The Journal of Thoracic and Cardiovascular Surgery, 2013
Tricuspid regurgitation is a significant risk factor for reoperation and mortality in patients wi... more Tricuspid regurgitation is a significant risk factor for reoperation and mortality in patients with hypoplastic left heart syndrome. The effects of tricuspid valve repair on quantitative measures of right ventricle and tricuspid valve remodeling have not been well documented. We reviewed retrospectively the 2-dimensional echocardiograms of 17 tricuspid valve repairs (male, n = 12; female, n = 5; median age, 30 months; age range, 1.5-53 months) performed 1 month before and after tricuspid valve repair between 2005 and 2011. From the apical 4-chamber view, we measured right ventricle end-diastolic area, right ventricle fractional area change, and tricuspid valve leaflet coaptation length. The severity of tricuspid regurgitation was graded qualitatively. A 2-sided paired t test was used to compare changes in tricuspid valve and right ventricle outcomes, and the Wilcoxon signed-rank test was used to compare changes in tricuspid regurgitation grades. Right ventricle end-diastolic area decreased significantly after tricuspid valve repair from 14.1 ± 5.2 to 11.8 ± 3.9 cm(2) (P = .001), whereas right ventricle fractional area change declined from 44.4% ± 6.4% to 39.7% ± 8.5% (P = .016). The coaptation length of the lateral and septal leaflet improved significantly after tricuspid valve repair (0.4 ± 2.4 mm vs 3.1 ± 2.7 mm, P = .002; 2.0 ± 2.7 vs 3.4 ± 2.0 mm, P = .036; respectively). Furthermore, the tricuspid regurgitation grade improved after tricuspid valve repair (3.1 ± 0.6 to 1.7 ± 0.9, P < .001). Tricuspid valve repair improved significantly the tricuspid valve coaptation length and reduced right ventricle volume in children with hypoplastic left heart syndrome. Further follow-up of decreased right ventricle function is required to determine whether this is a temporary phenomenon related to reduced right ventricle preload, permanent right ventricle dysfunction from late repair of the tricuspid valve, or unavoidable sequelae of a right ventricle exposed to systemic vascular resistance.
There are few investigations of the changes in tricuspid valve (TV) and right ventricular (RV) mo... more There are few investigations of the changes in tricuspid valve (TV) and right ventricular (RV) morphology following bidirectional cavopulmonary anastomosis (BCPA). The 2-D echocardiograms of 35 children (male, n=23; female, n=12; median age, 6 months; range, 3-10 months) with hypoplastic left heart syndrome, 1 month before and after BCPA performed between 2005 and 2011, were retrospectively reviewed. Patients who underwent TV repair at BCPA were excluded. From the 4-chamber view, the coaptation length, vena contracta width and RV end-diastolic area before and after BCPA were measured and indexed to surface area. The severity of tricuspid regurgitation was graded qualitatively. After BCPA, RV end-diastolic area decreased from 2,951 ± 584 to 2,580 ± 591 mm(2)/m(2) (P<0.001). The coaptation length of the anterior leaflet (8.8 ± 5.8 vs. 11.0 ± 6.2 mm/m(2), P=0.0014) and of the septal leaflet (13.5 ± 5.3 vs. 15.8 ± 5.4mm/m(2), P=0.0072) increased after BCPA. The vena contracta width decreased (5.8 ± 4.9 vs. 4.3 ± 4.2 mm/m(2), P=0.035), although there was no change in tricuspid regurgitation grade after BCPC (1.4 ± 0.7 vs. 1.4 ± 0.9, P=0.234). In children with hypoplastic left heart syndrome after BCPA, the coaptation length of the anterior and septal leaflets of the TV improved concomitantly with vena contracta width and RV end-diastolic area despite unchanged tricuspid regurgitation grade. This suggests that favorable RV and TV remodeling accompanies the reduction in RV volume load following BCPA.
