Regulation of human heart contractility by essential myosin light chain isoforms.

Most of the patients with congenital heart diseases express the atrial myosin light chain 1 (ALC-1) in the right ventricle. We investigated the functional consequences of ALC-1 expression on the myosin cycling kinetics in the intact sarcomeric structure using multicellular demembranated fibers ("skinned fibers") from the right ventricular infundibulum of patients with Tetralogy of Fallot (TOF), double outlet right ventricle (DORV), and infundibular pulmonary stenosis (IPS), Force-velocity relation was analyzed by the constant-load technique at maximal Ca2+ activation (pCa 4.5). Half-time of tension development (t1/2) was investigated by monitoring contraction initiation upon photolytic release of ATP from caged-ATP in rigor. The patients investigated here expressed between 0 and 27% ALC-1. There was a statistically significant correlation between ALC-l and maximal shortening velocity (Vmax) which rose 1.87-fold from 1.2 muscle length per second (ML/s) to 2.25 ML/s in a normal (0% ALC-1) and diseased (19.9% ALC-1) ventricle. Half-time of tension development decreased 1.85-fold with increasing ALC-1 expression (t1/2) was 0.252 s and 0.136 s at 2 and 18.4% ALC-1, respectively). We conclude that the expression of ALC-1 in the human heart modulates cross-bridge cycling kinetics accelerating shortening velocity and isometric tension production.

Transcatheter closure of atrial septal defects without fluoroscopy: feasibility of a new method.

BACKGROUND: In an effort to reduce x-ray exposure, we developed a technique for transcatheter closure of atrial septal defects under echocardiographic guidance without fluoroscopy. To assess the efficiency of this procedure for routine use, we compared our initial results with those for the conventional procedure. METHODS AND RESULTS: Twenty-two randomly selected patients (median age 18 years; range 2 to 66 years) with atrial septal defects (n=13) or patent foramen ovale (n=9) underwent cardiac catheterization for possible interventional defect closure with echocardiography as the only imaging tool. Median stretched diameter was 9 mm (range 6 to 26 mm); median left-to-right shunt over the atrial septal defects was Qp/Qs=1.8 (range 1.5 to 2.6). An Amplatzer septal occluder was successfully implanted in 19 defects without fluoroscopy and in 3 with the help of radiography. After 1 month, complete defect closure was documented in all patients. Compared with the conventional procedure of a control group of 131 patients, procedure times were not significantly different (88 versus 100 minutes; P=0.09). However, the study group received significantly higher doses of propofol for sedation (9.9 versus 5.6 mg/kg body weight; P=0.002) owing to extended transesophageal echocardiography. CONCLUSIONS: In the majority of patients in whom transcatheter closure of interatrial communications with the Amplatzer septal occluder is possible, the procedure can be safely performed under echocardiographic guidance without fluoroscopy.

Comparison of modified short axis view and apical four chamber view in evaluating right ventricular function after repair of tetralogy of Fallot.

BACKGROUND: In clinical settings an easy and reliable method for following up right ventricular (RV) function in patients after repair of tetralogy of Fallot (TOF) is needed. It is, however, unclear whether the novel modified short axis view from echocardiography is superior to the apical four chamber view in this aspect. MATERIALS AND METHODS: Thirty postoperative TOF patients with median age 17 years (range 6-45 years) and follow up period of 10 years (range 0.5-40 years) were examined echocardiographically using the apical four chamber view and the novel modified short axis view. RV areas in end-systole (Amin) and end-diastole (Amax) were measured and an area fraction [(Amax - Amin)/Amax * 100%] was calculated from the respective view. RV ejection fraction was assessed through magnetic resonance imaging (MRI). The RV area fractions from echocardiography were compared to the RV ejection fraction. RESULTS: The right ventricular area fraction derived from the modified short axis view was significantly lower than that from the apical four chamber view (34.3+/-9.1% vs. 42.5+/-10.2%, p=0.007). Both the RV area fractions obtained from the modified short axis view (r=0.674, p<0.001) and from the apical four chamber view (r=0.512, p=0.025) correlated significantly with the MRI derived RV ejection fraction. CONCLUSION: The novel modified short axis view from echocardiography may be superior to the apical four chamber view for routine follow up of patients after TOF repair, in whom the right ventricular outflow tract plays an important role in the right ventricular systolic function.

