Structural evaluation of porcine heart valve prostheses with radiofrequency ultrasound.

BACKGROUND: Bioprosthetic heart valve use is limited by progressive degeneration. Early degenerative changes are often occult, making assessment of tissue integrity difficult. Ultrasound tissue characterization may detect alterations in tissue structure and allow early detection of leaflet degeneration. METHODS: Using a modified echocardiographic unit (Acuson), radiofrequency (RF) integrated backscatter amplitude (IBA) (integral/RF/dt) was measured in 38 leaflets from nine explanted and six control porcine valves. Regions of interest in each leaflet were studied using four ultrasound frequencies. Radiographic gray scale mean and leaflet thickness were measured at each region of interest. Percent collagen and mineral were calculated for each region of interest using color-image processing of histologic sections and compared to IBA. RESULTS: IBA values for control vs. explanted leaflets were (mean value+/-standard deviation): 8.2+/-4.69 dB vs. -4.7+/-4.64 dB at 7.0 MHz; -5.8+/-4.34 dB vs. -3.1+/-5.34 dB at 5.0 MHz; -3.8+/-3.38 dB vs. -2.1+/-3.18 dB at 3.5 MHz; and -9.0+/-4.58 dB vs. -7.1+/-4.25 dB at 2.5 MHz. Collagen content was 27.7+/-8.50% vs. 33.2+/-10.90%, mineral content was 0.1+/-0.10% vs. 2.1+/-4.30%, and radiographic gray scale mean was 150.6+/-1.96 vs. 145.3+/-5.14 for control vs. explanted leaflets, respectively. For control and explanted leaflets IBA, collagen content, mineral content, and radiographic gray scale mean were different (control vs. explanted P<0.05). Leaflet thickness was also noted to be different between the two groups. IBA was different among explanted leaflets with low, medium, and high mineral content. CONCLUSION: IBA was found to be a useful technique to differentiate normal from explanted porcine prosthetic valves in vitro. This method may be useful in the serial assessment of bioprosthetic leaflet degenerative properties in vivo.

Echocardiographic prevalence of mitral and/or aortic regurgitation in patients exposed to either fenfluramine-phentermine combination or to dexfenfluramine.

We evaluated the prevalence of valvular regurgitation in patients who have taken anorectic medications. Two-dimensional echocardiograms with color flow Doppler were recorded in 200 consecutive patients referred to a major metropolitan hospital for evaluation of cardiac function because of a history of anorectic medication use. Each patient filled out a questionnaire at the time of the visit or through telephone contact. Each echocardiogram was reviewed by 2 observers. The degree of valvular regurgitation was graded by a consensus of both observers. Significant valvular regurgitation was defined as at least moderate mitral regurgitation (MR) or at least mild aortic regurgitation (AR), as recommended by the Food and Drug Administration and Centers for Disease Control and Prevention. For all patients having taken anorectic drugs, there was a 5% prevalence of at least moderate MR, a 12% prevalence of at least mild AR, and a 16% prevalence of significant MR and/or AR. Patients with significant AR and/or MR were older than those without significant valvular regurgitation (49+/-12 vs 44+/-11 years, p = 0.03). Patients with significant MR and/or AR had a longer exposure duration (8 vs 6 months, p = 0.049) to anorectic drugs. There was no difference in weight loss between those with and without significant regurgitation (p = NS). The 2 largest subgroups were patients who took the fenfluramine-phentermine combination (n = 127) and those who took dexfenfluramine alone (n = 42). The prevalence of significant MR and AR was 5% and 9% for the fenfluramine-phentermine group and 0% and 14% for the dexfenfluramine group, respectively. There was also a high subthreshold level of MR and AR in these patients.

Atherosclerotic plaque evolution in the descending thoracic aorta in familial hypercholesterolemic patients. A transesophageal echo study.

We explored the concept that transesophageal echocardiography can be used as a tool to detect, characterize, and study plaque morphology in the descending thoracic aorta. The pattern of atherosclerotic plaques in the descending thoracic aorta in familial hypercholesterolemic (FH) patients was evaluated. Additionally, evolution of plaque characteristics as a result of therapy was analyzed. In a randomized prospective protocol, eight FH patients (five men and three women, aged 23 to 65 years [mean +/- SD, 42 +/- 14 years]) receiving standard therapy (n = 3; baseline low-density lipoprotein [LDL] cholesterol, 222 +/- 71 mg/dL, mean +/- SD) or LDL apheresis (n = 5; baseline LDL cholesterol, 262 +/- 51 mg/dL) were studied. Baseline and follow-up (mean, 12 months) transesophageal echocardiographic studies were performed. Measurements obtained were atherosclerotic plaque area (PA), aortic wall area (WA), total arterial area (TAA), and plaque-to-wall area ratio (PWR). LDL cholesterol decreased in both groups. The greatest severity of plaque was detected at 30 to 35 cm from the incisors (approximately 15 to 20 cm from the aortic arch). The smallest plaques were present at the arch and more distal descending aorta. In the control group, TAA, PA, and PWR did not change significantly (P = NS versus baseline). In the LDL-apheresis group, TAA increased (P < .05 versus baseline), PA decreased in three of five patients (P = NS versus baseline), and PWR fell (P < .05 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in the diagnosis of bioprosthetic valve dysfunction by transesophageal echocardiography.