The development of a safe, portable, accurate, and adaptable system to deliver nitric oxide to pa... more The development of a safe, portable, accurate, and adaptable system to deliver nitric oxide to patients with pulmonary hypertension. A prospective, clinical study. Tertiary care pediatric intensive care unit and cardiac catheterization laboratory. One hundred twenty-three patients (median age 11 months, range 1 day to 72 yrs) with pulmonary hypertension who were administered nitric oxide between November 1991 and July 1993. Ninety-one patients were mechanically ventilated (volume-controlled ventilator, n = 53; pressure-controlled ventilator, n = 5; and a pressure-limited, time-cycled infant ventilator, n = 25). The system was adapted to allow high-frequency oscillator (n = 2) or hand ventilation, and for intraoperative use with an anesthesia machine (n = 6). Thirty-two patients were breathing spontaneously through a mask without assistance. Nitric oxide was delivered at 10 to 80 parts per million (ppm); the dose was adjusted independently of the FIO2 without altering minute ventilation or tidal volume. Nitrogen dioxide was continuously monitored and exceeded 3 ppm in only four patients. Methemoglobin concentrations were < 5% in all but four patients. Nitric oxide doses remained stable, independent of minute ventilation and could be changed easily and quickly. Inhaled nitric oxide can be administered precisely and reliably through a variety of delivery systems which can be used in patients of any size. Potential toxicity requires careful monitoring and continued improvement on apparatus design.
Automatic detection of the 1st (S1) and 2nd (S2) heart sounds is difficult, and existing algorith... more 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). 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. 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. 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.
In 2001, the Institute of Medicine identified healthcare transparency as a necessity for re-desig... more In 2001, the Institute of Medicine identified healthcare transparency as a necessity for re-designing a quality healthcare system; however, despite widespread calls for publicly available transparent data, the goal remains elusive. The transparent reporting of outcome data and the results of congenital heart surgery is critical to inform patients and families who have both the wish and the ability to choose where care is provided. Indeed, in an era where data and means of communication of data have never been easier, the paucity of transparent data reporting is paradoxical. We describe the development of a quality dashboard used to inform staff, patients, and families about the outcomes of congenital heart surgery at the Stollery Children's Hospital.
The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwen... more The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwent cardiac operations. Forty-five patients were divided into two groups, those with a high pulmonary blood flow (HF group; n = 23) and those with a normal or low flow (NF group; n = 22). Seven blood samples were taken: immediately before cardiopulmonary bypass, immediately after removing the aortic cross-clamps, immediately after discontinuing bypass, and at 20 minutes and 3, 6, and 24 hours after termination of bypass. The plasma levels of endothelin-1 were similar in both groups before bypass. From the time the aortic crossclamps were removed, the plasma endothelin-1 levels in both groups increased significantly, to reach a peak level at 3 to 6 hours. The increase was significantly greater in the HF than in the NF group, and the maximum values in the two groups were 12.6 +/- 1.1 and 9.6 +/- 0.8 fmol/ml, respectively (mean +/- standard error of the mean, p < 0.05). The value 20 minutes after bypass showed a positive correlation with the mean pulmonary arterial pressure measured at the preoperative cardiac catheterization study (r = 0.41, p < 0.05). In addition, a significant positive correlation was obtained between endothelin-1 3 hours after bypass and the maximum pulmonary/systemic arterial pressure ratio during the first 12 hours after operation (r = 0.86, p < 0.05). These results suggest that cardiopulmonary bypass is associated with an immediate postoperative increase in circulating endothelin and that patients who had a high pulmonary blood flow before the operation are particularly vulnerable, bypass having a more injurious effect on a lung with preexisting endothelial dysfunction. A high level of circulating endothelin may predispose to pulmonary vascular lability and pulmonary hypertensive crises in the postoperative period.
We hypothesized that vibrations created by the pulmonary circulation would create sound like the ... more 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.
