Systemic Oxygen Saturation Research Articles

The Effect of Volume Loading on Systemic Oxygenation After Bidirectional Superior Cavopulmonary Anastomosis

The unique series arrangement of the cerebral and pulmonary circulation in bidirectional superior cavopulmonary anastomosis (BCPA) makes the pulmonary blood flow dependent upon the cerebral blood flow. Until now, several investigators have tried to correct post-BCPA hypoxemia with various methods such as induced hyperventilation, the addition of carbon dioxide, and inhaled nitric oxide with variable success rates. We prospectively studied 25 children with univentricular physiology undergoing BCPA surgery at 5 different time points in the preoperative (1 time point) and postoperative period (4 time points, each separated by at least 3 mm Hg changes in the superior vena cava [SVC] pressure). Intravenous fluids were administered in the postoperative period to raise the SVC pressure. The systemic arterial oxygen saturation (Sao2) increased significantly (p = 0.000) from a preoperative value of 80% ± 7% to 86% ± 7%, 91% ± 3% and 95% ± 4% at SVC pressures of 9 ± 1.6 mm Hg, 13 ± 1.3 mm Hg, and 16 ± 1.4 mm Hg, respectively, and then decreased to 94% ± 4% at SVC pressure of 20 ± 1.7 mm Hg. Systolic and diastolic blood pressure increased significantly and simultaneously with SVC pressure from 71 ± 8 mm Hg and 42 ± 6 mm Hg to 89 ± 11 mm Hg and 52 ± 7 mm Hg, respectively (p = 0.000). Administration of intravenous fluids improves the SVC pressure, possibly due to an increase in the cerebral blood flow and the SVC flow, and thus raises the arterial oxygen tension (Pao2) and Sao2. Each patient has a unique SVC pressure where the Sao2 and the Pao2 are maximum; beyond that limit, the Sao2 does not improve.

Changes in right heart haemodynamics and echocardiographic function in an advanced phenotype of pulmonary hypertension and right heart dysfunction associated with pulmonary fibrosis

BackgroundPulmonary hypertension (PH)-targeted therapy in the setting of pulmonary fibrosis (PF) is controversial; the main clinical concern is worsening of systemic hypoxaemia. We sought to determine the effects of gentle...

Transient Elastography May Identify Fontan Patients with Unfavorable Hemodynamics and Advanced Hepatic Fibrosis

Transient elastography (TE) offers a noninvasive correlate with the degree of hepatic fibrosis. However, factors other than fibrosis affect liver stiffness. We sought to determine whether hepatic congestion related to hemodynamics in Fontan circulation influences liver stiffness measurement (LSM) assessed by TE. We studied 45 subjects with Fontan circulation undergoing cardiac catheterization with or without simultaneous liver biopsy. Subjects underwent TE within 5 days before catheterization. Clinical history, hemodynamic and biopsy data, and hepatic biomarkers were collected. Five subjects who had previously undergone liver biopsy and TE were also included. Median age was 13.1 years (range 2.4-57.8); median time since Fontan was 9.9 years (range 0.1-32.5). No subject had known hepatitis C. Mean LSM for the entire cohort was 21.4 ± 10.8 kPa. Univariate regression analysis using LSM as a continuous outcome variable shows significant correlations with age (R = 0.35, P = .01), time since Fontan (R = 0.41, P = .003), Fontan pressure (R = 0.31, P = .04), cardiac index (R = 0.33, P = .03), pulmonary vascular resistance (R = 0.34, P = .03), systemic arterial oxygen saturation (R = 0.31, P = .04), and platelet count (R = 0.29, P = .05). On multiple regression analysis, Fontan pressure (β = 0.901, P = .03) and cardiac index (β = 2.703, P = .02) were significant predictors of LSM with overall model R(2) = 0.206. Univariate analysis shows LSM to be associated with more severe centrilobular fibrosis (P = .05). Higher LSM is associated with unfavorable Fontan hemodynamics and advanced centrilobular hepatic fibrosis. TE may be a useful tool for identifying Fontan patients who warrant invasive testing.