Expression of calcium channel subunits in the normal and diseased human myocardium.

We investigated the expression of alpha1 and beta subunits of the L-type Ca2+ channel on the protein level in cardiac preparations from normal human heart ventricles and from the hypertrophied septum of patients with hypertrophic obstructive cardiomyopathy (HOCM). 1,4-Dihydropyridine (DHP) binding and immunorecognition by polyclonal antibodies directed against the C-terminal amino acid sequences of the beta2 and beta3 subunits were used for detection and quantification of alpha1, beta2, and beta3 subunits. Bmax of high-affinity DHP binding was 35 +/- 2 fmol/mg protein in HOCM and 20 +/- 2 fmol/mg protein in normal human hearts (P<0.05). In rabbit hearts the anti-beta2 subunit antibody immunoprecipitated 80% of the total amount of DHP-labeled Ca2+ channels present in the assay. Under identical experimental conditions 25% of labeled Ca2+ channels were recovered in the immunoprecipitates of both normal and HOCM ventricles. A similar partial immunoprecipitation was observed in pig hearts. Immunoblot analysis demonstrated that the beta2 subunit was associated with the DHP receptor/Ca2+ channel in cardiac muscle of rabbit, pig, and human heart. In neither of these purified cardiac Ca2+ channels was the beta3 subunit isoform detected. Our results suggest that both alpha1 and beta2 subunit expression is upregulated in HOCM in a coordinate manner.

Left and right ventricular adaptation to right ventricular overload before and after surgical repair of tetralogy of Fallot.

On the basis of angiographic projections, left (n = 43) and right (n = 56) ventricular volume data were obtained in patients with tetralogy of Fallot before and after surgical repair. The postoperative patients were divided into 3 groups according to the degree of an additional volume load secondary to a residual ventricular septal defect or pulmonary insufficiency, or both. The decreased left ventricular ejection fraction (p less than 0.01) in preoperative tetralogy of Fallot in the presence of a normal sized left ventricle suggests depressed global myocardial function, which is not improved after surgical repair, even if excellent results are achieved. A certain functional reserve, however, seems to be preserved, since the ejection fraction did not decrease further with increasing additional volume loads. Similar enlargement of the right ventricle secondary to comparable degrees of pulmonary insufficiency and residual ventricular septal defect indicates similar effects of additional diastolic and systolic filling on right ventricular function in patients with tetralogy of Fallot after surgical repair. Even in patients with excellent surgical results, such as those without significant right ventricular outflow tract obstruction and additional volume load, right ventricular pump function is depressed, the ejection fraction being significantly (p less than 0.01) lower than normal. The further decrease of global myocardial function with increasing volume load suggests a loss of functional reserve. Attempts to minimize right ventricular volume load after surgical repair seem advisable.

Right ventricular imaging with digital subtraction angiocardiography using intraventricular contrast injection.

Angiocardiography is of considerable value in the dimensional analysis of the right ventricular (RV) cavity, but conventional angiocardiography requires large amounts of contrast medium. In this study digital subtraction angiocardiography was applied to biplane RV projections of 25 children with congenital heart disease after direct injection of a small dose of contrast medium. Volume measurements were compared with those obtained by conventional angiocardiography. The amount of contrast medium required was reduced to 30%, flow rate to 57% and ventricular ectopic activity to 60% of that used in conventional angiocardiography, and the degree of radiation exposure was reduced considerably. There was a good correlation for end-diastolic (r = 0.996) and end-systolic volume (r = 0.990) determined with both techniques. Digital subtraction angiography after selective RV injection allows accurate volume measurements of the right ventricle in children with congenital heart disease. The main benefits of this method are reduction of the amount of contrast medium, flow rate during injection, radiation and ventricular ectopic activity.

