Detection of ischemic myocardium in vivo through the chest wall by quantitative ultrasonic tissue characterization

Quantitative analysis of ultrasound offers a potentially valuable method for noninvasive differentiation of specific types of cardiac disease and for assessment of their severity. Clinical application necessitates quantitative measurement of the ultrasonic properties of myocardium through the chest wall. This study was designed to determine whether such measurements could be made noninvasively with the aid of conventional M mode echocardiographic guidance and to characterize the quantitative effects of intervening tissue (chest wall) on the ultrasonic signals backscattered by ischemic and normal myocardium. Frequency-dependent ultrasonic backscatter (2 to 7 MHz) from normal myocardium was measured in dogs in vivo through the closed chest with the use of M mode guidance and with the chest open, directly from the myocardium. Closed-chest and open-chest measurements were repeated after ligation of the left anterior descending coronary artery in the same animals. Closed-chest data were compensated by correcting for the average value for the slope of the attenuation-frequency function of chest wall, which was determined from measurements obtained by analysis on excised tissue. Compensated closed-chest measurements correlated with measurements obtained from the epicardial surface of the heart. The differentiation of normal from ischemic myocardium with both the closed- and open-chest measurements was consistent (p < 0.005). The successful differentiation of normal from ischemic myocardium by determination of quantitative backscatter through the intervening chest wall supports the concept that tissue characterization by quantitative analysis of backscattered ultrasound is a potentially useful, clinically applicable approach to noninvasive detection and differentiation of intrinsic properties of normal and diseased myocardium.     

Infective endocarditis in heroin addicts: epidemiological observations and some unusual cases

The total number of cases of heroin-induced endocarditis occurring over a four-year period were reviewed in order to explain an increase in the number of cases in the last year studied (1975). Brown heroin was noted to be used more frequently by addicts during the period of increased incidence. Cultures of "street samples" of brown and white heroin as well as cocaine were obtained in order to elucidate a possible relationship between the increased use of brown heroin and the increased number of endocarditis cases. Despite frequent contamination of both white and brown heroin, none of the common endocarditis-causing pathogens were isolated from the samples. Staphylococcus aureus, the most common etiological agent, frequently resulted in tricuspid endocarditis. That the accepted criteria for tricuspid endocarditis may be present without actual cardiac valve involvement is demonstrated by a most unusual case of hepatic vasculature infection.     

Pre- and postoperative hemodynamic and cineangiocardiographic assessment of left ventricular function in patients with aortic regurgitation.

Hemodynamic and angiocardiographic analysis was performed prior to and 14 months on the average following valve replacement in 11 patients with severe, isolated, pure, chronic aortic regurgitation.The aortic diastolic pressure, reduced prior to surgery, reverted to normal as did the cardiac index. Left ventricular filling pressure, elevated prior to surgery, returned to normal while aortic systolic pressure did not vary substantially. The markedly increased stroke volume returned to normal as did the net left ventricular stroke work. Left ventricular end-diastolic and end-systolic volumes, also markedly elevated, decreased but did not return to normal levels.The shape of the left ventricle, which was more spherical than normal during end-systole prior to surgery, as evidenced by the decrease in the systolic axis ratio, reverted to normal.The ejection fraction, severely reduced before surgery, increased moderately (46 ± 13 vs 51 ± 19 per cent) as did the extent of circumferential fiber shortening (δD) (21 ± 8 vs 27 ± 12 per cent). The mean velocity of fiber shortening ($\text{VCF}$) increased significantly (0.68 ± 0.2 vs 1.03 ± 0.47 circ./sec.), as did the mean left ventricular ejection rate (1.32 ± 0.48 vs 1.91 ± 0.76).Comparative analysis of the evolution of left ventricular function indices and of extramyocardial factors (end-diastolic fiber stretching and impedance to ejection) showed that whereas in some cases myocardial damage appeared to be irreversible, in others dramatic improvement sometimes occurred following surgery. It was not possible, however, to determine the threshold below which the damage was irreversible.It may therefore be concluded that in some patients with severe regurgitation attended by profound myocardial insufficiency, correction of the valvular defect could produce not only clinical and hemodynamic improvement, but also improvement in myocardial contractile status.     

Maternal Physical Activity Is Associated With Improved Blood Pressure Regulation During Late Pregnancy

Background

Cardiovagal baroreflex gain (cBRG) reflects an individual's ability to buffer swings in blood pressure. It is not well understood how this mechanism is influenced by physical activity in pregnancy. Because pregnant women tend to engage in low levels of moderate-to-vigorous physical activity (MVPA) and high levels of sedentary behaviour, we sought to determine the influence of MVPA and sedentary behaviour on cBRG and mean arterial pressure (MAP) in pregnancy.

Arterial pulse waves and velocity and systolic time intervals in diabetic children

Arterial pulse wave velocities, pulse wave contours, and systolic time intervals were recorded in thirty-nine diabetic children and were compared with recordings taken in twenty-seven normal children. Systolic time intervals were similar in the two groups of subjects. However, brachial and aortic pulse wave velocities were significantly greater in the diabetic than in the normal children (p < 0.025 and < 0.005, respectively). Also, in the diabetic children the time interval from the incisura to the midpoint of the dicrotic wave (I-D) was significantly shortened in both the brachial (p < 0.005) and carotid (p < 0.05) pulse waves as compared to the normal children. These changes in pulse wave velocity and contour are associated with increased wall stiffness that occurs with aging and suggest that the large arteries of diabetic children may exhibit acceleration of the aging process. The severity of these changes bore no direct correlation with the degree of carbohydrate intolerance as judged by insulin requirement.     

Echocardiographic criteria for aortic root dissection.

Echocardiographic findings from 10 patients without clinical indications of aortic root dissection or aortic valve disease from 1 patient with angiographic confirmation of aortic root dissection are reported and compared. Previously reported echocardiographic findings were confirmed in the patient with aortic root dissection. These include (1) a widened posterior or anterior aortic wall, or both; (2) parallel motion of the separated margins of the aortic walls; and (3) aortic root dilatation (42 mm or more at end-systole). However, all three findings were also noted in 5 of the 10 patients without clinical indications of aortic root dissection or aortic valve disease, and at least two of the three findings were noted in the remaining 5 patients. Echocardiographic detection of aortic root dissection appears to be most reliable when clinical indications of the anomaly are present.