Short procedure of GHRH plus arginine test in clinical practice

Either in children or in adults, arginine (ARG) alone and combined with GHRH (GHRH+ARG) are reliable tests for the diagnosis of GH deficiency. The procedures of these tests generally include GH measurement every 15 min from baseline up to 90-120 min. Aim of our study was to verify if the procedure of these tests could be usefully shortened in clinical practice. To this goal we have studied 173 normally growing children and adolescents (C, 117 M and 56 F, age: 11.3 +/- 0.4 yr.) and 125 young and middle aged normal adults (A, 68 M and 57 F, age: 30.0 +/- 0.6 yr.). ARG alone test was performed by 81 C and 33 A (0.5 g/kg arginine, i.v., from 0 to +30 min, up to a maximum of 30 g) while GHRH (1 microg/kg i.v. bolus at 0 min) + ARG test was performed by 92 C and 92 A. After ARG alone, taking into account data from +15 to +105 min, GH values above the 3rd centile limit of arbitrary cut-off (7 or 10 microg/l in C and 5 microg/l in A) occurred in 85% or 64% and 94% subjects, respectively. After GHRH+ARG test, taking into account only data at +30, +45, +60 min GH values above the 3rd centile limit (20 microg/l in C and 16.5 microg/l in A) occurred in 99% of subjects in both groups. Taking into account only these 3 timing points, the percentage of GH peak above the third centile limits after ARG alone was never higher than 60% in C and 85% in A. In conclusion, this study shows that single GHRH+arginine test can be reliably performed in a shortened procedure which makes easier the clinical practice and further reduces costs.

Effect of Trendelenburg head position during cardiac deairing on cerebral microemboli in children: a randomized controlled trial

OBJECTIVES

We prospectively evaluated the effects of head position during cardiac deairing on the Doppler ultrasonography-detected cerebral microemboli in children and the association between the embolic counts and the clinical assessment of deairing.

METHODS

Children requiring exposure of the systemic ventricle under cardiopulmonary bypass were randomized to Trendelenburg (-15 degrees ) and horizontal (0 degrees ) head positions during and after standard surgical deairing. Complexity of repair was categorized as follows: group I consisted of single simple lesions, and group II consisted of multiple complex lesions. Transcranial Doppler ultrasonography identified high-intensity transient signals in the right middle cerebral artery within the first 5 minutes after aortic declamping (release) and from this ending period until cardiopulmonary bypass termination (residual). Electrocardiographic alterations after deairing were documented. A predefined 5-point scale was used by the surgeon for blinded assessment of deairing.

RESULTS

High-intensity transient signals were identified in 97% of 128 patients (aged 5 days to 17 years). The median total high-intensity transient signal count was 60 (25th-75th quartiles, 14-189). Head position or surgeon did not affect the rate of high-intensity transient signals (P >.20). During the residual interval, occurrence of HITS in group I was less than that in group II (P <.05), but there was no difference at release. The incidence of high-intensity transient signals and electrocardiographic alterations correlated with the clinical assessment of deairing (P <.01).

CONCLUSIONS

Trendelenburg head position as a complement of cardiac deairing in children does not decrease the cerebral microembolic load compared with the horizontal head position. The cerebral microembolic count and the occurrence of electrocardiographic alterations usually increases when the surgeon is less confident in the efficacy of deairing.

Cerebral vascular effects of aortovenous cannulations for pediatric cardiopulmonary bypass

BACKGROUND

The effects of aortovenous cannulations for pediatric cardiopulmonary bypass on cerebral blood flow velocity (CBFV) and electroencephalography (EEG) were evaluated.

METHODS

CBFV and EEG were continuously recorded before (baseline), during, and after cannulations until initiation of cooling (mean +/- 95% confidence interval). Vasopressors and/or volume replacement were administered if mean arterial pressure (MAP) decreased below 35 mm Hg. Cannulation-related EEG slowing was used as a criterion for electrocortical alteration.

RESULTS

We studied 124 children (3 days to 17 years of age). Aortic and venous cannulations decreased mean CBFV by 10+/-3% and 13+/-4%, respectively, from baseline (p < 0.001). MAP diminished (p < 0.01) by 8+/-3% and 12+/-4%, respectively, from precannulation values (53+/-2 mm Hg). Right atrial cannulation, which was often chosen because the patient was hemodynamically unstable, was more frequently associated with pharmacologic intervention when compared with superior vena cava (SVC) cannulation (p < 0.01). Transient EEG alterations (n = 20) were associated with persistently low MAP (< 30 mm Hg), low CBFV (< 69%), and aortic (n = 4) or SVC (n = 7) cannula malposition. Infants with right atrial cannulation and intervention had more frequent EEG alterations (p = 0.04). Patients requiring intervention were younger (p < 0.01) and had longer hospital stay (p < 0.01) than those without intervention.

