Transesophageal echocardiography for the diagnosis and management of nonobstructive thrombosis of mechanical mitral valve prosthesis.

BACKGROUND: Diagnosis of a mechanical mitral valve prosthesis thrombosis is currently made with transthoracic Doppler echocardiography and occasionally with fluoroscopy. However, identifying a thrombus on a valve prosthesis may be difficult, especially if the thrombus is nonobstructive. To prospectively define the role of transesophageal echocardiography for identification of nonobstructive thrombi, we studied a series of patients in whom the prosthetic valve was considered to function normally on clinical examination and transthoracic echocardiography. METHODS AND RESULTS: One hundred fourteen consecutive patients with mechanical mitral valve prosthesis were investigated by both transthoracic echocardiography and transesophageal echocardiography. These examinations were performed for recent systemic emboli (15 patients), fever of unknown etiology (11 patients), routine postoperative evaluation (56 patients), and other reasons (32 patients). Based on transthoracic echo diagnosis, all prostheses were considered normal. Yet, in 20 patients transesophageal echocardiography revealed the presence of a 2- to 15-mm-long mobile thrombus localized on the atrial surface of the prosthesis. When compared with the remaining 94 patients with no visible thrombi, there was no significant difference between the two groups in terms of incidence of atrial fibrillation (65% versus 52%), left atrial size (48 +/- 9 versus 51 +/- 13 mm), left ventricular end-diastolic diameter (49 +/- 10 versus 51 +/- 13 mm) and fractional shortening (28 +/- 9% versus 31 +/- 10%), presence of spontaneous contrast to the left atrium (40% versus 41%), transprosthetic mean pressure gradient (4.0 +/- 1.4 versus 3.9 +/- 1.5 mm Hg), or the type of prosthesis used. After we discovered a nonobstructive thrombosis, patients were treated with heparin (n = 9) or oral anticoagulation (n = 11). The presence of a localized thrombus was confirmed in 3 patients who were operated on. In the present study, evolution appeared to depend on thrombus size: of 14 patients exhibiting a small (< 5 mm) thrombus, 10 had an uneventful course, whereas 5 of 6 patients with a large (> or = 5 mm) thrombus developed complications or died. CONCLUSIONS: Transesophageal echocardiography appears to be a reliable method to diagnose thrombi on a mechanical mitral valve prosthesis, even when transthoracic Doppler echocardiographic parameters appear to be normal. Transesophageal echo assessment of thrombus size may be helpful in deciding whether a patient with mitral prosthesis should be treated by anticoagulation, thrombolysis, or valve rereplacement.

[Failure and complications of transesophageal echocardiography. Apropos of 1500 consecutive cases]. / Echecs et complications de l'échocardiographie transoesophagienne. A propos de 1,500 examens consécutifs.

Transesophageal echocardiography (TEE) requires the introduction of a flexible probe into the oesophagus and therefore cannot be strictly considered to be non-invasive. This manipulation exposes the patient to complications which are benign in the large majority of cases. The authors report their experience in a prospective study analysing the failures and complications of TEE in the first 1,500 cases performed in their laboratory between May 1988 and May 1992, in mainly adult and ambulatory patients. The probe could not be introduced in 24 patients (1.6%), including 5 cases during the initial learning period. No serious complications were observed during of after TEE. Minor incidents were noted in 28 cases (1.9%) intolerance of the probe (12 cases), nausea and/or vomiting (4 cases), dyspnea (4 cases) due to tracheal intubation in 2 patients, laryngeal in 1 patient and to cardiac failure in 1 case. Pharyngeal haemorrhage (2 cases), atrial fibrillation (3 cases), vertigo (1 case), mandibular dislocation (1 case) and salivary hypersecretion affecting the quality of the imaging (1 case), were also observed. The investigation had to be interrupted prematurely in 12 cases (0.8%) usually because of intolerance of the probe. These results show that TEE is not dangerous in trained hands. Failure to introduce the probe is usually encountered during the learning period, which reinforces the need for apprenticeship in a teaching center. The safety of this technique, plus its considerable diagnostic value in many clinical indications, justify its present role in everyday cardiological practice.

[Comparison of VVI and DDD cardiac stimulation during exercise test evaluated by respiratory gas exchange measurement. Study of patients with normal systolic function and complete atrioventricular block unchanged during exercise test]. / Comparaison des modes de stimulation cardiaque VVI et DDD sur la performance à l'effort évaluée par la mesure des échanges gazeux respiratoires. Etude de patients à fonction systolique normale, affectés de bloc auriculoventriculaire complet ne s'accélérant pas à l'effort.

