Poor sensitivity of routine fetal anomaly ultrasound screening for antenatal detection of atrioventricular septal defect

OBJECTIVE

To report the antenatal detection rate in a consecutive series of liveborn infants with atrioventricular septal defect (AVSD).

DESIGN

Review and analysis of referrals for detailed fetal echocardiography and postnatal diagnosis of AVSD.

SETTING

Tertiary referral centre for congenital heart disease centre with data prospectively collected between 1996 to 2001.

RESULTS

92 consecutively liveborn infants with AVSDs were identified of which 27 (29%) were detected by routine obstetric antenatal ultrasound. The antenatal diagnosis rate was worse for liveborn infants with trisomy 21 (12 of 49 (25%) v 15 of 43 (35%) chromosomally normal children) and for infants with AVSD without other structural heart disease (18 of 74 (24%) v 9 of 18 (50%) infants with associated structural heart disease).

CONCLUSION

Despite the potential ability of fetal ultrasound to detect AVSDs, the antenatal diagnosis rate is poor. This is particularly true for infants with trisomy 21 and is of importance when counselling parents with an apparently normal fetal ultrasound scan.

Dystrophic calcification of the fetal myocardium

Intramural cardiac masses were detected antenatally in three fetuses by echocardiography. The masses were initially thought to be rhabdomyomas. All three pregnancies were terminated and histology showed dystrophic calcification in all, with no evidence of tumour. Therefore, dystrophic calcification of the fetal myocardium may have a similar appearance to single or multiple rhabdomyomas. This should be considered when counselling parents after detection of masses in the fetal heart, particularly when considering the risk of associated tuberous sclerosis.

Multiple cardiac rhabdomyomas: tuberous sclerosis or not?

Images

Temporal differences in praziquantel- and oxamniquine-induced tegumental damage to adult Schistosoma mansoni: implications for drug-antibody synergy

A temporal study of the effects on the tegument of Schistosoma mansoni adult worm following in vivo praziquantel and oxamniquine treatment was performed. Drug-induced damage to the tegument, exposure of surface antigens and attachment of host antibody occurred rapidly, within 1 h, following praziquantel treatment. Oxamniquine-treated worms required 4-8 days for these effects to be apparent. The 2 drugs differed in the degree and sites of damage on the worm surface. The administration of 2 different polyspecific rabbit sera with drug significantly increased the efficacy of praziquantel when administered with the drug, but not when given 6-9 days after drug treatment. In contrast, only 1 serum was synergistic with oxamniquine when administered with drug and both sera were synergistic when given 6-9 days after drug treatment. The effect of immune killing of drug-treated worms is discussed.

Transoesophageal echocardiography in neonates, infants and children: applicability and diagnostic value in everyday practice of a cardiothoracic unit

OBJECTIVE

To determine the applicability of and information obtained by transoesophageal echocardiography in neonates, infants, and children in every day practice of a cardiothoracic unit.

DESIGN

Four month prospective study.

SETTING

Supraregional centre for paediatric cardiothoracic services.

PATIENTS AND METHODS

58 patients aged between four days and 16 years with a wide range of cardiovascular disease underwent transoesophageal echocardiography under sedation or general anaesthetic. One of two paediatric probes (6 or 7 mm diameter), or an adult probe (13 mm in diameter) was used. Whenever possible the investigation was immediately preceded by precordial echocardiography.

MAIN OUTCOME MEASURES

Success, failure, technical difficulties, and complications of probe introduction and, when possible, comparison of the information obtained with that obtained from precordial echocardiography.

RESULTS

Introduction of the probe was successful in 57 of the 58 patients. The only complication encountered was transient bradycardia during manipulation of the probe in a 2.2 kg baby. The adult (13 mm) probe was successfully used in children as small as 7.0 kg. Below this weight a smaller paediatric probe was required. In 56% of cases transoesophageal ultrasound provided information not obtained from the precordial approach. The technique was of particular value perioperatively and in the immediate postoperative period in neonates and infants and in the presence of valve prostheses and the investigation of mediastinal tumours in older children.

