In the presence of impaired LV function with long-term RV apical pacing, alternative sites of ventricular pacing that simulate normal biventricular electrical activation should be explored to preserve function in pediatric patients in need of long-term pacing.

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Biventricular, alternative, and multisite pacing are currently being explored to improve cardiac function among patients with medically refractory, end-stage dilated cardiomyopathies. Although, due to inherent myocardial abnormalities, patients with repaired congenital heart defects may be at a greater risk than others to develop heart failure, often requiring cardiac transplantation. The efficacy of biventricular pacing among these patients is unknown. This report presents a patient with successfully repaired congenital heart disease in infancy who developed a symptomatic dilated cardiomyopathy at 22 years of age. Following biventricular pacing, systemic ventricular function showed a 14% improvement in ventricular dP/dt. One month later, subjective symptoms improved and cardiac ultrasound illustrated a 125% increase in fractional area of change. Exercise stress testing showed a 17% improvement in aerobic work capacity.

To determine the effect of intracoronary perfluorochemical on endothelial cell structure and function, 16 dogs were randomized to receive either low-dose (15 ml/kg) intracoronary perfluorochemical (Fluosol-DA) or saline after 90 min of proximal occlusion of the left anterior descending coronary artery (LAD). The animals underwent reperfusion for 60 min with the introduction of perfluorochemical or saline 5 to 10 min after the onset of reperfusion. Endothelium-dependent coronary vasodilatory reserve was determined in vivo both at baseline and 1 hr after reperfusion by infusion of acetylcholine and then serotonin into the distal LAD bed in 12 animals (six in each group). Both agonists significantly increased regional flow measured by 133Xe washout in the two groups before occlusion, but at 1 hr after reperfusion only animals given perfluorochemical demonstrated a significant increase in flow. Vasodilatory reserve was assessed in vitro with cumulative dose-reponse curves to acetylcholine on LAD rings proximal and distal to the snare in all animals. These studies demonstrated a significant reduction in endothelial cell-mediated relaxation of epicardial arterial segments in the ischemic segment of control but not treated animals. Light microscopy revealed the presence of neutrophils within vessels in the ischemic zones in control animals only. Electron microscopy showed capillary obstruction by endothelial cell protrusions and neutrophil and red cell plugging in control animals in the ischemic region but an intact endothelium and predominantly unobstructed capillaries in treated animals. These findings suggest that the structural and functional endothelial damage after reperfusion may be prevented by the administration of intracoronary perfluorochemical after the onset of reperfusion. Circulation 76, No. 2, 469-479, 1987. EARLY CORONARY REPERFUSION reduces infarct size and improves ventricular function in man and animals.'-5 However, certain biochemical and anatomic changes occur with reperfusion that may result in the conversion of reversibly injured myocardial cells to irreversibly injured cells.6 The role of the endothelium is of particular interest in this phenomenon. Capillary damage has been suggested to be a major contributing factor to the development of microvascular damage We have previously demonstrated that intracoronary administration of the artificial blood substance, perfluorochemical (Fluosol-DA 20%; Alpha Therapeutic Corp., Los Angeles), soon after reperfusion significantly reduces infarct size and improves regional ventricular function in both the short-and long-term canine preparation.'0' 11 However, the mechanisms by which this drug salvages myocardium have not been investigated. We postulated that because of its small particle size and low viscosity, perfluorochemical may penetrate into the ischemic microvascular bed after reperfusion and potentially preserve the endothelium.

Dynamic three-dimensional echocardiographic reconstructions of 27 cardiac septation defects were performed in 19 sedated infants and children. Using a subxiphoid rotational scanning approach, complete visualization of the entire shape and breadth of the defect was attained in 11 of 16 ventricular septal defects and 9 of 11 atrial septal defects. This technique enabled the operator to cut slices from the three-dimensional block of echocardiographic data in order to present septation defects in a region- or lesion-oriented fashion. Poor baseline two-dimensional image quality and certain small septation defects that were readily obscured by nearby structures led to inadequate three-dimensional reconstructions. The application of dynamic three-dimensional echocardiography for assessment of cardiac septation defects uniquely provided (1) the ability to present en face views of atrial and ventricular septal defects; and (2) a means by which intracardiac anatomy can be displayed in a region- and lesion-oriented fashion for interventional and surgical planning purposes.

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The advantages of atrial synchrony over asynchronous ventricular pacing remain unclear in the young, chronically right ventricular (RV) - paced patient. This is in contrast to the older patient with inherent diastolic dysfunction who has been shown to benefit from atrial synchrony with dual chamber (DDD,R/VDD), over single chamber rate response (VVI,R) ventricular pacing. The goal of this study was to noninvasively assess cardiac function in a group of young, RV-paced patients before and after establishment of atrial synchrony. Echocardiographic data were retrospectively analyzed from 10 patients with congenital or acquired complete AV block, who were VVI,R paced for 10.2 +/- 2 years (mean age at study 19.2 +/- 8.9 years), and were subsequently converted to DDD,R/VDD pacing (mean age at study 20.7 +/- 9.5 years). Paired t-test analysis of left ventricular (LV) systolic and diastolic function during VVI,R versus DDD,R/VDD pacing did not result in any short-term difference in LV short axis fractional area of change or FAC (53% +/- 7.5% vs 56.8% +/- 8.7%) or mitral maximal velocity (E) normalized to mitral flow velocity time integral (VTI) (5.2/s +/- 1.5 vs 4.4/s +/- 1.5). A decrease in mitral flow E/A ratio was observed after short-term DDD,R/VDD pacing (2.2 +/- 0.5 vs 1.9 +/- 0.3). Atrial synchronous dual chamber pacing in young patients with complete AV block does not lead to any appreciable early change in global LV function over single-site RV pacing. Therefore, early establishment of atrial synchrony in the young asymptomatic VVI,R-paced patient with normal intrinsic ventricular function may not be warranted.