Faculty Bibliography

Sudden cardiac death is one of the most important causes of mortality in the modern industrialized world. Although it has been described for at least several centuries, we believe in fact that Hippocrates provided a concise, but historically compelling, description of sudden cardiac death in his Aphorisms II, 41: 'Those who are subject to frequent and severe fainting attacks without obvious cause die suddenly.' This would be the earliest description of sudden cardiac death known. The Aphorism was analyzed in the context of genuine Hippocratic writings as well as ancient Greek culture. The Aphorism describes recurrent syncope in otherwise healthy individuals. Therefore, only certain select cardiac conditions are likely described by this Aphorism. Such conditions-long QT syndrome, hypertrophic cardiomyopathy, congenital coronary artery syndromes, and arrhythmogenic right ventricular dysplasia, chief among them-are linked by a final common pathway of an arrhythmic death. Relying solely on clinical experience based on careful history-taking and keen powers of observation, Hippocrates was the first to describe sudden cardiac death due to a select group of cardiac conditions. This analysis establishes such conditions as being an important cause of sudden death 2400 years ago, much as they are among the most important causes of sudden death today

When cardiac function and blood flow are first established are fundamental questions in mammalian embryogenesis. The earliest erythroblasts arise in yolk sac blood islands and subsequently enter the embryo proper to initiate circulation. Embryos staged 0 to 30 somites (S) were examined in utero with 40- to 50-MHz ultrasound biomicroscopy (UBM)-Doppler, to determine onset of embryonic heartbeat and blood flow and to characterize basic physiology of the very early mouse embryonic circulation. A heartbeat was first detected at 5 S, and blood vascular flow at 7 S. Heart rate, peak arterial velocity, and velocity-time integral showed progressive increases that indicated a dramatically increasing cardiac output from even the earliest stages. In situ hybridization revealed an onset of the heartbeat coincident with the appearance of yolk sac-derived erythroblasts in the embryo proper at 5 S. Early maturation of the circulation follows a tightly coordinated program

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