High Incidence of Abdominal Venovenous Collaterals After Kawashima Operation

Systemic venous collaterals have been found at different stages of single-ventricle palliation, specifically after Kawashima operation. In this study, we present the incidence, clinical features, associated risk factors, and management of such venovenous collaterals (VVCs) after Kawashima procedure. A retrospective review of all the patients who underwent Kawashima procedure prior to December 2011 at Hamad General Hospital, Qatar, was performed. Data were collected and reviewed from medical records. The study group involved a total of six patients with Kawashima procedure. The median age of patients was 112.7 months (range 46-336 months), and median age at the time of Kawashima operation was 31.7 months (range 15-187 months). Mean systemic arterial oxygen saturation (Spo 2) after Kawashima operation was 94.5% ± 1.5%. In five patients, during a median follow-up of 53.4 months (range 16.9-147.9 months), the Spo 2 declined to a mean of 78.8% ± 8.2%. A total of 16 venous collaterals were observed in the study group, and majority (70%) of these collaterals were subdiaphragmatic. In our study, abdominal VVCs were observed in 100% of the patients who were followed after Kawashima operation. We therefore recommend that thorough evaluation for such VVCs should be part of the ongoing evaluation of patients after Kawashima operation, especially in those with low Spo 2. We also recommend early surgical rerouting of hepatic veins to pulmonary arteries in all post-Kawashima patients.

Pulmonary artery banding for univentricular heart beyond the neonatal period

It is standard practice to band the pulmonary artery at 2 to 4 weeks of age in patients with univentricular hearts with increased pulmonary blood flow. The behavior of patients banded beyond the neonatal period has not been well elucidated. This was a retrospective chart review of 32 consecutive patients (one neonate) who underwent pulmonary artery banding for functionally univentricular heart. The mean age at banding was 5.7 ± 6.0 months, and 34.4% were over 6-months old. Mortality was 15.6%. The mean systolic pulmonary artery pressure decreased from 43.6 ± 9.7 to 29.6 ± 7.0 mm Hg. The mean pre-discharge echocardiographic band gradient was 60.6 ± 13.6 mm Hg (mean systemic systolic pressure 73.7 ± 11.0 mm Hg) and systemic oxygen saturation was 81.7% ± 5.8%. At a mean follow-up period of 44.9 ± 30.0 months, 6 patients were lost to follow-up, 13 had undergone bidirectional Glenn shunt, and 7 had Fontan operations. Pulmonary artery mean pressure was 17.2 ± 4.6 mm Hg at pre-Glenn catheterization. Of the 5 patients who had not undergone further surgery, only one was inoperable. All were in functional class I or II. Pulmonary artery banding beyond the neonatal period in suitable patients with univentricular hearts provides reasonable palliation in the intermediate term, with a significant number successfully undergoing Fontan stages.

Four- and Seven-Year Outcomes of Patients With Congenital Heart Disease–Associated Pulmonary Arterial Hypertension (from the REVEAL Registry)

Uncorrected congenital heart disease (CHD) frequently leads to pulmonary arterial hypertension (PAH), the most severe form of which is Eisenmenger syndrome (ES). We compared patients with idiopathic or heritable PAH (IPAH or HPAH; n = 1,626) against those with CHD-associated PAH (n = 353) who were enrolled in the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL Registry). Of patients with CHD-associated PAH, 151 had ES. Compared with the IPAH or HPAH cohort, the ES cohort had greater systemic blood flow (2 ± 1 vs 3 ± 2 L/min/m(2), p <0.001), lower mean right atrial pressure (10 ± 6 vs 7 ± 4 mm Hg, p <0.001), higher mean pulmonary artery pressure (53 ± 14 vs 65 ± 17 mm Hg, p <0.001), higher pulmonary vascular resistance index (22 ± 12 vs 32 ± 31 Wood units × m(2), p <0.001), and lower systemic arterial oxygen saturation at rest (92 ± 11% vs 84 ± 13%, p <0.001). At 4 years from enrollment and 7 years from diagnosis, survival rate was similar between IPAH or HPAH and CHD-associated PAH cohorts. For the overall CHD-associated PAH cohort, longer 6-minute walk distance, lower mean right atrial pressure, brain natriuretic peptide level <50 pg/ml, and the presence of acute vasoreactivity were predictors of survival at 4 years from enrollment; younger age and lower mean right atrial pressure were predictors of survival at 7 years from diagnosis. In conclusion, these observations support predicted physiologic differences (e.g., hemodynamics) between patients with IPAH or HPAH and patients with CHD-associated PAH, with or without a systemic-pulmonary shunt. These differences, however, did not translate into significantly improved 4- and 7-year survival rates in patients with ES versus IPAH or HPAH and CHD-associated PAH.

