Urotensin II is raised in children with congenital heart disease.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
D J Penny
Publications and source records attributed to D J Penny.
Rate dependence of mechanically induced electrophysiological changes in right ventricle of anaesthetized lambs during pulmonary artery occlusion.
AIM: Mechanically induced early afterdepolarization (EAD) is morphologically similar but different in the mechanisms with drug-induced EAD, which lead to arrhythmia. Pacing suppresses the drug-induced EAD and arrhythmia, however the effect of pacing on mechanically induced EAD and arrhythmia is not clear. This study addressed this issue in right ventricle (RV) of anaesthetized lambs. METHODS: Six lambs were anaesthetized, and their hearts exposed. Nine monophasic action potential (MAP) electrodes were placed on RV apex, outflow and inflow regions, and recorded before, during, and after a 10 s occlusion of pulmonary artery at a number of pacing rates. RESULTS: Pacing significantly reduced the baseline MAP duration at 90% repolarization (MAPD90), decreased the reduction of MAPD at early repolarization at the peak of occlusion. Nonetheless, the percentage of reduction was not significantly different among them. Pacing was able to reduce the frequencies, size of mechanically induced EADs. MAPD90 at the peak of occlusion was all shortened during pacing rather than some lengthened at intrinsic rate. Therefore, the dispersion of MAPD90 at the peak of occlusion reduced from 86 +/- 6 ms at intrinsic rate to 42 +/- 4 ms at 120 beats min-1, 38 +/- 3 ms at 150 beats min-1 and 26 +/- 3 ms at 170 beats min-1. Ultimately, pacing reduced/suppressed mechanically induced premature ventricular beats. These alterations were inversely related to heart rates. CONCLUSION: Pacing reduces/suppresses both stretch-induced EADs and arrhythmia. These modulations are remarkably similar to those on other EADs by the pacing.
Action Potentials↗
Improved early ventricular performance with a right ventricle to pulmonary artery conduit in stage 1 palliation for hypoplastic left heart syndrome: evidence from strain Doppler echocardiography.
OBJECTIVE: To quantify non-invasively right ventricular (RV) performance in infants after stage 1 palliation for hypoplastic left heart syndrome (HLHS). DESIGN: Prospective, observational study with two dimensional and strain Doppler echocardiography. SETTING: Single tertiary paediatric cardiology centre. PATIENTS: Convenience sample of nine consecutive infants with HLHS. Four whose surgery involved a systemic to pulmonary artery (S-PA) shunt were compared with five whose surgery incorporated a right ventricle to pulmonary artery (RV-PA) conduit. METHODS: Basal RV free wall longitudinal strain rate, systolic strain (epsilon), and RV percentage area change were calculated during a single assessment between 27-50 days after surgery. RESULTS: Cardiopulmonary bypass time was longer in patients who underwent RV-PA (226 (30) minutes v 181 (18) minutes, p = 0.03), but cross clamp time, duration of ventilation, and inotrope use did not differ. Two patients in the S-PA group died, on days 29 and 60 after surgery. Peak systolic strain rate (-1.24 (0.19)/s v -0.91 (0.21)/s, p = 0.048), peak epsilon (-17.8 (1.8)% v -13.4 (2.0)%, p = 0.01), and RV percentage area change (56 (6)% v 25 (6)%, p < 0.01) were all greater among RV-PA patients. These indices also tended to be greater in survivors as a group. Ventricular loading conditions (oxygen saturations, diuretic treatment, and blood pressure) were similar in both groups. CONCLUSION: Strain Doppler echocardiography shows improved RV longitudinal systolic contractility in patients during convalescence after the RV-PA modification of stage 1 palliation for HLHS compared with those with an S-PA shunt.
Anastomosis, Surgical↗
Bedside balloon atrial septostomy on neonatal units.
Traditionally, neonates with transposition of the great arteries are immediately transferred to a cardiac centre. Travelling to the bedside to perform a balloon atrial septostomy and allowing the child to remain there for a few days before transfer is safe, effective, and a good use of medical resources.
Cardiology Service, Hospital↗
Increased systemic oxygen consumption offsets improved oxygen delivery during dobutamine infusion in newborn lambs.
