Detection and significance of subclinical mitral regurgitation by colour Doppler techniques.
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Adult↗
Biomedical subjects
D Sahn
Publications and source records attributed to D Sahn.
Phase II, placebo-controlled trial of MRX115 (Aerosomes) for left heart and myocardial perfusion imaging.
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Adult↗
Phase I clinical trials of MRX-115. A new ultrasound contrast agent.
RATIONALE AND OBJECTIVES: Stabilized microbubbles are under development as contrast agents for medical ultrasound. The authors report the results of Phase I clinical trials of a new ultrasound contrast agent based on lipidencapsulated perfluorocarbon gas microbubbles. METHODS: Lipids encapsulating perfluoropropane gas (Aerosomes MRX-115, ImaRx Pharmaceutical Corp., Tucson, AZ) were evaluated in Phase I clinical trials. Two separate studies were performed. The first was a single escalating-dose study (n = 30 subjects), and the second was a multiple-dose study (n = 18 subjects) with rechallenge in several subjects (n = 4) after 21 days. Echocardiographic examinations were performed before and after contrast agent for each test drug administration for both studies, with the exception of the rechallenge group. Doses tested in the single-dose study ranged from 0.005 mL/kg to 0.100 mL/kg body weight. In the multiple-dose study, five doses of 0.005 mL/ kg to 0.030 mL/kg (0.025-0.150 mL/kg total dose) were evaluated. Studies were single-masked, placebo-controlled, and safety assessment and adverse events were monitored. RESULTS: All doses in both studies were well tolerated with no treatment-related changes in safety measures for either study. Left ventricular cavity and myocardial enhancement were seen with all doses of MRX-115. CONCLUSIONS: MRX-115 is a promising new intravascular ultrasound contrast agent that was safe and well tolerated at the doses evaluated in these studies.
Adult↗
Prospective multicentre study of pregnancy outcome after lithium exposure during first trimester.
Lithium carbonate is an effective drug for prophylaxis and treatment of major affective disorders. In-utero exposure to lithium during the first trimester of pregnancy might be associated with an increased risk of cardiac malformations, especially the rare Ebstein's anomaly. We prospectively recruited and followed 148 women (mean age 30 years, SD 5 range 15-40) using lithium during the first trimester of pregnancy, who consulted four teratogen information centres in the USA and Canada. Pregnancy outcome was compared with that of controls matched for maternal age. We had complete follow-up of pregnancy outcome in 138 of 148 patients recruited. In the other 10, fetal echocardiograms were available but postnatal follow-up was not done. Mean daily dose of lithium was 927 mg (SD 340). Rates of major congenital malformations did not differ between the lithium (2.8%) and control (2.4%) groups. 1 patient in the lithium group chose to terminate pregnancy after Ebstein's anomaly was detected by a prenatal echocardiogram. There was 1 ventricular septal defect in the controls. Birthweight was significantly higher in the lithium-exposed infants than in the controls despite identical gestational ages (3475 [660] g vs 3383 [566] g, p = 0.02). The true difference in birthweight might have been even larger, since significantly more women using lithium than controls were cigarette smokers (31.8% vs 15.5%, p = 0.002). These results indicate that lithium is not an important human teratogen. Women with major affective disorders who wish to have children may continue lithium therapy, provided that adequate screening tests, including level II ultrasound and fetal echocardiography, are done.
Abnormalities, Drug-Induced↗
Report of the Council on Scientific Affairs: ultrasonic imaging of the heart: report of the Ultrasonography Task Force.
The use of ultrasonography in cardiology has progressed so dramatically that not only is anatomic information available but information can also be derived about cardiac hemodynamics. Applications range from intravascular ultrasonic imaging of coronary atherosclerosis to predictions of the severity of fetal valvular pulmonic stenosis detected in utero. We reviewed cardiac ultrasonography as utilized in B-mode imaging, pulsed and continuous-wave spectral Doppler, and Doppler color flow mapping. We reviewed specialized areas, including stress echo for wall motion analysis, valvular and congenital heart disease applications, and new applications in intraoperative, transesophageal, contrast echography, coronary imaging, and fetal echocardiography. Finally, future applications of quantitative flow mapping and intraluminal and interventional ultrasonography were considered along with the required technological advances.
Contrast Media↗
Evaluation of Björk-Shiley prosthetic valves by real-time two-dimensional Doppler echocardiographic flow mapping.
