Richard E. Swensson

Real-time Doppler color flow mapping for detection of patent ductus arteriosus.

In this study, ultrasound Doppler color flow mapping systems were utilized to examine flow in the pulmonary artery in 31 premature and term infants (aged 4 hours to 9 months) with patent ductus arteriosus accompanying respiratory distress syndrome, as an isolated lesion, or with patent ductus in association with other cyanotic or acyanotic congenital heart disorders. The flow mapping patterns were compared with those of a control population of 15 infants who did not have patent ductus arteriosus. In unconstricted ductus arteriosus, the flow from the aorta into the pulmonary artery was detected in late systole and early diastole and was distributed along the superior leftward lateral wall of the main pulmonary artery from the origin of the left pulmonary artery back in a proximal direction toward the pulmonary valve. In constricted patent ductus arteriosus, or especially in a ductus in association with cyanotic heart disease, the position of the ductal shunt in the pulmonary artery was more variable, often directed centrally or medially. Waveform spectral Doppler sampling could be performed in specific positions guided by the Doppler flow map to verify the phasic characteristics of the ductal shunt on spectral and audio outputs. Shunts through a very small patent ductus arteriosus were routinely detected in this group of infants, and right to left ductal shunts could also be verified by the Doppler flow mapping technique. This study suggests substantial promise for real-time two-dimensional Doppler echocardiographic flow mapping for evaluation of patent ductus arteriosus in infants.

Acute and follow-up intravascular ultrasound findings after balloon dilation of coarctation of the aorta.

The study objective was to examine the vascular wall changes caused by balloon dilation of coarctation of the aorta (CoA) acutely and at short-term follow-up using intravascular ultrasound imaging. Intravascular ultrasound has been valuable in assessing the vessel wall changes in coronary and peripheral arteries after balloon dilation, often with more detail than angiography. Methods and ResultsIntravascular ultrasound imaging, using 4.8F, 20-MHz or 6.2F, 12.5-MHz catheters on either Diasonics or HP scanners, was performed in 17 patients during balloon angioplasty for native (n=12) and recurrent (n=5) CoAs. Nine patients were also studied at the time of follow-up cardiac catheterization 28.1±18.0 months after angioplasty. Immediately after dilation, the mean pressure gradient across the CoA decreased from 42.9±16.4 to 9.0±5.4 mm Hg (P < .001) and the mean diameter of the coarcted segment increased from 4.4±1.9 to 7.9±2.4 mm (P < .001). An intimal tear or flap was noted by ultrasound in 12 of the 12 native CoAs and 4 of the 5 recoarctations. In contrast, only 6 of the native CoAs and 2 of the recoarctations had an intimal flap or dissection detected by angiography. At follow-up, the residual pressure gradient did not significantly change from that measured immediately after dilation, but the CoA diameter increased from 7.8±1.5 to 9.9±2.3 mm (P < .01). No aneurysms were detected. Four of the 9 patients showed ultrasonic and angiographic evidence of healing and remodeling with diminution in size or disappearance of the intimal tears. ConclusionsThere is a high incidence of intimal tears and dissections immediately after balloon angioplasty for native and recurrent CoAs. Intravascular ultrasound is more sensitive than angiography in detecting the vascular wall changes. Even significant intimal tears are not necessarily associated with aneurysm formation, and many decrease in size or disappear at short-term follow-up.

Color Doppler flow mapping in patients with coarctation of the aorta: new observations and improved evaluation with color flow diameter and proximal acceleration as predictors of severity.

