Temperature and manganese as determining factors in the presence of diatom or blue-green algal floras in streams

Diatoms are usually the major component of the algal flora in many streams, although green and blue-green algae may be present. These experiments were designed to determine if high temperature or a shift in the chemical composition of the water might bring about a dominance of blue-green algae and/or green algae rather than a dominance of diatoms in the algal flora.The results of these experiments indicate that an average temperature of 34 degrees to 38 degrees C results in a shift of dominance in the algal flora from diatoms to blue-green algae. Furthermore, a blue-green and green algal flora of species typically found in organically polluted water in favored if the manganese content is a few parts per billion. If the manganese content averaged 0.02-0.043 mg/liter in the natural stream to 0.04-0.28 mg/liter in the recycled water experiment, a diatom flora remained dominant.

Systemic arteriovenous fistulae for end-stage cyanosis after cavopulmonary connection: a useful bridge to transplantation

OBJECTIVE

Intractable cyanosis after partial or complete cavopulmonary connection may rarely be managed by creating a systemic arteriovenous fistula. We investigated the long-term performance of arteriovenous fistulae.

METHODS

All 21 patients who received an arteriovenous fistula at The Hospital for Sick Children since the 1950s were investigated using parametric competing risk techniques. Primary arteriovenous fistula indication was (1) suboptimal pulmonary blood flow (N = 15) or (2) pulmonary shunting via pulmonary arteriovenous malformations (N = 6). Arteriovenous fistula longevity was determined by time to "occlusion" (absence of arteriovenous fistula flow via surgical ligation or spontaneous occlusion).

RESULTS

All 21 patients had previously undergone second-stage palliation (Glenn shunt = 13; bidirectional shunt = 9). Five patients had undergone Fontan completion. Death in the presence of a functioning arteriovenous fistula occurred in 5 patients. Patients with bidirectional shunts had a significantly higher risk of death with a functioning arteriovenous fistula in situ (P = .04). High hemoglobin concentrations were associated with best outcome, and levels less than 170 g/L were associated with a high risk of death despite a functioning arteriovenous fistula (P < .01). Arteriovenous fistula occlusion occurred in 10 patients. Earlier occlusion was associated with previous Fontan completion (P = .02) and pulmonary arteriovenous malformations (P = .03). Surgical ligation during cardiac transplantation was the cause of occlusion in 7 patients. In these 7 patients, the arteriovenous fistula functioned for a median of 4.8 years. After transplantation, survival was 67% + or - 19% at 5 years. Overall survival was 73% + or - 10% 15 years after receiving an arteriovenous fistula (longest survival, 27.3 years).

CONCLUSION

In patients with adequate hematocrit, arteriovenous fistula offers an effective bridge to transplantation when a high-risk Fontan procedure is deferred. Performance is best after unidirectional cavopulmonary connection and worse in the presence of pulmonary arteriovenous malformations. Survival is 75% at 15 years, despite being considered end stage.

GridPP: the UK grid for particle physics

The start-up of the Large Hadron Collider (LHC) at CERN, Geneva, presents a huge challenge in processing and analysing the vast amounts of scientific data that will be produced. The architecture of the worldwide grid that will handle 15 PB of particle physics data annually from this machine is based on a hierarchical tiered structure. We describe the development of the UK component (GridPP) of this grid from a prototype system to a full exploitation grid for real data analysis. This includes the physical infrastructure, the deployment of middleware, operational experience and the initial exploitation by the major LHC experiments.

NKX2-5 regulates the expression of beta-catenin and GATA4 in ventricular myocytes

Background

The molecular pathway that controls cardiogenesis is temporally and spatially regulated by master transcriptional regulators such as NKX2-5, Isl1, MEF2C, GATA4, and β-catenin. The interplay between these factors and their downstream targets are not completely understood. Here, we studied regulation of β-catenin and GATA4 by NKX2-5 in human fetal cardiac myocytes.

Methodology/Principal Findings

Using antisense inhibition we disrupted the expression of NKX2-5 and studied changes in expression of cardiac-associated genes. Down-regulation of NKX2-5 resulted in increased β-catenin while GATA4 was decreased. We demonstrated that this regulation was conferred by binding of NKX2-5 to specific elements (NKEs) in the promoter region of the β-catenin and GATA4 genes. Using promoter-luciferase reporter assay combined with mutational analysis of the NKEs we demonstrated that the identified NKX2-5 binding sites were essential for the suppression of β-catenin, and upregulation of GATA4 by NKX2-5.

