A new three-dimensional echocardiographic method of right ventricular volume measurement: in vitro validation.

Right ventricular volume is difficult to measure accurately from one or two views because the complexity of right ventricular shape invalidates simplifying geometric assumptions. This article describes a new three-dimensional echocardiographic reconstruction method of right ventricular volume calculation, and reports the results of testing this method in vitro using normal animal hearts and pathologic specimens from infants and children who died with aortic stenosis or hypoplastic left heart. The correlation with reference volumes was excellent for both groups (r = 0.98, n = 25 for the animal data; r = 0.97, n = 15 for the human data). Given the calculated echocardiographic volume (Vc), the reference volume (Vr) was best estimated by the equation Vr = 1.16 Vc for the animal data and Vr = 0.92 Vc for the human data. Three-dimensional echocardiographic measurement of right ventricular volume is an accurate method that deserves further study and application in a clinical setting.

Intravascular ultrasound guidance for catheter-based coronary interventions.

Intravascular ultrasound is a new method for visualizing the details of vascular pathology, providing high resolution images of plaque and thrombus. This review summarizes the potential applications of ultrasound imaging in the guidance of balloon angioplasty, atherectomy, laser ablation and stenting. Ultrasound differs from angiography and angioscopy in its ability to penetrate below the surface of the vessel lumen, demonstrating specific aspects about the distribution and composition of plaque. Because the different layers of the arterial wall have different acoustic properties, ultrasound catheters are able to define the layers of normal wall in comparison with plaque. Particularly in combination with therapeutic techniques designed to remove or ablate plaque, ultrasound may prove useful in maximizing the amount of plaque treated and minimizing trauma to normal vessel wall components. Combined imaging/therapeutic devices are in the pilot phase of development and show promise for enhancing the safety and efficacy of the catheter devices.

Abnormal left ventricular early diastolic filling during dobutamine stress Doppler echocardiography is a sensitive indicator of significant coronary artery disease.

OBJECTIVES: This study was designed to assess changes in Doppler indexes of left ventricular ejection and filling in response to high dose (40 micrograms/kg body weight per min) dobutamine stress and their utility in detection of coronary artery disease compared with that of new wall motion abnormalities. METHODS: Ten patients with a low likelihood of coronary artery disease served as a control group, and 23 patients with documented single-vessel coronary artery disease underwent baseline and peak dobutamine echocardiographic and Doppler studies. RESULTS: In both groups dobutamine induced similar increases in heart rate and systolic blood pressure. During the test, 14 patients had new wall motion abnormalities, 13 had angina, and 7 had electrocardiographic ST segment changes. No markers of ischemia occurred in the control subjects. Dobutamine induced qualitatively similar changes from baseline to peak dobutamine stress in control subjects and patients in peak aortic velocity (46% vs. 42%, p = NS), average aortic acceleration (61% vs. 43%, p = 0.03) and systolic time-velocity integral (7% vs. 2%, p = NS). Dobutamine caused marked increases in control subjects and decreases in patients in peak early filling velocity (E) (33% vs. -22%, p < 0.0001) and average E acceleration (76% vs. -28%, p < 0.0001). The response of Doppler early filling indexes to dobutamine stress was abnormal in all patients. There was no overlap in the percent change from baseline to peak dobutamine stress between control subjects and patients for E and E acceleration. CONCLUSIONS: During dobutamine stress testing, an abnormal response of Doppler indexes of left ventricular early filling is a more sensitive marker of significant single-vessel coronary disease than are new wall motion abnormalities, and it is far superior to the response of Doppler ejection variables as a predictor of coronary artery disease.

Kaposi's sarcoma of genitourinary tract.

Kaposi's sarcoma of the external genitalia is rare. Four cases with the initial lesion on the glans penis and 13 cases with secondary involvement of the external genitalia are presented. A high association between Kaposi's sarcoma and malignant lymphoma is noted. The natural history is one of multiple recurrences in the immediate vicinity of the primary site or at distant locations at varying time intervals. Wide margin electron beam irradiation is the recommended treatment. A variety of chemotherapeutic agents also have produced favorable responses; yet prognosis for cure is poor because of the generalized nature of the disease--the course of which is nevertheless often prolonged.

Angiomyolipoma of penis.

We report a case of angiomyolipoma of the penis in a fifty-three-year-old patient. This lesion is rare outside of its usual intrarenal location, and, to our knowledge, has never before been reported to occur in the penis.

Two-dimensional intravascular ultrasound: technical development and initial clinical experience.