Pulmonary venous hypertension may be caused by increased pressure anywhere between the intraparen... more Pulmonary venous hypertension may be caused by increased pressure anywhere between the intraparenchymal pulmonary veins and the left ventricle. Pulmonary venous hypertension has different causes in children compared with adults. In adults the most common cause of pulmonary venous hypertension is left ventricular diastolic disease. In children, congenital heart diseases, acquired and congenital cardiomyopathies are the usual causes of pulmonary
The functional and structural status of the pulmonary vascular bed plays a pivotal role in the pr... more The functional and structural status of the pulmonary vascular bed plays a pivotal role in the presentation and outcome of the child with congenital and acquired cardiovascular disease. Pulmonary vascular disease secondary to congenital heart disease is classified as category 1 together with other causes of pulmonary hypertension that share similar histological and endothelial cell abnormalities. Our review suggests that
American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, Jan 14, 2015
Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECM... more Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECMO) due to high risk of cerebral hemorrhage. Rarely has successful LTx been reported in children over 10 years of age receiving awake or ambulatory veno-venous ECMO. LTx following support with ambulatory veno-arterial ECMO (VA ECMO) in children has never been reported to our knowledge. We present the case of a 4-year-old, 12-kg child with heritable pulmonary artery hypertension and refractory right ventricular failure. She was successfully bridged to heart-lung transplantation (HLTx) using ambulatory VA ECMO. Initial resuscitation with standard VA ECMO was converted to an ambulatory circuit using Berlin heart cannulae. She was extubated and ambulating around her bed while on VA ECMO for 40 days. She received an HLTx from an oversized marginal lung donor. Despite a cardiac arrest and Grade 3 primary graft dysfunction, she made a full recovery without neurological deficits. She achieved 104...
As many as one third of the 35,000 to 40,000 infants born in the United States each year with sig... more As many as one third of the 35,000 to 40,000 infants born in the United States each year with significant congenital heart defects require surgery before the first year of life. Intraoperative support techniques, including cardiopulmonary bypass, can precipitate a complex, systemic inflammatory response that impairs the function of multiple organs and results in more hemodynamic instability and early morbidity in newborns than in older infants and children. Vasoactive agents are routinely used in the postoperative management of these patients either to treat or prevent hemodynamic instability and low cardiac output. However, the effectiveness of vasoactive agents used either individually or in combination in achieving specific therapeutic goals such as maintenance of a minimum cardiac index or arteriovenous oxygen saturation difference has not been systematically evaluated in preterm and term neonates. In addition, there are insufficient safety data for these agents in preterm and t...
The Journal of thoracic and cardiovascular surgery, 1993
The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwen... more The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwent cardiac operations. Forty-five patients were divided into two groups, those with a high pulmonary blood flow (HF group; n = 23) and those with a normal or low flow (NF group; n = 22). Seven blood samples were taken: immediately before cardiopulmonary bypass, immediately after removing the aortic cross-clamps, immediately after discontinuing bypass, and at 20 minutes and 3, 6, and 24 hours after termination of bypass. The plasma levels of endothelin-1 were similar in both groups before bypass. From the time the aortic crossclamps were removed, the plasma endothelin-1 levels in both groups increased significantly, to reach a peak level at 3 to 6 hours. The increase was significantly greater in the HF than in the NF group, and the maximum values in the two groups were 12.6 +/- 1.1 and 9.6 +/- 0.8 fmol/ml, respectively (mean +/- standard error of the mean, p < 0.05). The value 20 minute...
1. Exercise tolerance is impaired in congenital heart disease. To examine the possible contributi... more 1. Exercise tolerance is impaired in congenital heart disease. To examine the possible contribution of abnormalities in skeletal muscle bioenergetics, we used 31P nuclear magnetic resonance spectroscopy to investigate muscle metabolism in 10 subjects with congenital heart disease with cyanosis (median age 17.3 years) and in eight healthy age-matched control subjects. Spectra were collected from the gastrocnemius muscle at rest and during exercise and recovery. 2. In resting muscle there were significant elevations in cytosolic pH and in the cytosolic concentration of inorganic phosphate in the patients, and a strong positive correlation between cytosolic pH and blood haemoglobin concentration in all subjects. 3. During plantar flexion exercise the patients showed increased phosphocreatine depletion and cytosolic acidification over a shorter duration of exercise. The rise in calculated cytosolic ADP concentration was similar in both groups. 4. After cessation of exercise, the recover...