Conclusions

This study suggests that NKX2-5 modulates the β-catenin and GATA4 transcriptional activities in developing human cardiac myocytes.

The Impact of Patch Augmentation on Left Atrioventricular Valve Dynamics in Patients with Atrioventricular Septal Defects: Early and Midterm Follow-up

OBJECTIVE

Left atrioventricular valve pericardial patch may prevent valve replacement. We assessed patch annular dynamics compared with conventional repair and normal annuli.

METHODS

Transesophageal 3-dimensional echocardiography was acquired preoperatively and postoperatively in atrioventricular septal defects (n = 10, 5 patch, 5 conventional repair). Real-time 3-dimensional annular motion at midterm was compared with that of healthy children (n = 10). Parameters were: annular area, perimeter, segmental diameter, bending angle, stenosis, and regurgitation.

RESULTS

Regurgitant jet area ratio decreased in both patient groups. Conventional repair reduced annular area (P = .02). Patch repair showed an annular area larger than normal (P = .01). Control subjects had increased systolic area whereas operative groups showed a reduction. Patch repair had segmental diameters similar to normal whereas conventional repair was inhomogeneous. Annular bending angle was maintained after operation.

CONCLUSION

Patch repair in pediatrics shows durability without shrinkage or expansion. Improved stenosis and regurgitation does not change by midterm. Operation causes increased annular stiffness and diminished compliance. Neither technique establishes normal annular eccentricity.

Aneurysm of Right Atrium Diagnosed by 3-Dimensional Real-time Echocardiogram

We describe a case of giant aneurysm of right atrium in a child with a previous diagnosis of Ebstein's anomaly of tricuspid valve. Three-dimensional real-time echocardiography provided more precise anatomic detail of the tricuspid valve, right atrium, and right ventricle than did its 2-dimensional counterpart.

How is pulmonary arterial blood flow affected by pulmonary venous obstruction in children? A phase-contrast magnetic resonance study

BACKGROUND

Hemodynamic changes within a stenosed pulmonary vein might not reflect the severity of the obstruction if redistribution of pulmonary artery flow occurs.

OBJECTIVE

The purpose was to investigate flow changes in branch pulmonary arteries in the presence of pulmonary vein stenosis.

MATERIALS AND METHODS

Twelve children (age range 3-180 months) who had undergone MRI for pulmonary vein stenosis were identified. The severity of vein stenosis was assessed from percentage diameter reduction. Pulmonary artery flow distribution was correlated with the severity of pulmonary vein stenosis. Nine of the patients had unilateral stenosis; three had bilateral involvement.

RESULTS

Unilateral vein stenosis was associated with diastolic reversal in the ipsilateral branch pulmonary artery (mean flow reversal 12.3%, range 2.4-42%) and continuous diastolic forward flow in the contralateral pulmonary artery in seven of nine patients. Severe stenosis was associated with decreased systolic flow to the ipsilateral lung. The ratio of net forward flow through pulmonary arteries correlated well with the cross-sectional area ratio of pulmonary arteries (r=0.75, P=0.006).

CONCLUSIONS

Severe pulmonary vein obstruction results in redistribution of pulmonary arterial flow. When investigating pulmonary vein stenosis by MR, an evaluation of the pulmonary arterial system should be included to assess the functional importance of an obstruction.

Outcomes of mitral valve replacement in children: A competing-risks analysis

OBJECTIVE

We sought to define patient characteristics, outcomes, and associated factors after mitral valve replacement in children.

METHODS

We included 104 children undergoing at least one mitral valve replacement between 1980 and 2003 and reviewed clinical records. Competing-risks methodology was used to determine time-related prevalence and associated risk factors after initial mitral valve replacement for death and repeat replacement.

RESULTS

The underlying mitral valve disease was congenital in 83%, rheumatic in 13%, Marfan syndrome in 3%, and isolated endocarditis in 1%, with 64% having primarily regurgitation, 16% having stenosis, 20% having both, and 32% having undergone previous valvotomy, valvuloplasty, or repair. There were 137 valve replacements, with 26 patients having more than one. Valve prosthesis type was St Jude Medical in 37%, Bjork-Shiley in 25%, Carbomedics in 20%, Ionescu-Shiley in 10%, and other types in 8%. Both early and late complications were common. Median age at the initial replacement was 5.9 years (range, birth to 19 years). Competing-risks analysis predicted 19% to have died at 15 years after initial replacement, with risk factors including noncongenital valve morphology, lower weight, and longer duration of cardiopulmonary bypass. A repeat replacement was predicted for 71%, with risk factors including the presence of multiple left-heart obstructive lesions and Ionescu-Shiley valve prosthesis.

