Interaction between pulmonary vasculature and the patent ductus arteriosus in very premature infants.

Background: The benefits of closing the ductus arteriosus in very preterm infants have not been convincingly shown in numerous clinical trials. Because a large untreated ductus arteriosus can cause death from congestive heart failure in infants born at term, we need to explain why this might not occur in premature infants born at <28 weeks' gestation.

Methods: Based on information in the literature, I have commented on the possible relationship between the pulmonary vasculature and the shunt through the patent ductus arteriosus.

Pulse oximetry in neonates at high altitudes: a modified Colorado protocol.

Pulse oximetry for detecting critical CHD produces more false positive tests at high altitudes than at sea level, because at altitude the average resting saturation is lower and the variability is higher. This increases diagnostic difficulties, especially in small isolated communities without paediatric echocardio-graphy, and requires expensive transport to a regional medical centre. One way of reducing diagnostic errors is to measure arterial oxygen saturation while the infant is breathing 100% oxygen.

A Preliminary Study of Left Ventricular Rotational Mechanics in Children with Noncompaction Cardiomyopathy: Do They Influence Ventricular Function?

Background: Current diagnostic criteria for noncompaction cardiomyopathy (NCC) lack specificity, and the disease lacks prognostic indicators. Reverse apical rotation (RAR) with abnormal rotation of the cardiac apex in the same clockwise direction as the base has been described in adults with NCC. The aim of this study was to test the hypothesis that RAR might differentiate between symptomatic NCC and benign hypertrabeculations and might be associated with ventricular dysfunction.

The Ratio Fallacy, with Special Reference to the Cardiac Index.

When comparing cardiac outputs in children of different sizes, or deciding on the normality of these outputs, we often convert the absolute output to the output per m body surface area-the cardiac index. For small infants, this leads to potentially large errors. The best way to evaluate these outputs is to determine their z values.

The challenge in diagnosing coarctation of the aorta.

Critical coarctation of the aorta in neonates is a common cause of shock and death. It may be the most difficult of all forms of critical congenital heart disease to diagnose because the obstruction from the coarctation does not appear until several days after birth (and after discharge from the hospital), and because there are no characteristic murmurs. Some of these patients may be detected by neonatal screening by pulse oximetry, but only a minority is so diagnosed.

Will the real ventricular architecture please stand up?

Ventricular twisting, essential for cardiac function, is attributed to the contraction of myocardial helical fibers. The exact relationship between ventricular anatomy and function remains to be determined, but one commonly used explanatory model is the helical ventricular myocardial band (HVMB) model of Torrent-Guasp. This model has been successful in explaining many aspects of ventricular function, (Torrent-Guasp et al.

The history of the microsphere method for measuring blood flows with special reference to myocardial blood flow: a personal memoir.

We use many types of equipment and technologies to make our measurements but give little thought to how they developed. Evolution was once described as a series of recoils from blind alleys, and this is exemplified by the gradual development of the microsphere method of measuring blood flows. The microsphere method is one of the most frequently used methods for measuring blood flow to organs and portions of organs.

At what age should tetralogy of Fallot be corrected?

Tetralogy of Fallot can be corrected with very low mortality at any age, even in neonates, but this does not necessarily mean that it should be corrected in the neonatal period. Although there are many advantages to early correction, a high proportion of these neonates have residual stenosis or pulmonary regurgitation that impairs ventricular function and may require further surgery or implantation of a pulmonary valve. Before we had the ability to correct this anomaly with low mortality in small children, a variety of palliative procedures had to be performed.

Is spontaneous closure of a patent arterial duct common?

As closing a patent arterial duct is relatively simple, safe, and successful, most children with a patent arterial duct have it closed soon after diagnosis. The larger ducts are closed to prevent congestive heart failure, pulmonary vascular disease, or aneurysmal dilatation of the ductus, and smaller ducts are closed to prevent infective endocarditis. Consequently, there is no opportunity to determine whether spontaneous closure or diminution in size of the patent arterial duct is common.

