“CARDIOVASCULAR PERFORMANCE IN FETAL AND
NEONATAL DISEASE”
SickKids Main Auditorium
19 May 2009
9:00 am-1:00 pm
Physiology &
Experiemental Medicine
Nico Blom, MD, PhD: Leiden University Medical Centre, Leiden, Netherlands
The prescence of accessory atrioventricular pathways during normal and abnormal cardiac
development
In the early tubular heart the atrial myocardium is continuous with the ventricular myocardium and the blood is pumped
forward by peristaltic contractions. During cardiac development the ventricular activation shifts from base to apex activation in
the primitive looped heart to apex to base activation in the mature heart. This transition in ventricular activation pattern reflects
the formation of the specialized His-Purkinje system and coincides with completion of ventricular septation and isolation of the
atrioventricular (AV) junction. We will discuss processes involved in the formation of the fibrous annulus and persistence of
functional remnants of AV myocardial connections as possible substrate for AV re-entrant tachycardia.
Edgar Jaeggi, MD, FRCP(C): Physiology & Experimental Medicine, Fetal Cardiac Program, The Hospital for Sick
Children, Toronto, Canada
Intrauterine growth restriction and its impact on cardiac function and on arterial compliance
in the young child
A direct association between low birth weight and early-onset of essential arterial hypertension has been articulated in the “fetal
origins of adult disease hypothesis”. This presentation will focus on the relationship between intrauterine growth restriction,
low birth weight and vascular modifications in the young child. We will characterize the impact of early and late-onset
intrauterine growth restriction related to placental failure on fetal and early postnatal cardiovascular performance. We will
determine the degree of correlation between peripheral and central arterial stiffness, placental stem arterial vascular changes
and umbilical arterial wall properties and finally discuss their potential roles as early predictors of arterial hypertension.
Gil Gross, MD, FRCP(C): Physiology & Experimental Medicine, Cardiology, The Hospital For Sick Children, Toronto,
Canada
Heart rate: A key determinant of myocardial electrophysiologic and contractile function
Altered heart rate (HR) has long been viewed as an essentially passive response to underlying disease. Recently, there is
growing recognition that HR independently predicts cardiac and all-cause mortality in cardiovascular disease; moreover,
therapeutic interventions targeting HR itself impact significantly on clinical outcome. In our model of HR-dependent
myocardial remodeling, chronic bradycardia enhances contractility while impairing repolarization, in contrast to tachycardia
which negatively affects both parameters. Cellular mechanisms and ongoing studies of these phenomena will be discussed.
Patrick McNamara,MD,FRCP(C): Physiology & Experimental Medicine, Neonatology, The Hospital For Sick
Children, Toronto, Canada
Impaired myocardial performance following neonatal asphyxial cardiac arrest. Impact of
resuscitation medications
Despite significant advances in perinatal care and the refinement of neonatal resuscitation guidelines the outcome following
neonatal cardiac arrest remains dismal. Unfortunately these guidelines are based on indirect extrapolations from adult literature
-based in turn, on laboratory data- and do not take into account the unique transitional physiology of newborns. Epinephrine,
although an integral part of every published protocol for neonatal resuscitation, may cause more harm than good; it may
increase mortality. Our group has shown that epinephrine leads to pulmonary edema and increased mortality, secondary to left
ventricular diastolic dysfunction, in an adult rodent model of asphyxial cardiac arrest. Vasopressin may be a more effective
agent for neonatal resuscitation, as it elevates CPP without direct cardiotoxicity and has specific pulmonary vasodilator
properties. A comparative evaluation of vasopressin and epinephrine is presented.
Lior Gepstein, MD, PhD: Technion – Israel Institute of Technology, Haifa, Israel
Human pluripotent stem cells: potential implications for basic and applied pediatric
cardiovascular research
This presentation will focus on the potential implications of human pluripotent stem cells for paediatric cardiovascular research.
Initially, our efforts in establishing a cardiomyocyte differentiating system from human embryonic stem cells (hESC) will be
described and examples for its applications in cardiovascular development biology, (patho)physiology modeling,
pharmacological testing, and cardiac regenerative medicine will be provided. We will next present the recently described
induced pluripotent stem cell (iPS) technology and detail its potential impact on cardiac in-vitro modeling and regenerative
medicine.