CONCLUSIONS

Mitral valve replacement might be necessary in children with extremely dysplastic valves and severe hemodynamic impairment or after failed repair. However, with the appropriate selection of the prosthetic valve and reduction of cardiopulmonary bypass time, surgeons might decrease mortality and increase prosthesis longevity.

Predictors of mortality and neurological morbidity in children undergoing extracorporeal life support for cardiac disease

OBJECTIVES

The objective of this study was to determine the incidence and risk factors for death and adverse neurological outcomes in children receiving extracorporeal life support (ECLS) for cardiac indications.

METHODS

A retrospective single centre consecutive cohort study was conducted in children who received ECLS for cardiac indications between January 1990 and June 2000. Health records and neuroimaging films were assessed, and long-term outcomes were obtained by standardized telephone follow-up or by assessments performed in outpatient clinic. Clinical, neuroimaging and surgical predictors of outcome were tested.

RESULTS

Of 90 children studied, short-term clinical neurological events (during hospitalization) occurred in 20 children (22%) during or following ECLS. Long-term neurological sequelae were present in 11 of 31 children discharged alive, after a mean follow-up interval of 4.5 years (range 4 months to 9 years). Death occurred in 59 children (66%) during hospitalisation, and in 3 following discharge. Of the 28 long-term survivors, only 15 children (17%) survived without neurological sequelae. Abnormal neuroimaging was associated with short-term neurological events (P = 0.03, OR 10.5), and the use of CPR prior to ECLS (P = 0.02, OR 2.9) was the only significant predictor of death. There were no significant predictors of long-term neurological sequelae.

CONCLUSIONS

More than two-thirds of the children receiving ECLS died, and 39% (11/28) of long-term survivors had neurological deficits. Although mortality is close to 100% without this type of support, there is still a significantly high morbidity and mortality with this type of support.

Pulmonary atresia with intact ventricular septum: management of, and outcomes for, a cohort of 210 consecutive patients

OBJECTIVES

We sought to determine trends, and outcomes, for a cohort of patients with pulmonary atresia with intact ventricular septum born between 1965 and 1998.

BACKGROUND

Pulmonary atresia with intact ventricular septum is a complex lesion that remains a therapeutic challenge, particularly regarding the suitability for biventricular repair.

METHODS

We identified 210 consecutive patients, and reviewed their medical records, initial angiograms, and echocardiograms, along with the relevant surgical and pathology reports.

RESULTS

The mean initial Z-score for the diameter of the tricuspid valve was -0.99 +/- 1.95, with Ebstein's malformation in 8%. A right ventricular dependent coronary arterial circulation was found in 23%. The proportion of patients who received treatment increased over time, although placement of an arterial shunt was the predominant initial procedure throughout the experience. At the last follow-up, 107 patients had not reached the planned final stage of their repair, and 79% of these had died. Of the 103 reaching the final stage of planned repair, 58 had undergone attempted biventricular repair, with 34% dying; 14 had undergone attempted one and a half ventricular repair, with 7% dying, and 31 had undergone attempted functionally univentricular repair, with 10% dying. Overall, survival was 57% at the age of 1 year, 48% at 5 years, and 43% at 10 years. Survival improved over time, with survival of 75% at 1 year, and 67% at 5 years, for patients born between 1992 and 1998. An earlier date of birth, the presence of Ebstein's malformation, and prematurity were all significant independent factors associated with decreased survival. A greater severity of coronary arterial abnormalities was significantly associated with a greater likelihood of left ventricular dysfunction during follow-up.

CONCLUSIONS

The outcomes for patients born with pulmonary atresia with intact ventricular septum have improved over time, albeit that careful initial management, and better selection, is still indicated for those planned to undergo biventricular repair.