Effects of angiocardiographic contrast media on the pulmonary circulation in pigs.

In 12 open-chest pigs, mean weight 18 kg, simultaneous beat-to-beat measurements of pressure in the right and left atria and right and left ventricles, and of pressure and flow in the pulmonary artery, were performed before, during and after the injection of 0.8 ml/kg with 10 to 15 ml/s of diatrizoate, ioxaglate and iopamidol as well as mannitol, normal saline solution and own blood into the right atrium, right ventricle and pulmonary artery. Within 5 beats after injection, all determined hemodynamic values reached their maxima of change independent of site of injection and kind of injectate. After 10 to 20 beats, pulmonary resistance diminished, and the reduction was more pronounced and longer lasting the higher the osmolality of the injectate. Hemodynamic changes during the first beats were a result of the rapidly injected volume; longer lasting hemodynamic changes were associated with an osmolality-dependent decrease in pulmonary resistance.

Right ventricular function in patients treated with inhaled nitric oxide after cardiac surgery for congenital heart disease in newborns and children.

Measurement of right ventricular (RV) function is essential for complete assessment of the effects of inhaled nitric oxide in the postoperative cardiac patient; nitric oxide therapy can result in a decrease in pulmonary vascular resistance and improved echocardiographic RV ejection fraction without necessarily inducing a significant change in pulmonary artery pressure.

Value of image enhancement and injection of contrast medium for right ventricular volume determination by two-dimensional echocardiography in congenital heart disease.

To determine factors that influence the accuracy of echocardiographically estimated right ventricular volume and to improve the echocardiographic input information by applying image enhancement techniques, quantitative contrast echocardiography (4-chamber view) and biplane angiocardiography were performed in 23 children during routine diagnostic cardiac catheterization. Volumes calculated on the basis of unprocessed and processed echocardiographic cross sections (area-length method and sphere model) underestimated angiocardiographic volumes significantly (p less than 0.01), and more so in end-diastole (50.6%) than in end-systole (35.9%). Thus, ejection fraction was significantly (p less than 0.01) underestimated; mean values were 0.48 +/- 0.12 and 0.60 +/- 0.08, respectively. The best comparison between echocardiography and angiocardiography at end-diastole was achieved with the sphere model using image enhancement techniques and injection of contrast media, where y = 0.54x - 6.8, r = 0.97, sy.x = 7.3. Correlations, however, in which unprocessed echocardiograms were used showed only slightly less good correlations. With the 6 image-enhancement techniques, a more homogeneous structure of the image and a more distinct outline of the internal surface was achieved. The statistical error improved only slightly. The echocardiographic 4-chamber view allows right ventricular volume determination with an acceptable accuracy. Its underestimation is related to inadequate visualization of trabeculations and mainly to the models used. Application of image enhancement techniques allows easier outlining of the internal cavity surface. The advantage gained by the combination of contrast infection and image enhancement techniques does not warrant the routine central injection of available contrast material.

Influence of the two-stage anatomic correction of simple transposition of the great arteries on left ventricular function.

To evaluate the influence of the 2-stage anatomic correction of simple transposition of the great arteries on left ventricular (LV) function, pressure and angiocardiographic volume data were analyzed during resting conditions shortly before banding of the pulmonary trunk (n = 12) and before (n = 17) and after anatomic correction (n = 11), and compared with data from controls (n = 12). Age at banding and anatomic correction was between 1 and 44 months (mean 16 +/- 10) and between 13 and 47 months (mean 24 +/- 10), respectively. The interval between anatomic correction and the investigation ranged from 10 to 29 months (mean 20 +/- 7). After banding, LV ejection fraction decreased (p less than 0.01) and LV peak systolic pressure (p less than 0.01) as well as LV end-diastolic pressure (p less than 0.05) increased. After anatomic correction, these variables and LV end-systolic wall stress were not significantly different from control values. The LV end-systolic wall stress-ejection fraction relation in 7 of 11 patients after anatomic correction was within control range. The highest values were found in the youngest patients at banding and at anatomic correction. In contrast to measures of global myocardial function, such as LV ejection fraction and LV end-diastolic pressure data, the LV end-systolic stress-ejection fraction relation suggest that LV function may not be normal in some patients 20 months after anatomic correction. Young age at operation, however, appears to be advantageous in preserving LV function. Hemodynamic alterations after banding probably reflect LV adaptation to systemic pressures in a hypoxemic circulation.