We studied the value of two-dimensional Doppler echocardiographic color flow mapping for identifying normal transvalve flow profiles and valve malfunction in 20 patients with Björk-Shiley prosthetic valves. Seven patients had Björk-Shiley prosthetic valves in the aortic position alone, seven in the mitral position, and six had prosthetic valves in both the aortic and mitral positions. In 10 patients with normally functioning mitral valves, the ratios of the maximal major and minor Doppler-imaged orifice flow diameters to the valve ring diameters were 25 +/- 3% (mean +/- SD) and 24 +/- 3%, respectively, similar to values reported in in vitro studies. No mitral regurgitation was found in these patients by two-dimensional Doppler echocardiographic flow mapping or by spectral Doppler. Of the 10 clinically normal aortic Björk-Shiley valves, no valvular regurgitation was found by color flow mapping, whereas mild aortic regurgitation was found in two patients with the use of spectral Doppler. Malfunction of six valves was documented in five patients and was confirmed by cardiac catheterization and/or surgery. These included one case of focal fibrous ingrowth involving primarily the minor orifice of a mitral prosthetic valve, one case of mitral valve prosthetic thrombosis with decreased major and minor orifice flow diameters and valvular regurgitation, and four cases of paravalvular regurgitation involving prosthetic valves in the aortic position (three patients) and the mitral position (one patient). Two-dimensional Doppler echocardiographic flow mapping provides new observations that may aid in identifying Björk-Shiley prosthetic valve malfunction. By localizing precisely the site of prosthetic stenosis or regurgitation, it may also assist in defining the cause of valve malfunction.
Adolescent↗
Hydrops due to myocarditis in a fetus.
At 18 weeks of gestation a fetus was studied sonographically because of advanced maternal age and found to have hydrops of unknown etiology with ascites, pleural, and pericardial effusions. An abortion was performed and in the fetal/placental material myocarditis and thyroiditis were documented. Maternal antibodies to Coxsackie virus B5 showed a onefold rise. Tentatively, the hydrops is assigned to Coxsackie virus myocarditis, a lesion not previously identified in fetuses.
Adult↗
Prophylactic treatment of very premature infants with human surfactant.
We undertook a randomized, controlled trial to determine whether human surfactant administered endotracheally at birth to very premature infants (gestational age, 24 to 29 weeks) would prevent the respiratory distress syndrome or reduce its severity. Thirty-one treated infants (birth weight, 938 +/- 286 g) were compared in a blinded fashion with 29 control infants (birth weight, 964 +/- 174 g). The lecithin/sphingomyelin ratio was less than 2 in all infants, and phosphatidylglycerol was not present in amniotic fluid or tracheal fluids at birth, indicating a deficiency of surfactant in the lungs. The principal dependent variables were neonatal death, the incidence of bronchopulmonary dysplasia, and the infant's requirement for respiratory support (and its complications). The surfactant-treated group had significantly fewer deaths than the control group (16 percent vs. 52 percent, P less than 0.001), fewer cases of bronchopulmonary dysplasia (16 percent vs. 31 percent), and significantly fewer cases of pulmonary interstitial emphysema (P less than 0.001) and pneumothorax (P less than 0.02). Prophylactic treatment with human surfactant also substantially reduced the period of neonatal intensive care. We conclude that treatment with human surfactant offers promise for improving the survival of very premature infants with a surfactant deficiency and for reducing the pulmonary sequelae of the respiratory distress syndrome.
Amniotic Fluid↗
Septum primum defect repair.
Two technical maneuvers in septum primum defect repair have resulted in improved mitral valve function and security against heart block. One maneuver, critical to restoring mitral competence, is accurate reconstruction of the leading edge of the mitral valve. A second maneuver, suturing the septal defect patch at its inferior aspect to the mitral valve near the annulus instead of to the inferior septal defect margin or to the tricuspid annulus, eliminates the hazard of atrioventricular node or bundle injury.
Heart Block↗
Echocardiographic criteria for normal newborn infants.
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Aorta, Thoracic↗
Have structural adjustments led to health sector reform in Africa?
