The Voice of the Heart: Vowel-Like Sound in Pulmonary Artery Hypertension.

Increased blood pressure in the pulmonary artery is referred to as pulmonary hypertension and often is linked to loud pulmonic valve closures. For the purpose of this paper, it was hypothesized that pulmonary circulation vibrations will create sounds similar to sounds created by vocal cords during speech and that subjects with pulmonary artery hypertension (PAH) could have unique sound signatures across four auscultatory sites. Using a digital stethoscope, heart sounds were recorded at the cardiac apex, 2nd left intercostal space (2LICS), 2nd right intercostal space (2RICS), and 4th left intercostal space (4LICS) undergoing simultaneous cardiac catheterization. From the collected heart sounds, relative power of the frequency band, energy of the sinusoid formants, and entropy were extracted. PAH subjects were differentiated by applying the linear discriminant analysis with leave-one-out cross-validation. The entropy of the first sinusoid formant decreased significantly in subjects with a mean pulmonary artery pressure (mPAp) ≥ 25 mmHg versus subjects with a mPAp < 25 mmHg with a sensitivity of 84% and specificity of 88.57%, within a 10-s optimized window length for heart sounds recorded at the 2LICS. First sinusoid formant entropy reduction of heart sounds in PAH subjects suggests the existence of a vowel-like pattern. Pattern analysis revealed a unique sound signature, which could be used in non-invasive screening tools.

Hyperoxia Reduces Oxygen Consumption in Children with Pulmonary Hypertension.

High inspired oxygen concentration (FiO2 > 0.85) is administered to test pulmonary vascular reactivity in children with pulmonary hypertension (PH). It is difficult to measure oxygen consumption (VO2) if the subject is breathing a hyperoxic gas mixture so the assumption is made that baseline VO2 does not change. We hypothesized that hyperoxia changes VO2. We sought to compare the VO2 measured by a thermodilution catheter in room air and hyperoxia. A retrospective review of the hemodynamic data obtained in children with PH who underwent cardiac catheterization was conducted between 2009 and 2014. Cardiac index (CI) was measured by a thermodilution catheter in room air and hyperoxia. VO2 was calculated using the equation CI = VO2/arterial-venous oxygen content difference. Data were available in 24 subjects (males = 10), with median age 8.3 years (0.8-17.6 years), weight 23.3 kg (7.5-95 kg), and body surface area 0.9 m2 (0.4-2.0 m2). In hyperoxia compared with room air, we measured decreased VO2 (154 ± 38 to 136 ± 34 ml/min/m2, p = 0.007), heart rate (91 [Formula: see text] 20 to 83 [Formula: see text] 21 beats/minute, p=0.005), mean pulmonary artery pressure (41 [Formula: see text] 16 to 35 [Formula: see text] 14 mmHg, p=0.024), CI (3.6 [Formula: see text] 0.8 to 3.3 [Formula: see text] 0.9 L/min/m2, p = 0.03), pulmonary vascular resistance (9 [Formula: see text] 6 to 7 [Formula: see text] 3 WU m2, p = 0.029), increased mean aortic (61 [Formula: see text] 11 to 67 [Formula: see text] 11 mmHg, p = 0.005), pulmonary artery wedge pressures (11 [Formula: see text] 8 to 13 [Formula: see text] 9 mmHg, p = 0.006), and systemic vascular resistance (12 [Formula: see text] 6 to 20 [Formula: see text] 7 WU m2, p=0.001). Hyperoxia decreased VO2 and CI and caused pulmonary vasodilation and systemic vasoconstriction in children with PH. The assumption that VO2 remains unchanged in hyperoxia may be incorrect and, if the Fick equation is used, may lead to an overestimation of pulmonary blood flow and underestimation of PVRI.

The unique heart sound signature of children with pulmonary artery hypertension.

