Transcatheter closure of congenital portosystemic shunts - A multicenter experience.

Background: Congenital portosystemic shunts (CPSS) are rare and present variably with hepatic encephalopathy, pulmonary arteriovenous malformations (PAVMs), and pulmonary hypertension (PH). Objective: The objective of the study was to see the feasibility of transcatheter closure of CPSS and their outcome. Materials and Methods: We analyzed the data of 24 patients of CPSS who underwent transcatheter closure from five institutions (March 2013 to April 2019). Baseline evaluation included echocardiography with bubble contrast study, ultrasound examination of the abdomen, computed tomography angiogram, and cardiac catheterization with test balloon occlusion of the CPSS. The evaluation showed cyanosis due to PAVM in 12, PH in 8, and respiratory distress in 2. Two had both cyanosis and PH. Criteria for eligibility for complete catheter closure of CPSS included demonstration of intrahepatic portal vein (PV) radicals together with a PV pressure of ≤18 mmHg on occlusion. Results: The median age and weight were 8 years (0.5-21) and 19.5 kg (4.2-73), respectively. Transcatheter closure was performed in 21 patients (22 procedures) using a variety of occlusive devices and stent-graft exclusion was done in one patient. Closure was not done in 3 in view of high portal venous pressures and hypoplastic PVs. During the follow-up (median: 42 months and range: 61 days-4.8 years), saturation normalized in 14 patients with PAVM. PH declined in all eight patients who underwent the procedure. Respiratory distress improved in two patients. Conclusions: Early and short-term follow-up results of catheter closure of CPSS appear promising. However, further, follow-up is needed to demonstrate long-term effectiveness.

Inhaled iloprost as an add-on therapy for advanced pulmonary arterial hypertension: An Indian perspective.

Background Pulmonary arterial hypertension (PAH) is a progressive disease with high morbidity and mortality. Risk stratification and initiation of dual or triple combination therapy has a better clinical response, especially in high-risk patients. Unfortunately, prostacyclin analogues are not marketed in India; hence, the use of these medications is limited. We report the benefits and difficulties of using iloprost inhalation in patients with advanced PAH in India. Methods In this prospective observational study, we included patients with group 1 PAH. Inhaled iloprost was initiated as an add-on therapy for patients who had clinical, echocardiographic or laboratory deterioration on dual oral medications. Patients with clinical instability were excluded. All patients underwent thorough clinical evaluation, detailed echocardiogram and laboratory investigations. Patients were started on inhaled iloprost 2.5 µg six times daily and closely followed up. The dose was escalated if necessary. On follow-up, clinical echocardiographic and laboratory evaluation was done on all patients. Results Fourteen patients (11 women) with a median age of 32 years (2-66 years) with group 1 PAH were started on inhaled iloprost as an add-on therapy. Improvement in clinical parameters, WHO functional class, echocardiographic-derived right ventricular function, and N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels were observed in 10 of 14 patients. A median increase of 31% (4.2, 106%) in the distance travelled during 6-minute walk test, a median increase of 45% (-20, 120%) in right ventricular fractional area change, a median increase of 27% (-16.7, 60%) in tricuspid annular peak systolic excursion and a median decrease of 36.7% (-69.6, 17.2%) in NT-pro-BNP levels were observed after initiation of medication. Three patients had progression of symptoms and were then referred for lung/heart-lung transplant. One patient developed progression of symptoms after an excellent initial response and transitioned to subcutaneous treprostinil. Improvement in clinical, echocardiographic and laboratory features allowed us to successfully perform surgical Potts shunt in 2 patients. The medications were well tolerated with minimal and transient side-effects. There were no deaths. Conclusion Inhaled iloprost can be used with acceptable benefits and minimal side-effects in patients with PAH.

Impact of COVID-19 pandemic on pediatric cardiac services in India.

