Biomedical subjects

W A Helbing

Publications and source records attributed to W A Helbing.

27 records · Page 2Linked to original sources

PubMed1995

Comparison of echocardiographic methods with magnetic resonance imaging for assessment of right ventricular function in children.

Assessment of right ventricular (RV) function is clinically relevant in the follow-up of various forms of congenital heart disease. Agreement on the value of different echocardiographic approaches for this purpose is lacking. Magnetic resonance imaging (MRI) provides dimensionally accurate RV volumes and ejection fraction. Transthoracic 2-dimensional echocardiography from 3 different views and gradient-echo tomographic MRI were performed in 16 children with congenital heart disease and 17 age-matched healthy children. RV volumes and ejection fraction were calculated with 5 mono- and biplane area-length and multiple-slice echocardiographic methods. Adequate MRI and echocardiographic apical 4-chamber images could be obtained in all 33 children. The best correlation between MRI and echocardiographic volumes was with the biplane pyramidal approximation method. End-diastolic volume by MRI was 92 +/- 27 ml: systematic difference with echocardiography was +14 +/- 16 ml (r = 0.86). End-systolic volume by MRI was 33 +/- 13 ml: systematic difference with echocardiography was -4 +/- 7 ml (r = 0.82). Ejection fraction by MRI was 65 +/- 8%: systematic difference with echocardiography was +5 +/- 7% (r = 0.72), using monoplane ellipsoid approximation. For all echocardiographic methods, significant effects of RV geometry were noted. Echocardiographic mono- and biplane area-length and multiple-slice calculations demonstrated moderate correlation and significant systematic errors compared with MRI-derived RV volumes. Echocardiographic results were influenced by RV geometry. The relatively simple monoplane area-length method provides ejection fraction results acceptable for clinical practice; results are not improved by more complex biplane and/or multislice methods.

Adolescent↗

PubMed1995

Quantification of right ventricular function with magnetic resonance imaging in children with normal hearts and with congenital heart disease.

In clinical treatment of children with congenital heart disease (CHD) assessment of right ventricular (RV) function is important. Available imaging techniques have been of limited value because of technical factors and the complex geometry of the right ventricle. To validate magnetic resonance (MR) imaging measurements of RV function in children, gradient echo MR imaging of both ventricles and MR flow mapping of great vessel and tricuspid flow was performed in 20 children with CHD affecting the right ventricle and in 22 healthy children ranging in age from 5 to 16 years. Close correlation between RV versus LV stroke volumes (r = 0.96) and RV stroke volume versus great artery (r = 0.97) or tricuspid flow (r = 0.97) was observed with small interobserver and intraobserver variability. Results of healthy children were end-diastolic volume: 70 +/- 9 ml/m2, end-systolic volume: 21 +/- 5 ml/m2, and ejection fraction: 70% +/- 4%. In the patient groups clinically important differences were noted. We conclude that MR imaging provides accurate noninvasive measurements of RV function in healthy children and patients with (operated) CHD.

Adolescent↗

PubMed1995

Automated contour detection and acoustic quantification.

Echocardiographic left and right ventricular sequences are usually interpreted visually, but current quantitation techniques have been found to be tedious, time-consuming and associated with significant inter- and intra-observer variabilities. In an attempt to eliminate these problems, we have developed the Echocardiographic Analysis System (EAS) which uses robust automated border detection techniques both for single frames as well as for sequences. Comparison of LV cross-sectional area with the semi-automated border detection (AUTO) and those assessed from manual tracings (MAN) yielded a systematic difference (MAN-AUTO) of -6.6% (p < 0.001), and a random difference (standard deviation of paired signed differences) of 11.8%. Current developments are directed towards real-time automated border detection with an Accelerator board, integration of Acoustic Quantification (AQ) data as edge information into EAS, and intravascular echocardiographic applications.

Computers↗

PubMed1995

MR velocity mapping of tricuspid flow in healthy children and in patients who have undergone Mustard or Senning repair.

PURPOSE: To determine the feasibility and accuracy of measuring tricuspid volume flow with magnetic resonance (MR) velocity mapping in healthy children and in patients after a Mustard or Senning repair. MATERIALS AND METHODS: MR studies were performed in 14 healthy children (mean age, 12 years +/- 3) and in 12 patients (mean age, 17 years +/- 5) late after a Mustard or Senning repair. MR measurements of tricuspid volume flow were validated against right ventricular stroke volumes measured tomographically. Diastolic filling parameters were derived from the flow measurements. RESULTS: Tricuspid volume flow and right ventricular stroke volume showed close agreement in the healthy children (r = .98) and in the patients (r = .94). Children after Senning repair, compared with healthy children, showed a delayed and higher peak tricuspid flow rate during early filling and a lower peak flow rate during atrial contraction (P < .05). CONCLUSION: MR measurement of tricuspid flow is feasible and accurate in healthy children and in patients after a Mustard or Senning operation, who often demonstrate abnormal tricuspid flow patterns.

Adolescent↗

PubMed1994

[Nitric oxide to combat pulmonary hypertension in an infant following heart surgery for septum defect].