This article reviews the development and current status of catheter-based, intravascular ultrasound imaging. The first section provides an introduction to some of the general technical issues encountered in the design of the catheter imaging systems and compares the potential merits of the multiple-element versus the mechanical approach. The second section of the article reviews the data from early studies correlating the intravascular ultrasound images with histologic sections (in vitro) and angiography (in vivo). The article concludes with a discussion of potential clinical applications and future technical developments.

Multiplane transesophageal echocardiography: latest evolution in an imaging revolution.

Multiplane imaging with a rotating phased-array transducer from within the esophagus represents the latest development in transesophageal cardiac ultrasound. Transverse, longitudinal, and all possible intermediate oblique planes are easily obtained from the same transducer with minimal probe manipulation. Three-dimensional conceptualization of complex structures and pathologic conditions is facilitated. The major advantages are a simplified examination procedure and much less patient discomfort than monoplane and biplane probe imaging.

The velocity distribution in the aortic anulus in normal subjects: a quantitative analysis of two-dimensional Doppler flow maps.

The velocity distribution in the aortic anulus is commonly assumed to be uniform. A skewed velocity profile may have consequences for the accuracy of volume flow estimates by the Doppler echocardiographic technique. To assess this issue, the velocity distribution in the aortic anulus in 12 normal subjects was studied by computer analysis of digital velocity data from two-dimensional Doppler ultrasound flow maps. The velocity profiles in the aortic anulus were found to be flat but slightly skewed, with the highest velocities toward the septum. There was little interindividual variation. Our findings imply that the centerline velocity is the best estimate for the spatial mean velocity at the aortic anulus in normal subjects. The importance of this finding in patients is unknown. In normal subjects, the results suggest that stroke volume might be overestimated by approximately 15% by Doppler echocardiography if the cross-sectional velocity profile is not accounted for.

A multiple active contour model for cardiac boundary detection on echocardiographic sequences.

Tracing of left-ventricular epicardial and endocardial borders on echocardiographic sequences is essential for quantification of cardiac function. The authors designed a method based on an extension of active contour models to detect both epicardial and endocardial borders on short-axis cardiac sequences spanning the entire cardiac cycle. They validated the results by comparing the computer-generated boundaries to the boundaries manually outlined by four expert observers on 44 clinical data sets. The mean boundary distance between the computer-generated boundaries and the manually outlined boundaries was 2.80 mm (sigma=1.28 mm) for the epicardium and 3.61 (sigma=1.68 mm) for the endocardium. These distances were comparable to interobserver distances, which had a mean of 3.79 mm (sigma=1.53 mm) for epicardial borders and 2.67 mm (sigma=0.88 mm) for endocardial borders. The correlation coefficient between the areas enclosed by the computer-generated boundaries and the average manually outlined boundaries was 0.95 for epicardium and 0.91 for endocardium. The algorithm is fairly insensitive to the choice of the initial curve. Thus, the authors have developed an effective and robust algorithm to extract left-ventricular boundaries from echocardiographic sequences.

Acute mitral valve regurgitation created in sheep using echocardiographic guidance.

BACKGROUND AND AIM OF STUDY: This study was designed to determine: (i) Whether acute mitral valve regurgitation (MVR) due to chordal rupture can be reproducibly created under echocardiographic guidance; (ii) what degree of MVR can be created; (iii) what degree of acute regurgitation is survivable; and (iv) whether acute MVR due to chordal rupture progresses over time. METHODS: In a pilot group of six juvenile farm-bred sheep, selected chordae tendineae were ruptured using either a biopsy needle or endoscopic scissors under echocardiographic guidance, without need for cardiopulmonary bypass. Sheep were sacrificed acutely (n = 2), and at six weeks (n = 2) or eight weeks (n = 2). When the technique was optimized, five sheep entered a study group in which chords were ruptured using endoscopic scissors; the sheep were sacrificed 16 weeks after surgery. RESULTS: In the pilot study, acute MVR (grade 2-4+) was produced in all sheep, normal ventricular wall motion was maintained, with minimal progression of regurgitation over time. In one pilot sheep which did not survive, grade 4+ MVR was created acutely. Use of endoscopic scissors was preferable to the biopsy needle. In the study group, acute MVR (grade 2-4+) was produced in all five sheep, and was still present at 16 weeks, with progression in only one animal. CONCLUSIONS: This pilot study demonstrated that controlled degrees of survivable acute MVR due to chordal rupture can be created under echocardiographic guidance, with minimal progression of MVR over time. This animal model can be applied to investigate the pathogenesis of clinical MVR, and to suggest appropriate medical or surgical intervention.

Autocorrelation length of normal and myopathic human myocardium measured by acoustic microscopy: implications for clinical ultrasonic tissue characterization.

