Gunnar Norgård

Effects of respiration on right ventricular size and function: An echocardiographic study

SummaryThe effects of quiet respiration and body position on right ventricular (RV) size and function were assessed by two-dimensional (2DE) and M-mode echocardiography in 15 healthy children. All end-diastolic echocardiographic dimensions, areas, and volumes increased slightly but significantly with inspiration. At end-systole similar changes were found. RV ejection fractions were significantly higher during inspiration, as were stroke volume indices. RV dimensions also increased from supine to left lateral decubitus position. Thus, our results indicate a need for standardization of 2DE and M-mode measurements not only for body position, but also for respiratory phase when used to assess RV size and function.

Right ventricular size and function as assessed by echocardiography and angiography in patients with different volume load

A comparative study of right ventricular (RV) function, assessed by echocardiography and angiography, undertaken in 20 patients, 10 of whom had atrial septal defects (ASDs) and 10 had various other heart diseases. All of the measured echocardiographic variables of RV size, apart from RV length, were larger in the patients with ASD. When assessed by multiple regression analysis, the RV M-mode dimension was an independent variable of RV angiographic end-diastolic volume (EDV) in patients without RV volume load (R=0.92,R2=0.85,p<0.001). In the patients with ASD, echocardiographic RV end-diastolic area was an independent variable of angiographic RVEDV (R=0.75,R2=0.55,p<0.05), whereas M-mode dimension had a weaker correlation (r=0.29). The agreement between RV ejection fraction (RVEF) obtained by echocardiography and angiography was moderate in both patient groups. However, fractional area change and fractional length change could not estimate RVEF better. Thus care should be taken to use single measurements and derivatives as the only parameters of RV size and function.

Pulmonary Valve Replacement With a Bovine Pericardial Valve A Five Year Follow-Up Study

Objectives: From a population of 90 patients after pulmonary valve replacement with a biological valve (Carpentier-Edwards Perimount valve), 56 of 80 available patients were examined five years after surgery. Background: Pulmonary valve replacement is needed in many patients with congenital heart disease. Homografts have limited availability and predictable degeneration, and mechanical valves require anticoagulation. No superiority of one kind of pulmonary valve replacement has been shown. Biological valves that are readily available are being used and evaluated in increasing numbers. Methods: In this cross-sectional study, five years following surgery, data were gathered from hospital charts, echocardiography, stress echocardiography, magnetic resonance imaging, and exercise testing. Results: In 90 patients, there were three new valve replacements, one early cardiac death, and four late noncardiac deaths. Echocardiographic assessment of the study group showed pulmonary Doppler velocities (m/s) before, after operation, and at five-year follow-up of 2.8 ± 1.1, 1.6 ± 0.4, and 2.3 ± 0.7, respectively. The assessed insufficiencies (0-3) at the same times were 2.3 ± 1.0, 0.3 ± 0.4, and 1.1 ± 0.8. Maximal oxygen uptake increased from 65.6% ± 10.1% to 77.1% ± 18.2% of predicted and QRS width increased by 7 ± 23ms. Valve degeneration could be associated with young age but not with diagnosis or valve size. Conclusion: In our study, the biological valve in the pulmonary position showed excellent mid-term results with few reoperations, low gradients, and mild to moderate insufficiency. Oversizing, in contrast to young age, was not a risk factor for valve degeneration. In younger patients, this allows later percutaneous replacement, reducing the need for further surgery. However, longer follow-up is needed.

Hemodynamic Status in Repaired Tetralogy of Fallot Assessed by Doppler Echocardiography and Cardiac Catheterization: Comparisons with Healthy Subjects and Elucidation of Factors Associated with Cardiorespiratory Function

Thirty-four patients were studied after corrective surgery for tetralogy of Fallot (mean follow-up 10 years) and compared with healthy matched controls. All underwent Doppler echocardiography, spirometry and treadmill exercise test. Post-operative cardiac catheterization had been performed on 26 (76%) of the patients and showed poor hemodynamic results in four (15%). Significant correlations of pressure gradients obtained from catheterization and estimated by Doppler echocardiography were right ventricular to right atrial (r = 0.77), pulmonary outflow (r = 0.75), pure valvular pulmonary outflow (r = 0.94) and diastolic pulmonary pressure gradients (r = 0.53). Pulmonary outflow gradients and right ventricular to right atrial pressure gradients estimated from tricuspid regurgitation jets were significantly increased in the patients. Diastolic pulmonary artery pressure, vital capacity and ventilatory anaerobic threshold were independent factors of maximal oxygen consumption. It is suggested that Doppler-derived diastolic pulmonary artery pressure, lung function studies and exercise testing with assessment of the ventilatory anaerobic threshold should be included in follow-up after repair of Fallots tetralogy.