Evolution of heart rate control after transplantation: conduction versus autonomic innervation

In cardiac transplantation, the donor organ is not initially innervated and demonstrates decreased heart rate variability (HRV). However, HRV may improve after several months. The mechanism for HRV improvement has not been elucidated; autonomic "reinnervation" of the donor heart has been proposed. The role of atrioatrial conduction from recipient to donor organ has not been evaluated. We prospectively evaluated cardiac transplant patients with a limited electrophysiology study at the time of their surveillance biopsies. Recordings were made of recipient and donor signals, observing conduction properties between recipient and donor atria. Holter recordings were analyzed and HRV was determined using spectral analysis techniques, recording mean RR interval, low-frequency power (LF), high-frequency power (HF), and the LF/HF ratio. These were compared to published norms. From November 1999 to May 2000, 21 patients (6 female) who underwent cardiac transplantation participated at a median age of 101 months (range, 4.1-217 months). Time posttransplant ranged from 26 days to 71 months. Holter data were available for 20 patients and demonstrated dissociated P waves in 13 (65%). The mean heart rate on Holter was 111 beats per minute (bpm) (range, 85-161 bpm). We were able to record distinct recipient atrial signals in 16 of 21 (76%) patients. The average recipient tissue heart rate was 55% that of the donor heart rate. We documented atrioatrial association in only 1 patient. HRV did not reach normal values for most patients and did not increase with time posttransplantation. The LF values were in the normal range for most patients, whereas 3 patients had normal HF values and 2 patients had values just below normal. Recipients of heart transplantation have a predominantly sympathetic influence of HRV. These preliminary data suggest that atrioatrial conduction does not play a role in reestablishing normal heart rate control following pediatric cardiac transplantation.

Glycoprotein biosynthesis in porcine aortic endothelial cells and changes in the apoptotic cell population

Porcine aortic endothelial cells (PAECs) produce glycoproteins with important biological functions, such as the control of cell adhesion, blood clotting, blood pressure, the immune system, and apoptosis. Cell surface glycoproteins play important roles in these biological activities. To understand the control of cell surface glycosylation, we elucidated biosynthetic pathways leading to N- and O-glycans in PAECs. Based on the enzyme activities, PAECs should be rich in complex biantennary N-glycans. In addition, the enzymes synthesizing complex O-glycans with core 1 and 2 structures are present in PAECs. The first enzyme of the O-glycosylation pathway, polypeptide GalNAc-transferase, was particularly active. Its specificity toward synthetic peptide substrates was found to be similar to that of purified bovine colostrum enzyme T1. A significant fraction of PAECs treated with tumour necrosis factor alpha or human serum detached from the culture plate, and most of these cells were apoptotic. The apoptotic cell population exhibited decreased core 2 beta 6-GlcNAc-transferase activity. In contrast, the activities of core 1 beta 3-Gal-transferase, which synthesizes O-glycan core 1, and of alpha 3-sialyltransferase (O), which sialylates core 1, were increased in apoptotic PAECs. Thus, apoptotic PAECs are predicted to have fewer complex O-glycans and a higher proportion of short, sialylated core 1 chains.

Extracardiac conduit versus lateral tunnel cavopulmonary connections at a single institution: impact on outcomes

OBJECTIVE

To compare outcomes of extracardiac conduit and lateral tunnel Fontan connections in a single institution over a concurrent time period.

METHODS

Between January 1994 and September 1998, 60 extracardiac conduit and 47 lateral tunnel total cavopulmonary connections were performed. Age, sex, and weight did not differ between the 2 groups. Compared with the lateral tunnel group (LT group), patients undergoing the extracardiac conduit procedure (EC group) had a trend to a higher incidence of morphologically right ventricle (EC group 48% vs LT group 32%; P <.09), a higher incidence of isomerism/heterotaxy syndrome (EC 22% vs LT 0%; P <.001), worse atrioventricular valve regurgitation (EC 11% moderate-plus vs LT 0%; P <.06), and lower McGoon indices (EC 1.8 +/- 0.5 vs LT 2.1 +/- 0.5; P <.03). Preoperative arrhythmias, transpulmonary gradients, room air oxygen saturations, ejection fractions, ventricular end-diastolic pressure, and pulmonary artery distortion did not differ between groups. Cardiopulmonary bypass times and fenestration usage were similar in both groups.