Influence of variations in systemic blood flow and pressure on cerebral and systemic oxygen saturation in cardiopulmonary bypass patients

BackgroundAlthough both pressure and flow are considered important determinants of regional organ perfusion, the relative importance of each is less established. The aim of the present study was to evaluate the impact of variations in flow, pressure, or both on cerebral and whole-body oxygen saturation. MethodsThirty-four consenting patients undergoing elective cardiac surgery on cardiopulmonary bypass were included. Using a randomized cross-over design, four different haemodynamic states were simulated: (i) 20% flow decrease, (ii) 20% flow decrease with phenylephrine to restore baseline pressure, (iii) 20% pressure decrease with sodium nitroprusside (SNP) under baseline flow, and (iv) increased flow with baseline pressure. The effect of these changes was evaluated on cerebral ScO2 and systemic SvO2 oxygen saturation, and on systemic oxygen extraction ratio (OER). Data were assessed by within- and between-group comparisons. ResultsDecrease in flow was associated with a decrease in ScO2 [from 63.5 (7.4) to 62.0 (8.5) %, P<0.001]. When arterial pressure was restored with phenylephrine during low flow, ScO2 further decreased from 61.0 (9.7) to 59.2 (10.2) %, P<0.001. Increase in flow was associated with an increase in ScO2 from 62.6 (7.7) to 63.6 (8.9) %, P=0.03, while decreases in pressure with the use of SNP did not affect ScO2. SvO2 was significantly lower (P<0.001) and OER was significantly higher (P<0.001) in the low flow arms. ConclusionsIn the present elective cardiac surgery population, ScO2 and SvO2 were significantly lower with lower flow, regardless of systemic arterial pressure. Moreover, phenylephrine administration was associated with a reduced cerebral and systemic oxygen saturation.

Long-term effects of continuous prostacyclin therapy in adults with pulmonary hypertension associated with congenital heart disease

The continuous administration of prostacyclin analogs (PGI2) is a proven and effective therapy in patients with group 1 pulmonary arterial hypertension (PAH). However, few studies have addressed its use in adults with PAH associated with congenital heart disease (CHD-PAH). Concerns remain regarding the theoretical risk of worsening right-to-left intracardiac shunt. In this study, we present the hemodynamic and clinical effects of long-term, continuous PGI2 administration in eight adult patients with CHD-PAH. We retrospectively reviewed the records of patients with CHD-PAH treated with continuous prostacyclin analogs epoprostenol and treprostinil. Nine patients were identified; one patient had no documentation of an intracardiac shunt and was excluded from this study. Hemodynamic, functional, laboratory, and clinical data were included. Mean duration of continuous PGI2 therapy was 1 year. Compared to baseline, patients exhibited significant improvements in mean pulmonary artery (PA) pressure and PA oxygen saturation, without a significant decline in systemic blood pressure or systemic oxygen saturation. Metabolic equivalents (METs) achieved on exercise testing increased, with an improvement in oxygen desaturation. World Health Organization functional classification remained the same. Long-term continuous PGI2 therapy in CHD-PAH patients resulted in hemodynamic and clinical improvements similar to those with group 1 PAH. The increase in PA oxygen saturation suggests that the net effect of PGI2 therapy did not result in increased right-to-left shunting, but, instead, diminished shunt. Though larger studies are needed, PGI2 should be considered as a potential treatment modality in adult patients with severe CHD-PAH who fail conventional therapy.