We performed color Doppler flow mapping in 15 patients, 1 week to 17 years old (mean 42 months), with coarctation of the aorta that was confirmed subsequently by angiography and/or surgery. Twelve patients had native coarctation and three had mild recoarctation after surgical repair. Color Doppler flow maps were analyzed with a digital analysis package and a Sony computer system. The diameter in the region of coarctation from the color Doppler flow map (mean = 2.0 +/- 0.8 mm [SD]) correlated well with the coarctation diameter measured at angiography (mean = 1.8 +/- 0.8 mm; r = .83, SEE 0.43 mm) in the 10 patients with native coarctation undergoing angiography, but the coarctation diameter measured by two-dimensional echocardiography (3.9 +/- 1.5 mm) was poorly predictive of the angiographic severity (r = .23). Additionally, spatial acceleration was seen in all patients proximal to the coarctation site, with an aliased and accelerating stream narrowing progressively as it proceeded toward the coarctation site, a pattern that is not seen in healthy subjects. Computer analysis of the color Doppler images provided pseudo three-dimensional and digital velocity maps for blue, red, and green (turbulent) flow velocities to allow an enhanced appreciation of the accelerating stream, easily separating this from normal descending aortic aliasing patterns. The narrowing of the acceleration area in the proximal descending aorta (distal/proximal acceleration zone ratio) was also predictive of the angiographic severity of coarctation (r = .83). The distribution of low-level turbulence seen proximally paralleled the distribution of the proximal accelerating stream.(ABSTRACT TRUNCATED AT 250 WORDS)

Elucidation of the Natural History of Ventricular Septal Defects by Serial Doppler Color Flow Mapping Studies

Two-dimensional echocardiography has provided information to aid in the diagnosis and management of infants with ventricular septal defect, but its inability to resolve very small ventricular septal defects and problems with defining ventricular septal defect orifice size (because of overlying muscle or tricuspid tissue) have made it unsuitable as a standard for defining the natural history of ventricular septal defect. In this study, 114 serial two-dimensional Doppler color flow mapping studies were performed to define ventricular septal defect anatomy, location and color flow diameter as an indicator of shunt size in 66 patients (over a 40 month period). Twenty-five patients first studied at 6 months of age (mean age at most recent study 15.9 months) had congestive heart failure and 41 (mean age 45 months) did not. In the congestive heart failure group, there were 24 perimembranous and 1 muscular ventricular septal defect and aneurysm formation was present in 17. Mean (+/- SD) color flow diameter was 8.2 +/- 1.9 mm and color flow diameter/aortic root diameter ratio was 0.63. In the 30 patients who underwent cardiac catheterization, color flow diameter bore a close relation to angiographic diameter (r = 0.96) and pulmonary/systemic flow ratio (Qp/Qs) (r = 0.88). In the patients with congestive heart failure, 4 of the 25 ventricular septal defects, all with aneurysm present or positioned adjacent to the tricuspid valve, became smaller but none closed. Of the 41 patients without congestive heart failure, 21 had a perimembranous defect (15 with aneurysm), 18 had a muscular ventricular septal defect and 2 had a supracristal ventricular septal defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive Doppler color flow mapping for detection of anomalous origin of the left coronary artery from the pulmonary artery and for evaluation of surgical repair

Anomalous origin of the left coronary artery from the pulmonary artery is a rare but important cause of congestive heart failure in infancy and of sudden death at all ages. Diagnosis is often missed when based solely on physical examination and noninvasive methods. A 4 year old patient is presented in whom mitral regurgitation was noted by a referring physician and an anomalous left coronary artery was found by Doppler color flow mapping upon referral and verified at cardiac catheterization. Doppler color flow mapping was also used intraoperatively using a gas-sterilized transducer to further clarify the hemodynamics and assess the surgical result. After creation of an intrapulmonary artery tunnel from the ostium of the left coronary artery to the aorta, anterograde coronary artery flow and absence of a residual left to right pulmonary artery shunt were verified during surgery by Doppler flow mapping. Postoperatively, residual mitral regurgitation and patency of the left coronary artery graft have been followed up serially by Doppler flow mapping. Therefore, Doppler color flow mapping is useful in the diagnosis and intraoperative and postoperative management of this important and potentially life-threatening abnormality.

Two-Dimensional Doppler Color Flow Mapping for Detecting Atrial and Ventricular Septal Defects: Studies in Animal Models and in the Clinical Setting

Two-dimensional Doppler echocardiography is an established and useful technique for imaging, localizing, and providing prognostic information related to ventricular septal defect (VSD) and atrial septal defect (ASD)—as well as for providing estimates of volume flow and pulmonary to systemic flow ratios (QP: QS). The Doppler technique, however, has not yet been widely applied systematically for the identification of defects that are too small to image—or for characterization of flow patterns across the ventricular septum or the atrial septum.

