Myocardial protection during ischemia by prior feeding with the creatine analog: cyclocreatine.

The ability of 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine), a synthetic creatine analog, to protect myocardium during global ischemia was assessed in isovolumic rat hearts using phosphorus-31 nuclear magnetic resonance spectroscopy. Wistar rats were fed a 1% cyclocreatine diet. After 2 weeks, cyclocreatine-fed (n = 8) and control (n = 7) rats were anesthetized, the heart was excised and retrograde perfusion was begun at 10 ml/min per g with 37 degrees C, phosphate-free buffer containing glucose and oxygen.

Left ventricular systolic circular index: an echocardiographic measure of transseptal pressure ratio.

An echocardiographic index of left ventricular (LV) short axis circularity can be defined by the equation: left ventricular systolic circularity index (LVSCI) = 4 pi(LV area) X 100/(LV perimeter). This index was measured from two-dimensional echocardiograms in 98 children (ages 1 day to 19 years) with congenital heart disease, and results were compared to right ventricular/left ventricular peak systolic pressure ratios (RVP/LVP) determined at cardiac catheterization. LVSCI was also computed in 50 children without cardiovascular or pulmonary disease to define the normal range.

Right atrioventricular valve atresia: anatomic evaluation with MR imaging.

MR was used to differentiate the classical form of tricuspid atresia, in which the atrioventricular connection is absent, from a rare type of right atrioventricular obstruction, in which the valve is imperforate, and from some Ebstein's malformations in which atrioventricular flow is obstructed by a displaced tricuspid valve. ECG-gated, T1-weighted spin-echo MR imaging was performed at 0.3 or 1.

Alterations of energy metabolism in the spontaneously hypertensive rat: a 31P nuclear magnetic resonance study.

We quantified high-energy phosphate metabolites in hypertensive hypertrophied and normal myocardium and monitored temporal changes using the non-invasive 31P nuclear magnetic resonance (NMR) spectroscopy. Hearts from 18 month spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto rats (WKY) were perfused with a phosphate-free buffer at 10 cc/min per g and paced at 240 beats/min on a modified Langendorff apparatus. Perfusion pressure, left ventricular pressure (LVP) and dP/dt were recorded and successive 31P NMR spectra were collected during a 24-min baseline period (oxygenated buffer), anoxia (N2-bubbled and glucose-free buffer) until a 70% fall in LVP occurred, and recovery.