Percutaneous embolization of a giant collateral vessel originating from the azygos vein via the inferior vena cava

We present the case of a 45-year-old man with univentricular heart, small outlet chamber, and L-transposition of the great vessels. As an infant, the patient underwent multiple palliative surgical interventions. He presented with worsening dyspnea and fatigue and was found to have systemic oxygen saturation of 85% on 2 L of oxygen by nasal cannula, whereas he had chronically remained between 90 and 95% throughout most of adulthood. There was no evidence of significant valvular regurgitation or stenosis, nor was there an overt intracardiac shunt by echocardiography. Cardiac CT and cardiac MRI revealed a large serpiginous systemic to pulmonary venovenous collateral located behind the left atrium. The collateral drained into the lower right pulmonary vein as it entered the left atrium. The tributary veins to the "giant" collateral were determined by these images modalities. The patient underwent a percutaneous embolization of this giant venovenous collateral via a remnant supracardinal vein originating from the infrarenal inferior vena cava using two Amplatzer Vascular Plug II. Immediately after the procedure the patient's oxygen saturation increased to 90% on room air at rest. At 2 months follow-up the patient had a marked clinical improvement with oxygen saturation as high as 95% on room air while walking. Our case illustrates a successful embolization of a giant collateral via an embryological venous remnant connecting the IVC to the azygos system.

Cerebral and systemic tissue oxygen saturation are more dependent on flow than on pressure maintenance

Cerebral and systemic tissue oxygen saturation are more dependent on flow than on pressure maintenance

Sa1817 Tissue Hypoxia in Pathogenesis of Ulcerative Colitis; Should We Change All Our Beliefs?

Department of Surgery, University of Minnesota, Minneapolis, USAMany studies have focused on the role of irregularmucosal immune response, but there are noteworthyevidences regarding the role of ischemia in pathogen-esis of ulcerative colitis (UC). Hypoxia-induciblefactor-1 alpha (HIF1a) is an intranuclear proteinwhich is produced by decreased level of intracellularoxygen level. Increased levels of HIF1a in tissuespecimens and high levels of vascular endothelialgrowth factor (VEGF) in serum samples of UCpatients are novel findings, strongly congruent withthe role of ischemia in UC pathogenesis. The aim ofthis study is to evaluate the value of tissue hypoxia incellular level in pathogenesis of UC [1–3].Forty subjects in four groups were enrolled inour case control study as follows: 1) ten patientswithleftUC(toobtainbiopsyspecimensfromsparingpartsofthecolon);2)tenhealthyindividuals(referreddue to screening purposes); 3) ten formalin-fixedparaffin-embedded (FFPE) tissue samples frompatients with mesenteric ischemia; and 4) ten FFPEsamples from patients with infectious colitis. Subjectsin group 1 and 2 underwent colonoscopy. In group 1,two biopsy samples were taken, one from ulcerativetissue, and the other from spared intestinal tissue.In group 2, biopsy specimens were obtained from theleft colon. All subjects were evaluated for tissue hyp-oxia by a single expert pathologist utilizing HIF1aimmunohistochemical staining (Novus BiologicalsCompany, Clone ESEE122). Systemic and perirectalarteriolar oxygen saturation was then evaluated ingroups 1 and 2. Systemic oxygen saturation was mea-sured by radial artery blood sampling. Endoscopicultrasound was used for arteriolar blood sampling inperirectal level. The venules and arterioles were dis-tinguished according to wall thickness (Figure 1).Oxygen saturation was quantified within one minuteof blood sampling.Nine (90%) of the biopsy specimens of patientswith ulcerative colitis (ulcerative parts) as well as8 (80%) of the specimens of the subjects with mesen-teric ischemia showedtissue hypoxia in HIF-1a stain-ing. By contrast, only 1 (10%) of the biopsy samplesfrom subjects with infectious colitis and none of thesamples from healthy individuals and samples fromsparing parts of the colon of patients with UChad tissue hypoxia. There were no significant differ-ences between systemic saturation in groups 1 and2 (94.4 vs. 94.3%, p = 0.8), but pericapillary satura-tion was significantly higher in ulcerative colitispatients (96.4 vs. 94.3%, p = 0.001).Our data suggest that ischemia is the main pathol-ogy in a majority of UC patients. In support of ourconclusion, previous studies have shown that HIF1ais involved in triggering cell immune response [4] and

Predicting operability in children with acyanotic congenital heart diseases and severe pulmonary hypertension

