement with coronary bypass (17.9%) and mitral valve surgery with or without coronary bypass (21.4%). Urgent operations were performed in 39 patients (20.4%) with a total perioperative mortality rate of 35.9%; urgent coronary artery bypass was performed in 26 patients (67%) with an in-hospital mortality rate of 23.1%. Clinical evidence of left ventricular failure, functional class IV symptoms, left ventricular ejection fraction less than 50%, mitral valve repair or replacement for severe mitral regurgitation and urgent operation were associated with an increased perioperative mortality rate. Follow-up study in all 155 patients surviving postoperative hospitalization at 22.6 +/- 14.8 months showed significant improvement in symptom status in all surgical subgroups. There were 18 follow-up deaths (11.6%); 10 were noncardiac. The actuarial survival rate of the entire study group was significantly better than that in age- and gender-matched control subjects (p = 0.037).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

Value and limitations of transesophageal echocardiography in assessment of mitral valve prostheses.

BACKGROUND: Transthoracic Doppler echocardiography examination has become an integral part of the investigations performed in patients with mitral valve prostheses. The limitations of the transthoracic approach are well documented. Transesophageal echocardiography provides a unique window for achieving a clear view of the mitral prosthesis. METHODS AND RESULTS: This study shows the usefulness of transesophageal echocardiography in clinical practice for assessment of patients with a mitral valve prosthesis. This technique demonstrated an abnormality in 48% of patients who had normal results on transthoracic examination. The overall sensitivity of transesophageal echocardiography was 96%. CONCLUSIONS: Transesophageal echocardiography constitutes an essential part of a comprehensive two-dimensional/Doppler echocardiographic examination in patients with suspected malfunction of mitral prostheses.

Adolescent↗
PubMed1990

Transesophageal echocardiography in critically ill patients.

The feasibility, safety and clinical impact of transesophageal echocardiography were evaluated in 51 critically ill intensive care unit patients (28 men and 23 women; mean age 63 years) in whom transthoracic echocardiography was inadequate. At the time of transesophageal echocardiography, 30 patients (59%) were being mechanically ventilated. Transesophageal echocardiography was performed without significant complications in 49 patients (96%), and 2 patients with heart failure had worsening of hemodynamic and respiratory difficulties after insertion of the transesophageal probe. The most frequent indication, in 25 patients (49%), was unexplained hemodynamic instability. Other indications included evaluation of mitral regurgitation severity, prosthetic valvular dysfunction, endocarditis, aortic dissection and potential donor heart. In 30 patients (59%), transesophageal echocardiography identified cardiovascular problems that could not be clearly diagnosed by transthoracic echocardiography. In the remaining patients, transesophageal echocardiography permitted confident exclusion of suspected abnormalities because of its superior imaging qualities. Cardiac surgery was prompted by transesophageal echocardiographic findings in 12 patients (24%) and these findings were confirmed at operation in all. Therefore, transesophageal echocardiography can be safely performed and has a definite role in the diagnosis and expeditious management of critically ill cardiovascular patients.

Echocardiography↗
PubMed1990

Doppler echocardiography in aortic stenosis: feasibility and clinical impact.

The clinical utility of Doppler echocardiography for the assessment of aortic stenosis was prospectively studied in 425 consecutive patients referred to the echocardiography laboratory over 1 year with the clinical diagnosis of aortic stenosis. Optimal peak Doppler velocities were obtained in 405 (95%) patients of all ages. In 108 patients, the severity of aortic stenosis as determined by subsequent cardiac catheterization was compared with that found by Doppler assessment. Categorization of severity was concordant in 8 (89%) of 9 cases of mild aortic stenosis and in 28 (78%) of 36 cases of severe aortic stenosis, but there was considerable diagnostic overlap in cases of moderate stenosis. Forty-nine patients with mild aortic stenosis as determined clinically had moderate or severe stenosis as assessed by Doppler; 7 (14%) of these patients underwent subsequent replacement of the aortic valve. Increased aortic velocity, as determined by Doppler, was associated with a significant incidence of subsequent (mean follow-up period, 22 months) cardiac events (cardiac death, aortic valvar replacement, New York Heart Association functional class III or IV). Patients with mild aortic stenosis as assessed by Doppler (peak aortic velocity less than 2.5 m/sec) had greater than 95% event-free survival at 1 year and rarely required cardiac catheterization. Conversely, only 45% of patients with severe aortic stenosis as determined by Doppler were free of a cardiovascular event at 1 year. Although the noninvasive assessment of aortic stenosis should ideally include determination of the area of the aortic valve and the mean aortic gradient by Doppler echocardiography, this is not always possible. Prognostic information derived from peak aortic velocity alone is clinically useful. It has the additional advantage that it is much less laborious and time-consuming to obtain and is obtainable in almost all (99%) patients.