RESULTS

Overall operative mortality was 5.6% and did not differ between groups. The LT group had a significantly higher incidence of postoperative sinoatrial node dysfunction (45% vs EC group 15%; P <.007), supraventricular tachycardia (33% vs EC group 8%; P <.0009), and need for temporary postoperative pacing (32% vs 12%; P <.01). Median duration of intensive care unit stay (EC 2 days, range 1-10 days, vs LT 2.8 days, range 1-103 days; P <.07) and ventilatory support (EC 1 day, range 0.25-10 days, vs LT 1 day, range 0.25-99 days; P <.03) were all longer in the LT group. Median chest tube drainage (EC 8 days, LT 9 days) was similar in both groups. Follow-up averaged 2.5 +/- 1.4 years in the EC group and 2.8 +/- 1.9 years in the LT group. There were 2 late deaths. Overall survival is 94% at 1 month, 92% at 1 year, and 92% at 5 years. Late ejection fraction or atrioventricular valve function did not differ between groups. Intermediate follow-up Holter analysis showed a higher incidence of atrial arrhythmias in the LT group (23% vs 7%; P <.02). Multivariable analysis showed that (1) prolonged cardiopulmonary bypass time was the only independent predictor for perioperative mortality, prolonged ventilation and intensive care unit length of stay, and increased time to final removal of chest tube drains and (2) lateral tunnel Fontan connection is an independent predictor of early postoperative and intermediate atrial arrhythmias.

CONCLUSIONS

Although patients in the EC group were at higher preoperative risk, their outcomes were comparable with those of the LT group. Use of the extracardiac conduit technique for the modified Fontan operation reduces the risk of early and midterm atrial arrhythmia.

Outcomes of intraoperative device closure of muscular ventricular septal defects

BACKGROUND

The surgical management of muscular ventricular septal defects (mVSD) in the small infant is a challenge particularly when multiple and associated with complex cardiac lesions. Devices for percutaneous implantation have the advantage of ease of placement and for the double umbrella designs a wide area of coverage. We reviewed our experience and clinical outcomes of intraoperative mVSD device closure for such defects in small infants.

METHODS

Since October 1989, intraoperative VSD device closure was a component of the surgical strategy in 14 consecutive patient implants (median age, 5.5 months; range, 3 to 11 kg), whose defects were thought difficult to approach using conventional techniques. Nine patients had associated complex cardiac lesions, 10 multiple mVSDs, and 4 patients had a previous pulmonary artery banding.

RESULTS

There were 2 early deaths, 1 in a severely ill child who preoperatively had pulmonary hypertension and left ventricular failure and another in a patient with a hypoplastic left heart. Mean pulmonary to systemic flow ratio before device insertion was 3.5:1. Complete closure was achieved in 5 patients and clinically insignificant residual shunts persisted in 7. In 2 infants with significant residual lesions concomitant pulmonary artery banding was required. Postoperative mean pulmonary to systemic flow ratio was 1.7:1. In follow-up of the 12 surviving infants (mean, 41 months), 8 had complete closure and 3 persistent residual shunts. One patient with no residual shunting required heart transplantation for progressive ventricular failure 9 years after operation. All devices were well positioned on postoperative echocardiograms. There was 1 late death due to aspiration in a patient with a tiny residual shunt.

CONCLUSIONS

Infants requiring operative intervention with mVSDs are difficult to manage and have an increased mortality and morbidity. Intraoperative VSD device placement for closure of mVSDs is feasible, can avoid ventriculotomy, division of intracardiac muscle bands, and is ideally suited for the neonate or infant.

Mycophenolate mofetil in pediatric heart transplant recipients: a single-center experience