Quantitative analysis of structure and function of the cardiovascular system by roentgen-video-computer techniques.

A survey of the evolution of roentgen-video-computer techniques is given which was initiated by the development of videodensitometry by Wood and his associates. Following fundamental studies of the usefulness and limitations of x-ray equipment for quantitative measurements and the applicability of the Lambert-Beers law to x-ray absorption, videodensitometry has been used experimentally and clinically for various circulatory studies and has proved to be particularly valuable for the quantitation of aortic, pulmonic, and mitral valvular regurgitation. The second offspring of these techniques, so-called videometry, uses dimensional measurements from single and biplane angiocardiograms for the assessment of size, shape, and contraction pattern of the heart chambers. Volumes of the right and left ventricles can be determined clinically with a standard error of estimate below 10%. On the basis of these studies, normal values have been derived for all age groups, and they depict geometric changes of the growing heart. Cardiac index and ejection fractions proved to be age-independent biologic constants. Finally, methods for complete digital processing of video-image sequences in an off-line and real-time mode are described which allow digital image storage and documentation, dynamic background subtraction for contrast enhancement, and intravenous angiocardiography, in addition to functional imaging by parameter extraction from a matrix of pixel densitograms. Wall thickness and motion determinations, regional flow distribution measurements, and various image-composition techniques are also feasible.

Comparison of results and complications of surgical and Amplatzer device closure of atrial septal defects.

OBJECTIVES: Results and complications of surgical versus transcatheter treatment of atrial septal defect in the current era are compared. METHODS: All consecutive patients with a secundum atrial septal defect and a pulmonary/systemic flow ratio of 1.5:1 or more who presented between May 1997 and June 1998 were enrolled in this study. All patients except those who initially had defects not feasible for interventional occlusion were catheterized to allow interventional closure of the defects. All patients in whom interventional closure could not be performed underwent surgical closure. RESULTS: Sixty-one patients underwent surgery at a median age of 20 years (0.5-74 years) and 61 had the defect closed with an Amplatzer device (AGA Medical Corporation, Golden Valley, Minn) at a median age of 12 years (0.8-77.7 years) (P >.2). Hospital stay in surgically treated patients was 8 days (6-19 days) versus 3 days (3-14 days) in interventionally treated patients (P <.001). Atrial septal defect and shunt sizes were larger in the surgical group ( P <.001). Closure rates in the 2 groups were identical (98%). One patient (68 years) in the surgical group had a perforated duodenal ulcer that necessitated an operation 8 days after closure of the atrial septal defect, and 1 (26 years) had an infected lateral thoracotomy wound necessitating plastic surgery. Embolization of the Amplatzer device to the left ventricle was observed in 1 patient (29 years). The device could be retrieved from the heart, but vascular surgery was required to extract it from the femoral artery. CONCLUSIONS: As complete closure rates and complications are identical, but duration of hospital stay is shorter with less morbidity, we prefer implantation of an Amplatzer septal occluder to surgery wherever possible.

Anomalous origin of the left coronary artery from the pulmonary artery. Early results with direct aortic reimplantation.