Transthoracic two-dimensional echocardiography has been considered the method of choice for the non-invasive assessment of bioprosthetic valves. Recently, transesophageal echocardiography has provided a better imaging window for detecting valve abnormalities not identified otherwise, but pathologic confirmation is essential to establish the role of new diagnostic techniques in clinical practice. Therefore, the purpose of this study was to evaluate the usefulness of transesophageal echocardiography in determining the etiology of bioprosthetic valve dysfunction. Transthoracic and transesophageal two-dimensional and color-flow Doppler echocardiography were performed on 44 consecutive patients with suspected bioprosthetic dysfunction who underwent surgical intervention. At surgery a total of 63 abnormalities in 44 bioprostheses were identified: 31 (49.2%) flail cusps, 14 (22.2%) vegetations, four (6.3%) abscesses, four (6.3%) dehiscences, and 10 (15.9%) stenoses. Transesophageal echocardiography was superior to its transthoracic counterpart for the detection of flail cusps (96.7% vs. 54.8%, p < 0.01), vegetations (85.7% vs. 42.8%, p < 0.01), abscesses (100% vs. 25.0%, p < 0.05), and dehiscences (100% vs. 25.0%, p < 0.05). All patients with flail cusps had severe regurgitation as evaluated by color-flow Doppler. In bioprosthetic mitral stenosis, both methods provided accurate estimates of valve area, while in bioprosthetic aortic stenosis, transthoracic Doppler velocity measurements allowed calculation of valve area in four of six patients. In two patients with high flow velocities, the valve area was not estimated because of an inability to measure the left ventricular outflow tract dimension. Conversely, the transesophageal approach provided measurement of the outflow tract in all six patients, but Doppler velocities were not obtained in any of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathologic and angiographic correlations of transesophageal echocardiography in prosthetic heart valve dysfunction.

To determine the diagnostic accuracy of transesophageal echocardiography (TEE) in prosthetic valve dysfunction, the pathologic and/or angiographic data from 37 valves were compared with that obtained by transesophageal and transthoracic echocardiography. Of the 21 prostheses with severe regurgitation, TEE identified all 14 mitral, the five aortic, and one of the two tricuspid valves; on the other hand transthoracic echocardiography identified 2 of the 14 mitral, the five aortic, and one of the two tricuspid valves. Of the 10 prostheses with flail cusp(s), nine (90%) were correctly identified by TEE and four (40%) were correctly identified by transthoracic echocardiography. All five prostheses with paravalvular regurgitation were detected through the esophageal window and one detected through the precordial window. TEE was unable to document the two prosthetic aortic stenoses, whereas the transthoracic examination correctly quantified the gradient in one but underestimated it in the other case. Seven patients underwent valve replacement on the basis of the clinical and TEE information alone. In assessing cause, origin, and severity of prosthetic mitral regurgitation, TEE is the method of choice. In selected cases, TEE can avoid angiography and facilitate optimal timing of reoperation. In selected aortic and tricuspid dysfunction, TEE may provide additional morphologic, but limited hemodynamic information.

Plaque and structural characteristics of the descending thoracic aorta using transesophageal echocardiography.

The in vivo acoustic and structural characteristics of atherosclerosis in the descending thoracic aorta have not been well delineated. We prospectively evaluated the descending thoracic aorta of 147 patients (35 women and 112 men; age, 61 +/- 14 years) who underwent clinically indicated transesophageal echocardiography. Patients with suspected disease of the aorta were excluded. Thirty-eight patients (26%) had protruding plaques (men, 25%; women, 29%). Six patients had mobile intimal densities with the mobile area ranging up to 1 cm2. As expected, aortic lumen area was decreased (plaque-free, 3.53 cm2; plaque, 3.19 cm2; p less than 0.05) and wall area was increased (plaque-free, 1.51 cm2; plaque, 1.92 cm2; p less than 0.05) in the regions of the plaque. However, total arterial area was not increased (plaque-free, 5.04 cm2; plaque, 5.09 cm2; difference not significant) in a compensatory manner as observed in other arterial beds. Plaque gray scale was less than the gray scale of plaque-free wall (plaque-free, 141.2; plaque, 122.7; p less than 0.05) when compared at the same level of the descending thoracic aorta or with a second aortic plaque-free level (plaque-free, 150.4; plaque, 122.7; p less than 0.05). Standard deviation of gray scale level was similar between plaque and normal regions. Unsuspected protruding plaques in the descending thoracic aorta occurred in one quarter of the patients referred for routine transesophageal examination. Plaques tended to have lower echogenicity and were differentiated from plaque-free walls within patients. Plaque formation did not result in increased total arterial area. These data suggest that the degree or character of compensatory atherosclerotic remodeling in the highly elastic descending thoracic aorta may differ from other arterial beds.

Transesophageal echocardiography in the awake elderly patient: its role in the clinical decision-making process.

To assess the impact on the management and safety of transesophageal echocardiography (TEE) in the elderly population, the results and limitations of this technique were retrospectively analyzed in 88 patients. TEE was indicated whenever the transthoracic approach was not diagnostic or was inconsistent with the clinical setting. The most frequent clinical indications were to investigate the source of emboli, assess valvular regurgitation, and identify valvular vegetations. In 72 patients (82%) TEE significantly influenced management decisions. In selected patients TEE avoided the use of more invasive diagnostic procedures. Adverse effects included occasional premature atrial or ventricular beats (11 patients), sinus bradycardia (six patients), and protracted nausea (one patient). We conclude that in elderly patients with cardiovascular diseases, TEE plays a significant role in the decision-making process without adding a significant risk.

A guide to the radiographic identification of prosthetic heart valves: an addendum.

Several years ago "A Guide to the Radiographic Identification of Prosthetic Heart Valves" (Circulation 57:613, 1978) described the radiographic silhouettes of 40 different cardiac prosthesis in clinical use. Since that time a number of prostheses have been developed and introduced to clinical practice. Ten of these newer prostheses manufactured by six domestic companies were photographed and radiographed as they would be expected to appear in standard chest radiographs. The radiographic silhouettes are described and distinguishing features are discussed.