We hypothesized that vibrations created by the pulmonary circulation would create sound like the vocal cords during speech and that subjects with pulmonary artery hypertension (PAH) might have a unique sound signature. We recorded heart sounds at the cardiac apex and the second left intercostal space (2LICS), using a digital stethoscope, from 27 subjects (12 males) with a median age of 7 years (range: 3 months-19 years) undergoing simultaneous cardiac catheterization. Thirteen subjects had mean pulmonary artery pressure (mPAp) < 25 mmHg (range: 8-24 mmHg). Fourteen subjects had mPAp ≥ 25 mmHg (range: 25-97 mmHg). We extracted the relative power of the frequency band, the entropy, and the energy of the sinusoid formants from the heart sounds. We applied linear discriminant analysis with leave-one-out cross validation to differentiate children with and without PAH. The significance of the results was determined with a t test and a rank-sum test. The entropy of the first sinusoid formant contained within an optimized window length of 2 seconds of the heart sounds recorded at the 2LICS was significantly lower in subjects with mPAp ≥ 25 mmHg relative to subjects with mPAp < 25 mmHg, with a sensitivity of 93% and specificity of 92%. The reduced entropy of the first sinusoid formant of the heart sounds in children with PAH suggests the existence of an organized pattern. The analysis of this pattern revealed a unique sound signature, which could be applied to a noninvasive method to diagnose PAH.

Detection of Heart Sounds in Children with and without Pulmonary Arterial Hypertension--Daubechies Wavelets Approach.

BACKGROUND: Automatic detection of the 1st (S1) and 2nd (S2) heart sounds is difficult, and existing algorithms are imprecise. We sought to develop a wavelet-based algorithm for the detection of S1 and S2 in children with and without pulmonary arterial hypertension (PAH). METHOD: Heart sounds were recorded at the second left intercostal space and the cardiac apex with a digital stethoscope simultaneously with pulmonary arterial pressure (PAP). We developed a Daubechies wavelet algorithm for the automatic detection of S1 and S2 using the wavelet coefficient 'D6' based on power spectral analysis. We compared our algorithm with four other Daubechies wavelet-based algorithms published by Liang, Kumar, Wang, and Zhong. We annotated S1 and S2 from an audiovisual examination of the phonocardiographic tracing by two trained cardiologists and the observation that in all subjects systole was shorter than diastole. RESULTS: We studied 22 subjects (9 males and 13 females, median age 6 years, range 0.25-19). Eleven subjects had a mean PAP < 25 mmHg. Eleven subjects had PAH with a mean PAP ≥ 25 mmHg. All subjects had a pulmonary artery wedge pressure ≤ 15 mmHg. The sensitivity (SE) and positive predictivity (+P) of our algorithm were 70% and 68%, respectively. In comparison, the SE and +P of Liang were 59% and 42%, Kumar 19% and 12%, Wang 50% and 45%, and Zhong 43% and 53%, respectively. Our algorithm demonstrated robustness and outperformed the other methods up to a signal-to-noise ratio (SNR) of 10 dB. For all algorithms, detection errors arose from low-amplitude peaks, fast heart rates, low signal-to-noise ratio, and fixed thresholds. CONCLUSION: Our algorithm for the detection of S1 and S2 improves the performance of existing Daubechies-based algorithms and justifies the use of the wavelet coefficient 'D6' through power spectral analysis. Also, the robustness despite ambient noise may improve real world clinical performance.

Cardiac catheterization in children with pulmonary hypertensive vascular disease.