CONCLUSIONS

Cerebral effects of cannulations are greater in young infants. This was found to be associated with low MAP during heart manipulation or consequence of cannula malpositions.

Cerebral blood flow velocity during tilt table test for pediatric syncope

BACKGROUND

Brain hypoperfusion during neurocardiogenic syncope develops as a consequence of hypotension and bradycardia. Transcranial Doppler indicates that an increase in cerebral vascular resistance occurs before or during the loss of consciousness.

OBJECTIVE

Cerebral blood flow velocity was studied during tilt table testing in pediatric patients with neurocardiogenic syncope. We assessed whether a critical reduction in flow velocity (>40%) was predictive of the presyncopal manifestations during the test.

METHODS

A 2-MHz transcranial Doppler measured blood flow velocity in the right middle cerebral artery in 27 pediatric patients (ages, 8 to 18 years) during a three-stage 80 degrees tilt table test protocol. A positive test required development of syncope or presyncope with at least 30% decrease in systolic blood pressure and/or heart rate relative to preceding values. Patients were divided into: group I (isoproterenol-induced positive tests), group II (positive without isoproterenol), and group III (negative tests).

RESULTS

Within the first 3 minutes of the upright position mean cerebral blood flow velocity in groups I, II, and III decreased by 18%, 29%, and 17%, respectively, as the systolic and diastolic blood pressures showed only minimal changes. A decreased mean blood flow velocity of 48% and 45% and an increase in resistance index of 42% and 26% from supine values in the absence of hypotension, were detected in groups I and II at 46 seconds (range, 30-120 seconds) and 50 seconds (range, 0-300 seconds) before any clinical symptom (presyncope latency). Mean blood flow velocity during presyncope decreased by 58% and 59%, whereas resistance index was double. A significant correlation (rho = -0.62) was found between presyncope latency and the decreased mean cerebral blood flow velocity. Similar blood flow velocity changes were not detected in group III.

CONCLUSION

A sustained reduction >40% in mean cerebral blood flow velocity in the absence of hypotension always resulted in presyncopal or syncopal manifestations. It seems that once this critical threshold is identified during the tilt table testing, supine position may be resumed several seconds before the clinical manifestations of syncope.

Cerebral blood flow velocity during occlusive manipulation of patent ductus arteriosus in children

Patent ductus arteriosus (PDA) with left-to-right shunting modifies the Doppler flow pattern of the intracranial circulation. The ability of increases in cerebral blood flow velocity (CBFV) to predict shunt resolution during PDA occlusion was evaluated. A 2 MHz transcranial Doppler (TCD) monitored diastolic and mean CBFV, plus the systolic/mean CBFV ratio in the middle cerebral artery from before (baseline) to immediately after PDA occlusion. Shunt resolution was verified by echocardiography and/or angiography. A minimum of 40% increase in diastolic-CBFV from baseline was considered successful resolution. Patients were age-stratified into group I (< 15 months; n = 23) and group II (> 15 months; n = 10). Thirty-three children were studied (age, 0.1 to 109 months) during surgical (n = 22) or coil occlusions (n = 11). Transcranial Doppler successfully identified shunt resolution in 78% of cases in group I, as compared to 0% in group II (p < 0.01). Identification rate decreased from 79% in cases of minimum ductal diameter of 3 mm (n = 19) to 21% in smaller ductuses (n = 14) (p < 0.01). Body weight and left-atrium size (p = 0.004) in group I and PDA diameter in group II (p = 0.02), were the only preoperative ductal parameters associated with diastolic-CBFV changes after ductus occlusion. Transcranial Doppler detects shunt resolution in infants with moderate to large PDAs.

Aortic cusp prolapse in ventricular septal defect and its association with aortic regurgitation--appropriate timing of surgical repair and outcomes

OBJECTIVES

To determine the appropriate indications and timing for surgery in children with either a perimembranous or a subarterial type of ventricular septal defect (VSD) associated with aortic cusp prolapse.

DESIGN

Retrospective review of children with VSD and associated aortic cusp prolapse with or without aortic regurgitation. This review was based on data obtained from clinical findings, two-dimensional echocardiography, cardiac catheterization and angiocardiography.

SETTING

Tertiary health care facility with two-dimensional and colour Doppler echocardiographic and cardiac surgery facilities, and a catheterization laboratory.

PATIENTS

Forty-eight patients were found to have perimembranous or subarterial VSDs in association with aortic cusp prolapse with or without aortic regurgitation.

INTERVENTIONS

All 48 patients had high resolution two-dimensional and colour Doppler echocardiography. Of the 19 patients who underwent surgical closure of their VSD, five also had an aortic valvuloplasty and one had an aortic valve replacement. Cardiac catheterization was performed in 16 of the 19 surgical patients and 12 of the 29 nonsurgical patients.