OBJECTIVE: To determine: 1) if dobutamine elicited a thermogenic response during postnatal development; and 2) if this response impacted on the balance between systemic O(2) delivery (DO(2)) and O(2) consumption (VO(2)), and involved one or a combination of adrenoceptor subtypes. DESIGN: Prospective non-randomized unblinded study. SETTING: University research laboratory. SUBJECTS: Thirty-five Border-Leicester cross lambs used in a main study performed at 1-2 days (n=7), 7-10 days (n=7), and 6-8 weeks (n=8), and in a adrenoceptor blockade substudy performed at 1-2 days (n=13). INTERVENTIONS: Lambs were instrumented under anaesthesia and dobutamine was infused at incremental rates of 1-40 microg/kg per minute. In separate subgroups of 1-2 day-old lambs, dobutamine was infused after selective or combined alpha1, beta 1, and beta 2-adrenoceptor blockade. MEASUREMENTS: Cardiac output, aortic and pulmonary arterial blood gases, and body temperature were measured. DO(2) and VO(2) were calculated. MAIN RESULTS: Dobutamine increased DO(2) similarly at all three ages. Dobutamine also increased VO(2) in the absence of muscle shivering, but the average rise in 1-2 day-old lambs was sevenfold to 12-fold greater (P<0.001) than in 7-10 day-old and 6-8 week-old animals, was associated with an increase in systemic O(2) extraction, and accounted for approximately 90% of the rise in DO(2). Body temperature rose by 1.3+/-0.5 degrees C in 1-2 day-old animals (P<0.001), but was unchanged in 7-10 day-old or 6-8 week-old lambs. In 1-2 day-old lambs, rises in DO(2), VO(2), and body temperature induced by dobutamine were not affected by selective alpha1, beta1 or beta2 adrenoceptor blockade, but were markedly attenuated by combined adrenoceptor blockade. CONCLUSIONS: A substantial rise in VO(2) which accompanied a pronounced thermogenic effect of dobutamine in newborn lambs utilized most of the associated increase in DO(2) and appeared to be dependent on activation of multiple adrenoceptor subtypes.
Adrenergic alpha-1 Receptor Antagonists↗
Cardiac complications in children following infection with varicella zoster virus.
Infection with varicella zoster virus, leading to chicken pox in susceptible hosts, is usually a benign self-limiting disease conferring immunity in those affected. Cardiac complications are rare, but when present may lead to severe morbidity or mortality. We have recently encountered three children, all of whom developed significant cardiac complications secondary to infection with varicella. Myocarditis has long been associated with such infection. The pathological mechanism is presumed similar to other cardiotropic viruses, where both direct cytopathic and secondary auto-immune effects contribute to myocardial cellular destruction and ventricular dysfunction. Complications include arrhythmias and progression to dilated cardiomyopathy. Pericarditis, and secondary pericardial effusion, related to infection with the virus is most commonly associated with secondary bacterial infiltration. Both cardiac tamponade and chronic pericardial constriction may result. Endocarditis complicating varicella has only been described in the last fifteen years, and is associated with the emergence of virulent strains of both streptococcus and staphylococcus, the two organisms most commonly associated with endocarditis. The exact mechanism by which varicella causes secondary bacterial endocarditis remains unclear. Whilst cardiac complications of infection with the varicella zoster virus are rare, the resulting complications are potentially life threatening. Evidence of varicella-induced carditis must be aggressively pursued in any child with signs of acute cardiac decompensation in whom chicken pox is confirmed or suspected.
Chickenpox↗
Pulmonary vascular resistance after cardiopulmonary bypass in infants: effect on postoperative recovery.