ObjectiveTo investigate whether peri-operative risk stratification of children with ventricular septal defect (VSD) and complete atrioventricular septal defect (CAVSD) complicated with elevated pulmonary vascular resistance could be predicted solely based on measuring systemic oxygen saturation (SaO2) without performing cardiac catheterization. MethodsRecords of patients with VSD and CAVSD, who underwent cardiac catheterization from 2002 to 2012 were reviewed and grouped as low (A) and high (B) risk, based on the pulmonary vascular resistance (PVRI) of ⩽ or >6Woods units (WU) in room air, respectively. Patients in group B underwent oxygen study to assess pulmonary vascular reactivity. Patients with PVRI⩽6WU in either room air or on 100% oxygen were deemed operable. ResultsSeventy-six patients; (VSD=45, CAVSD=31) underwent measurement of pulmonary vascular resistance. All patients with VSD were operated. Forty-two of them had systemic oxygen saturation (SaO2)⩾94%. Twenty-four of 31 patients with CAVSD were operated and had SaO2⩾83%. SaO2 of ⩾83% in CAVSD and ⩾94% in VSD had sensitivity and specificity of 95% and 100%, respectively to predict pulmonary vascular resistance based operability. ConclusionOxygen saturation on pulse oximetry of ⩾94% in children with VSD and 83% with CAVSD accurately identified operable patients. This criterion may be used as an alternate to invasive assessment of pulmonary vascular resistance. Outcome of operable patients having PVRI>6WU in room air is good and similar to those with PVRI<6WU.

Balloon Angioplasty and Stent Implantation Performed Through Systemic-to-Pulmonary Artery Shunts in Infants and Neonates

Branch pulmonary artery stenosis (BPAS) in the setting of systemic-pulmonary artery shunts (SPS) may result in significant sequelae. Limited information exists regarding the safety and efficacy of pulmonary artery balloon angioplasty and stent implantation via SPS in neonates and infants. This study aimed to examine the feasibility, safety, and efficacy of balloon angioplasty/stent implantation for BPAS performed via SPS in neonates and infants. A single-center retrospective analysis of all patients weighing 10 kg or less who underwent angioplasty for BPAS via SPS was performed. Systemic oxygen saturations and vessel diameter before, during, and after the procedure were compared. Between July 1996 and February 2008, 15 patients underwent 20 catheterizations for the treatment of 27 BPAS via SPS. The patients had a mean weight of 5.6 kg (range, 2.6-10 kg) and a mean age of 7.6 months (range, 7 days to 33 months). The SPS diameter ranged between 2 and 5 mm (median, 3.5 mm). Angioplasty was performed for all 27 lesions, and an additional stent was placed in 5 of these. The average lesion diameter increased from 2.3 ± 1.5 to 4.7 ± 1.7 mm (p < 0.05), and 25 (93 %) of the 27 lesions met the predetermined criteria for success. Systemic oxygen saturation increased from 73 ± 9.5 % to 82 ± 6.8 % immediately after intervention and was 83 ± 7.9 % at discharge (p < 0.05). There were no instances of shunt thrombosis. Two patients experienced transient hypotension during the procedure. No procedural deaths occurred. The study findings suggest that balloon angioplasty or stent implantation performed via SPS appears to be safe and effective treatment for BPAS in neonates and infants.

Hemodynamic Changes during Off-Pump Coronary Ar-tery Bypass Graft Surgery: Experience Using Pericardial Bands for Target Stabilization

Background: The off-pump coronary artery bypass graft surgery (OPCAB) may produce significant hemodynamic instability necessitating conversion to on-pump surgery. This study evaluated the hemodynamic parameters in patients undergoing OPCAB using pericardial bands for stabilization of the coronary target sites. Methods: In 250 patients undergoing OPCAB the hemodynamic parameters including continuous cardiac output and systemic venous oxygen saturation (SvO2) were recorded at baseline after pericardiotomy, during each coronary artery anastomosis at 3, 5, 10, 15 min, and after release of the pericardial bands used for target stabilization. Vasopressors were used to maintain mean arterial pressure (MAP) > 60 mmHg. Results: SvO2 and cardiac index (CI) decreased significantly after target stabilization and during all coronary anastomoses with greater decreases noted during obtuse marginal branch of left circumflex (OM) anastomosis. The MAP and heart rate were maintained without significant change but central venous pressure increased significantly during all coronary anastomoses. The significant increase in pulmonary capillary wedge pressure and mean pulmonary artery pressure were noted only during anastomosis of the left anterior descending artery. The highest dose of vasopressor was used during OM anastomosis. Conclusions: During OPCAB surgery using pericardial bands for coronary target stabilization, MAP was maintained constantly, but SvO2 and CI decreased immediately after target stabilization and reduced further during all coronary artery anastomoses. During OM anastomosis SvO2 and CI were significantly lower as compared to that of LAD and right coronary artery. Careful monitoring and management of hemodynamic variables are warranted to avoid conversion to on-pump technique.