The risks associated with cardiac catheterization in children with pulmonary hypertension (PH) are increased compared with adults. We reviewed retrospectively all clinical data in children with PH [mean pulmonary artery pressure (mean PAp) ≥25 mmHg and pulmonary vascular resistance index (PVRI) ≥3 Wood units m(2)] undergoing cardiac catheterization between 2009 and 2014. Our strategy included a team approach, minimal catheter manipulation and sildenafil administration prior to extubation. Adverse events occurring within 48 h were noted. Seventy-five patients (36 males), median age 4 years (0.3-17) and median weight 14.6 kg (2.6-77 kg), underwent 97 cardiac catheterizations. Diagnoses included idiopathic or heritable pulmonary arterial hypertension (PAH) (29 %), PAH associated with congenital heart disease (52 %), left heart disease (5 %) and lung disease (14 %). Mean PAp was 43 ± 19 mmHg; mean PVRI was 9.7 ± 6 Wood units m(2). There were no deaths or serious arrhythmias. No patient required cardiac massage. Three patients who suffered adverse events had suprasystemic PAp (3/3), heritable PAH (2/3), decreased right ventricular function (3/3), and pulmonary artery capacitance index <1 ml/mmHg/m(2) (3/3) and were treatment naïve (3/3). No patient undergoing follow-up cardiac catheterization suffered a complication. In 45 % of cases, the data acquired from the follow-up cardiac catheterization resulted in an alteration of therapy. Three percent of children with PH undergoing cardiac catheterization suffered adverse events. However, there were no intra or post procedural deaths and no one required cardiac massage or cardioversion. Follow-up cardiac catheterization in patients receiving pulmonary hypertensive targeted therapy is safe and provides useful information.

An increased incidence of conduit endocarditis in patients receiving bovine jugular vein grafts compared to cryopreserved homograft for right ventricular outflow reconstruction.

BACKGROUND: We compared the outcome of patients receiving bovine jugular vein grafts versus cryopreserved homografts for right ventricular outflow tract reconstruction. METHODS: Between 2000 and 2012, 379 conduits (244 bovine jugular vein grafts, 135 homografts) were implanted in 298 patients (median age 50 months) with a median follow-up of 3.4 years. RESULTS: Freedom from reoperation at 1, 5, and 7 years was 96.3%, 79.3%, and 64.2% after bovine jugular vein graft and 94.6%, 75.7%, and 68.6% after homograft insertion (p = 0.086). There were 24 cases of endocarditis, 23 associated with bovine jugular vein grafts (9.4%) and 1 associated with a homograft (0.7%; p < 0.001) at median follow-up of 44 months (range, 15 days to 10 years) after conduit implantation. After endocarditis, 15 of 24 conduits were replaced. Three patients had recurrent endocarditis in the revised conduit. Multivariate logistic regression analysis showed age less than 3 years and endocarditis to be significant risk factors associated with conduit replacement. Age more than 3 years and bovine jugular vein grafts were significant risk factors for graft endocarditis. Patients more than 3 years of age at bovine jugular vein graft implantation had significantly lower freedom from reoperation (p = 0.01). CONCLUSIONS: Compared with homograft conduits, the use of bovine jugular vein grafts for right ventricular outflow tract reconstruction was associated with a significantly higher incidence of bacterial endocarditis and conduit deterioration in older children at our institution. That may influence decision making regarding conduit choice for right ventricular outflow tract reconstruction. Patients and practitioners should be aware of the late risks of bacterial endocarditis after bovine jugular vein graft implantation.

Cumulative radiation exposure in pediatric patients with congenital heart disease.

Certain pediatric patients undergoing surgery for the most severe forms of congenital heart disease are exposed to high doses of ionizing radiation. The amount of cumulative radiation exposure from all modalities has not yet been evaluated. The purpose of our study was to evaluate the cumulative radiation exposure in a contemporary cohort of patients with congenital heart disease undergoing single-ventricle palliation. This is a single-center, retrospective study of pediatric patients undergoing Fontan completion between May 2005 and May 2010. Radiation exposure from all procedures including cardiac catheterizations, computed tomography (CT) scans, plain film radiography, and nuclear medicine scans was evaluated. Radiation dose was calculated as the dose area product (µGy m(2)) and was measured in all cardiac catheterizations, CT scans, and other imaging modalities. Seventy patients who underwent Fontan completion at a mean age of 3.6 ± 1.5 years (range 1.4-8 years) were included in the study. Mean number of chest X-rays was 32 ± 8 (range 10-285) with a mean cumulative total exposure of 1,320 µGy m(2) (range 480-12,960) per patient. Mean number of cardiac catheterizations was 2.45 ± 1.3 (range 1-8), and mean fluoroscopy and cine angiography exposures per case were 1,103 ± 245 and 1,412 ± 273 µGy m(2) giving a mean cumulative exposure of 9,054 µGy m(2) (range 2,515-201,200) per patient for all catheterizations. Mean number of CT scans performed was 0.44 ± 0.4 (0-11), and the mean exposure was 352 µGy m(2), giving a mean cumulative total of 154 µGy m(2) (range 0-3,872) per person. A total of five lung perfusion scans were carried out. Radiation exposure in patients with congenital heart disease undergoing single-ventricle palliation is quite variable. Most of the exposure to ionizing radiation occurs during cardiac catheterization. Strategies to utilize other imaging modalities such as MRI would decrease exposure in this particular group of patients who may be particularly vulnerable to its side effects.