Two‐Dimensional Doppler Color Flow Mapping for Detecting Atrial and Ventricular Septal Defects

In experimental studies in six dogs as well as in clinical studies in eleven patients with atrial septal defect and 27 patients with ventricular septal defect, the diagnostic usefulness of color Doppler echocardiography in detection of small septal defects and multiple defects was analyzed. The study showed that atrial or ventricular septal defects with a size of 2.5 to 3 mm or more, which eluded detection with two-dimensional echocardiography, were easily identified with the color Doppler method. Additionally, multiple defects were reliably demonstrated. In atrial septal defects, according to the results of this study, the shunt area in the color Doppler image enables a semiquantitative estimation of the shunt volume.

Prostaglandin E1 responsive ductus at 11 months of age

SummaryAn 11-month-old boy with congestive heart failure and an intermittently closing patent ductus arteriosus (PDA) is presented. During cardiac catheterization, the ductus proved responsive to prostaglandin E1. Permanent closure of the PDA could not be attained with indomethacin. The infant underwent surgical ligation of the PDA.

Single coronary artery complicating repair of pulmonic stenosis

supplied an appreciable amount of anterior and inferior left ventricular myocardium. Dunn et al.’ found that exercise-induced ST segment elevation in ECG leads V, or aVL was highly specific for the presence of LAD coronary artery stenosis and reversible anterior wall myocardial ischemia. Alternatively, we cannot exclude the possibility that coexistent coronary vasospasm superimposed on a critical coronary stenosis was responsible for the observed exercise-induced ST segment elevation, although there were no associated clinical features or abnormal ST segment shifts during ambulatory ECG monitoring to support this. Weiner et al6 have previously described exercise-induced ST segment elevation during the recovery phase of exercise testing in four patients with variant angina, two of whom had associated fixed coronary stenoses. Three of their patients exhibited ST segment depression during exercise, and ST segment elevation was not observed until 2 or 3 minutes after the cessation of exercise.6 We hypothesize that this patient developed subendocardial &hernia manifested by ST segment depression at a significant level of exercise (rate-pressure product 25,000), which rapidly progressed to “silent” transmural myocardial ischemia at maximal exercise and early into recovery. Undoubtedly, the exercise test was continued beyond the point of diagnostic ischemic ST segment changes because of the patient’s asymptomatic status. The subsequent appearance of marked anterior wall ST segment elevation delineated the presence of a strikingly positive exercise study, which ultimately led to catheterization and angioplasty. We conclude that asymptomatic exercise-induced ST segment elevation in the absence of prior ECG Q waves may be a manifestation of significant “silent myocardial ischemia,” presumably due to highgrade fixed coronary artery disease and/or superimposed coronary vasospasm. These findings should prompt consideration for urgent invasive evaluation.

Improved Diagnostic Information from Digital Angiography Performed Simultaneously with Cineangiography in Pediatric Patients

Digital angiography has most often been used in pediatric cardiology to achieve cardiovascular imaging in simple disorders of septation or for abnormalities of great arteries—often to achieve detailed visualization of pulmonary artery structures or left-sided systemic and aortic arch structures from intravenous (IV) injections. As such, its application has, to a large extent, been directed at decreasing the invasiveness of angiocardiography [1–3]. While, with the present limited size of matrix memories, digital angiography does not yet approach the spatial resolution of film, digital processing can provide flexibility in imaging, image enhancement capabilities, and unique opportunities for quantitization of angiographie information [4]. In the present study, we acquired digital angiographic images during selective cardiac catheterization and routine cineangiography from 37 patients by digital image acquisition performed simultaneously with cineangiography. The system we used has a mirror/image-splitter within the image intensifier, which directs 10% of the received photon output into a video camera for digitization while passing the remainder of the photons to the cine camera. The MDS computer in the system digitized images at 15 frames/s into a 256 × 256, 8-bit matrix and processed them in the computer via a terminal in the catheterization lab, so that immediate digital processing of at least one plane is available as playback, along with videotape and videodisc playback.