OBJECTIVE: We sought to define the contemporary clinical effect of increased pulmonary vascular resistance in infants after congenital heart operations with cardiopulmonary bypass. METHODS: Fifteen infants (median age, 0.31 years; median weight, 5.1 kg) underwent cardiac operations involving cardiopulmonary bypass (range, 49-147 minutes). Pulmonary vascular resistance was measured in the immediate postoperative period in the intensive care unit by means of the direct Fick principle, with respiratory mass spectrometry to measure oxygen consumption. The effect of ventilation with an inspired oxygen fraction of 0.65, with additional infusion of L -arginine, substance P, and inhaled nitric oxide, was assessed and subsequently correlated with the length of mechanical ventilation from the end of cardiopulmonary bypass to successful extubation. RESULTS: Overall, pulmonary vascular resistance at baseline (11.7 +/- 5.6 WU. m(2)) could be reduced to a minimum of 6.1 +/- 3.5 WU. m(2). The ventilatory time was 0.86 to 14.9 days (median, 1.75 days) and correlated directly with the lowest pulmonary vascular resistance value achieved during the pulmonary vascular resistance study (r (2) = 0.64, P <.01). The patient subgroup with mechanical ventilation of greater than 2 days had significantly higher pulmonary vascular resistance at all stages of the study protocol, and in this group there was a correlation of cardiopulmonary bypass time and ventilatory support time (r (2) = 0.48, P <.05). CONCLUSION: Increased pulmonary vascular resistance, either directly or as a surrogate of the systemic inflammatory response after cardiopulmonary bypass, continues to have a significant effect on postoperative recovery of infants after cardiac operations.
Analysis of Variance↗
Right ventricular distension alters monophasic action potential duration during pulmonary arterial occlusion in anaesthetised lambs: evidence for arrhythmogenic right ventricular mechanoelectrical feedback.
Abnormal loading and distension of the right ventricle may induce arrhythmia through the process of mechanoelectrical feedback. Nonetheless, the electrophysiological effects of right ventricular distension are ill-defined and the mechanisms which underpin mechanoelectrical feedback in the right ventricle are unknown. We examined the effects of changes in right ventricular load (complete occlusion of both caval veins or the main pulmonary artery) in 14 anaesthetised lambs, instrumented with right ventricular surface electrodes and strain gauges for recording monophasic action potential and segment length, and an integrated conductance and micromanometer-tipped catheter for measurement of right ventricular pressure and volume. Caval occlusion did not alter right ventricular segment length and monophasic action potential duration. By contrast, pulmonary arterial occlusion increased the segment length and decreased the monophasic action potential duration at 25, 50 and 70% repolarisation by 29 +/- 6, 22 +/- 4 and 17 +/- 3 ms, respectively (all P < 0.01). Of the 42 pulmonary arterial occlusions, 38 were associated with early afterdepolarisations (EADs) which increased progressively in magnitude as the occlusion was maintained until, in 32, overt arrhythmia was observed. By contrast, none of the four occlusions in which EADs were not observed resulted in arrhythmia. As a result, the proportion of occlusions which resulted in arrhythmia were greater in those associated with EADs than in those which were not (P = 0.002). Right ventricular distension alters the pattern of repolarisation, precipitates early afterdepolarisations and results in a variety of ventricular arrhythmia, including ventricular tachycardia.
Action Potentials↗
Management of the neonate with symptomatic congenital heart disease.
Explore the source record for details and available documents.
Critical Illness↗
Severe airflow limitation after the unifocalization procedure: clinical and morphological correlates.
BACKGROUND: While unifocalization techniques have improved the treatment options in patients with pulmonary atresia, ventricular septal defect (PA-VSD), and major aortopulmonary collaterals (MAPCAs), severe airflow limitation contributes to significant early postoperative morbidity and mortality. Although this has been attributed to bronchospasm, characteristically it is refractory to bronchodilators, suggesting that other mechanisms may play a role. METHODS AND RESULTS: The clinical course and preoperative angiograms of patients who underwent unifocalization were reviewed. Patients who developed airflow limitation early after surgery underwent fiberoptic bronchoscopy. In addition, the anatomy of the MAPCAs was examined in 14 heart-lung blocks from patients with PA-VSD. Twenty-two procedures were performed in 16 children. Three developed marked airflow limitation early after surgery, necessitating prolonged high-pressure ventilation. Bronchoscopy demonstrated tracheobronchial epithelial necrosis in 2 and signs of tracheobronchial ischemia in the third. Two were successfully extubated after 15 and 16 days, but the third died after 57 days of ventilatory support. Review of the preoperative angiograms demonstrated an extensive peribronchial arterial supply arising from a MAPCA in 1 of the patients who developed severe airway necrosis after unifocalization. This was also obvious in a second patient, but the MAPCA was not included in the unifocalization. In 7 autopsy specimens, MAPCAs contributed to a peribronchial or peritracheal vascular network. Dissection of the distribution of these branches in 2 specimens revealed extensive intrapulmonary peribronchial anastomoses. CONCLUSIONS: Airflow limitation early after unifocalization is related to airway ischemia resulting from interruption of the tracheobronchial blood supply during mobilization of MAPCAs.