Spectral analysis of the heart sounds in children with and without pulmonary artery hypertension.

BACKGROUND: Pulmonary artery hypertension (PAH) is difficult to recognize clinically. Digital stethoscopes offer an opportunity to re-evaluate the diagnosis of PAH. We hypothesized that spectral analysis of heart sound frequencies using recordings from a digital stethoscope would differ between children with and without PAH. METHODS: We recorded heart sounds using a digital stethoscope from 27 subjects (12 males) with a median age of 7 years (3 months to 19 years) undergoing simultaneous cardiac catheterization. 13 subjects had a mean pulmonary artery pressure (mPAp)<25 mm Hg (8-24 mm Hg). 14 subjects had a mPAp≥25 mm Hg (25-97 mm Hg). We applied the fast Fourier transform, power spectral analysis, separability testing, and linear discriminant analysis with leave-one-out cross-validation to the heart sounds recorded from the cardiac apex and 2nd left intercostal space (LICS) to examine the frequency domain. The significance of the results was determined using a t-test and rank-sum test. RESULTS: The relative power of the frequencies 21-22 Hz of the heart sounds recorded at the 2nd LICS was decreased significantly in subjects mPAp≥25 mm Hg versus<25 mm Hg. CONCLUSIONS: Heart sound signals of patients with PAH contain significantly less relative power in the band 21-22 Hz compared to subjects with normal PAp. Information contained in the frequency domain may be useful in diagnosing PAH and aid the development of auscultation based techniques for diagnosing PAH. In the future, utilizing the diagnostic information contained in heart sounds recordings may require analysis of both the time and frequency domains.

Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0.9) and sagittal oblique MRA of left pulmonary artery (LPA) (Δ 0.2 ± 1.1 mm, ICC 0.9). CMR PA measurements were compared to surgical measurements in 25 children (5.4 ± 4.8 years). All MRI sequences demonstrated good agreement (ICC > 0.8) with the best (ICC 0.9) from axial cine bSSFP for both RPA and LPA. Maximal cross sectional and angulated oblique reformatted MRA provide the best correlation to catheterization for measurement of branch PA's and stenosis diameter. This is likely due to similar angiographic methods based on reformatting techniques that transect the central axis of the arteries. Axial cine bSSFP CMR was the best surgically measured correlate of PA branch size due to this being a measure of stretched diameter. Knowledge of these differences provides more precise PA measurements and may aid catheter or surgical interventions for RVOTO lesions.

Right ventricular dysfunction in children supported with pulsatile ventricular assist devices.