Aged↗
PubMed1990

Ultrasonic aortic valve decalcification: serial Doppler echocardiographic follow-up.

Serial two-dimensional and Doppler echocardiography was performed on 61 patients who had surgical ultrasonic aortic valve decalcification for calcific aortic stenosis. The mean patient age at the time of operation was 77.4 +/- 7.0 years; 93% had moderate to severe preoperative symptomatic limitation. Compared with preoperative studies, Doppler echocardiographic evaluation before hospital discharge revealed a significant reduction in the mean aortic valve pressure gradient (45.3 +/- 16.2 to 14.4 +/- 6.5 mm Hg, p less than 0.0001) and improvement in aortic valve area (0.62 +/- 0.17 to 1.33 +/- 0.33 cm2, p less than 0.0001). There was no initial change in aortic regurgitation grade. Follow-up Doppler echocardiographic evaluation was possible in 43 patients alive at 9.3 +/- 3.9 months. A small but statistically significant trend toward aortic restenosis was found; only one patient had severe restenosis. Severe aortic regurgitation had developed in 26% of patients and moderate aortic regurgitation in 37%. Aortic valve replacement was performed in six patients (14%) with severe symptomatic aortic regurgitation. Significant deficiency in central coaptation as a result of cusp scarification and retraction appeared to be the mechanism of postdecalcification regurgitation. Attempted salvage of the native aortic valve in severe calcific stenosis by ultrasonic decalcification adequately relieves stenosis but leads to an unacceptable incidence of significant aortic regurgitation at follow-up study.

Aged↗
PubMed1990

Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications.

Clinical transesophageal echocardiography is a rapidly expanding diagnostic procedure. Conventional transesophageal endoscopes allow imaging from a single array mounted in the horizontal plane. This article introduces the clinical application of biplanar imaging, which incorporates a second orthogonal longitudinal plane. Our clinical experience with 291 patients who underwent biplanar transesophageal echocardiography is presented. The examination, technique, and resultant anatomic correlations unique to this new examination are discussed and illustrated. The anatomy is displayed in a familiar format comparable to the precordial examination. Biplanar imaging adds substantially to the comprehensive anatomic delineation of certain cardiac structures.

Adolescent↗
PubMed1990

Low pressure cardiac tamponade: diagnosis facilitated by Doppler echocardiography.

A case of low pressure cardiac tamponade is reported in which hypovolaemia altered the clinical findings of tamponade and complicated the diagnosis. Venous pressure was not raised and there was no pulsus paradoxus. In this patient, a man of 67, characteristic variations in diastolic inflow signals and the isovolumic relaxation period throughout the respiratory cycle were shown by Doppler echocardiography and led to the diagnosis of cardiac tamponade in the absence of characteristic signs and symptoms.

Aged↗
PubMed1989

Left main coronary artery disease: radionuclide angiographic function versus anatomic correlates with visual and quantitative angiographic methods.

The results of exercise radionuclide angiography in 29 patients with significant left main coronary artery stenosis were examined to correlate functional left ventricular performance with anatomic severity of left main coronary artery stenosis. Change in ejection fraction, regional wall motion, and peak ejection fraction were widely variable; none of these parameters correlated with severity of left main stenosis as assessed by visual or quantitative angiographic methods. Twenty-five patients (86%) had two or more of the following indicators of ischemia with exercise: chest pain, significant ST-segment depression, systolic hypotension, definite decrease in ejection fraction, or definite decline in regional wall motion. However, four patients (14%) had only mild abnormalities in ejection fraction and regional wall motion, although they did have hemodynamic and electrocardiographic evidence of severe ischemia. Exercise radionuclide angiography yields heterogeneous results in patients with significant left main coronary artery stenosis. Anatomically severe left main coronary artery stenosis is not always associated with mechanical evidence of severe ischemia.

Adult↗
PubMed1989

Preoperative assessment of cardiac patients undergoing noncardiac surgical procedures.