A 5-month-old female infant with Down syndrome underwent surgical repair of a complete atrioventricular septal defect and a patent ductus arteriosus. The postoperative course was complicated by life-threatening pulmonary hypertensive crises which did not respond to conventional vasodilating therapy. Nitric oxide inhalation resulted in rapid decrease in pulmonary artery pressure and improvement of haemodynamics and oxygenation without causing any untoward side effects. Inhalation of NO was continued over the next 4 days, with a maximum NO concentration of 20 ppm during a period of 12 hours. The subsequent postoperative course was uneventful and the patient was discharged from the hospital in good health on the 23rd postoperative day.

Down Syndrome↗

PubMed1994

Long-term results of atrial correction for transposition of the great arteries. Comparison of Mustard and Senning operations.

Few data exists on the differences in long-term outcome between Mustard and Senning operations. We reviewed available data of all hospital survivors of these operations and assessed risk factors for late death and sinus node dysfunction. Of those patients undergoing the Mustard operation, 60 were hospital survivors (46 simple transposition, 14 complex); of those patients undergoing the Senning operation, 62 were hospital survivors (43 simple, 19 complex). Median duration of follow-up was 16 years (maximum 25 years) for Mustard operation, 11 years (maximum 20 years) for Senning operation. No reoperations were done, except for pacemaker implantation. No differences were found between the two groups with regard to baffle-associated problems, right ventricular failure, sudden death (6% in both groups), and functional status at final follow-up (New York Heart Association class I or II, except for four patients). For patients undergoing the Mustard operation, survival at 16-year follow-up was 91% with simple transposition and 60% with complex transposition (p = 0.027); for both groups of patients undergoing the Senning operation, survival at 16-year follow-up was 78%. Survival in the absence of rhythm disturbance at 16-year follow-up was 18% for Mustard operation and 53% for Senning operation (p < 0.001). In multivariate analysis, significant independent risk factors for late death turned out to be complex transposition (versus simple) and active arrhythmias. The only significant risk factor for the occurrence of sinus node dysfunction was the Mustard operation. We conclude that apart from the difference in the loss of sinus rhythm, no differences were found in the long-term clinical results of the two types of operations.

Arrhythmias, Cardiac↗

PubMed1991

[Attacks of apnea in an infant with achondroplasia].

Infants and children with achondroplasia are at increased risk of sudden death because of apneic attacks caused by compression of the medulla oblongata or spinal cord by a constricted foramen magnum or narrow upper cervical spinal canal. This history of an infant with achondroplasia is discussed. As a result of apneic attacks she developed severe brain damage. Cervicomedullary compression was revealed at CT-scan and NMRI of the basicranium and upper cervical canal, and confirmed at decompressive surgery. Early symptoms can be clues to the existence of cervicomedullary compression. These clues are indication for further investigations. Decompressive surgery has good results when performed at an early stage. Knowledge of the signs and symptoms of cervicomedullary compression and of factors which increase the risk of complications are important in the management of achondroplastic patients.

Achondroplasia↗

PubMedDate not supplied

On-line automated border detection for echocardiographic quantification of right ventricular size and function in children.

Rapid, accurate assessment of right ventricular (RV) size is important for the management of children with congenital heart disease. The usefulness of the Acoustic Quantification system of automated border detection (ABD) and on-line quantification (AQ) for assessment of RV size was tested in 36 children. AQ data were compared to "corrected AQ" measurements (after correction for cavity areas erroneously included in the region of interest) required for AQ. Furthermore, the influence of necessary changes to gain settings was tested in "lateral gain control" (LGC) images obtained by removal of ABD overlays. All results were compared to conventional echocardiography (echo), and agreement with magnetic resonance imaging (MRI) RV areas was assessed. Systematic differences (+/-) limits of agreement with MRI (transverse plane) for conventional echo and AQ (apical four-chamber view) were as follows: end-diastolic -0.8 +/- 3.8 (conventional echo) versus -1.7 +/- 4.6 (AQ) cm2/m2 (p < 0.001); end-systolic -1.3 +/- 3.2 versus -4.9 +/- 5.8 (AQ) cm2/m2 (p < 0.001); fractional area change 7.8 +/- 17.0% versus 26.9 +/- 31.4% (AQ) (p < 0.001). Differences between conventional echo, LGC, and corrected AQ areas were not statistically significant. The best agreement between MRI and echocardiography was with conventional echo. We conclude that automated border detection of the RV can be performed successfully with the AQ system at a fixed point in the cardiac cycle. For adequate assessment of RV function manual corrections of online AQ results are still required, which results in an important reduction of the time gain of on-line quantification.

Child↗

PubMedDate not supplied

Clinical applications of cardiac magnetic resonance imaging after repair of tetralogy of Fallot.

In the past 15 years, cardiovascular magnetic resonance (MR) has evolved into an imaging technique that provides adequate, and in part unique, information on residual problems in the follow-up of patients operated for tetralogy of Fallot. Spin-echo or gradient-echo cine magnetic resonance imaging allow detailed assessment of intracardiac and large vessel anatomy, which is particularly helpful in Fallot patients with residual abnormalities of right ventricular outflow and/or pulmonary artery. Multisection gradient-echo cine MRI can be used to obtain accurate measurements of biventricular size, ejection fraction, and wall mass. This allows serial follow-up of biventricular function. MR velocity mapping is the only imaging technique available that provides practical quantification of pulmonary regurgitation volume. MR velocity mapping can also be used to quantify right ventricular diastolic function in the presence of pulmonary regurgitation.

Coronary Circulation↗