OBJECTIVES: To describe the incidence and severity of right ventricular dysfunction (RVD) in pediatric ventricular assist device (VAD) recipients and to identify the preoperative characteristics associated with RVD and their effect on outcomes. METHODS: Children bridged to transplantation from 2004 to 2011 were included. RVD was defined as the use of a left VAD (LVAD) with an elevated central venous pressure of >16 mm Hg with inotropic therapy and/or inhaled nitric oxide for >96 hours or biventricular assist (BiVAD). RESULTS: A total of 57 children (median age, 2.97 years; range 35 days to 15.8 years) were supported. Of the 57, 43 (75%) had an LVAD, and of those, 10 developed RVD. The remaining 14 (25%) required BiVAD. Thus, RVD occurred in 24 of 57 patients (42%). Preoperative variables such as younger age (P = .01), use of extracorporeal mechanical support (P = .006), and elevated urea (P = .03), creatinine (P = .02), and bilirubin (P = .001) were associated with RVD. Multiple logistic regression analysis indicated that elevated urea and extracorporeal mechanical support (odds ratio, 26.4; 95% confidence interval, 2.3-307.3; and odds ratio, 27.8; 95% confidence interval, 2.5-312.3, respectively) were risk factors for BiVAD. The patients who developed RVD on LVAD had a complicated postoperative course but excellent survival (100%), comparable to those with preserved right ventricular function (91%). The survival for those requiring BiVAD was reduced (71%). CONCLUSIONS: RVD occurred in approximately 40% of pediatric VAD recipients and affects their peri-implantation morbidity and bridging outcomes. Preoperative extracorporeal membrane oxygenation and elevated urea were risk factors for BiVAD. Additional studies of the management of RVD in children after VAD implantation are warranted.

Time-domain analysis of heart sound intensity in children with and without pulmonary artery hypertension: a pilot study using a digital stethoscope.

We studied digital stethoscope recordings in children undergoing simultaneous catheterization of the pulmonary artery (PA) to determine whether time-domain analysis of heart sound intensity would aid in the diagnosis of PA hypertension (PAH). Heart sounds were recorded and stored in .wav mono audio format. We performed recordings for 20 seconds with sampling frequencies of 4,000 Hz at the second left intercostal space and the cardiac apex. We used programs written in the MATLAB 2010b environment to analyze signals. We annotated events representing the first (S1) and second (S2) heart sounds and the aortic (A2) and pulmonary (P2) components of S2. We calculated the intensity (I) of the extracted event area (x) as [Formula: see text], where n is the total number of heart sound samples in the extracted event and k is A2, P2, S1, or S2. We defined PAH as mean PA pressure (mPAp) of at least 25 mmHg with PA wedge pressure of less than 15 mmHg. We studied 22 subjects (median age: 6 years [range: 0.25-19 years], 13 female), 11 with PAH (median mPAp: 55 mmHg [range: 25-97 mmHg]) and 11 without PAH (median mPAp: 15 mmHg [range: 8-24 mmHg]). The P2∶A2 (P = .0001) and P2∶S2 (P = .0001) intensity ratios were significantly different between subjects with and those without PAH. There was a linear correlation (r > 0.7) between the P2∶S2 and P2∶A2 intensity ratios and mPAp. We found that the P2∶A2 and P2∶S2 intensity ratios discriminated between children with and those without PAH. These findings may be useful for developing an acoustic device to diagnose PAH.

Measurement of oxygen consumption in children undergoing cardiac catheterization: comparison between mass spectrometry and the breath-by-breath method.

Accurate measurement of oxygen consumption (VO2) is important to precise calculation of blood flow using the Fick equation. This study aimed to validate the breath-by-breath method (BBBM) of measuring oxygen consumption VO2 compared with respiratory mass spectroscopy (MS) for intubated children during cardiac catheterization. The study used MS and BBBM to measure VO2 continuously and simultaneously for 10 min in consecutive anesthetized children undergoing cardiac catheterization who were intubated with a cuffed endotracheal tube, ventilated mechanically, and hemodynamically stable, with normal body temperature. From 26 patients, 520 data points were obtained. The mean VO2 was 94.5 ml/min (95 % confidence interval [CI] 65.7-123.3 ml/min) as measured by MS and 91.4 ml/min (95 % CI 64.9-117.9 ml/min) as measured by BBBM. The mean difference in VO2 measurements between MS and BBBM (3.1 ml/min; 95 % CI -1.7 to +7.9 ml/min) was not significant (p = 0.19). The MS and BBBM VO2 measurements were highly correlated (R (2) = 0.98; P < 0.0001). Bland-Altman analysis showed good correspondence between MS and BBBM, with a mean difference of -3.01 and 95 % limits of agreement ranging from -26.2 to +20.0. The mean VO2 indexed to body surface area did not differ significantly between MS and BBBM (3.4 ml/min m(2); 95 % CI -1.4 to 8.2; p = 0.162). The mean difference and limits of agreement were -3.8 ml/min m(2) (range, -19.9 to 26.7). Both MS and BBBM may be used to measure VO2 in anesthetized intubated children undergoing cardiac catheterization. The two methods demonstrated excellent agreement. However, BBBM may be more suited to clinical use with children.