BACKGROUND: COVID-19 pandemic has disrupted pediatric cardiac services across the globe. Limited data are available on the impact of COVID.19 on pediatric cardiac care in India. AIMS: The aims are to study the impact of COVID-19 pandemic on the care of children with heart disease in India in terms of number of outpatient visits, hospitalizations, catheter-based interventions, and cardiac surgeries. SETTINGS AND DESIGN: This is a retrospective, multicentric, observational study. METHODS: We collected monthly data on the number and characteristics of outpatient visits, hospitalizations, catheter-based interventions, and cardiac surgeries and major hospital statistics, over a period of 5 months (April to August 2020), which coincided with the first wave of COVID-19 pandemic in India and compared it with data from the corresponding months in 2019. RESULTS: The outpatient visits across the 24 participating pediatric cardiac centers decreased by 74.5% in 2020 (n = 13,878) as compared to the corresponding period in 2019 (n = 54,213). The reduction in the number of hospitalizations, cardiac surgeries, and catheterization procedures was 66.8%, 73.0%, and 74.3%, respectively. The reduction in hospitalization was relatively less pronounced among neonates as compared to infants/children (47.6% vs. 70.1% reduction) and for emergency surgeries as compared to elective indications (27.8% vs. 79.2%). The overall in-hospital mortality was higher in 2020 (8.1%) as compared to 2019 (4.8%), with a higher postoperative mortality (9.1% vs. 4.3%). CONCLUSIONS: The current COVID-19 pandemic significantly impacted the delivery of pediatric cardiac care across India with two-third reduction in hospitalizations and cardiac surgeries. In an already resource-constrained environment, the impact of such a massive reduction in the number of surgeries could be significant over the coming years. These findings may prove useful in formulating strategy to manage subsequent waves of ongoing COVID-19 pandemic.

Outcome of COVID-19-positive children with heart disease and grown-ups with congenital heart disease: A multicentric study from India.

BACKGROUND: Outcome data of children with heart disease who acquired COVID-19 infection are limited. AIMS: We sought to analyze outcome data and identify risk factors associated with mortality in children with heart disease and grown-ups with congenital heart disease (GUCH) who had a laboratory-confirmed COVID-19 infection. SETTINGS AND DESIGN: This is a retrospective, multicentric, observational study. MATERIALS AND METHODS: The study included children with heart disease and GUCH population, who presented with either symptomatic or asymptomatic COVID-19 infection to any of the participating centers. COVID-19-negative patients admitted to these centers constituted the control group. RESULTS: From 24 pediatric cardiac centers across India, we included 94 patients with a median age of 12.5 (interquartile range 3-96) months and 49 (52.1%) patients were males. Majority (83 patients, 88.3%) were children. One-third of the patients (n = 31, 33.0%) had acyanotic congenital heart disease, and 41.5% (n = 39) were cyanotic, with > 80% of the patients being unoperated. Only 30 (31.9%) patients were symptomatic for COVID-19 infection, while the rest were incidentally detected positive on screening. A total of 13 patients died (case fatality rate: 13.8%). The in-hospital mortality rate among hospitalized patients was significantly higher among COVID-19-positive cases (13 of 48; 27.1%) as compared to COVID-negative admissions (9.2%) during the study period (P < 0.001). On multivariate analysis, the independent predictors of mortality among COVID-19-positive cases were severity of illness at admission (odds ratio [OR]: 535.7, 95% confidence interval [CI]: 6.9-41,605, P = 0.005) and lower socioeconomic class (OR: 29.5, 95% CI: 1.1-814.7, P = 0.046). CONCLUSIONS: Children with heart disease are at a higher risk of death when they acquire COVID-19 infection. Systematic preventive measures and management strategies are needed for improving the outcomes.

Potts shunt as an effective palliation for patients with end stage pulmonary arterial hypertension.

BACKGROUND: Potts shunt has been suggested as an effective palliative therapy for patients with pulmonary artery hypertension (PAH) not associated with congenital heart disease. MATERIALS AND METHODS: This is a prospective single-center study performed to assess outcomes of Potts shunt in patients with PAH who are in functional class III or IV. RESULTS: 52 patients in functional class III/IV with pulmonary arterial hypertension without significant intra or extracardiac shunt on maximal medical therapy were evaluated and counseled for undergoing Potts shunt/patent ductus arteriosus (PDA) stenting. 16/52 patients (13 females) consented for the procedure; 14 patients underwent surgical creation of Potts, and 2 underwent transcatheter stenting of PDA, which physiologically acted like a Potts shunt. Standard medical therapy was continued in patients who did not consent for the procedure. 12/16 patients survived the procedure. Patients who did not survive the procedure were older, with severe right ventricular systolic dysfunction, and functional class IV. Patients who survived the procedure were followed up in the pulmonary hypertension clinic. The Median follow-up was 17 months (1-40 months). 11/13 patients discharged after the operation showed sustained clinical, echocardiographic, and biochemical improvement, which reduced need for pulmonary vasodilator therapy in 10/13 patients. There was one death in the follow-up period 16 months post-surgery due to lower respiratory tract infection. CONCLUSION: Potts shunt is feasible in patients with PAH without significant intra or extracardiac shunts. It can be done safely with an acceptable success rate. Patient selection, preoperative stabilization, and meticulous postoperative management are essential. It should be performed at the earliest sign of clinical, echocardiographic, or laboratory deterioation for optimal outcomes. Long-term follow-up is required to see a sustained improvement in functional class and the need for a lung transplant in the future.