The pattern of acoustic speckle present in ultrasonic images of tissue may be affected by pathological changes in the tissue. To investigate the possibility for such an effect in dilated cardiomyopathy, we examined acoustic micrographs of frozen sections of normal (autopsy) and myopathic (transplant recipient) human myocardium. The resulting images were digitized, and the major axis autocorrelation length calculated for each image. For the normal specimens (n = 75, four patients), the mean autocorrelation length was 37 +/- 18 microns, with the maximum value of 92 microns. The myopathic specimens (n = 64, four patients) had a mean of 52 +/- 19 microns, with a maximum of 100 microns. We conclude that the changes in structure between normal and myopathic myocardium are significant (p less than 0.001), but on so small a scale in relation to the wave length of clinical ultrasound that there will only be changes in the intensity of the backscattered signal, not the pattern of speckle.

Estimation of regurgitant volume and orifice in aortic regurgitation combining CW Doppler and parameter estimation in a Windkessel-like model.

A method for noninvasive estimation of regurgitant orifice and volume in aortic regurgitation is proposed and tested in anesthetized open chested pigs. The method can be used with noninvasive measurement of regurgitant jet velocity with continuous wave ultrasound Doppler measurements together with cuff measurements of systolic and diastolic systemic pressure in the arm. These measurements are then used for parameter estimation in a Windkessel-like model which include the regurgitant orifice as a parameter. The aortic volume compliance and the peripheral resistance are also included as parameters measurements in the open chest pigs are used. Electromagnetic flow measurements in the ascending aorta and pulmonary artery are used for control, and a correlation between regurgitant volume obtained from parameter estimation and electromagnetic flow measurements of 0.95 over a range from 2.1 to 17.8 mL is obtained.

Congenital diaphragmatic hernia: determination of the optimal time for operation by echocardiographic monitoring of the pulmonary arterial pressure.

Preoperative stabilization and delayed operation rather than emergency repair of congenital diaphragmatic hernia (CDH) may improve survival, but there are no clear criteria for how long operation should be delayed. Because increased pulmonary vascular resistance (PVR) may be an important risk factor, we used Doppler echocardiography to study patients with CDH presenting with respiratory distress immediately after birth. During the study period 10 patients were admitted, but 2 were moribund on admission and died shortly thereafter. In the remaining patients the pulmonary arterial pressure (PAP) and direction of ductal shunt were estimated by Doppler echocardiography. Initial PAPs were in the range of 45 to 90 mm Hg, with bidirectional or right-to-left shunt through the ductus arteriosus. Reduction of pressure to 25 to 55 mm Hg, or reversal of shunt to left-to-right, reflecting decreased PVR, occurred after ventilation for 3 to 20 days (mean, 8 days). Patients underwent operation after there was evidence of reduced PVR. None developed persistent fetal circulation, and all 8 patients survived. We conclude that postponing operation until PVR has decreased seems to improve survival in patients with CDH presenting within hours of birth.

An overview of intravascular ultrasound.

Intravascular ultrasound is a new technique based on the use of high-frequency transducers mounted in or on flexible catheters which can be inserted into arteries or veins. Although this technique is extremely promising for the evaluation or guidance of intravascular interventions, this application has yet to be proven conclusively. Intravascular ultrasound is already established as a research technique, especially for the evaluation of details of lesion size, morphology, or the results of interventions. Catheters can be divided into two principles of operation, mechanical or electronic. The mechanical systems can be further subdivided according whether the core, rotating element is fixed relative to the outside sheath, or can be moved. Interpretation of images requires knowledge of the histology of the arterial wall, as well as of the physics of ultrasound at high frequencies. Studies are now underway to assess the contribution of intravascular ultrasound to prognosis and outcome in interventional procedures.

Safety of intracoronary ultrasound: data from a Multicenter European Registry.

The clinical use of intracoronary ultrasound imaging is growing, serving as a useful adjuvant to contrast angiography, and providing additional information to assist with catheter-based interventions. Despite the increasing use of this technique, it remains an invasive procedure, the safety of which has not been definitively established. Data from multiple European centers performing intracoronary ultrasound (ICUS) examinations were collected under the auspices of the Subgroup on Intravascular Ultrasound of the Working Group on Echocardiography of the European Society of Cardiology. Information was obtained about the number of examinations performed, complications related to ICUS imaging, and any adverse clinical consequences related to ICUS imaging. Twelve centers submitted information about their experience with ICUS. Eight (1.1%) complications were reported (spasm, vessel dissection, or guide wire entrapment) in a total of 718 examinations. All complications occurred in patients with atherosclerotic coronary disease with a diagnosis of unstable or stable angina who underwent percutaneous transluminal coronary angioplasty. No permanent adverse clinical consequences due to ICUS imaging were reported. There was no difference in frequency of complications between centers, as assessed by chi-square analysis (P = 0.232). These data suggest that ICUS examinations can be performed safely with a very low rate of complications.