The Journal of Thoracic and Cardiovascular Surgery, 2013
Tricuspid regurgitation is a significant risk factor for reoperation and mortality in patients wi... more Tricuspid regurgitation is a significant risk factor for reoperation and mortality in patients with hypoplastic left heart syndrome. The effects of tricuspid valve repair on quantitative measures of right ventricle and tricuspid valve remodeling have not been well documented. We reviewed retrospectively the 2-dimensional echocardiograms of 17 tricuspid valve repairs (male, n = 12; female, n = 5; median age, 30 months; age range, 1.5-53 months) performed 1 month before and after tricuspid valve repair between 2005 and 2011. From the apical 4-chamber view, we measured right ventricle end-diastolic area, right ventricle fractional area change, and tricuspid valve leaflet coaptation length. The severity of tricuspid regurgitation was graded qualitatively. A 2-sided paired t test was used to compare changes in tricuspid valve and right ventricle outcomes, and the Wilcoxon signed-rank test was used to compare changes in tricuspid regurgitation grades. Right ventricle end-diastolic area decreased significantly after tricuspid valve repair from 14.1 ± 5.2 to 11.8 ± 3.9 cm(2) (P = .001), whereas right ventricle fractional area change declined from 44.4% ± 6.4% to 39.7% ± 8.5% (P = .016). The coaptation length of the lateral and septal leaflet improved significantly after tricuspid valve repair (0.4 ± 2.4 mm vs 3.1 ± 2.7 mm, P = .002; 2.0 ± 2.7 vs 3.4 ± 2.0 mm, P = .036; respectively). Furthermore, the tricuspid regurgitation grade improved after tricuspid valve repair (3.1 ± 0.6 to 1.7 ± 0.9, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001). Tricuspid valve repair improved significantly the tricuspid valve coaptation length and reduced right ventricle volume in children with hypoplastic left heart syndrome. Further follow-up of decreased right ventricle function is required to determine whether this is a temporary phenomenon related to reduced right ventricle preload, permanent right ventricle dysfunction from late repair of the tricuspid valve, or unavoidable sequelae of a right ventricle exposed to systemic vascular resistance.
There are few investigations of the changes in tricuspid valve (TV) and right ventricular (RV) mo... more There are few investigations of the changes in tricuspid valve (TV) and right ventricular (RV) morphology following bidirectional cavopulmonary anastomosis (BCPA). The 2-D echocardiograms of 35 children (male, n=23; female, n=12; median age, 6 months; range, 3-10 months) with hypoplastic left heart syndrome, 1 month before and after BCPA performed between 2005 and 2011, were retrospectively reviewed. Patients who underwent TV repair at BCPA were excluded. From the 4-chamber view, the coaptation length, vena contracta width and RV end-diastolic area before and after BCPA were measured and indexed to surface area. The severity of tricuspid regurgitation was graded qualitatively. After BCPA, RV end-diastolic area decreased from 2,951 ± 584 to 2,580 ± 591 mm(2)/m(2) (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). The coaptation length of the anterior leaflet (8.8 ± 5.8 vs. 11.0 ± 6.2 mm/m(2), P=0.0014) and of the septal leaflet (13.5 ± 5.3 vs. 15.8 ± 5.4mm/m(2), P=0.0072) increased after BCPA. The vena contracta width decreased (5.8 ± 4.9 vs. 4.3 ± 4.2 mm/m(2), P=0.035), although there was no change in tricuspid regurgitation grade after BCPC (1.4 ± 0.7 vs. 1.4 ± 0.9, P=0.234). In children with hypoplastic left heart syndrome after BCPA, the coaptation length of the anterior and septal leaflets of the TV improved concomitantly with vena contracta width and RV end-diastolic area despite unchanged tricuspid regurgitation grade. This suggests that favorable RV and TV remodeling accompanies the reduction in RV volume load following BCPA.