Abnormalities, Multiple↗
Failure of stroke volume augmentation during exercise and dobutamine stress is unrelated to load-independent indexes of right ventricular performance after the Mustard operation.
BACKGROUND: Impaired right ventricular function has been implicated as a cause of reduced maximal exercise capacity after the Mustard operation for transposition of the great arteries. METHODS AND RESULTS: Fourteen asymptomatic survivors of the Mustard operation were studied. Each underwent conventional cardiac catheterization, and after satisfactory hemodynamics were confirmed, load-independent indexes of ventricular function were derived by conductance catheter during dobutamine infusion (0, 5, and 10 microg x kg(-1) x min(-1)). Seven patients also underwent upright exercise testing on a bicycle ergometer with analysis of respiratory gas exchange by continuous mass spectrometry. Accessible pulmonary blood flow was measured at each workload with an automated acetylene rebreathing technique. All patients exercised to a satisfactory end point (respiratory quotient >1.1). Maximum oxygen consumption during exercise was impaired compared with predicted values (mean, 77%; P:<0.02). Both exercise and dobutamine infusion were associated with an increase in cardiac index and heart rate and a reduced stroke volume index response. This was despite significantly improved indexes of myocardial contraction (end-systolic pressure volume relation, P:<0.001), preload recruitable stroke work index (P:<0.01), VA coupling (P:<0.001), and isovolumic relaxation (P:<0.001) during dobutamine infusion. There were no changes observed in end-diastolic pressure-volume relations, but there was failure to augment ventricular filling manifest by absence of change in dV/dt (P:=NS). CONCLUSIONS: The stroke volume response to exercise stress is reduced in patients after the Mustard operation. A similar failure to augment stroke volume occurs during dobutamine stress despite appropriate responses in load-independent indexes of contraction and relaxation. This is due to failure to augment right ventricular filling rates during tachycardia, presumably as a result of impaired AV transport, consequent to the abnormal intra-atrial pathways.
Cardiac Surgical Procedures↗
Negative pressure ventilation as haemodynamic rescue following surgery for congenital heart disease.
A low cardiac output state is an important cause of morbidity and mortality following repair of tetralogy of Fallot (ToF). This is often refractory to conventional measures. The cardiac output of these patients is highly dependent on diastolic pulmonary arterial flow which is enhanced during spontaneous respiration, but much reduced by intermittent positive pressure ventilation (IPPV). We report the successful use of negative pressure ventilation (NPV) as haemodynamic therapy in three children with a low output secondary to restrictive right ventricular (RV) physiology following ToF repair. NPV produced a significant haemodynamic improvement, with increases in cardiac output of greater than 100 % in two of the children. By augmenting pulmonary blood flow, and hence cardiac output, NPV has a role as adjunctive haemodynamic therapy in patients with a low output secondary to diastolic RV dysfunction, in whom early extubation is not possible.
Cardiac Output, Low↗
Oxygen consumption after cardiopulmonary bypass surgery in children: determinants and implications.