Safety and efficacy of prolonged dexmedetomidine use in critically ill children with heart disease*

To evaluate the safety and efficacy of prolonged dexmedetomidine administration (≥ 96 hrs) in critically ill children with heart disease. Retrospective observational study. Cardiovascular intensive care unit in a single, tertiary care, academic children's hospital. None. We conducted a retrospective review of the charts of all critically ill infants and children (up to 18 yrs of age) with congenital or acquired heart disease who received dexmedetomidine for ≥ 96 hrs in our pediatric cardiovascular intensive care unit between January 2009 and March 2010. Patients were divided into two groups for study purposes: the dexmedetomidine group (n = 52) included patients who received a dexmedetomidine infusion along with other conventional sedation agents, and the control group (n = 42) included patients who received conventional sedation agents without the use of dexmedetomidine. Clinical outcomes evaluated in our study included days of mechanical ventilation, cardiovascular intensive care unit length of stay, hospital length of stay, and mortality. To evaluate the safety of dexmedetomidine, we collected physiologic data, including heart rate, mean arterial pressure, respiratory rate, systemic oxygen saturation by pulse oximetry, and inotrope score. To assess the efficacy of dexmedetomidine, we examined the amount and duration of concomitant sedation and analgesic infusions over a period of 24 hrs in both dexmedetomidine and control groups. We also examined the number of rescue boluses for each category prior to the initiation of sedative infusion, during the sedative infusion, and after the termination of the sedative infusion. The potential side effects evaluated in our study included nausea, vomiting, abdominal distension, dysrhythmias, neurological abnormalities, seizures, and signs and symptoms of withdrawal. Patients' baseline characteristics were similar in the two groups. Patient complexity as measured by Risk-Adjusted Classification for Congenital Heart Surgery-1 score, ventricular ejection fraction, and proportion of patients receiving mechanical ventilatory support at the time of initiation of sedative infusion was also similar. The duration and amount of continuous midazolam and morphine infusions were significantly lower in the dexmedetomidine group when compared to the control group. During dexmedetomidine infusion, there was no statistical difference in the heart rate and blood pressure between the two groups. Inotrope score was significantly lower in the dexmedetomidine group as compared to the control group in the last 6 hrs prior to termination of dexmedetomidine infusion (p < .001), and at 1 hr (p < .001) and 6 hrs (p < .001) after termination of dexmedetomidine infusion. There was no difference in duration of mechanical ventilation (p = .77), cardiovascular intensive care unit length of stay (p = .29), or hospital length of stay (p = .43) in the two groups. One patient experienced junctional rhythm at 130 beats/min requiring temporary pacing. No other significant side effects were noted. A higher proportion of patients in the dexmedetomidine group were administered clonidine when compared to the control group after termination of dexmedetomidine (31% vs. 7%, p = .005). Prolonged dexmedetomidine administration in children with heart disease appears to be safe and is associated with decreased opioid and benzodiazepine requirement and decreased inotropic support.