MEASUREMENTS AND MAIN RESULTS

Annual clinical and echocardiographic assessments in the nonsurgical group did not demonstrate increasing aortic insufficiency. Two children in the nonsurgical group showed spontaneous resolution of aortic insufficiency. In the surgical group, four children with VSD and clinical aortic insufficiency had surgery at less than five years of age; two were found to be regurgitant-free, one had trivial clinical aortic insufficiency and the other had echocardiography-only insufficiency. Of the seven surgical patients older than five years with VSD and clinical aortic insufficiency, four were found to be regurgitant-free, one had echocardiography-only regurgitation and two were unchanged. Two children undergoing surgery with VSD and no aortic insufficiency had postoperative echocardiography-only regurgitation, presumably related to cusp deformity from presurgical prolapse. Children with large VSDs with or without aortic cusp prolapse required surgery for indications of shunt size and pulmonary resistance.

CONCLUSIONS

For children with small perimembranous VSDs and cusp prolapse, surgery is indicated only if there is clinical evidence of aortic regurgitation and progressive left ventricular enlargement.

Cerebral blood flow velocities monitored by transcranial Doppler during cardiac catheterizations in children

Transcranial Doppler (TCD) was used to evaluate brain circulation during cardiac catheterizations in 32 children requiring pulmonary (n=10) or aortic balloon dilatations (n=2), ductus arteriosus coil insertions (n=5), or angiography (n=15). Cerebral blood flow velocity (CBFV) in the middle cerebral artery was measured before (baseline), during, and after each procedure (mean+/-95%ci). High-intensity transient signals (HITS) were also detected during these maneuvers. Balloon angioplasty decreased CBFV by 63+/-11% from baseline (P < 0.01). Shorter durations of the inflation cycle resulted in earlier CBFV recovery (r=0.78). During angiography, CBFV increased by 11+/-4% (P < 0.01) in all except one case that showed retrograde diastolic flow. Mean total HITS count was 44 (95%ci.limits: 27,74). These signals were more frequently found in septal defects or systemic arterial manipulations. Pediatric cardiac catheterization may impose transient fluctuations in brain perfusion as indicated by TCD, but their clinical implications are uncertain. CBFV changes during balloon angioplasty emphasize the importance of rapid inflation/deflation cycles. TCD can monitor such changes and evaluate preventive measures.

Cerebral effects of aortic clamping during coarctation repair in children: a transcranial Doppler study

OBJECTIVE

Haemodynamic changes as a consequence of application and release of aortic clamps for surgical repair of aortic coarctation are compensated by cerebrovascular autoregulation. Transcranial Doppler was used to study the effect of these haemodynamic changes upon brain circulation in children during aortic coarctation repair.

METHOD

A 2-MHz transcranial Doppler system continuously recorded mean cerebral blood flow velocities from the left middle cerebral artery in 13 children (aged from 5 days to 14 years) during repair of their coarctation. Measurements were performed: prior to aortic clamping (baseline); during the first 5 min after clamp application; 1 min before declamping; at 1, 2, 4 and 6 min after the release of both proximal and distal aortic clamps; and at initial chest closure. A contralateral upper-limb non-invasive blood pressure cuff measured systemic blood pressures. Haemodynamic and anaesthetic parameters were monitored. Patients were stratified by age into two groups: age < 6 months (group A) and age > 6 months (group B).

RESULTS

With aortic clamping, systemic blood pressures (range from: -16 to +54%) and cerebral blood flow velocities (range from -40 to +19%) changed slightly (P > 0.05) from initiation to end of aortic clamping. In group A, release of aortic clamps resulted in moderate fluctuations in systemic blood pressures (range from -34 to +15%) (P > 0.05) and a marked reduction in cerebral blood flow velocities (range from -63 to -33%) (P < 0.01). At the time of surgical closure, flow velocities had improved in all infants except one. Group B did not show major reductions in either cerebral blood flow velocity or systemic blood pressures throughout all measurements (P > 0.05). During aortic clamp release, young infants responded with lower brain blood flow velocities as compared to older children (r = 0.68; P < 0.05).

CONCLUSION

Transient central nervous system hypotension results as a consequence of flow redistribution during aortic declamping in young infants. Older children usually show a faster autoregulatory compensation to these haemodynamic changes. The observed age-related physiologic differences, suggest that young infants may require higher systemic blood pressures during declamping to prevent the cerebral blood flow reduction. Transcranial Doppler appears to be a valuable monitor of these cerebral haemodynamic changes.