OBJECTIVE: We sought to assess oxygen consumption and its determinants in children shortly after undergoing cardiopulmonary bypass operations. METHODS: Twenty children, aged 2 months to 15 years (median, 3.75 years), undergoing hypothermic cardiopulmonary bypass operations were studied during the first 4 hours after arrival in the intensive care unit. Central and peripheral temperatures were monitored. Oxygen consumption was continuously measured by using respiratory mass spectrometry. Oxygen delivery was calculated from oxygen consumption and arterial and mixed venous oxygen contents, which were sampled every 30 minutes. Oxygen extraction was derived by the ratio of oxygen consumption and oxygen delivery. Arterial blood lactate levels were measured every 30 minutes. RESULTS: There was a correlation between oxygen consumption and age in patients older than 3 months (r = -0.76). Mean oxygen consumption increased by 14.7% during the study. The increase in oxygen consumption was correlated with the increase in central temperature (r = 0.73). Nine patients had an arterial lactate level above 2 mmol/L on arrival. There were no significant differences in oxygen consumption, oxygen delivery, and oxygen extraction between the group with lactate levels between 2 and 3 mmol/L and the groups with normal lactate levels both on arrival and at 2 hours. One patient with a peak lactate level of 6.8 mmol/L had initially low oxygen delivery (241.3 mL. min(-1). m(-2)). CONCLUSIONS: During the early hours after a pediatric cardiac operation, the increase in oxygen consumption is mainly attributed to the increase in central temperature. Oxygen consumption is negatively related to age. Mild lactatemia is common and does not appear to reflect oxygen delivery or oxygen consumption or a more complicated recovery.
Adolescent↗
Early extubation after surgical repair of tetralogy of Fallot.
In recent years, post-operative intensive care of the child with congenital cardiac disease has placed an emphasis on earlier weaning from mechanical ventilation. We describe our experience of postoperative fast-tracking of children undergoing cardiac surgery during a charitable mission in Venezuela, where resources and equipment were severely limited. During our stay, 11 children, with a median age of 2 years, underwent total correction of tetralogy of Fallot. The median duration of ventilation was 2.5 hours, and all patients were extubated within 12 hours of surgery. Effective analgesia was achieved without the need for continuous intravenous infusions of opiates. This experience shows that early extubation can safely be carried out in well-selected patients after surgery to correct congenital cardiac malformations. This allows faster throughput of patients, and helps provide an efficient and cost-effective service.
Child↗
Pre-excitation syndrome secondary to cardiac rhabdomyomas in tuberous sclerosis.
Rhabdomyomas are not uncommon in infants with tuberous sclerosis. We describe a neonate who presented with hydrops fetalis arising from a tachyarrhythmia during fetal life related to rhabdomyomas. After reversion of the arrhythmia, pre-excitation was noted on an interval electrocardiogram. Following regression of the tumours, the delta wave disappeared with no further arrhythmias noted.
Cesarean Section↗
Serial assessment of left ventricular diastolic function after Fontan procedure.
OBJECTIVE: To assess longitudinal changes in systemic ventricular diastolic function late after the Fontan procedure. DESIGN AND PATIENTS: Prospective study of 13 patients at 2.8 (2.0) years (early) and again at 11.4 (2.0) years (late) after the Fontan procedure by Doppler echocardiography with simultaneous ECG, phonocardiogram, and respirometer. SETTING: Tertiary paediatric cardiac centre. RESULTS: The isovolumic relaxation time (IVRT) was significantly longer, and E wave deceleration time, E and A wave velocities, and E:A velocity ratio were reduced compared to normal both early and late after the procedure. The mean (SD) z score of IVRT decreased significantly from +2.50 (1.00) to +1.24 (0.80) (p = 0.002), and the z score of the E wave deceleration time decreased from -1.69 (1.31) to -2.40 (1.47) (p = 0.03) during follow up. The A wave deceleration time also tended to decrease (early 80 (12) ms v late 73 (11) ms, p = 0.13) with increased follow up. There were no changes of the E and A wave velocities and E:A velocity ratio. The E wave velocity was inversely related to IVRT both early (r = -0.82, p = 0.001) and late (r = -0.59, p = 0.034) after the operation. The prevalence of diastolic flow during isovolumic relaxation decreased from 85% (11/13) to 38% (5/13) (p = 0.04), while that of mid diastolic flow increased from 23% (3/13) to 77% (10/13) (p = 0.02) between the two assessments. CONCLUSIONS: Left ventricular diastolic function remains highly abnormal late after the Fontan procedure. The longitudinal changes demonstrated on follow up are compatible with reduction of left ventricular compliance in addition to persisting abnormalities of relaxation.