Successful use of Solitaire FR for stroke in a pediatric ventricular assist device patient.

Acute ischemic stroke (AIS) remains a devastating and relatively common complication after pediatric ventricular assist device (VAD) placement, with a reported incidence of 29%. We describe an 8-year-old cardiomyopathy patient who had received a HeartWare device, complicated by AIS, and successful treatment with a Solitaire FR device with complete recanalization. This is the first report of the use of this device in a VAD patient and the first reported use in a pediatric patient with middle cerebral artery AIS.

Antithrombotic strategies in children receiving long-term Berlin Heart EXCOR ventricular assist device therapy.

BACKGROUND: Thromboembolic events while receiving ventricular assist device (VAD) support remain a significant cause of morbidity and mortality despite standard anti-coagulation and anti-platelet therapies. The use of bivalirudin and epoprostenol infusions as an alternate anti-thrombotic (AT) regimen in pediatric VAD patients was reviewed. METHODS: This was a retrospective record review of 6 pediatric patients (aged ≤17 years) at 2 institutions treated with bivalirudin and epoprostenol infusions while being supported with the Berlin Heart EXCOR (Berlin Heart GmbH, Berlin, Germany) VAD. RESULTS: Six patients (age, 0.8-14 years; weight, 6.7-29.7 kg) were treated. Diagnoses included cardiomyopathy in 2 and congenital heart disease in 4. VAD support was left VAD in 2 and bi-VAD in 4, with duration of support of 21 to 155 days. Three patients required extracorporeal membrane oxygenation before VAD support. Bivalirudin/epoprostenol was used after recurrent thromboses on conventional medication in 3 patients, heparin-induced thrombocytopenia in 2, and in 1 patient considered high risk with a prosthetic mitral valve. The bivalirudin dose was titrated to partial thromboplastin time (PTT) of 1.5- to 2-times baseline (0.1-0.8 mg/kg/hour); the epoprostenol dose was 2 to 10 ng/kg/min. Additional anti-platelet agents included acetylsalicylic acid, dipyridamole, and clopidogrel in 5 patients each. No bleeding complications occurred. One patient sustained a cerebrovascular infarct on therapy, with subsequent complete recovery. No other complications occurred. Five patients underwent successful transplantation, and 1 patient died of multisystem organ failure. CONCLUSIONS: This report provides data on estimated safety and efficacy of bivalirudin and epoprostenol as an AT strategy in pediatric patients on extended VAD support. The short drug half-life and predictable AT response facilitated conversion to standard AT regimens at the time of transplantation (heparin-induced thrombocytopenia-negative patients). These agents should be considered for management of pediatric VAD patients when standard regimens fail.

Moderate altitude is not associated with adverse postoperative outcomes for patients undergoing bidirectional cavopulmonary anastomosis and Fontan operation: a comparative study among Denver, Edmonton, and Toronto.