Predicting surgical outcome in children with acyanotic congenital heart diseases and severe pulmonary hypertension

Elevated pulmonary vascular resistance is a contraindication for surgical repair of acyanotic congenital heart diseases. Whether perioperative outcome of children with ventricular septal defect (VSD) and complete atrioventricular septal defect (CAVSD), complicated with severe pulmonary Hypertension could be ascertained only by clinical evaluation. Medical records of patients with VSD and CAVSD, who underwent diagnostic cardiac catheterization from 2001 to 2009 were reviewed and grouped as low (A) and high (B) risk, based on the pulmonary vascular resistance (PVR) of ⩽ or >6 Woods units (w.u) in room air, respectively. Patients with PVR ⩽6 w.u. in either room air or 100% oxygen were deemed operable. Eighty five patients (VSD = 47, CAVSD = 37) underwent measurement of pulmonary vascular resistance. All patients with VSD were operated. Forty-four of them had systemic oxygen saturation (SaO 2) ⩾ 94%. Twenty-five of 38 patients with CAVSD were operated and had SaO 2 ⩾ 83%. All operated patients had congestive heart failure. SaO 2 of ⩾83% in CAVSD and ⩾94% in VSD patients had sensitivity and specificity of 95% and 100% respectively to predict PVR based operability. There was no significant difference in any of the operative and postoperative outcome variables between the low risk and high risk groups. SaO 2 ⩾ 94% in children with VSD and 83% with CAVSD accurately identified operable patients. These criteria may be used as an alternate to cardiac catheterization to identify operability in these patients.

Assessment of circulatory adjustments during underwater apnoea in elite divers by means of a portable device

Considering that sympathetic activation is induced by exercise, it is reasonable to assume that hemodynamic adjustments to exercise act in opposition to those elicited by the diving response. However, cardiovascular measurements have never been performed during underwater dynamic apnoea (DA), and this hypothesis remains speculative. Data concerning heart rate (HR), stroke volume (SV) and cardiac output (CO) during static apnoea (SA) and DA were collected from 12 elite divers by means of an impedance cardiograph adapted to the underwater environment. Mean arterial pressure (MBP), systemic vascular resistance (SVR) and arterial oxygen saturation (SaO(2)) were also assessed. Five trials were performed by the divers: head-out immersion during normal breathing (test A); 3 min of SA immersed at the surface (B) and at 3 m depth (C); DA till exhaustion immersed at the surface (D) and at 3 m depth (E). Both B and C conditions led to bradycardia (-17%) compared to A and also induced a decrement in SV (-8%) and in CO (-25%), while MBP was maintained because of an increase in SVR. A significant MBP increment (+11%) was detected only during tests D and E, when a SaO(2) drop was also present, whereas HR, SV and CO remained unchanged. We concluded that typical diving response was present only during SA, while sympathetic activation was induced by exercise during DA, which partially obscured the effects of the diving response.

A Mathematical Model of Transitional Circulation Toward Biventricular Repair in Hypoplastic Left Heart Syndrome

Although the traditional surgical approach for left hypoplastic heart syndrome is to perform staged, palliative procedures as a single ventricle lesion, certain anatomical subsets of patients are candidates for a 2-ventricle repair either as a primary or as a staged procedure. The pulmonary blood flow (Q(P))/systemic blood flow (Q(S)) range necessary to optimize systemic oxygen delivery (DO(2)) and systemic venous oxygen saturation has been delineated for patients undergoing conventional interventions as a single ventricle physiology where the left ventricle is assumed to make no contribution to systemic cardiac output. However, in the transitional circulations created during staging to a 2-ventricle repair, the left ventricle does contribute to cardiac output. The Q(P)/Q(S) at which systemic DO(2) and systemic venous oxygen saturation are optimized in the latter circulations has not yet been evaluated. Using computer modeling, we investigated parameters to optimize systemic oxygen delivery. We designed model circulations after both modified stage I operation and modified bidirectional Glenn shunt with Sano shunt, which are transitional circulations created during staging to a 2-ventricle repair. Mathematical equations were derived to describe DO(2) in both models. Using a computer and an Excel spreadsheet, we used the equations to examine the relationships between DO(2) and arterial oxygen saturation (Sao(2)), venous oxygen saturation (SvO(2)), SaO(2) - SvO(2), Q(P)/Q(S), and the oxygen excess factor SaO(2)/(SaO(2) - SvO(2)). In both circulations, SaO(2) or SvO(2) alone does not accurately predict DO(2) or Q(P)/Q(S). The relationships between these variables are further altered by the degree of systemic cardiac output supplied by the left ventricle. To the contrary, DO(2) demonstrates the linear relationship with the oxygen excess factor Sao(2)/(Sao(2) - Svo(2)) irrespective of the degree of systemic cardiac output supplied by the left ventricle. Commonly obtained clinical values such as SaO(2) and SvO(2) alone are not accurate assessments of DO(2) or Q(P)/Q(S). Therefore, these cannot be used in isolation to guide perioperative therapy.

