Oxygen inhalation decreases the central venous pressure in adult patients late after Fontan operations

BACKGROUND

Elevated central venous pressure (CVP) and decreased arterial oxygen saturation (SaO2) are the characteristics of patients after Fontan operations and determine morbidity and mortality in the long-term. Oxygen inhalation therapy theoretically increases SaO2 and may decrease the elevated CVP in these patients. However, there is no previous study to support this hypothesis. This study aimed to determine the acute effects of oxygen inhalation on the hemodynamics of adult patients late after Fontan operations using cardiac catheterization.

METHODS

This study enrolled 58 consecutive adult patients (median age, 30 years; female, n = 24) who had undergone Fontan operations. We assessed the hemodynamic changes during oxygen inhalation (2 L/min) with a nasal cannula in cardiac catheterization. We divided the studied patients into two groups according to the reduction in CVP during oxygen inhalation using the median value: responders (>2 mmHg) and non-responders (≤2 mmHg). Clinical characteristics of the responders to oxygen inhalation were investigated with uni- and multivariate analyses.

RESULTS

SaO2 increased from 93.3 % (91.3-94.5 %) to 97.5 % (95.2-98.4 %) (p < 0.001) and CVP decreased from 12 mmHg (11-14 mmHg) to 10 mmHg (9-12 mmHg) (p < 0.001) after oxygen inhalation. There was a weak but significant correlation between the increase in SaO2 and the decrease in CVP (R = 0.29, p = 0.025). Pulmonary blood flow increased from 4.1 L/min (3.5-5.0 L/min) to 4.4 L/min (3.7-5.3 L/min) (p = 0.007), while systemic blood flow showed no significant changes. A multivariate analysis revealed that high baseline CVP was associated with a larger decrease in CVP (>2 mmHg) after oxygen inhalation.

CONCLUSIONS

Oxygen inhalation increased SaO2 and decreased CVP, especially in patients with high baseline CVP. Further studies with home oxygen therapy are needed to investigate the long-term effects of oxygen inhalation in adult patients who underwent Fontan operations.

Normal Ventricular and Regional Blood Flow Volumes and Native T1 Values in Healthy Japanese Children Obtained from Comprehensive Cardiovascular Magnetic Resonance Imaging

Age-related mean and reference ranges for ventricular volumes and mass, regional blood flow measurements, and T1 values using cardiovascular magnetic resonance (CMR) imaging are yet to be established for the pediatric population. Especially in infants and toddlers, no consistent flow volume sets or T1 values have been reported. The purpose of this study was to determine the relevant normal values.Twenty-three children (aged 0.1-15.3 years) without cardiovascular diseases were included. Comprehensive CMR imaging including cine, 2-dimensional phase-contrast, and native T1 mapping, were performed. Ventricular volumes and masses, 11 sets of regional blood flow volumes, and myocardial and liver T1 values were measured. All intraclass correlation coefficient values were > 0.94, except for the right ventricular mass (0.744), myocardial (0.868) and liver T1 values (0.895), reflecting good to excellent agreement between rates.Regression analysis showed an exponential relationship between body surface area (BSA) and ventricular volumes, mass, and regional blood flow volumes (normal value = a*BSAb). Left ventricular myocardial T1 values were regressed on linear regression with age (normal value = -7.39*age + 1091), and hepatic T1 values were regressed on a quadratic function of age (normal value = 0.923*age2 -18.012*age + 613).Comparison of the 2 different methods for the same physical quantities by Bland-Altman plot showed no difference except that the right ventricular stroke volume was 1.5 mL larger than the main pulmonary trunk flow volume.This study provides the normal values for comprehensive CMR imaging in Japanese children.