The aim of this study was to compare respiratory gas exchanges during exercise during VVI and DDD modes of cardiac pacing, the latter offering the possibility of preserving the atrio-ventricular sequence and of increasing the heart rate during exercise. Ten patients with normal systolic function (6 men, 4 women; average age 51 years), complete atrioventricular block and no acceleration of the heart rate during exercise, undergoing implantation of a dual-chamber pacemaker, performed maximal exercise stress testing after programming VVI or DDD modes successively with a one hour interval between the two investigations. The parameters recorded at peak exercise capacity were compared according to the pacing mode. Exercise duration (8 +/- 2 mn), maximal heart rate (133 +/- 10 bpm), systolic blood pressure (175 +/- 24 mmHg), work load (104 +/- 20 watts) were significantly higher in the DDD than in the VVI mode (6 +/- 2 mn, 73 +/- 8 bpm, 147 +/- 22 mmHg, 84 +/- 17 watts respectively, p < 0.001 for each parameter). Above all, peak oxygen uptake in the DDD mode was 23.2 +/- 6 ml/kg/mn compared to 19.2 +/- 5.1 ml/kg/mn in the VVI mode (p < 0.001). The increased heart rate obtained with DDD pacing seems to be the main factor which explains the differences observed. At lower exercise levels, there was no significant difference in ventilatory threshold between VVI and DDD pacing. The absence of underlying cardiac disease and a single, fixed atrioventricular delay may reduce the value of maintaining the atrioventricular sequence at more moderate exercise levels. This study shows that dual-chamber pacing increases maximal exercise capacity. These observations may be useful when considering the choice of a cardiac pacemaker.

[Dissecting aneurysms of the aorta: from causes to therapeutic indications]. / Anévrysmes disséquants de l'aorte: de l'étiologie aux indications thérapeutiques.

In its acute phase, aortic dissection (a term that is now preferred to dissecting aneurysm of the aorta) is a medico-surgical emergency. The diagnosis is suspected on clinical data: intensive thoracic pain with recently appeared diastolic murmur and abolition of a peripheral pulse, contrasting with an electrocardiogram that is either normal or not suggestive of acute coronary thrombosis. It is confirmed by imaging methods, notably echocardiography and/or angiography. These methods, rapidly performed in all circumstances, provide the surgeon with useful information on the size and extent of the dissection and on its complications. Surgery still is the only effective treatment of dissections involving the ascending aorta. In dissections of the descending aorta it may or may not be envisaged, depending on the results of medical treatment. In chronic aortic dissections, which may have a long course, surgery is not mandatory, byt it is necessary in case of mediastinal compression or severe aortic insufficiency.

[Echocardiography by the transesophageal route. Technique and the main clinical indications]. / L'échocardiographie par voie transoesophagienne. Technique et principales indications cliniques.

Transoesophageal Doppler-echocardiography is a new heart imaging technique avoiding many of the problems which sometimes limit standard transthoracic exploration. The transducer, mounted on a fibroscope sheath, is introduced into the oesophagus and therefore lies in the immediate vicinity of the atrial complex, the mitral valve, the aortic valve and the different segments of the thoracic aorta. The examination can be carried out on ambulatory patients in the echocardiography laboratory. The main clinical indications of this technique are: studies of prosthetic valves (notably the mitral valve); detection of vegetations or annular abscesses in infective endocarditis; determination of an emboligenic focus after arterial embolism; study of the causative mechanism in mitral valve regurgitation; pathology of the thoracic aorta and, in particular, of aortic dissection. The usual lack of difficulty in skilled hands, the quality of the images obtained and the diagnostic value of information collected by this route explain why this relatively new technique has very rapidly progressed from evaluation to routine use in most echocardiography laboratories.

Comparison of oxygen uptake during bicycle exercise in patients with chronic heart failure and in normal subjects.

Prediction of oxygen uptake (VO2) during exercise from relations established in normal subjects between VO2 and work load in watts (W) may be inaccurate in patients with chronic heart failure because these patients could manifest delayed VO2 kinetics at final stages of exercise. To test the hypothesis that even at low levels of work, patients exhibit a lower VO2 than do normal subjects, 77 patients with heart failure and 27 control subjects with a normal heart or with disease other than heart failure underwent bicycle exercise with respiratory gas analysis. Work load was increased by 10 W/min from an initial 20 W. VO2 (ml/min per kg) was measured every 15 s. The delta VO2/delta W ratio was significantly reduced only in the most severely impaired patients in heart failure class C-D (8.75 +/- 2.14 versus 11.05 +/- 0.38, p less than 0.05). Class B patients showed a lower ratio at a work load of greater than or equal to 80 W, whereas class C-D patients manifested a lower ratio at greater than or equal to 20 W. Even with a low incremental work rate protocol, compared with sedentary normal subjects or patients without heart failure, patients with heart failure demonstrate impaired oxygen uptake. This observation suggests the presence of anaerobic metabolism or delayed VO2 uptake, or both; accordingly, indirect estimates of VO2 requirements derived from intensity or duration of exercise in such patients are overestimated.

[Doppler echocardiography in myocardial infarction and its complications]. / L'exploration échographique Doppler de l'infarctus du myocarde cicatrisé et de ses complications.

Echocardiography has established an important role in the surveillance of patients with myocardial infarction. Segmental wall motion abnormalities are easily identified and their extension reflects the size of the infarct. Global left ventricular function may be assessed and left ventricular dilatation documented. This information is useful in evaluating the long-term prognosis. In addition, Doppler echocardiography is valuable for detecting complications persisting or occurring after the acute phase such as pericardial effusion, mural thrombus, aneurysm or mitral regurgitation. The indications of Doppler echocardiography should be guided by the symptomatology and the results of clinical examination.