Percutaneous closure of atrial right-to-left shunt in patients with Ebstein’s anomaly of the tricuspid valve

Patients with Ebstein's anomaly of the tricuspid valve may have right-to-left shunt at atrial level resulting in hypoxaemia, high haematocrit and hyperviscosity syndrome. The purpose of this study was to assess the results of percutaneous closure of atrial right-to-left shunt in patients with Ebstein's anomaly. Records of patients treated between January 2002 and June 2010 were reviewed. Their condition before and after shunt closure (clinical data, oxygen saturation and haematocrit) were studied. During this period nine selected patients with Ebstein's anomaly and right-to-left shunt at atrial level were treated. Ages ranged from six to 67 years; seven were male. Mean pulmonary artery pressures were under 25 mmHg in all. Three patients had previous episodes of stroke and three had very high haematocrit, two of whom required therapeutic phlebotomies. Test occlusion of the shunt was performed in all patients with a balloon catheter, revealing an increase in systemic oxygen saturation, with right atrial pressures remaining <18 mmHg in all. Percutaneous closure of atrial shunt was achieved in all. There were no major complications. Arterial oxygen saturations increased in all patients from 85.0 ± 4.5% to 96.7 ± 1.5% (mean ± standard deviation). Medium follow-up was five years. The three patients with very high haematocrit levels had a decrease in its values from 62.9 ± 2.8% to 45.5 ± 3.9% after device occlusion. Both therapeutic phlebotomy programs were discontinued. All patients reported a marked improvement in effort tolerance. Percutaneous closure of atrial right-to-left shunt in selected patients with Ebstein's anomaly offers significant improvement, abolishing hypoxaemia and hyperviscosity and preventing paradoxical embolisation.

Long-Term Effect of Bosentan Therapy on Cardiac Function and Symptomatic Benefits in Adult Patients With Eisenmenger Syndrome

BackgroundBosentan improves symptoms in patients with Eisenmenger syndrome (ES). This study evaluated the effect of long-term bosentan therapy on cardiac function and its relation to symptomatic benefits in ES patients. Methods and ResultsTwenty-three consecutive adult ES patients (15 with ventricular septal defect, 6 with atrial septal defect, and 2 with patent ductus arteriosus) underwent standard and tissue Doppler echocardiography before and 24 ± 9 months after bosentan therapy. Echocardiographic measurements included pulmonary arterial systolic pressure (PASP), myocardial performance index (MPI), tricuspid and lateral mitral annular pulsed-wave tissue Doppler systolic (Sa) and early diastolic (Ea) long-axis motions. Patients’ World Health Organization (WHO) functional class, 6-minute walk distance (6MWD), and systemic arterial oxygen saturations (SaO2) were also recorded. The PASP, WHO functional class, 6MWD, and SaO2 all improved (118 ± 22 to 111 ± 19 mm Hg, 3.2 ± 0.4 to 2.4 ± 0.5, 286 ± 129 m to 395 ± 120 m, and 84.6 ± 6.5% to 88.8 ± 3.9%, respectively; all P < .01) after therapy. There was also significant improvement in right ventricular (RV) MPI (by 23.9%: 0.46 ± 0.15 to 0.35 ± 0.09) and biventricular long-axis function (tricuspid Sa and Ea: 6.7 ± 1.5 to 8.8 ± 1.7 cm/s and 5.7 ± 1.3 to 7.0 ± 1.2 cm/s, respectively; lateral Sa and Ea: 6.8 ± 1.3 to 8.4 ± 1.5 cm/s and 7.6 ± 2.0 to 8.5 ± 2.1 cm/s, respectively; all P < .05). Posttherapy RV MPI was moderately correlated with PASP and 6MWD. ConclusionsSustained improvement of pulmonary arterial hypertension and RV function in ES patients was evident 2 years after bosentan therapy, and this may provide insights on the symptomatic benefits gained in these patients.