Is Pulse Oximetry Useful for Screening Neonates for Critical Congenital Heart Disease at High Altitudes?

Now that pulse oximetry is used widely to screen for critical congenital heart disease, it is time to consider whether this screening method is applicable to those who live at high altitudes. Consideration of basic physical principles and reports from the literature indicate that not only is the 95 % cutoff point for arterial oxygen saturation incorrect at high altitudes, but the lower saturations are accompanied by greater variability and therefore there is the possibility of a greater percentage of false-positive screening tests at high altitudes. Because of ethnic differences in response to high altitudes, normative data will have to be collected separately in different countries and perhaps for different ethnic groups.

Ventricular structure-function relations in health and disease: Part I. The normal heart.

The heart's structure-function relationships explain normal cardiac dynamics and clarify how they are disrupted by disease. For 500 years, anatomists described circumferential and helical cardiac fibres, yet disagreed about their relationships. One current model is attributed to Torrent Guasp who described functional pathways, the helical ventricular myocardial band (HVMB) with two interconnected loops: an outer basal loop with transverse fibres surrounds an inner apical helical loop that is composed of oblique descending and ascending segments that create a conical apical vortex.

Ventricular structure-function relations in health and disease: part II. Clinical considerations.

Normal cardiac function of the left and right ventricles, together with the septum, is related to form/function interactions within the helical ventricular myocardial band. This knowledge is a prerequisite to understanding form/function interactions in diseases and for planning new treatments. Topics discussed include congestive heart failure in dilated hearts of ischaemic, valvar or nonischaemic origin as well as diastolic dysfunction.

Right ventricular architecture responsible for mechanical performance: unifying role of ventricular septum.

The right ventricle (RV) is composed of a free wall containing a wrap-around circumferential muscle at its base and a septum composed of helical fibers that are oblique and cross each other at 60° angles. This structure is defined by the helical ventricular myocardial band and defines RV function because the wrap-around transverse fibers constrict or compress to cause the bellows motion responsible for 20% of RV output, whereas the oblique fibers determine shortening and lengthening that produces 80% of RV systolic function. Clinical shortening is quantified by tricuspid annular plane systolic excursion and measured by echocardiography.

Abnormal origins of the coronary arteries from the aortic root.

Anomalous origin of a coronary artery from the aorta is a potentially serious anomaly that occurs in about 0.1-0.2% of the population.

The global burden of congenital heart disease.

Although the incidence of congenital heart disease (CHD) is similar worldwide, the burden of supporting these patients falls more heavily on countries with high fertility rates. In a country with a fertility rate of about eight per woman, the population has to support four times as many children with CHD as in a country with a fertility rate of two. Countries with the highest fertility rates tend to have the lowest incomes per capita, thus accentuating the disparity.

Stem cell antigen-1 in skeletal muscle function.

Stem cell antigen-1 (Sca-1) is a member of the Ly-6 multigene family encoding highly homologous, glycosyl-phosphatidylinositol-anchored membrane proteins. Sca-1 is expressed on muscle-derived stem cells and myogenic precursors recruited to sites of muscle injury. We previously reported that inhibition of Sca-1 expression stimulated myoblast proliferation in vitro and regulated the tempo of muscle repair in vivo.

Normal and abnormal pulmonary arteriovenous shunting: occurrence and mechanisms.

Severe cyanosis due to pulmonary arteriovenous fistulas occurs often after a bidirectional superior cavopulmonary anastomosis (Glenn operation) and also in some congenital anomalies in which hepatic venous blood bypasses the lungs in the first passage. Relocation of hepatic flow into the lungs usually causes these fistulas to disappear. Similar pulmonary arteriovenous fistulas are observed in hereditary haemorrhagic telangiectasia, and in liver disease (hepatopulmonary syndrome).