Blood Flow Velocity↗
Pulmonary vascular-bronchial interactions: acute reduction in pulmonary blood flow alters lung mechanics.
BACKGROUND: Postoperative pulmonary hypertension in children after congenital heart surgery is a risk factor for death and is associated with severe acute changes in both pulmonary vascular resistance and lung mechanics. OBJECTIVE: To examine the impact of changes in pulmonary blood flow on lung mechanics in preoperative children with congenital heart disease, in order to assess the cause-effect relation of pulmonary vascular-bronchial interactions. DESIGN: Prospective, cross sectional study. SETTING: Cardiac catheterisation laboratory, general anaesthesia with mechanical ventilation. INTERVENTIONS: Variation of pulmonary blood flow (Qp) by either balloon occlusion of an atrial septal defect before interventional closure, or by complete occlusion of the pulmonary artery during balloon pulmonary valvuloplasty for pulmonary valve stenosis. MAIN OUTCOME MEASURES: Ventilatory tidal volume (Vt), dynamic respiratory system compliance (Cdyn), respiratory system resistance (Rrs). RESULTS: 28 occlusions were examined in nine patients with atrial septal defect (median age 9.5 years) and 22 in eight patients with pulmonary stenosis (median age 1.2 years). Normalisation of Qp during balloon occlusion of atrial septal defect caused no significant change in airway pressures and Rrs, but there was a small decrease in Vt (mean (SD): 9.61 (0.85) to 9.52 (0.97) ml/kg; p < 0.05) and Cdyn (0.64 (0.11) to 0.59 (0.10) ml/cm H(2)O*kg; p < 0.01). These changes were more pronounced when there was complete cessation of Qp during balloon valvuloplasty in pulmonary stenosis, with a fall in Vt (9.71 (2.95) to 9.32 (2.84) ml/kg; p < 0.05) and Cdyn (0.72 (0.29) to 0.64 (0.26) ml/cm H(2)O*kg; p < 0.001), and there was also an increase in Rrs (25.1 (1. 7) to 28.8 (1.6) cm H(2)O/litre*s; p < 0.01). All these changes exceeded the variability of the baseline measurements more than threefold. CONCLUSIONS: Acute changes in pulmonary blood flow are associated with simultaneous changes in lung mechanics. While these changes are small they may represent a valid model to explain the pathophysiological impact of spontaneous changes in pulmonary blood flow in clinically more critical situations in children with congenital heart disease.
Adolescent↗
Blunting of pulmonary but not systemic vasodilator responses to dobutamine in newborn lambs.
Little is known about the changes in systemic and pulmonary vascular responses to dobutamine that occur during postnatal development. To address this question, vascular pressures and cardiac output were measured in anesthetized 1- to 2-d-old (n = 6), 7- to 10-d-old (n = 7), and 6- to 8-wk-old lambs (n = 6) while dobutamine was infused incrementally in the dose range of 0.5-40 microg x kg(-1) x min(-1). Dobutamine reduced pulmonary vascular resistance in the three age groups (all p<0.005). However, although this reduction reached a plateau over the infusion range of 15-40 microg x kg(-1) x min(-1) at all ages, its magnitude was less (p<0.02) in 1- to 2-d-old lambs (24+/-2%) than in 7- to 10-d-old (41+/-7%) or 6- to 8-wk-old lambs (42+/-6%). Over the same infusion range, dobutamine produced a fall in systemic vascular resistance (all p<0.005) that was proportionally similar in 1- to 2-d-old (51+/-3%), 7- to 10-d-old (48+/-3%), and 6- to 8-wk-old lambs (42+/-6%). In separate subgroups of 1- to 2-d-old lambs, pulmonary and systemic responses to dobutamine were not affected by pretreatment with selective alpha1-, beta1-, or beta2-adrenoceptor antagonists. Taken together, these findings suggest that the pulmonary but not systemic vasodilator response to dobutamine in lambs is blunted in the initial days after birth, and that this pulmonary effect is not directly related to the adrenoceptor-stimulating properties of dobutamine.
Adrenergic Antagonists↗