Between January 1991 and June 1993, eleven children with anomalous origin of the left coronary artery from the pulmonary artery underwent direct aortic reimplantation of the left coronary artery at the German Heart Institute Berlin. The patients' ages ranged from 2.5 months to 10.5 years; six were infants. Three infants were intubated and their lungs ventilated before the operation, and one was resuscitated 2 days before the operation. The electrocardiograms of eight patients indicated deep Q waves. All but three of these patients had insufficient collaterals between the right and left coronary arteries. The entire group exhibited reduced left ventricular ejection fraction (minimum 15%) including mitral valve incompetence, which was moderate in six patients and severe in three. All six infants underwent emergency operations, and the remaining children, who were older, underwent elective operations involving moderate hypothermic perfusion and cold crystalloid cardioplegia. Aortic cross-clamping time ranged from 22 to 79 minutes (mean 54 minutes). A two-coronary artery system was established in all patients by direct reimplantation of the anomalous left coronary artery into the ascending aorta. Three patients who also exhibited severe mitral valve incompetence underwent modified Kay mitral valve annuloplasty. A delayed sternal closure procedure (closure performed 1 to 10 days after the operation) was used on eight patients. A 10-month-old patient was successfully treated after the operation with a centrifugal left heart assist device and a 9-year-old patient received extracorporeal membrane oxygenation because of severe heart failure. No postoperative deaths occurred. Left ventricular end-diastolic volume decreased dramatically after the operation and returned to near normal values 1 to 9 months postoperatively. At the same time, the preoperatively depressed left ventricular ejection fraction returned to normal and mitral valve incompetence decreased or vanished in eight patients. Color Doppler echocardiograms (eleven patients) and coronary angiograms (three patients) indicated that the reimplanted left coronary artery was patent in all eleven patients during the follow-up period. Reimplantation of the left coronary artery into the ascending aorta is an effective method of establishing a two-coronary artery system in children with anomalous origin of the left coronary artery from the pulmonary artery. Mitral valve annuloplasty is recommended for patients who also have severe mitral valve incompetence. Prolonged assisted circulation must be used in cases of severe postoperative heart failure.

Superior function of a bicuspid over a monocuspid patch for reconstruction of a hypoplastic pulmonary root in pigs.

In an experimental study in pigs, the function of monocuspid and bicuspid patches was compared to improve surgical reconstruction of a hypoplastic pulmonary root. Segments from glutaraldehyde-treated porcine aortic roots served as monocuspid and bicuspid patches. Their leaflets and commissures were marked with radiopaque metal clips. Marker movements were recorded at 100 frames/sec. Quantification of pulmonary insufficiency, right ventricular stroke volume, as well as pressures in the right ventricle, pulmonary artery, and aorta was performed before and after patch plasty. The cyclic motion of the leaflets showed a three-phase pattern in monocuspid and bicuspid patches: (1) a rapid opening motion with a significantly longer distance to be covered in monocuspid patches (7.5 mm in monocuspid versus 4.9 mm in bicuspid patches); (2) a slow closing motion that was significantly greater in monocuspid patches (31.5% of maximal displacement in monocuspid versus 18.2% and 23.8% in bicuspid patches); (3) a similar rapid closure motion in both types of patches. The commissural expansion was less than 6% for monocuspid and bicuspid patches and began 10 to 20 msec before valve opening. Considerable irregularities in the movement of the different leaflet markers, especially in monocuspid patches, indicated leaflet buckling as a result of redundant leaflet tissue. There was a significant pulmonary regurgitant fraction only in monocuspid patches (19% in monocuspid versus 7% in bicuspid patches) that occurred during early diastole. No pressure gradients were observed across either type of patch. In monocuspid patches, a greater leaflet displacement during rapid closure was correlated with an increased pulmonary insufficiency (r = 0.8875). In conclusion, the function of a bicuspid patch is superior to that of a monocuspid patch for repair of a hypoplastic pulmonary root and allows the construction of a competent and stenosis-free valve mechanism.

Short-term hemodynamic results after right ventricular outflow tract reconstruction using a cusp-bearing transannular patch.