The development of a safe, portable, accurate, and adaptable system to deliver nitric oxide to pa... more The development of a safe, portable, accurate, and adaptable system to deliver nitric oxide to patients with pulmonary hypertension. A prospective, clinical study. Tertiary care pediatric intensive care unit and cardiac catheterization laboratory. One hundred twenty-three patients (median age 11 months, range 1 day to 72 yrs) with pulmonary hypertension who were administered nitric oxide between November 1991 and July 1993. Ninety-one patients were mechanically ventilated (volume-controlled ventilator, n = 53; pressure-controlled ventilator, n = 5; and a pressure-limited, time-cycled infant ventilator, n = 25). The system was adapted to allow high-frequency oscillator (n = 2) or hand ventilation, and for intraoperative use with an anesthesia machine (n = 6). Thirty-two patients were breathing spontaneously through a mask without assistance. Nitric oxide was delivered at 10 to 80 parts per million (ppm); the dose was adjusted independently of the FIO2 without altering minute ventilation or tidal volume. Nitrogen dioxide was continuously monitored and exceeded 3 ppm in only four patients. Methemoglobin concentrations were &lt; 5% in all but four patients. Nitric oxide doses remained stable, independent of minute ventilation and could be changed easily and quickly. Inhaled nitric oxide can be administered precisely and reliably through a variety of delivery systems which can be used in patients of any size. Potential toxicity requires careful monitoring and continued improvement on apparatus design.
Automatic detection of the 1st (S1) and 2nd (S2) heart sounds is difficult, and existing algorith... more 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). 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 &amp;amp;amp;amp;#39;D6&amp;amp;amp;amp;#39; 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. We studied 22 subjects (9 males and 13 females, median age 6 years, range 0.25-19). Eleven subjects had a mean PAP &amp;amp;amp;amp;lt; 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. 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 &amp;amp;amp;amp;#39;D6&amp;amp;amp;amp;#39; through power spectral analysis. Also, the robustness despite ambient noise may improve real world clinical performance.
In 2001, the Institute of Medicine identified healthcare transparency as a necessity for re-desig... more In 2001, the Institute of Medicine identified healthcare transparency as a necessity for re-designing a quality healthcare system; however, despite widespread calls for publicly available transparent data, the goal remains elusive. The transparent reporting of outcome data and the results of congenital heart surgery is critical to inform patients and families who have both the wish and the ability to choose where care is provided. Indeed, in an era where data and means of communication of data have never been easier, the paucity of transparent data reporting is paradoxical. We describe the development of a quality dashboard used to inform staff, patients, and families about the outcomes of congenital heart surgery at the Stollery Children's Hospital.
The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwen... more The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwent cardiac operations. Forty-five patients were divided into two groups, those with a high pulmonary blood flow (HF group; n = 23) and those with a normal or low flow (NF group; n = 22). Seven blood samples were taken: immediately before cardiopulmonary bypass, immediately after removing the aortic cross-clamps, immediately after discontinuing bypass, and at 20 minutes and 3, 6, and 24 hours after termination of bypass. The plasma levels of endothelin-1 were similar in both groups before bypass. From the time the aortic crossclamps were removed, the plasma endothelin-1 levels in both groups increased significantly, to reach a peak level at 3 to 6 hours. The increase was significantly greater in the HF than in the NF group, and the maximum values in the two groups were 12.6 +/- 1.1 and 9.6 +/- 0.8 fmol/ml, respectively (mean +/- standard error of the mean, p &amp;amp;amp;amp;lt; 0.05). The value 20 minutes after bypass showed a positive correlation with the mean pulmonary arterial pressure measured at the preoperative cardiac catheterization study (r = 0.41, p &amp;amp;amp;amp;lt; 0.05). In addition, a significant positive correlation was obtained between endothelin-1 3 hours after bypass and the maximum pulmonary/systemic arterial pressure ratio during the first 12 hours after operation (r = 0.86, p &amp;amp;amp;amp;lt; 0.05). These results suggest that cardiopulmonary bypass is associated with an immediate postoperative increase in circulating endothelin and that patients who had a high pulmonary blood flow before the operation are particularly vulnerable, bypass having a more injurious effect on a lung with preexisting endothelial dysfunction. A high level of circulating endothelin may predispose to pulmonary vascular lability and pulmonary hypertensive crises in the postoperative period.
We hypothesized that vibrations created by the pulmonary circulation would create sound like the ... more 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) &amp;amp;amp;amp;lt; 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 &amp;amp;amp;amp;lt; 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.
