Spontaneous Echocardiographic Contrast (SPE) – An In-Vitro Study of the Impact of Cardiac-Output, Left-Ventricular DP/DT and Temperature

Recent clinical studies have indicated echocardiographic observations of gaseous emboli in the left ventricle (LV) and atrium (LA) during studies in patients with mechanical heart valves (MHV) in the mitral position. These reports have shown that the intensities of these gas bubbles in elderly patients are less than those in younger patients. These facts may indicate a correlation between formation of the gas bubbles and the LV functions. The goal was to utilize our pulse duplication system to create the corresponding physiologic conditions and to understand the impact of these parameters on SpE formation

Arterio-venous access in end-stage renal disease patients and pulmonary hypertension

Background: The syndrome of pulmonary hypertension (PHT) in end-stage renal disease (ESRD) has been described in patients on chronic hemodialysis (HD) therapy via arterial-venous (A-V) access. However, the exact timing for the development of the PHT is unknown. This study was designed to evaluate changes in pulmonary artery pressure (PAP) following creation of the vascular access. Patients and Methods: PAP and cardiac-output (CO) values were recorded in 12 pre-dialysis patients without PHT a few months after the access formation, before treatment with HD was started, and the prevalence of PHT was calculated. Clinical data was compared between patients with and without PHT. Results: The systolic PAP values were increased in “ve of the 12 pre-dialysis patients (42%) by 21±9 mm Hg to more than 35 mm Hg. Patients with and without PHT differed only in that CO was signi“cantly higher among the former. Conclusions: The development of PHT following access formation represents a failure of the pulmonary circulation to accommodate the access-mediated elevated CO. Pre-dialysis patients scheduled for access formation should be screened for the presence of sub-clinical PHT. “Positive” patients should proceed to peritoneal dialysis or advance to kidney transplantation; rather than getting access and HD therapy

Microbubbles and mitral valve prostheses — transesophageal echocardiographic evaluation

Objective: To assess whether microbubbles are associated with a specific type of mitral valve prosthesis and to investigate the relationship of microbubbles to ventricular function and mitral regurgitation. One of the types of spontaneous echocardiographic contrast observed in patients with prosthetic heart valves has been described as microbubbles. Methods: Clinical data and videotapes of patients with a prosthetic mitral valve who had undergone transesophageal echocardiography at the UCLA Medical Center between May 1989 and February 1995 were retrospectively reviewed. There were 109 studies (74 patients) available for review by two independent observers. Results: Microbubbles occurred in 49 of the 66 studies of St. Jude valves ( 74%), eight of the 12 studies of Bjork Shiley valves (67%), four of four studies of Medtronic valves (100%) and zero of 23 studies of tissue valves (0%). Patients with an estimated ejection fraction greater than 45% were found to have a much higher likelihood of having microbubbles observed. There was no statistically significant association between the degree of mitral regurgitation and the observation of microbubbles. Conclusions: Microbubbles are a common phenomenon occurring in patients with mechanical mitral prostheses compared with tissue mitral valve prostheses. Their formation depends on the systolic ventricular function, suggesting a cavitation-like phenomenon participating in their formation perhaps due to the rate or velocity of the valve closure

Reproducibility of quantitative myocardial contrast echocardiography

AbstractTo determine whether myocardial contrast echocardiography is quantitatively reproducible, repeated intracoronary injections of sonicated albumin (5%) were performed in eight open chest dogs. Paired injections were performed at baseline, during ischemia produced by ligation of a coronary artery, and during hyperemia induced by intravenous infusion of 0.75 mg/kg body weight of dipyridamole. Contrast washout curves were generated for the left anterior descending coronary artery territory (ischemic area) and left circumflex coronary artery territory (nonischemic area) by beat per beat analysis of frozen end-diastolic frames of left ventricular short-axis views. Peak contrast intensity, contrast washout half-time and area under the curve were derived from these curves. A total of 75 contrast washout curves were analyzed for the study of interinjection, intraobserver and interobserver reproducibility.The correlation coefficients between measurements obtained from paired injections of the echocardiographic contrast agent (interinjection reproducibility) ranged from 0.78 for peak contrast intensity to 0.87 for area under the curve. Percent error varied between 14.7% and 24.7%. The intraobserver variability in measurements was less than the interinjection variability, with a cumulative mean percent error of 17.8% and correlation coefficients of 0.72 (peak contrast intensity), 0.95 (area under the curve) and 0.96 (washout half-time). Interobserver correlation for all indexes was high (r = 0.92 to 0.96).It is concluded that peak contrast intensity, contrast washout half-time and the area under the curve derived from myocardial contrast washout curves can be measured reproducibly from videotapes. In addition, the variability between two injections attempted under identical conditions is greater than reader variability from videotapes