Congenital extrahepatic portocaval malformation: Rare but potentially treatable cause of pulmonary hypertension.

OBJECTIVE: Abernethy malformation (congenital extrahepatic portosystemic shunt) is a rare anomaly of the splanchnic venous system. Though rare, it is an important cause of pulmonary artery hypertension (PAH) which is often missed. All patients with PAH should be carefully evaluated for presence of Abernethy malformation before labelling them as Idiopathic PAH. METHODS: This is a retrospective analysis of prospectively collected data. We reviewed the data of all patients referred to our center for evaluation of PAH. 10 patients were diagnosed to have an extrahepatic portocaval malformation. We reviewed their presentation, diagnosis, catheterization data, intervention and their outcome along with review of literature. RESULTS: 10/104 patients with pulmonary hypertension and no intra or extracardiac shunt were found to have extrahepatic portocaval shunt (EHPCS). 3 patients had EHPCS type 1 and 7 had type 2 EHPCS. 6/7 patient with EHPCS type 2 underwent closure of the shunt. There was no procedure related complication. There was one death 3 months post procedure and one patient who was advised surgical closure was lost to follow up. Closure of the shunt resulted in normalization of the pulmonary artery pressures in 4/5 patients. CONCLUSION: Congenital portosystemic malformations form an important and potentially treatable cause of pulmonary hypertension.

Multisystem Inflammatory Syndrome in Children With COVID-19 in Mumbai, India.

OBJECTIVE: We describe the presentation, treatment and outcome of children with multisystem inflammatory syndrome with COVID-19 (MIS-C) in Mumbai metropolitan area in India. METHOD: This is an observational study conducted at four tertiary hospitals in Mumbai. Parameters including demographics, symptomatology, laboratory markers, medications and outcome were obtained from patient hospital records and analyzed in patients treated for MIS-C (as per WHO criteria) from 1 May, 2020 to 15 July, 2020. RESULTS: 23 patients (11 males) with median (range) age of 7.2 (0.8-14) years were included. COVID-19 RT-PCR or antibody was positive in 39.1% and 30.4%, respectively; 34.8% had a positive contact. 65% patients presented in shock; these children had a higher age (P=0.05), and significantly higher incidence of myocarditis with elevated troponin, NT pro BNP and left ventri-cular dysfunction, along with significant neutrophilia and lympho-penia, as compared to those without shock. Coronary artery dilation was seen in 26% patients overall. Steroids were used most commonly for treatment (96%), usually along with intra-venous immunoglobulin (IVIg) (65%). Outcome was good with only one death. CONCLUSION: Initial data on MIS-C from India is presented. Further studies and longer surveillance of patients with MIS-C are required to improve our diagnostic, treatment and surveillance criteria.

Early Outcomes of Neonatal Cardiac Surgery in India.

OBJECTIVE: To assess outcomes and factors influencing outcomes in neonates requiring cardiac surgery in India. METHODS: This study reports on review of hospital data from a tertiary care cardiac surgical institute from January-2009 to December-2015. RESULTS: A total of 200 neonates were included; of them, 5% of the cases were antenatally diagnosed and most of them had unmonitored transport (111, 55.5%). The overall mortality rate was 13.5%, (n=27) and 178 (89%) underwent complete defect repair. There was a significant association of mortality with shock, the number of inotropes, intra-operative procedure, residual lesion, aortic cross-clamp and deep hypothermic circulatory arrest time (all P<0.05). Logistic regression analysis showed ventilation duration, cardiac-bypass time, shock, and residual cardiac lesion as independent predictors of mortality. CONCLUSIONS: Cardiac defects were found to have late detection and most transports were unmonitored. Complete surgical repair and shorter cardiac bypass time can potentially improve neonatal cardiac surgical outcomes.

Elective delayed sternal closure portends better outcomes in congenital heart surgery: a retrospective observational study.