The Impact of the Pulmonary Artery Index and Aortopulmonary Collateral Artery Coil Embolization on Intractable Pleural Effusions After a Fontan Surgery

An intractable pleural effusion is a common comorbidity of a Fontan operation, occasionally leading to undesirable outcomes. The preventive effect of aortopulmonary collateral (APC) coil embolization against a pleural effusion before a Fontan operation is still controversial.This is a retrospective single-center study; among 227 Fontan cases, 57 cases with complete MRI data were analyzed at first. Factors associated with the duration of pleural drainage (median: 6 (2-41) days) and that of postoperative hospital stay (median: 25 (14-91) days) were analyzed using a multiple regression analysis. The pulmonary artery index (PAI; Nakata index) was associated with both the pleural drainage duration (P < 0.05, r² = 0.17) and postoperative hospital stay (P < 0.05, r² = 0.10).Thereafter, all the 227 patients were classified into the following three groups: Group A (12 patients in whom the embolization was performed within 30 days before the Fontan surgery), Group B (131 patients in whom the embolization was performed more than 30 days before the Fontan surgery), and Group C (84 patients in whom the embolization was not performed). Patients in Group A were found to be associated with the shortest length of both periods (P < 0.05).Lower PAI values were related to a prolonged pleural drainage duration and postoperative hospital stay. APC coil embolizations may reduce the risk if they are performed shortly (less than 30 days) before the operation.

Systemic-to-Pulmonary Collateral Flow Correlates with Clinical Condition Late After the Fontan Procedure

In the Fontan circulation, there is a substantial degree of systemic-to-pulmonary collateral flow (SPCF), which can be measured by cardiac magnetic resonance (CMR). However, the correlation between the degree of SPCF and long-term outcomes is not fully understood. We retrospectively studied 321 patients who underwent the Fontan procedure and CMR at a single center. Using CMR, we calculated SPCF as pulmonary blood flow - systemic blood flow. %SPCF was defined as SPCF ÷ pulmonary blood flow. The mean age of patients at CMR was 14.3 ± 7.5 years. The average %SPCF was 13.0% ± 11.0%. With a multivariate analysis, %SPCF was significantly correlated with time (i.e., the longer the time period since the Fontan procedure, the lower the %SPCF) (p = 0.006), previous total anomalous pulmonary vein drainage (p = 0.007), a low pulmonary artery index (Nakata index) before the Fontan procedure (p = 0.04), and older age at the time of the Fontan procedure (p = 0.002). Regarding the findings after the Fontan procedure, %SPCF was significantly correlated with ventricular end-diastolic volume (p < 0.001), ventricular end-systolic volume (p < 0.001), central venous pressure (p < 0.001), plasma brain natriuretic peptide concentration (p < 0.001), hemoptysis (p = 0.009), and poor New York Heart Association functional class (p = 0.007). SPCF was correlated with clinical condition after the Fontan procedure. The importance of sufficient growth of the pulmonary vascular bed should be emphasized because the development of SPCF is believed to result from the poor condition of the pulmonary circulation.

Intraoperative Flow Study Predicted the Postoperative Pulmonary Artery Pressure in the Bidirectional Glenn Operation

Background:

The aim of this study was to evaluate the predictability of postoperative pulmonary artery pressure (PAP) using intraoperative flow study in patients undergoing bidirectional Glenn operation.

Methods:

Patients who underwent Glenn operation under cardiopulmonary bypass (CPB) were included in the study. During the operation, after the completion of additional procedures under CPB, an intraoperative flow study was performed prior to Glenn anastomosis. After the completion of bidirectional Glenn, the patient was separated from the CPB and PAP was measured. The relationship between this pressure and flow study measurement was analyzed.

Results:

Nine patients who underwent bidirectional Glenn operation with additional procedures under CPB between July 2018 and January 2019 were included in the study. The median PAP was 9 mm Hg (interquartile range [IQR]: 7-10 mm Hg) in the flow study and 10 mm Hg (IQR: 8-11 mm Hg) after CPB, and the median difference between these pressures was 1 mm Hg (IQR: 1-3 mm Hg). There was a strong correlation between these two measurements ( r = 0.732; P = .025).

Conclusion:

The results of this study show that PAP after the Glenn procedure can be estimated using an intraoperative flow study. We believe that this method may be useful in intraoperative decision-making for Glenn operation in single ventricular patients who require extensive pulmonary artery (PA) reconstruction due to limited PA development, branch PA stenosis, or nonconfluent PAs. Also, this method can be used as a sort of intraoperative pulmonary resistance reversibility study in patients with high preoperative pulmonary vascular resistance due to surgically correctable pulmonary venous hypertension.