Eight years of pulmonary valve replacement with a suggestion of a promising alternative

Abstract In a retrospective study we assessed surgical results following right ventricular to pulmonary artery connection repair or replacement at a medium of 2.4 years (0–8) follow-up. Data were retrieved from hospital charts. Results. Three hundred and sixty five operations were performed in 286 patients in eight years starting in 2000 using different surgical methods. Homografts and Monocusps had a more than 50% significantly lower risk for reoperation than Contegra or bicuspid valves (p < 0.01). Data for infants and older children and grown ups were analysed separately. In the infant group no significant difference between the different methods (homograft, Contegra and Monocusp) was detected. In older patients, the Perimount valves performed extremely well with no need for reoperation after 2.5 years of follow-up. Perimount valves and homografts performed better than other solutions (p = 0.01). Conclusion. Although the follow-up for the Perimount valves was short, they are promising and need to be followed long-term. The homograft and the Monocusp remain valuable choices.

Interstitial Fluid Colloid Osmotic Pressure in Healthy Children

Objective The colloid osmotic pressure (COP) of plasma and interstitial fluid play important roles in transvascular fluid exchange. COP values for monitoring fluid balance in healthy and sick children have not been established. This study set out to determine reference values of COP in healthy children. Materials and Methods COP in plasma and interstitial fluid harvested from nylon wicks was measured in 99 healthy children from 2 to 10 years of age. Nylon wicks were implanted subcutaneously in arm and leg while patients were sedated and intubated during a minor surgical procedure. COP was analyzed in a colloid osmometer designed for small fluid samples. Results The mean plasma COP in all children was 25.6 ± 3.3 mmHg. Arbitrary division of children in four different age groups, showed no significant difference in plasma or interstitial fluid COP values for patients less than 8 years, whereas patients of 8-10 years had significant higher COP both in plasma and interstitial fluid. There were no gender difference or correlation between COP in interstitial fluid sampled from arm and leg and no significant effect on interstitial COP of gravity. Prolonged implantation time did not affect interstitial COP. Conclusion Plasma and interstitial COP in healthy children are comparable to adults and COP seems to increase with age in children. Knowledge of the interaction between colloid osmotic forces can be helpful in diseases associated with fluid imbalance and may be crucial in deciding different fluid treatment options. Trial Registration ClinicalTrials.gov NCT01044641

Fluid accumulation after closure of atrial septal defects: the role of colloid osmotic pressure

OBJECTIVES Following paediatric cardiac surgery with cardiopulmonary bypass (CPB), there is a tendency for fluid accumulation. The colloid osmotic pressure of plasma (COPp) and interstitial fluid (COPi) are determinants of transcapillary fluid exchange but only COPp has been measured in sick children. The aim of this study was to assess the net colloid osmotic pressure gradient in children undergoing atrial septal defect closure. METHODS Twenty-three patients had interventional and 18 had surgical atrial septal defect closures. Interstitial fluid was harvested using a wick method before and after surgery with CPB with concomitant blood samples. COP was measured using a colloid osmometer for small fluid samples. Baseline COP was compared with data from healthy children. RESULTS COPp at baseline was 21.9 ± 2.8 and 21.4 ± 2.2 mmHg in the interventional and surgical groups, respectively, and was significantly lower than in healthy children (25.5 ± 3.1 mmHg) (P < 0.001). In the surgical group, the use of CPB significantly reduced COPp to 16.9 ± 2.9 mmHg (P < 0.001) and the colloid osmotic gradient [ΔCOP (COPp - COPi)] to 2.9 ± 3.8 mmHg (P < 0.001) compared with interventional procedure. One hour after the procedure, COPi was 15.6 ± 3.8 mmHg and 9.9 ± 2.1 mmHg (P < 0.001) and the ΔCOP was 5.4 ± 3.0 mmHg and 9.1 ± 3.1 mmHg (P < 0.003) in the interventional and surgical groups, respectively. CONCLUSIONS Baseline COPp and COPi were lower in atrial septal defect patients compared with healthy children. The significantly lower COP gradient during CPB may explain the tendency for more fluid accumulation with pericardial effusion in the surgical group. The increased COP gradient after CPB may represent an oedema-preventive mechanism.