Correction of right ventricular outflow tract obstruction remains a challenge to cardiovascular surgeons. In order to relieve this obstruction and at the same time prevent or minimize pulmonary insufficiency, we inserted a cusp-bearing transannular patch (monocusp) in 14 patients. To test this objective, we restudied 13 of these patients 0.5 to 4 months postoperatively, including quantifying pulmonary insufficiency using an accurate videodensitometric method. In all patients a degree of pulmonary insufficiency ranging from 8% to 46% of total stroke volume (mean 22.7 +/- 10.6%) was measured, and in all but one a residual right ventricular outflow pressure gradient of 2 to 22 mm Hg (mean 10 +/- 7 mm Hg) was measured. There was an inverse relation between the degree of pulmonary insufficiency and both the pressure gradient (r = -0.89) and the ratio of the pulmonary valve ring diameter to monocusp depth (r = -0.67). An ideal reconstruction of the right ventricular outflow tract obstruction, without any postoperative pulmonary insufficiency and stenosis, was not achieved by the implantation of a monocusp in the described fashion. The postoperative results were acceptable in only a few patients. A reduction of pulmonary insufficiency seems to be associated with a small residual pressure gradient as well as a relatively small cusp size. Additional studies are necessary to further improve surgical correction of right ventricular outflow tract obstruction with reproducible and predictable results.

A modified repair technique for tricuspid incompetence in Ebstein's anomaly.

OBJECTIVE: A modified technique for tricuspid valve repair in Ebstein's anomaly restructures the valve mechanism at the level of the true tricuspid anulus by using the most mobile leaflet for valve closure without plication of the atrialized chamber. Midterm results of this therapeutic approach for patients with Ebstein's anomaly and tricuspid valve incompetence are reported. METHODS: Between October 1988 and April 1997, the incompetent tricuspid valve was repaired with our technique in 19 patients (12 female, 7 male; 2 to 54 years, mean 21 years). The indication for operation was congestive heart failure of various degrees in all patients. Tricuspid incompetence was grade II in two patients, grade III in 14, and grade IV in three. Associated congenital malformations were simultaneously repaired (interatrial communication in 18, ventricular septal defect in two, pulmonary stenosis in two, mitral valve prolapse in one). Follow-up ranged between 10 and 103 months (median 28 months) and was complete for all patients. RESULTS: There were no operative deaths. One patient with active endocarditis and pulmonary abscess died 2 months after the operation of recurrent sepsis; there were no late deaths. During follow-up, New York Heart Association functional class improved from 2.8 before the operation to 1.9 without recurrent cyanosis, and tricuspid incompetence decreased from a mean grade of 3.1 to one of 0.9, without any echocardiographic deterioration of the tricuspid valve function or right ventricular dilation. CONCLUSIONS: Our technique allows tricuspid valve repair in patients with Ebstein's anomaly, even in cases usually reserved for primary valve replacement, without late functional deterioration.

Randomised trial on the influence of continuous magnesium infusion on arrhythmias following cardiopulmonary bypass surgery for congenital heart disease.

OBJECTIVES: To check the hypothesis that continuous magnesium infusion protects the heart from arrhythmias following cardiopulmonary bypass surgery for congenital heart disease. DESIGN: A prospective randomised placebo-controlled study, with patients stratified in three weight groups. PATIENTS AND PARTICIPANTS: The study group ( n=65) postoperatively received a magnesium infusion (1 mmol/kg), the control group ( n=66) received placebo. In both groups serum and ionised magnesium values were followed, and all postoperative arrhythmias were documented for 24 h. MEASUREMENTS AND RESULTS: Serum and ionised magnesium in the blood was elevated after the end of bypass (0.54+/-0.15 mmol l(-1) pre-operatively, 0.88+/-0.24 mmol l(-1) postoperatively), where a cardioplegia solution containing magnesium was used. Magnesium values remained at this elevated level in the magnesium therapy group, and decreased to normal pre-operative values within 24 h in controls ( P<0.001). The incidence of postoperative arrhythmias was lower in the study group: 8/65 in the study group and 17/66 in the control group, respectively (chi-squared test, P=0.05). Lower patient weight (32.7 kg versus 22.6 kg), longer cardiopulmonary bypass time (128.7 min versus 87.9 min) and deeper body temperature during extracorporeal circulation (29.2 degrees C versus 32.6 degrees C) were identified as risk factors for postoperative arrhythmias ( P<0.05). CONCLUSIONS: Continuous magnesium infusion effectively reduces the rate of arrhythmias following cardiopulmonary bypass surgery for congenital heart disease and should, therefore, be routinely used.