INTRODUCTION: Delayed sternal closure is used in paediatric cardiac surgery as a management strategy for patients with unstable hemodynamics or postoperative bleeding routinely. We hypothesise that planned postponement of sternal closure leads to better outcomes than emergent reopening in the intensive care unit (ICU) in patients exhibiting some hemodynamic indication for the same. METHODS: We retrospectively analysed the outcomes of delayed sternal closure 220/2111 (10.42%) out of which 14 sternums were opened in the ICU after shifting the patients. RESULTS: A total of 220/2111 (10.42%) sternums were left open postoperatively, out of which 14 were opened after shifting to the ICU. Total mortality of the delayed sternal closure was 33/220, i.e. 15%. The patients whose sternums were left open from the theatre had a mortality of 23/206, i.e. 11.16%, whereas those patients whose sternums were opened in the ICU had a mortality of 10/14, i.e. 71.42%. CONCLUSION: In doubtful postoperatively hemodynamic, the choice of leaving the sternum open electively has better outcomes, rather than opening the sternum as a terminal bail out procedure.

Active right atrial emptying fraction predicts reduced survival and increased adverse events in childhood pulmonary arterial hypertension.

BACKGROUND: Right atrial (RA) function has been studied rarely in childhood pulmonary arterial hypertension (PAH). We sought to determine if RA and right ventricular (RV) area changes measured by echocardiography predicted outcomes. METHODS: We reviewed data from children with PAH undergoing cardiac catheterization and echocardiography. RA and RV areas were obtained from the apical 4-chamber view. Clinical worsening indicated initiation of parenteral prostanoid therapy, heart and/or lung transplantation, Potts shunt surgery or death. RESULTS: We studied 57 children (27 females), median age 3 years (range 0.30-17 years), body surface area 0.56 m2 (0.2-1.8), follow up 3 years (0.21-8.35), time to clinical worsening was 1.14 years (0.03-6.14) and mortality was 1.55 years (range 0.88-4.95). We determined from receiver operator curves that RA active emptying fraction (RA EaF) ≥60% predicted clinical worsening (sensitivity 78%, specificity 69%, AUC 0.7) and mortality (sensitivity 100%, specificity 65%, AUC 0.82). RV fractional area change (RVFAC) <25% predicted clinical worsening (sensitivity 72%, specificity 79%, AUC 0.85) and death (sensitivity 67%, specificity 69%, AUC 0.77). The combination of RA EaF ≥60% and RVFAC <33% were best predictors of clinical worsening (sensitivity 72%, specificity 82%, partial AUC 0.65) and mortality (sensitivity 100%, specificity 77%, partial AUC 0.75). CONCLUSION: In childhood PAH, RA EaF ≥ 60% and RVFAC <25% were associated with poor outcomes. RA EaF ≥60% and RVFAC <33% were best predictors of clinical worsening and may be useful markers in children with PAH who require closer observation and more intensive therapy.

Abernethy malformation: Single-center experience from India with review of literature.

Abernethy malformation is a rare congenital anomaly in which there is direct communication between the portal and systemic venous circulation. The clinical presentation ranges from asymptomatic with incidental detection on imaging to secondary complications of disease or related to associate anomalies. This is a retrospective analysis of data from nine patients with Abernethy malformation at a single center. This is a referral center for Pediatric Cardiology and for Hepatobiliary and Pancreatic Surgery. The patients presented to the Pulmonary Hypertension Clinic/the Hepatobiliary Surgery Clinic. Out of nine patients, four were male. Type II Abernethy malformation was present in five patients whereas three patients had type I malformation. One of the patients had communication between inferior mesenteric vein and internal iliac vein. Five out of nine patients were erroneously diagnosed as idiopathic primary pulmonary hypertension and were treated with vasodilators. One patient required living donor liver transplant. One patient was managed with surgical shunt closure whereas two patients required transcatheter shunt closure. The rest of the patients were managed conservatively. Abernethy malformation is more common than previously thought and the diagnosis is often missed. There are various management options for Abernethy malformation, which includes surgical or transcatheter shunt closure and liver transplant. Management of Abernethy malformation depends upon type, presentation, and size of shunt.

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.

Neonates with critical congenital heart defects: Impact of fetal diagnosis on immediate and short-term outcomes.