Pulmonary venous hypertension may be caused by increased pressure anywhere between the intraparen... more Pulmonary venous hypertension may be caused by increased pressure anywhere between the intraparenchymal pulmonary veins and the left ventricle. Pulmonary venous hypertension has different causes in children compared with adults. In adults the most common cause of pulmonary venous hypertension is left ventricular diastolic disease. In children, congenital heart diseases, acquired and congenital cardiomyopathies are the usual causes of pulmonary
The functional and structural status of the pulmonary vascular bed plays a pivotal role in the pr... more The functional and structural status of the pulmonary vascular bed plays a pivotal role in the presentation and outcome of the child with congenital and acquired cardiovascular disease. Pulmonary vascular disease secondary to congenital heart disease is classified as category 1 together with other causes of pulmonary hypertension that share similar histological and endothelial cell abnormalities. Our review suggests that
American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, Jan 14, 2015
Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECM... more Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECMO) due to high risk of cerebral hemorrhage. Rarely has successful LTx been reported in children over 10 years of age receiving awake or ambulatory veno-venous ECMO. LTx following support with ambulatory veno-arterial ECMO (VA ECMO) in children has never been reported to our knowledge. We present the case of a 4-year-old, 12-kg child with heritable pulmonary artery hypertension and refractory right ventricular failure. She was successfully bridged to heart-lung transplantation (HLTx) using ambulatory VA ECMO. Initial resuscitation with standard VA ECMO was converted to an ambulatory circuit using Berlin heart cannulae. She was extubated and ambulating around her bed while on VA ECMO for 40 days. She received an HLTx from an oversized marginal lung donor. Despite a cardiac arrest and Grade 3 primary graft dysfunction, she made a full recovery without neurological deficits. She achieved 104...
As many as one third of the 35,000 to 40,000 infants born in the United States each year with sig... more As many as one third of the 35,000 to 40,000 infants born in the United States each year with significant congenital heart defects require surgery before the first year of life. Intraoperative support techniques, including cardiopulmonary bypass, can precipitate a complex, systemic inflammatory response that impairs the function of multiple organs and results in more hemodynamic instability and early morbidity in newborns than in older infants and children. Vasoactive agents are routinely used in the postoperative management of these patients either to treat or prevent hemodynamic instability and low cardiac output. However, the effectiveness of vasoactive agents used either individually or in combination in achieving specific therapeutic goals such as maintenance of a minimum cardiac index or arteriovenous oxygen saturation difference has not been systematically evaluated in preterm and term neonates. In addition, there are insufficient safety data for these agents in preterm and t...
The Journal of thoracic and cardiovascular surgery, 1993
The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwen... more The plasma level of the potent vasoconstrictor endothelin-1 was measured in children who underwent cardiac operations. Forty-five patients were divided into two groups, those with a high pulmonary blood flow (HF group; n = 23) and those with a normal or low flow (NF group; n = 22). Seven blood samples were taken: immediately before cardiopulmonary bypass, immediately after removing the aortic cross-clamps, immediately after discontinuing bypass, and at 20 minutes and 3, 6, and 24 hours after termination of bypass. The plasma levels of endothelin-1 were similar in both groups before bypass. From the time the aortic crossclamps were removed, the plasma endothelin-1 levels in both groups increased significantly, to reach a peak level at 3 to 6 hours. The increase was significantly greater in the HF than in the NF group, and the maximum values in the two groups were 12.6 +/- 1.1 and 9.6 +/- 0.8 fmol/ml, respectively (mean +/- standard error of the mean, p < 0.05). The value 20 minute...
1. Exercise tolerance is impaired in congenital heart disease. To examine the possible contributi... more 1. Exercise tolerance is impaired in congenital heart disease. To examine the possible contribution of abnormalities in skeletal muscle bioenergetics, we used 31P nuclear magnetic resonance spectroscopy to investigate muscle metabolism in 10 subjects with congenital heart disease with cyanosis (median age 17.3 years) and in eight healthy age-matched control subjects. Spectra were collected from the gastrocnemius muscle at rest and during exercise and recovery. 2. In resting muscle there were significant elevations in cytosolic pH and in the cytosolic concentration of inorganic phosphate in the patients, and a strong positive correlation between cytosolic pH and blood haemoglobin concentration in all subjects. 3. During plantar flexion exercise the patients showed increased phosphocreatine depletion and cytosolic acidification over a shorter duration of exercise. The rise in calculated cytosolic ADP concentration was similar in both groups. 4. After cessation of exercise, the recover...
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