Complete external sphincterotomy: correlation between endoscopic observation and the anatomic sphincter.

Longitudinal cuts of various lengths and depths were made in the area of the external urethral sphincter in 18 male cadavers. The Iglesias resectoscope and the Collings knife electrode were used. Histologic sections of the prostate and of the membranous and bulbous urethra demonstrated that a cut of 2 cm. in length beginning from the verumontanum and 6 mm. in depth was necessary to completely incise the external urethral fibers. This procedure, when performed according to these criteria, effectively decreases urethral resistance, permits adequate bladder emptying and probably eliminates the need for a catheter.

Ureteral carcinoma in situ.

The incidence of ureteral carcinoma in situ at the time of cystectomy for bladder carcinoma is approximately 8.7 per cent. Followup records of 27 such patients as well as records of 6 patients with other ureteral abnormalities were reviewed. Clinically, no postoperative ureteral or upper urinary tract difficulty was noted in 29 of the 30 patients whose records were complete. The ureteral status of the 3 patients lost to followup remains uncertain. One patient had infiltrating ureteral carcinoma and he is well 8 years after cystectomy. Since ureteral carcinoma in situ at the time of cystectomy for bladder cancer has had little influence on the course of these patients, conservative treatment is probably indicated when the lesion is encountered.

[Congenital heart diseases in Sør-Trøndelag. Incidence, diagnosis, course and treatment]. / Medfødte hjertefeil i Sør-Trøndelag. Insidens, diagnostikk, forløp og behandling.

In the county of Sør-Trøndelag, Norway, 145 children with congenital heart disease were detected among 14,194 live-born children from 1 January 1987 to 31 December 1990. This represents an incidence of 10.2 per thousand live-born children. The children were followed for six to 42 months (mean 2.38 years). Ventricular septal defect was detected in 71 (49%) cases. Isolated ventricular septal defect was found in 56 (39%) cases, the muscular type being the most frequent (three times that of the membranous type). Other congenital defects were found in 28 cases (19%), either as chromosome aberrations, syndromes or extracardiac malformations. 13 (9%) children died. None had constant symptoms of congestive heart failure by the end of the study. 34 (23%) cases were referred from mother and child clinics. 8 (5.5%) cases were detected prenatally. Compared with the results of other studies, the total incidence of congenital heart disease was high, and mortality and incidence of other coexistent congenital defects were low. It seems that small and less severe heart defects were detected more frequently in this study. The difference was most marked for incidence of muscular ventricular septal defect, atrial septal defect and pulmonary stenosis. The probable reasons for these results are an almost complete register of cases, well established postnatal care and a short distance to a pediatric cardiologist.

Incorporating the four-chamber view of the fetal heart into the second-trimester routine fetal examination.

The four-chamber view of the fetal heart is reported to he the most useful view for detecting congenital heart defects. In 7322 non-selected, consecutive pregnancies of women attending a second-trimester (18 weeks) routine ultrasound scanning program, we examined our ability to obtain a four-chamber view in the fetus within the 30 min generally allocated to do the scan and record data. Five trained nurse-midwives performed the examinations between June 1988 and September 1990. In the first part of the study, a four-chamber view could not be obtained in 7%, while in the second part, the failure rate was 4%, which showed a learning effect over time. The demonstration of a four-chamber view was significantly better with a 5 MHz than with a 3.5 MHz transducer. The ability to obtain the four-chamber view improved as the gestational age increased. The main reason for not being able to obtain the four-chamber view with the 3.5 MHz transducer was poor imaging; for the 5 MHz transducer, it was an unfavorable position of the fetus. Education and experience, as well as good equipment, are important factors in obtaining good results. The time spent learning to obtain a four-chamber view reliably was relatively long.

Intravascular ultrasound as a guiding modality for mechanical atherectomy and laser ablation.

One of the most compelling practical applications for intravascular ultrasound imaging is in enhancing the safety and efficacy of the second-generation catheter devices designed to ablate or remove plaque. Initial studies have shown that intravascular ultrasound is well suited to demonstrate the amount of atheroma present in a vessel, and the distribution within the vessel wall at any given point. Further clinical studies are required to determine whether more complete debulking of atheroma, guided by ultrasound imaging, has a favorable impact in reducing the rates of acute closure and restenosis following the procedure.