This paper explores the issue of whether and how structural adjustment in Sub-Saharan Africa has altered the level and nature of state involvement in the health care system. Stabilization and structural adjustment generally entail a reduction in aggregate demand, especially government spending, and a reduced role for the state in the provision of many goods and services. Consequently, there is an a priori concern that stabilization and adjustment in Africa may have resulted in lower health expenditures with deleterious effects on the health status of the population, particularly the poor. This paper concludes that structural adjustment programs in Africa did not reduce public health expenditures. In fact, many countries experienced higher real expenditures after adjustment. The fact that many indicators of health status deteriorated during the 1980s, however, presents somewhat of a paradox given the patterns of health expenditures. This paradox is resolved, by an investigation of the intrasectoral allocation of health expenditures which reveals that there are systematic biases in public expenditures towards tertiary and curative care, and a general weakness in the public sector's capacity to deliver adequate health care services even with higher real health sector budgets. In many countries, these biases have persisted despite government and donor intentions to promote health care reform. Finally, the paper reviews a set of policy and institutional issues which hinder the efficient use of budget resources, including overcentralization of health care administration, inappropriate drug and supply procurement practices, the lack of mechanisms for cost recovery, and poor organization, financial and personnel management. At each level of analysis, the paper catalogs those instances where progress is being made towards effective health care reform, including intrasectoral budget rationalization, administrative decentralization, the adoption of user fees for cost recovery, privatization in service delivery, particularly through non-governmental organizations, and organizational and management reform.
Africa South of the Sahara↗
Demonstration of dual parallel jet interaction in an in vitro model of multivalvular disease by use of optical visualization and color Doppler flow mapping.
Parallel jets, such as those occurring in the heart in multivalvular diseases like combined mitral stenosis and aortic insufficiency, have created difficulty when color Doppler flow mapping or continuous wave Doppler has been used to localize or to measure the jets because they appear to merge. Dual jet interaction was reproduced in an in vitro transparent model by driving two parallel adjacent jets, one lower velocity, higher mass, through a 19 mm2 orifice, and the other higher peak velocity, smaller mass through two orifices, 0.27 mm2 and 1.5 mm2, by use of a solution of India ink and cornstarch to optically visualize the jet interaction and image the interaction by color Doppler. Consistent deviation of the lower velocity jet towards the higher velocity jet was observed, and the large jet angled more strongly towards the small jet for the 1.5 mm2 small jet orifice than for the 0.27 mm2 orifice for constant large and small jet velocities. There was a better linear correlation of the amount of large jet angulation to the ratio of both jets' Reynolds numbers than to the ratio of both flow rates. The jets interacted as close as 1.3 cm from their point of origin, and the region after the jets merged was a highly turbulent mixing zone where neither jet could be separately imaged or visualized. These observations suggest that relative velocity plays a primary role in determining jet interaction which is a recruitment phenomena but that other hydrodynamic parameters, such as flow rate and Reynolds numbers, determine the degree to which the jets deviate.
Aortic Valve Insufficiency↗
Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on Standards, Subcommittee on Quantitation of Two-Dimensional Echocardiograms.
We have presented recommendations for the optimum acquisition of quantitative two-dimensional data in the current echocardiographic environment. It is likely that advances in imaging may enhance or supplement these approaches. For example, three-dimensional reconstruction methods may greatly augment the accuracy of volume determination if they become more efficient. The development of three-dimensional methods will depend in turn on vastly improved transthoracic resolution similar to that now obtainable by transesophageal echocardiography. Better resolution will also make the use of more direct methods of measuring myocardial mass practical. For example, if the epicardium were well resolved in the long-axis apical views, the myocardial shell volume could be measured directly by the biplane method of discs rather than extrapolating myocardial thickness from a single short-axis view. At present, it is our opinion that current technology justifies the clinical use of the quantitative two-dimensional methods described in this article. When technically feasible, and if resources permit, we recommend the routine reporting of left ventricular ejection fraction, diastolic volume, mass, and wall motion score.
Algorithms↗
Effects of transmyocardial laser revascularization by using a prototype pulsed CO2 laser on contractility and perfusion of chronically ischemic myocardium in a porcine model.
The purpose of this study was to test a new prototype pulsed CO2 laser to be used for transmyocardial laser revascularization (TMR). We wanted to determine whether it can reduce thermal damage and mitigate induced ischemia with improvement in contractile reserve of the heart as evidenced by contrast echocardiography at rest and under dobutamine stress. TMR is an emerging surgical strategy for treatment of myocardial ischemia not amenable to conventional percutaneous or surgical revascularization. Eleven pigs underwent ameroid occluder placement at the origin of the circumflex coronary artery. Six weeks later, occlusion of the circumflex coronary artery was documented. TMR was then carried out on 10 pigs by using a prototype pulsed CO2 laser that delivered 8-12 joules in 1.5 ms with a spot size of 1 mm. Six weeks after TMR, the pigs were restudied. The animals developed significant ischemia after 6 weeks of ameroid occlusion, at rest (p = 0.01) and at peak stress (p = 0.004). Wall motion for the ischemic segments improved significantly 6 weeks after TMR at peak stress (p = 0.02). TMR results in an improvement in wall motion in our model of chronic ischemia and improves wall motion score index more during induced stress than at rest.
Animals↗