Faculty Bibliography

Atherosclerotic disease of the heart likely has its origins in childhood. The promotion of cardiovascular health in children, however, has been studied only for those practicing in general paediatrics. We hypothesised that paediatric cardiologists do not consistently discuss cardiovascular risk factors with patients and their families. We therefore, carried out a nationwide survey of paediatric cardiologists to determine how often they discussed atherosclerosis and 4 modifiable risk factors, specifically weight, smoking, diet and nutrition, and physical activity. Only two-fifths reported that they discussed atherosclerotic disease frequently to always. For patients with cardiovascular disease, weight was discussed frequently to always by 59%, smoking by 61%, diet and nutrition by 63%, and physical activity by 92%. In contrast, for patients without cardiovascular disease, weight was discussed frequently to always by 35%, smoking by 46%, diet and nutrition by 39%, and physical activity by 62%. These differences are statistically significant (p < 0.003 by chi2 analysis). Cardiovascular risk factors were discussed more consistently as children grew older (p < 0.0001). Respondents stated that, in their opinion, the promotion of cardiovascular health was a role more appropriate for providers of primary care than for paediatric cardiologists (p < 0.0001). Constraints of time, and the perceived role of the cardiologist, were the most common barriers to anticipatory guidance. We suggest that these findings indicate that paediatric cardiologists can assume a more prominent role in preventive cardiology and education, although their precise role or roles, and the optimal methods of anticipatory guidance, remain controversial

Characterizing embryonic circulatory physiology requires accurate cardiac output and flow data. Despite recent applications of high-frequency ultrasound Doppler to the study of embryonic circulation, current Doppler analysis of volumetric flow is relatively crude. To improve Doppler derivation of volumetric flow, we sought a preliminary model of the spatial velocity profile in the mouse embryonic dorsal aorta using ultrasound biomicroscopy (UBM)-Doppler data. Embryonic hematocrit is 0.05-0.10 so rheologic properties must be insignificant. Low Reynolds numbers (<500) and Womersley parameters (<0.76) suggest laminar flow. UBM demonstrated a circular dorsal aortic cross section with no significant tapering. Low Dean numbers (<100) suggest the presence of minimal skewing of the spatial velocity profile. The inlet length allows for fully developed flow. There is no apparent aortic wall pulsatility. Extrapolation of prior studies to these vessel diameters (300-350 microm) and flow velocities (~50-200 mm/s) suggests parabolic spatial velocity profiles. Therefore, mouse embryonic dorsal aortic blood flow may correspond to Poiseuille flow in a straight rigid tube with parabolic spatial velocity profiles. As a first approximation, these results are an important step toward precise in utero ultrasound characterization of blood flow within the developing mammalian circulation

BACKGROUND: The pulmonary venous flow velocity pattern (PVFVP) in atrial septal defect (ASD) has not been previously studied in detail. Normally, PVFVP is primarily determined by the left heart performance. We hypothesized that the impact of left-sided heart dynamics on PVFVP is diminished in patients with ASD because of the presence of a left-to-right shunt into the low-resistance right side of the heart. METHODS AND RESULTS: Transesophageal echocardiography was performed in 19 adults and 3 children with a large, uncomplicated secundum ASD (maximum diameter 0.6 to 3.0 cm). All patients were in normal sinus rhythm with an average heart rate of 78 bpm in adults and 116 bpm in children. In 21 subjects the antegrade PVFVP lacked distinct systolic (S) and diastolic (D) waves. Instead, we observed a single continuous antegrade wave extending from the beginning of systole to the onset of atrial contraction. Furthermore, the amplitude of the atrial reversal (AR) wave was smaller than in historical controls. In 3 patients in whom ASD was surgically repaired, we observed an immediate return of distinct S and D waves postoperatively. This confirmed that PVFVP abnormality was indeed the result of the ASD. Also a large increase in the AR wave amplitude (46 + 15 cm/s) was noted postoperatively. CONCLUSIONS: This previously unrecognized PVFVP comprising a single continuous antegrade wave and a diminished AR wave sheds new light on the hemodynamics of ASDs. Its presence may also alert the echocardiographer to the possibility of an ASD when the septal defect cannot be visualized directly

BACKGROUND: Knowledge of pressure gradients across valves, arteries, and ventricular septal defects (VSD) is important in patient management. It was determined how well such gradients can be estimated by auscultation of a murmur's frequencies. METHODS: In 151 patients with pulmonary stenosis (PS) (n = 77), aortic stenosis (AS) (n = 30), or VSD (n = 44), the auscultation gradient was estimated by a murmur's frequencies by use of an 'auscultatory scale.' The auscultation gradient was recorded before Doppler echocardiography was performed by a blinded cardiac sonographer. RESULTS: Auscultation correlated highly with Doppler echocardiography (Doppler = 0.99. Auscultation + 7.12; r = 0.84, P <.0001). Agreement was good (mean difference [Auscultation - Doppler] = -6.8 +/- 15.8 mm Hg). In 95 patients (63%), agreement was within 10 mm Hg. Auscultation was more accurate when Doppler gradients were < or =60 mm Hg (r = 0.76, P <.0001, vs r = 0.22, P not significant for >60 mm Hg; mean difference -2.6 +/- 10.6 mm Hg vs -16.5 +/- 20.9 mm Hg for >60 mm Hg, P <.0001). Among lesions, PS showed the highest correlation, although agreement for PS, AS, and VSD was not significantly different. Isolated valvar PS showed excellent accuracy (r = 0.92, P <.0001; mean difference -5.6 +/- 8.9 mm Hg). CONCLUSIONS: Auscultation of a murmur's frequency composition can estimate gradients accurately in most patients with PS (especially valvar PS), AS, or VSD, although it is less accurate for gradients >60 mm Hg. This innovative technique can improve diagnostic accuracy, thereby further substantiating the value of physical examination

The pulmonary artery is typically seen on transthoracic echocardiography in its longitudinal axis. Therefore, short axis views of the pulmonic valve leaflets are not generally obtained, and the distinction between tricuspid and bicuspid pulmonic valves is difficult or impossible. Bicuspid pulmonic valve is one cause of pulmonic stenosis, which is especially common in tetralogy of Fallot. Presented here are 2 patients in whom the orientation of the pulmonary artery was unusual, and the pulmonic valve was seen en face. The first patient had tetralogy of Fallot and a bicuspid pulmonic valve. The severe obstruction to right ventricular outflow was infundibular. The second patient had severe stenosis of a tricuspid pulmonic valve, which was treated with balloon valvuloplasty. These unusual views of the pulmonic valve leaflets were obtained because of anterior displacement of the pulmonary artery, and precise anatomic delineation of the problem in each case was possible with transthoracic echocardiography

Knowledge of early developmental circulatory physiology has lagged behind advances in molecular cardiology. Cardiovascular physiology changes during embryonic development in a highly complex and carefully orchestrated manner, tightly correlated with structural development. Circulatory changes in early development include increasing heart rate, preload, and cardiac output; decreasing peripheral resistance; and increasing ventricular compliance, paralleling the increasing metabolic needs of the growing embryo. Newer techniques and the recent ability to study mammalian models of development have led to further insight into changes in myocardial and peripheral vascular physiology. The next major challenges include understanding the mechanisms regulating cardiovascular hemodynamics, normal physiologic adaptation of the growing embryo, and the physiology of abnormal cardiovascular development