Acute hemodynamic effects of post cardiotomy peritoneal dialysis in neonates and infants.

OBJECTIVE: Evaluation of the acute hemodynamic changes during peritoneal dialysis in patients with low cardiac output syndrome and acute renal failure after open heart surgery. PATIENTS: Three newborns and three infants after corrective surgery of congenital heart disease with post cardiotomy dialysis. Five of these had an open thorax during dialysis. METHODS: Cardiac output measurements using the thermodilution technique on two consecutive days at four different times during the peritoneal dialysis cycle. RESULTS: We did not find a deterioration of the cardiac index or systemic vascular resistance measured over two cycles in each of the six patients. Pulmonary artery pressure rose slightly after instillation of the dialysate solution in all patients. Changes in central venous pressure and left atrial pressure were not clinically meaningful. In all patients fluid removal by peritoneal dialysis was effective. All five surviving patients recovered renal function. CONCLUSIONS: Peritoneal dialysis can be performed in newborns and infants following cardiac surgery without causing acute hemodynamic imbalances. An open chest may have a significant impact on hemodynamic stability during peritoneal dialysis by blunting any possible negative alterations of increased intraabdominal pressure.

Soluble L-selectin plasma concentrations in infants undergoing heart surgery: no association with capillary leak syndrome or need for respiratory support.

OBJECTIVE: In critical care patients at risk of developing the acute respiratory distress syndrome (ARDS), low soluble L-selectin (sCD62L) plasma concentrations have been shown to be associated with progression to ARDS and prolonged subsequent mechanical ventilation. This study aimed to determine the usefulness of sCD62L plasma concentrations to identify infants undergoing cardiovascular surgery who are at risk for postoperative pulmonary dysfunction and capillary leaks. DESIGN: Serial measurements of sCD62L plasma concentrations in a cohort of infants with congenital heart disease before, during, and after surgery for 4 consecutive days. SETTING AND PATIENTS: Infants aged 3-337 days undergoing cardiovascular surgery with (N = 27) or without (N = 12) cardiopulmonary bypass in a tertiary care center. RESULTS: sCD62L concentrations before surgery showed a strong correlation with the infant's age (r = 0.77, p < 0.001). During surgery, sCD62L levels dropped from 9.0 +/- 0.7 to 5.6 +/- 0.4 nmol/l (mean +/- SEM; p < 0.001). The minimum sCD62L concentration during and after surgery did not differ between infants operated upon with or without cardiopulmonary bypass (p > 0.1) or in infants who did (N = 10) or did not (N = 29) develop capillary leak syndrome. Whereas capillary leak syndrome was associated with prolonged mechanical ventilation (p < 0.01), there was no relationship between sCD62L concentrations at baseline or at any time thereafter and number of hours on the ventilator(p > 0.1). CONCLUSION: sCD62L concentrations before or after surgery are not apt to identify infants at increased risk of prolonged mechanical ventilation.

Acute ventilatory restriction in children after weaning off inhaled nitric oxide: relation to rebound pulmonary hypertension.

OBJECTIVE: To assess the interaction between pulmonary hemodynamics and respiratory mechanics during acute pulmonary hypertension. PATIENTS: Ventilated and paralysed children treated with inhaled nitric oxide because of post-operative pulmonary hypertension. INTERVENTIONS: Weaning of inhaled nitric oxide. MEASUREMENTS: Air flow and airway pressure, calculation of dynamic respiratory system compliance and respiratory system resistance for each breath by multiple linear regression. RESULTS: In four patients, increases in pulmonary arterial pressure from 26.1 to 56.7 mm Hg (p<0.001) during weaning off nitric oxide were associated with decreases in tidal volume (from 9.7-->8.2 ml/kg, p<0.01) and reductions in dynamic respiratory system compliance (from 0.52-->0.34 cm H20/ml/kg, p<0.001), while respiratory system resistance was unchanged. CONCLUSIONS: Impaired ventilation during acute pulmonary hypertension is predominantly related to a reduction in respiratory system compliance.