Magnetic Resonance Imaging of Patients with Increased Blood Pressure and Altered Blood Pressure Response to Exercise After Coarctation Repair

Objective—Patients successfully operated for calactation of the aorta are frequently subjected to altered blood pressure (BP) at rest and BP response during exercise. The relationship between these variables and blood flow, peak velocity, restenosis and other morphological features of the thoracic aorta as revealed by magnetic resonance imaging (MRI) was evaluated. Design—Fifty-one patients subjected to coarctectomy of the aorta were examined by MRI. In addition, a control group of 23 healthy volunteers was evaluated. Morphology of the aorta was demonstrated with both ECG-triggered SE imaging and gadolinium-enhanced MR aortography. Flow-weighted MRI was applied for quantitative flow and velocity measurements. Results—Structural alteration of the aorta was more commonly seen in those patients having increased BP at rest or altered BP response during exercise than those with a normal BP profile. The luminal diameter of the narrowest site of the aorta was decreased in all patient groups. Accordingly, the peak velocity at the corresponding site was significantly (p < 0.01) increased. However, blood flow was significantly (p < 0.01) decreased among those patients with normal BP profile compared with the other patient groups as well as the controls. Conclusion—Other structural changes than restenosis may contribute as well to the altered BP profile of patients subjected to coarctectomy. Reduced blood flow appears to correlate with normal BP profile, whereas the peak velocity measurements that are obtained by MRI are not able to differentiate between the patient groups. The comprehensive and reliable data obtained by non-invasive techniques, i.e. MRI and Doppler, may rep lace catheterization when deciding the need for intervention.

Fluid accumulation in the staged Fontan procedure: the impact of colloid osmotic pressures

OBJECTIVES Despite Fontan surgery showing improved results, fluid accumulation and oedema formation with pleural effusion are major challenges. Transcapillary fluid balance is dependent on hydrostatic and colloid osmotic pressure (COP) gradients; however, the COP values are not known for Fontan patients. The aim of this study was to evaluate the COP of plasma (COPp) and interstitial fluid (COPi) in children undergoing bidirectional cavopulmonary connection and total cavopulmonary connection. METHODS This study was designed as a prospective, observational study. Thirty-nine children (age 3 months-4.9 years) undergoing either bidirectional cavopulmonary connection or total cavopulmonary connection procedures were included. Blood samples and interstitial fluid were obtained prior to, during and after the preoperative cardiac catheterization and surgery with the use of cardiopulmonary bypass (CPB). Interstitial fluid was harvested using the wick method when the patient was under general anaesthesia. Plasma and interstitial fluid were measured by a colloid osmometer. Baseline values were compared with data from healthy controls. RESULTS Baseline COPp was 20.6 ± 2.8 and 22.0 ± 3.2 mmHg and COPi was 11.3 ± 2.6 and 12.5 ± 3.5 mmHg in the bidirectional cavopulmonary connection group and the total cavopulmonary connection group, respectively. These values were significantly lower than in healthy controls. The COPp was slightly reduced throughout both procedures and normalized after surgery. The COPi increased slightly during the use of CPB and significantly decreased after surgery, resulting in an increased COP gradient and was correlated to pleural effusion. CONCLUSIONS Fluid accumulation seen after Fontan surgery is associated with changes in COPs, determinants for fluid filtration and lymphatic flow. CLINICALTRIALS.GOV IDENTIFIER NCT 02306057: https://clinicaltrials.gov/ct2/results?cond=&term=NCT+02306057.

Blood Flow Imaging in Transesophageal Echocardiography during Atrial Septal Defect Closure: A Comparison with the Current References

Flow visualization before transcatheter atrial septal defect (ASD) closure is essential to identify the number and size of ASDs and to map the pulmonary veins (PV). Previous reports have shown improved visualization of ASD and PV using blood flow imaging (BFI), which supplements color Doppler imaging (CDI) with angle‐independent information of flow direction. In this study, we compared transesophageal BFI with the current references in ASD sizing (balloon stretched diameter, BSD) and PV imaging (pulmonary angiography).