CONCLUSIONS

Transoesophageal echocardiography is a valuable additional investigative tool for children of all ages. It is of particular value when acquisition of precordial image is impaired around the time of and after operation and in children with prosthetic valves or mediastinal tumour. Image quality was superior with the adult probe and we recommend the use of this probe unless the patient's weight is below 7 kg, when a paediatric probe allows this technique to be used usefully and safely in babies as small as 2.2 kg.

Continuous wave Doppler echocardiography after surgical repair of coarctation of the aorta

OBJECTIVE

To find how closely pressure gradients across the aortic arch derived from Doppler echocardiography reflect gradients measured by catheter after surgical repair of coarctation of the aorta.

DESIGN

Pressure drop across the aortic arch was measured simultaneously by continuous wave Doppler and double lumen catheter in 20 patients with repaired coarctation of the aorta.

RESULTS

The peak pressure drop estimated by Doppler was almost invariably higher than the peak to peak gradient measured by catheter, as might be expected. Wide variation was seen between the Doppler measured pressure drop and instantaneous peak gradient measured by catheter, ranging from +22 to -17 mm Hg. The reasons for these differences are unclear but are probably related to a combination of complex flow dynamics in the aortic arch, difficulty in closely aligning the Doppler beam with flow, and inability to measure flow velocity immediately proximal to the site of the surgical repair with continuous wave Doppler.

CONCLUSIONS

Continuous wave Doppler echocardiography may significantly overestimate or underestimate the pressure drop after repair of coarctation and it should be interpreted with caution in individual patients. Catheterisation with angiography remains the reference standard for assessment of surgical repair of the aortic arch.

Left atrial clot in patients with mitral prostheses: increased rate of detection after recent systemic embolism

We studied 70 patients with mitral valvar replacements by both transthoracic and transoesophageal echocardiography. Fifteen subjects had recently suffered a suspected embolic episode. The remainder (55) were studied for other clinical reasons. Transthoracic echocardiography demonstrated thrombus in only 1 of the 70 patients. By contrast, transoesophageal examination revealed thrombus in 8 out of 15 patients with recent suspected embolism and 3 out of 55 without. Thrombus was most commonly seen in patients with biological valvar prostheses whose anticoagulation had been discontinued. When patients with prosthetic mitral valves present with a suspected embolic episode, transoesophageal echocardiography is strongly recommended. This study also suggests that transoesophageal echocardiography may be useful for evaluating patients with biological valves if anticoagulation is withdrawn so as to identify formation of thrombus at the earliest possible stage.

Failure of Doppler ultrasound to detect coarctation of the aorta

Normal velocities of flow in the aortic arch were recorded in a patient presenting with clinical signs of aortic coarctation. Angiography demonstrated complete coarctation with extensive collateral supply to the descending aorta: there was a systolic pressure difference of 40 mm Hg between the ascending and descending segments of the aorta. Despite reports of the value of Doppler ultrasound in the diagnosis of coarctation, the finding of normal velocities of flow within the aortic arch does not necessarily exclude the presence of an obstructive lesion.

The value of transesophageal echocardiography in the investigation of acute prosthetic valve dysfunction

When patients present with suspected prosthetic valve dysfunction, investigation is usually instituted to delineate the site and cause thereof. Precordial cross-sectional echocardiography is often helpful in this respect, but in the patient with acute pulmonary edema, imaging may be impaired because of discomfort and respiratory distress. The information obtained may also be suboptimal as a result of concomitant obesity, chest wall deformity, and pulmonary disease. In addition, further difficulties may relate to the acoustic shadowing produced by the metallic portion of the valve and its sewing ring, especially with valves in the mitral position. In such patients, cardiac catheterization may cause further decompensation and is associated with a recognized increase in morbidity and mortality. Angiography does not accurately site regurgitant jets in relation to the prosthetic valve concerned and will not detect the presence of vegetations. Transesophageal echocardiography circumvents many of these imaging difficulties and we evaluated its use in five patients with prosthetic heart valves who presented acutely ill, in severe pulmonary edema and suspected prosthetic heart valve failure. In each case, the diagnosis of valve dysfunction was established, and precise information regarding the site and cause of the failure was obtained. No complications or deterioration in patient condition resulted from the procedure and the findings were confirmed at surgery performed within 24 hours in all five patients. Transesophageal echocardiography should be included in the assessment of acute prosthetic heart valve failure.