BACKGROUND: Fetal echocardiography is being increasingly used for prenatal diagnosis of congenital cardiac malformations, but its impact on the neonatal outcomes in low- and middle-income countries is still unknown. AIMS: The objective of this study is to determine the impact of fetal echocardiography on immediate postnatal and short-term outcome in a tertiary pediatric cardiac center. STUDY DESIGN: This is a prospective study. MATERIALS AND METHODS: One hundred consecutive patients with critical congenital heart defects (CHD) requiring active medical or surgical interventions in the 1st month of life were included in the study. The detailed history, postnatal examination findings, and fetal echocardiogram report were recorded. They were divided into two groups as antenatally diagnosed and postnatally diagnosed. Pre- and post-procedural variables were compared between the two groups. RESULTS: Twenty-nine neonates were diagnosed antenatally while 71 were diagnosed postnatally. Totally, 10 babies (34.5%) among the antenatally diagnosed group were delivered in a tertiary health-care setup. The mean age at presentation was 0 day in the antenatally diagnosed group while 10 days (0-30 days) in the postnatally diagnosed group (P = 0.01). A total of 17 (58.6%) patients in the antenatal group had duct dependent CHD, and 15 (88.2%) of these patients were transported on prostaglandin E1. In comparison, 19/34 (55.9%) patients in the postnatal group were transported on prostaglandin. The pH on admission in the antenatal group was 7.32 ± 0.05 as compared to 7.28 ± 0.05 in the postnatal group (P = 0.0004). There were 4 (5.6%) deaths in the postnatal group during transfer. There was no significant difference in the postoperative variables in both groups. CONCLUSIONS: Fetal echocardiography identifies patients with complex CHD resulting in better parental counseling, thus facilitating delivery at a tertiary care center and preoperative stabilization. This results in improved preoperative mortality and better stabilization.

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.

Acoustic diagnosis of pulmonary hypertension: automated speech- recognition-inspired classification algorithm outperforms physicians.

We hypothesized that an automated speech- recognition-inspired classification algorithm could differentiate between the heart sounds in subjects with and without pulmonary hypertension (PH) and outperform physicians. Heart sounds, electrocardiograms, and mean pulmonary artery pressures (mPAp) were recorded simultaneously. Heart sound recordings were digitized to train and test speech-recognition-inspired classification algorithms. We used mel-frequency cepstral coefficients to extract features from the heart sounds. Gaussian-mixture models classified the features as PH (mPAp ≥ 25 mmHg) or normal (mPAp < 25 mmHg). Physicians blinded to patient data listened to the same heart sound recordings and attempted a diagnosis. We studied 164 subjects: 86 with mPAp ≥ 25 mmHg (mPAp 41 ± 12 mmHg) and 78 with mPAp < 25 mmHg (mPAp 17 ± 5 mmHg) (p < 0.005). The correct diagnostic rate of the automated speech-recognition-inspired algorithm was 74% compared to 56% by physicians (p = 0.005). The false positive rate for the algorithm was 34% versus 50% (p = 0.04) for clinicians. The false negative rate for the algorithm was 23% and 68% (p = 0.0002) for physicians. We developed an automated speech-recognition-inspired classification algorithm for the acoustic diagnosis of PH that outperforms physicians that could be used to screen for PH and encourage earlier specialist referral.

Measurement of Oxygen Consumption in Critically Ill Children: Breath-by-Breath Method vs Mass Spectrometry.

BACKGROUND: Measurement of oxygen consumption (Vȯ2) is difficult in children but is essential to calculate cardiac index and systemic vascular resistance. OBJECTIVE: To compare measurements of Vȯ2 using respiratory mass spec trometry and the breath-by-breath method. METHODS: Vȯ2 was measured simultaneously and continuously for 10 minutes by using respiratory mass spectrometry and the breath-by-breath method in children receiving mechanical ventilation via cuffed endotracheal tubes. RESULTS: Sixteen children (7 boys; median [range]: age, 1.5 [0.2-6] years; weight, 11.5 [2.8-23.5] kg; body surface area, 0.55 [0.18-0.98] m(2)) were studied. The correlation between measurements of Vȯ2 by the 2 methods was good (R = 0.924). Mean Vȯ2 measured by mass spectrometry was 63 (95% CI, 47-78) mL/min vs 65 (95% CI, 47-83) mL/min measured by the breath-by-breath method. The mean Vȯ2 difference between the 2 methods was 3 (95% CI, -9 to 5) mL/min and statistically insignificant. Bland-Altman analysis showed that the 95% limits of agreement were between -28 and +23. Cardiac index did not differ significantly when calculated using Vȯ2 measured with one method or the other (mean difference, 0.1; 95% CI, -0.2 to 0.3). CONCLUSIONS: Measurements of Vȯ2 did not differ between mass spectrometry and the breath-by-breath method. Use of the breath-by-breath method may facilitate calculation of cardiac index and systemic vascular resistance in critically ill children.

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.