OBJECTIVE: Outcomes of patients with single ventricle physiology undergoing cavopulmonary palliations depend on pulmonary vascular resistance (PVR) and have been suggested to be adversely affected by living at elevated altitude. We compared the pulmonary hemodynamic data in correlation with postoperative outcomes at the 3 centers of Denver, Edmonton, and Toronto at altitudes of 1604, 668, and 103 meters, respectively. METHODS: Hemodynamic data at pre-bidirectional cavopulmonary anastomosis (BCPA) and pre-Fontan catheterization between 1995 and 2007 were collected. Death from cardiac failure or heart transplantation in the same period was used to define palliation failure. RESULTS: There was no significant correlation between altitude (ranged from 1 to 2572 meters) and PVR, pulmonary artery pressure (PAP) or transpulmonary gradient (TPG) at pre-BCPA and pre-Fontan catheterization. BCPA failure occurred in 11 (9.2%) patients in Denver, 3 (2.9%) in Edmonton, and 34 (11.9%) in Toronto. Fontan failure occurred in 3 (6.1%) patients in Denver, 5 (7.2%) in Edmonton, and 11 (7.0%) in Toronto. There was no significant difference in BCPA and Fontan failure among the 3 centers. BCPA failure positively correlated with PVR and the presence of a right ventricle as the systemic ventricle. Fontan failure positively correlated with PAP and TPG. CONCLUSIONS: Moderate altitude is not associated with an increased PVR or adverse outcomes in patients with a functional single ventricle undergoing BCPA and the Fontan operation. The risk factors for palliation failure are higher PVR, PAP, and TPG and a systemic right ventricle, but not altitude. Our study reemphasizes the importance of cardiac catheterization assessments of pulmonary hemodynamics before BCPA and Fontan operations.

Fast-track extubation after modified Fontan procedure.

OBJECTIVE: In 2007, we introduced a policy to plan to extubate all patients after a modified Fontan procedure in the operating room. Our objective was to review the feasibility, safety, and clinical outcomes of this approach. METHODS: Patients who underwent a modified Fontan operation between May 2004 and May 2010 were reviewed. RESULTS: Ninety-seven patients underwent a modified Fontan operation (mean age, 3.9 ± 2.2 years; mean weight, 15.1 ± 5.0 kg); 46 patients (47%) were extubated in the operating room (group A). Nineteen patients were extubated in the intensive care unit within 24 hours (group B), and 32 patients had delayed extubation (group C). The 3 groups were not significantly different with respect to preoperative characteristics. Twenty-four hours postoperatively, group A had a lower mean central venous pressure compared with patients in group B or C (13 vs 14 vs 17 mm Hg, respectively, P < .001); a higher base excess (0.4 vs -1.3 vs -3.4, P < .001); a lower fluid balance (234 vs 514 vs 730 mL, P < .001); and a lower inotrope score (4.6 vs 6.7 vs 10.8, P < .001). Group C had a longer median intensive care unit length of stay (2 vs 3 vs 6 nights, P = .01), kept their chest tubes longer (8 vs 9 vs 15 days, P = .001), and had a longer median hospital length of stay (9 vs 11 vs 21 days, P = .001). CONCLUSIONS: Extubation in the operating room after a modified Fontan procedure seems feasible. This approach is associated with improved early postoperative hemodynamics, earlier time to chest tube removal, and shorter intensive care unit and hospital lengths of stay.

The profile of the systemic inflammatory response in children undergoing ventricular assist device support.

OBJECTIVES: Serum C-reactive protein (CRP) has been used as a systemic inflammatory response (SIR) marker in the critical ill, including children after cardiopulmonary bypass surgery. Ventricular assist devices (VAD) have been increasingly used as a bridge support to heart transplantation in children. We aimed to examine the profiles of CRP in children receiving VAD support. METHODS: Charts of 13 children receiving Berlin Heart EXCOR(®) from 2005 to 2009 were reviewed. The data obtained prior to and during VAD support included: CRP, white blood cells, inotropes and steroid use, VAD mode and duration of VAD support. Ten patients received left VAD (LVAD) and 3 biventricular VAD (BiVAD). RESULTS: The median duration of VAD support was 59 days (ranged 3-678 days). Pre-VAD CRP was 35 ± 51 mg/l and increased to 109 ± 59 mg/l on days 1-3 after the VAD implantation (P = 0.01), then gradually decreased to 28 ± 28 mg/l by 4 months and normalized by 5 months (P < 0.0001). CRP was higher in BiVAD than in LVAD patients throughout the study period (P = 0.003). CRP positively correlated with the doses of the epinephrine and norepinephrine and the monocyte counts, and negatively correlated with the lymphocyte count. The lymphocyte count was 2.5 ± 0.4 x 10(9)/l prior to implantation, and decreased to 2.1 ± 1.3 x 10(9)/l on days 1-3 (P = 0.5) and then to 0.6 ± 0.1 x 10(9)/l by 6 months (P = 0.08). It tended to be lower in BiVAD patients (P = 0.06). CONCLUSIONS: SIR exists in children prior to VAD support. VAD implantation is associated with a significant and prolonged increase in CRP and a decrease in lymphocyte count, indicating a suppressed immune function, being more pronounced in BiVAD patients.