Mycophenolate mofetil (MMF) is emerging as an effective agent for the treatment of both established rejection and primary rejection prophylaxis in solid-organ transplantation (Tx). However, little data is available on the use of MMF in the pediatric population. We therefore report on our experience with MMF in 21 pediatric heart transplant recipients. Data were obtained by retrospective chart review. Median age at time of review was 12.3 yr (range 11 months to 16.9 yr). Median age at Tx was 10.7 yr (range 55 days to 16.7 yr). MMF was started at a median of 4.3 months after Tx (range 1 day to 4.5 yr). At the time of MMF institution, all patients were concurrently on prednisone and azathioprine; 20 of these patients were also undergoing treatment with tacrolimus (median dose 0.18 mg/kg, range 0.03-0.64 mg/kg) and one with cyclo-sporin A (10 mg/kg). Azathioprine was discontinued at the time of commencing MMF. The average MMF dose was 40 +/- 14 mg/kg. The rationale for switching to MMF included rejection (International Society for Heart and Lung Transplantation [ISHLT] 3A/B), 66%; inability to wean steroids, 14%; ABO blood group donor-recipient mismatch, 10%; coronary artery disease (CAD), 5%; and side-effects of immuno-suppression, 5%. Of the patients switched for rejection, 93% demonstrated resolved or improving rejection. Both ABO donor-recipient mismatch patients were started on tacrolimus/MMF as primary therapy and had no significant episodes of rejection. Two patients had rejection classified as unchanged (one with CAD, one treated with addition of sirolimus prior to improvement). Corticosteroids were successfully discontinued in 28% of patients, and 20% are currently on a reduced dose. Fourteen per cent developed significant rejection while attempting to reduce the steroid dose. Steroid reduction has not yet been attempted in 38% of patients. The following side-effects were reported in 38% of the patients: diarrhea, 10%; gastrointestinal discomfort, 20%; and leukopenia, 20%. Dose reduction or temporary discontinuation was required in 63% of the patients who experienced side-effects (24% of the total number of patients). Opportunistic infections developed in 10% (cryptococcus, cytomegalovirus). Hence, MMF appears to be effective for treatment of rejection in the pediatric heart transplant population and has an acceptable side-effect profile. In addition, it may have a role in primary rejection prophylaxis and may facilitate a reduced steroid dosage or a steroid-free immunosuppression regimen.

'Failure to rescue' as a measure of quality of hospital care: the limitations of secondary diagnosis coding in English hospital data

Although it is widely recognized that quality of care varies between hospitals, a robust and valid measure of outcome that can be used in comparisons has proven elusive. One measure that has recently been proposed by US researchers is the 'failure to rescue' (FTR) rate. This is based on the assumption that, whereas complications may reflect both patient severity and health care factors, the ability to save patients once complications arise is much more closely related to the quality of health care. We describe an evaluation of FTR in a national sample of English hospitals using hospital episode data. We found that the rate of secondary diagnosis recording in England is about one-tenth that in the United States. The FTR rate would be highly sensitive to variations in the completeness of coding of secondary diagnoses. Unless coding is of uniformly high quality, any attempt to compare severity adjusted outcomes will be potentially unreliable.

Local shielding of high dose rate brachytherapy in an operating theatre

A high-dose rate brachytherapy facility was installed into an established operating theatre by using local shielding in the form of mobile lead screens and by taking advantage of the ease with which staff movements can be controlled in an operating suite. This facility was inexpensive to develop, and has proved clinically efficient and entirely adequate from a radiation safety standpoint.

Public disclosure of health care performance reports: a response from the UK

In the UK, the experience with public disclosure of health care performance data related to provider organizations is limited to a small set of administrative data known as the 'Patient's Charter' which has concentrated mainly on aspects of efficiency and which is currently being reviewed, and, most recently, to a set of reference costs by case type (known as Healthcare Resource Groups). Clinically oriented performance data has been published in Scotland since 1994 and will be published in England and Wales early in 1999. Knowledge about the impact and effect of such publication is limited, even in the USA, but there is some evidence that consumers and purchasers become gradually familiar with them and confident in their use. However, even with this scant knowledge, it would appear that the publication of data across the public services will continue to be a policy of the current UK Government for the foreseeable future. It would seem likely that this policy will have the tacit approval of the general population who have been educated to be somewhat wary of professional self-regulation. The greater public accountability that public disclosure of information brings, needs to be evaluated against the overall costs of the exercise, particularly within a publicly financed system, and against the disadvantages in public confidence and impact on the patient-doctor relationship that might occur if not managed appropriately.

Complication of ventricular demand pacing after orthotopic heart transplantation: unusual case of pacemaker syndrome in an infant

BACKGROUND

Sinus node dysfunction is the most common indication for antibradycardiac permanent pacing after heart transplantation. Lack of atrioventricular synchrony during pacing can result in symptoms ranging from mild chest discomfort to severe manifestations such as dyspnea, hypotension, and cardiovascular collapse, all of which are ascribed to pacemaker syndrome. In infants pacemaker syndrome is often only recognized in the face of marked hemodynamic compromise.

RESULTS

This report details an unusual account of pacemaker syndrome in an infant after orthotopic heart transplantation.

CONCLUSIONS

Careful assessment of atrioventricular synchrony is important after infant transplantation.