Transoesophageal echocardiographic assessment of obstruction to the pulmonary venous pathway in children with Mustard or Senning repair

The morphology and mechanism of obstruction to the pulmonary venous pathway in patients following either Mustard or Senning repair of complete transposition was assessed using transoesophageal echocardiography. Seven patients underwent catheterization and complete transoesophageal study in both transverse and longitudinal planes, followed by balloon dilation of the obstructed venous pathway in five of seven under transoesophageal echocardiography guidance. A complete scan of both systemic and venous pathway was obtained in all patients. Four patients with a Mustard repair were found to have a 'tubular' baffle, with stenosis resulting from a discrete wedge of tissue arising from the atrial free wall in association with fibrous adhesions to the baffle. In the three patients with a Senning repair the intra-atrial baffle showed a characteristic 'peaked' appearance, with stenosis of the venous pathway stenosis related directly to contracture of the patch used to augment the atrial free wall. The mechanism of obstruction appears to be inherent to the different surgical techniques. Indwelling transoesophageal echocardiography provided immediate haemodynamic and morphologic assessment of the efficacy of dilation of the obstructed venous pathway.

Cerebral effects in superior vena caval cannula obstruction: the role of brain monitoring

A pediatric cardiac case of transient obstruction of the superior vena cava by the venous cannula before cardiopulmonary bypass is presented. With venous obstruction and increase in central venous pressure, reduced cerebral blood flow velocities and absence of diastolic Doppler flow were detected. This was followed by regional cerebral venous oxygen desaturation and global electroencephalographic slowing. Reposition of the venous cannula led to the recovery of these physiologic indicators and a noncomplicated clinical outcome.

The Hemopump as a left ventricular assist device in pediatric applications: initial Canadian applications

Three children aged 11 months, and eight and nine years were supported with a Hemopump as a potentially life saving measure for circulatory failure. Left ventricular assist time ranged from 10 to 32 h. None of the three patients could be successfully weaned from the device because of complications of bleeding, arrhythmia or neurological insult. Despite poor outcomes, each patient demonstrated important hemodynamic stabilization with the device. The Hemopump is suggested as a potentially life saving treatment modality for selected pediatric patients who have critical left ventricular failure.

Liposomal amphotericin B for postoperative Aspergillus fumigatus endocarditis

A 10-month-old infant girl presented with Aspergillus fumigatus endocarditis localized to a Gore-Tex patch used as part of the repair for double-outlet right ventricle. A new liposomal preparation of amphotericin B combined with surgical vegectomy resulted in a successful outcome with no evidence of disease recurrence at 15 months' follow-up. Echocardiography provided an optimal modality for ongoing evaluation of therapeutic outcome.

Subendocardial abscess as a complication of prolonged central venous access for parenteral nutrition

Patients with chronic gastrointestinal diseases may require long-term parenteral nutrition. The authors describe a case in which a subendocardial abscess developed in the right atrium in association with staphylococcal septicemia. The patient, a 15-year-old boy, had a malpositioned Silastic catheter, the tip of which was in his right atrium. Staphylococcal abscess of the heart has been described previously after cardiac surgery, but the authors believe this is the first reported case related to a central venous catheter.

Familial coarctation of the aortic arch with bilateral ptosis: a new syndrome?

A Newfoundland family with the apparently unique syndrome of complex coarctation of the aortic arch, bilateral stenoses of the subclavian arteries, bilateral ptosis, sensorineural deafness, and bronchial asthma is reported. This syndrome appears to have affected at least four generations, and has the characteristics of autosomal dominant inheritance.

Echocardiography of intracardiac filling defects in infants and children

Intracardiac masses are rare in infants and children. Early detection is essential to their successful management. We present seven patients in whom echocardiography established the diagnosis and was crucial in the management. Three of the masses were primary cardiac tumors and four were thrombi. Patient 1: an infant with a calcified left ventricular fibroma. Patient 2: a neonate who presented with cyanosis due to obstruction of the right ventricular inflow tract by a fibroblastic tumor. Patient 3: an infant with a right atrial myxoma presenting as sepsis. Patient 4: a child who had a pulmonary embolus after a pulmonary valvotomy and was found to have a right ventricular thrombus. Patient 5: a child with a right atrial thrombus following a Fontan procedure for univentricular atrioventricular connection. Patient 6: a child with a left ventricular thrombus due to a dilated cardiomyopathy in association with epidermolysis bullosa. Patient 7: An infant with bilateral lobar emphysema, an aorticopulmonary window with left ventricular fibroelastosis, who developed a left ventricular thrombus.

Successful one stage repair of coarctation of the aorta and aneurysm of the ascending aorta in a child

A case of successful one stage repair of aortic coarctation and ascending aortic aneurysm in a 10 year old boy with cystic medial necrosis and congenital bicuspid aortic valve is presented. The patient underwent correction of both lesions at the same operation through two separate incisions. The coarctation was repaired first. The aortic valve was found to be hemodynamically normal and was not replaced. The patient leads a normal life at five and half years after operation and is playing ice hockey with no limitations. Close and long-term follow-up is considered essential in view of the potential complications.