Reproducibility and persistence of abnormal transmitral flow velocity patterns detected by pulsed Doppler ultrasound

This prospective study examines the reproducibility and persistence of abnormal transmitral flow detected using pulsed Doppler ultrasound on 2 separate occasions between 2 days and 6 weeks apart. The 22 patients included were accepted consecutively from those having an abnormal diastolic flow pattern at initial examination. Abnormal flow velocity patterns were defined as those exhibiting reversal of the ratio of the passive filling velocity (E) and active atrial transport velocity (A). There was no significant difference between the separately recorded values for the ratio of the peak E and A velocities or of the ratio of the planimetered areas beneath each of the velocity waves, with positive correlations for both sets of values (r = 0.68, r = 0.67). Significant positive correlation also existed between the mean rates of acceleration to each of the E and A velocity peaks of the transmitral waveform recorded on separate occasions (r = 0.68, r = 0.95). Interobserver variation for the analysis of hard-copy pulsed Doppler recordings between two trained observers was less than 5% and intraobserver error for recording analysis was less than 2% for both observers. Abnormal transmitral flow velocity patterns persist unchanged in the absence of therapeutic intervention and the acceptably small observer error in the recording and analysis of such flow patterns allows consistent and clinically reliable data to be obtained.

Doppler ultrasound of normally functioning mechanical mitral and aortic valve prostheses

Doppler ultrasound flow velocities across clinically normally functioning mitral (Bjork-Shiley, Medtronic Hall, Lillehei-Kaster, Duromedic and Starr-Edwards) and aortic (Bjork-Shiley, Medtronic Hall, Lillehei-Kaster and Duromedic) valve prostheses are described. To enable ease of reference for the echocardiographer and to avoid the need for time-consuming calculations of pressure drops and effective valve orifice areas, peak flow velocities and, where relevant, pressure half times across valves of different types and sizes are tabulated. In the mitral position, there was significant negative correlation between peak velocity and valve size and between pressure half time and valve size only when a large number and a wide range of sizes of a given type of mitral prosthesis was studied. Similarly, there was significant negative correlation between peak velocity and aortic valve size for Bjork-Shiley and Duromedic valves. Regurgitant jets were detected across 18.4% of mitral and 42% of aortic prostheses.

Doppler echocardiographic characteristics of the Carpentier-Edwards xenograft

In order to define ranges of normal velocities for the Carpentier-Edwards xenograft, 38 mitral, 24 aortic and 9 tricuspid prostheses were studied with pulsed or continuous wave Doppler at a mean interval of 38 months following surgery. All patients had clinically normal prosthetic valve function and no clinical or radiographic signs of heart failure. Mean peak velocity across aortic prostheses was 244 cm s-1 (SD 48). There was weak correlation (r = 0.54, P less than 0.01) between peak velocity and time since valve implantation, but no significant difference in peak velocity across valves of different size. In the mitral position, mean peak velocity was 164 cm s-1 (SD 24) and mean pressure half time 90 ms (SD 23). There was again no significant difference between valves of different size. There was a weak correlation between pressure half time and time since implantation (r = 0.44, P less than 0.01), but there was no relationship between the latter and peak velocity. In the tricuspid position, mean peak velocity was 150 cm s-1 (SD 12) and mean pressure half time 163 ms (SD 50). The Doppler indices of obstruction to blood flow for prostheses in the mitral and aortic positions showed a significant increase with time after implantation.

Mechanism of late failure of the Alvarez disc valve prosthesis

An Alvarez disc valve prosthesis had been implanted in the mitral and tricuspid positions in 15 patients between 1964 and 1967 in this hospital. Of these 15 patients, only three survived longer than 10 years, all three dying unexpectedly between 16 and 18 years postoperatively. Two deaths were a direct result of disruption of the Alvarez prosthesis. The third patient was not examined at necropsy, but in retrospect the history was highly suggestive of valve malfunction. Cross sectional and pulsed Doppler echocardiography made valuable contributions to the diagnosis in both cases of valve disruption and, when available, should be part of the primary investigation of suspected prosthetic heart valve failure. The Alvarez valve prosthesis is liable to erosive wear which may cause late detachment of the disc from the valve ring with abrupt and catastrophic haemodynamic consequences.