A careful clinical history and physical examination are the most important components of the preoperative assessment of the cardiac patient who is to undergo a noncardiac surgical procedure. From these factors and the nature of the surgical procedure planned, a reasonable estimate of potential cardiac risk can be formulated to guide judicious preoperative testing for further definition of potentially high-risk patients. The potential risks associated with an invasive cardiac procedure or surgical intervention must always be considered along with the potential benefits of such a procedure in an attempt to reduce the cardiac risk of noncardiac operations. Aggressive and conscientious preoperative assessment and perioperative care of the high-risk patient by the concerted efforts of the medical consultant, anesthesiologist, and surgeon may substantially diminish cardiac-related morbidity and mortality during noncardiac surgical procedures.

Aged↗
PubMed1988

Transesophageal echocardiography: technique, anatomic correlations, implementation, and clinical applications.

The introduction of transesophageal echocardiography has provided a new acoustic window to the heart and mediastinum. High-quality images of certain cardiovascular structures [left atrial appendage, thoracic aorta, mitral valvular apparatus, and atrial septum] can be obtained readily (average examination, 15 to 20 minutes). In this article, we discuss the technique of image acquisition, image orientation, and anatomic validation. In addition, we describe our experience with the first 100 awake patients who underwent transesophageal echocardiography at our institution. The procedure was well accepted by the patients and associated with no major complications. The clinical indications for this procedure have included thoracic aortic dissection, prosthetic cardiac valve dysfunction, detection of an intracardiac source of embolism, endocarditis, cardiac and paracardiac masses, and mitral regurgitation. Transesophageal echocardiography also proved to be useful in assessment of critically ill patients in whom standard transthoracic echocardiographic images did not provide complete assessment. In these patients (who had extensive chest trauma, had undergone an operation, or were in an intensive-care unit), rapid assessment of the cardiovascular status at the bedside was possible with transesophageal echocardiography. On the basis of our initial experience, we conclude that transesophageal echocardiography complements standard two-dimensional Doppler and color flow examinations and will considerably improve the care of patients with cardiovascular disorders by providing high-quality unique images.

Aorta, Thoracic↗
PubMed1981

Effects of 5-hydroxytryptamine on neuroeffector junction in human pulmonary artery.

The effects of 5-hydroxytryptamine on release of norepinephrine and on contraction of smooth muscle in human pulmonary artery were studied. Helical strips were prepared from intra-parenchymal arteries removed 3-18 h after death. The strips were labeled with L-[7-3H]norepinephrine and mounted for superfusion and isometric tension recording. Electrical stimulation (10 V, 2 ms, 2 Hz) of the strips increased the release of total radioactivity; this release was blocked by tetrodotoxin. 5-Hydroxytryptamine (10(-5) M) exerted a cocaine-sensitive, indirect sympathomimetic effect on the overflow of norepinephrine from resting strips. This action was not blocked by methysergide. No effect of 5-hydroxytryptamine on release of norepinephrine from electrically stimulated tissue could be demonstrated. 5-Hydroxytryptamine (10(-5) M) also caused contractions of pulmonary smooth muscle, not blocked by phentolamine (10(-5) M) but mediated in part through methysergide-sensitive 5-hydroxytryptamine receptors.

Adolescent↗
PubMedDate not supplied

Severe tricuspid regurgitation after mitral valve repair: diagnosis by intraoperative transesophageal echocardiography.

Transesophageal echocardiography facilitates the evaluation of valvular repair in the operating room. The functional valvular morphology and degree of valvular regurgitation can be assessed before and after repair. This technique can also identify unsuspected findings--in this case, severe tricuspid regurgitation complicating cardiopulmonary bypass. We report a previously undescribed cause of traumatic tricuspid regurgitation.

Acute Disease↗
PubMedDate not supplied

Critical appraisal of transesophageal echocardiography: limitations, pitfalls, and complications.

Because transesophageal echocardiography is invasive, it has the potential for serious complications. Limitations occur because of the restricted transducer mobility within transducers for special situations. Pitfalls (potential erroneous diagnoses resulting from misinterpretation of normal and abnormal anatomy) are prevalent with this new technology. This report critically reviews transesophageal echocardiography and discusses and illustrates commonly encountered limitations, pitfalls, and complications.

Echocardiography↗
PubMedDate not supplied

Unruptured noncoronary sinus of Valsalva aneurysm: preoperative characterization by transesophageal echocardiography.

We describe a patient with a large unruptured sinus of Valsalva aneurysm that was discovered incidentally. Transesophageal echocardiography was used to characterize the aneurysm preoperatively, and was helpful intraoperatively in assessment of the degree of native aortic valvular regurgitation after repair. The use of transthoracic echocardiography, contrast echocardiography, Doppler echocardiography, and transesophageal echocardiography are discussed in this condition.

Adult↗