Validity of the LaFarge equation for estimation of oxygen consumption in ventilated children with congenital heart disease younger than 3 years--a revisit.

BACKGROUND: The LaFarge equation is the most commonly used equation to estimate oxygen consumption (Vo(2)) in patients of all ages with congenital heart disease, although it was generated in patients older than 3 years. We sought to determine the validity of the LaFarge equation in estimating Vo(2) in children younger than 3 years undergoing cardiac catheterization with general anesthesia. METHODS: Vo(2) was measured directly using respiratory mass spectrometry in 75 sedated, paralyzed, and mechanically ventilated children in the pediatric cardiac catheterization laboratory. Age ranged from 0.13 to 24 years; 40 children being younger than 3 years. Estimated values for Vo(2) were calculated using the LaFarge equation for all patients. The agreement between measured and estimated Vo(2) was evaluated by the bias and limits of agreement in the 2 age groups. Regression analysis was used to analyze the influence of age on the agreement. RESULTS: A failure of agreement between measured and estimated Vo(2) was noted in both groups of children. As compared to the older group of patients, the agreement was significantly poorer in children younger than 3 years, with a significantly greater overestimation introduced by the LaFarge equation (11% +/- 21% vs 53% +/- 52%, P < .0001). CONCLUSION: The LaFarge equation introduces significant error in the estimation of Vo(2) in ventilated patients with congenital heart disease of all ages, particularly in children younger than 3 years.

Clinically relevant safety issues associated with St. John's wort product labels.

BACKGROUND: St. John's wort (SJW), used to treat depression, is popular in the USA, Canada, and parts of Europe. However, there are documented interactions between SJW and prescription medications including warfarin, cyclosporine, indinavir, and oral contraceptives. One source of information about these safety considerations is the product label. The aim of this study was to evaluate the clinically relevant safety information included on labeling in a nationally representative sample of SJW products from the USA. METHODS: Eight clinically relevant safety issues were identified: drug interactions (SJW-HIV medications, SJW-immunosupressants, SJW-oral contraceptives, and SJW-warfarin), contraindications (bipolar disorder), therapeutic duplication (antidepressants), and general considerations (phototoxicity and advice to consult a healthcare professional (HCP)). A list of SJW products was identified to assess their labels. Percentages and totals were used to present findings. RESULTS: Of the seventy-four products evaluated, no product label provided information for all 8 evaluation criteria. Three products (4.1%) provided information on 7 of the 8 criteria. Four products provided no safety information whatsoever. Percentage of products with label information was: SJW-HIV (8.1%), SJW-immunosupressants (5.4%), SJW-OCPs (8.1%), SJW-warfarin (5.4%), bipolar (1.4%), antidepressants (23.0%), phototoxicity (51.4%), and consult HCP (87.8%). Other safety-related information on labels included warnings about pregnancy (74.3%), lactation (64.9%), discontinue if adverse reaction (23.0%), and not for use in patients under 18 years old (13.5%). The average number of a priori safety issues included on a product label was 1.91 (range 0-8) for 23.9% completeness. CONCLUSION: The vast majority of SJW products fail to adequately address clinically relevant safety issues on their labeling. A few products do provide an acceptable amount of information on clinically relevant safety issues which could enhance the quality of counseling by HCPs and health store clerks. HCPs and consumers may benefit if the FDA re-examined labeling requirements for dietary supplements.