In vivo and in vitro metacyclogenesis tests of two strains of Trypanosoma cruzi in the triatomine vectors Triatoma pseudomaculata and Rhodnius neglectus: short/long-term and comparative study.

Metacyclogenesis of Trypanosoma cruzi of the Y and Berenice strains was studied in Triatoma pseudomaculata and Rhodnius neglectus. Results in vivo showed a higher production of metacyclic trypomastigotes in R. neglectus' digestive tube than in T. pseudomaculata. In vitro experiments were also carried out in order to compare the behavior of culture forms of T. cruzi incubated in extracts of different compartments (stomach, intestine, and rectum) of the digestive tract of both species of triatomines. A higher percentage of metacyclic trypomastigotes for both parasite strains, Y and Berenice, was detected in the rectum extract of R. neglectus in comparison to that from T. pseudomaculata. The same results were obtained with in vitro experiments, using parasites incubated in urine from each of those vectors. The adhesion of parasites to the incubated rectum epithelial cells was also compared. In incubations with the Y strain no significant differences were detected between the two triatomine species but, however, with the Berenice strain the mean percentage of cells with adhered parasites was higher in R. neglectus than in T. pseudomaculata.

Reproducibility of asystole during head-up tilt testing in patients with neurally mediated syncope.

Tilt induced prolonged asystole has been considered to identify a distinct subgroup of patients with neurally mediated syncope and management including permanent pacemaker implantation has been suggested. To evaluate the reproducibility of asystolic response during head-up tilt testing (HUT), 33 patients with neurally mediated syncope and asystolic response (> or = 3 seconds) during HUT prospectively underwent two consecutive tests 13 +/- 15 days apart. On repeat tilt testing asystole was reproduced in 12 patients (36%), while 8 patients still had a positive HUT, but without asystole. Remarkably, 13 patients (40%) had a negative repeat HUT. Among 12 patients with asystole on both HUTs there was no significant difference in duration of asystole (14 371 +/- 11 430 ms vs 13 707 +/- 10 470 ms, P = ns) and time to syncope (36 +/- 20 min vs 37 +/- 20 min, P = ns) during initial and repeat HUTs. In conclusion, asystole during tilt testing does not seem to be a reproducible response.

Early cardioversion of atrial fibrillation and atrial flutter guided by transoesophageal echocardiography: a single centre 8.5-year experience.

AIMS: To analyse the safety and impact on maintenance of sinus rhythm of transoesophageal echocardiographically guided early cardioversion associated with short-term anticoagulation in a large series of patients with atrial fibrillation and atrial flutter. METHODS AND RESULTS: Patients who were candidates for cardioversion were eligible for inclusion if they had atrial fibrillation or atrial flutter lasting longer than 2 days or of unknown duration. Patients received short-term anticoagulation with warfarin or heparin and underwent transthoracic echocardiography followed by transoesophageal echocardiography. Early cardioversion was performed if no thrombus was seen on the transoesophageal study. Warfarin was maintained for 1 month after cardioversion. In patients with atrial thrombi, cardioversion was deferred and prolonged anticoagulation was prescribed. The study population included 183 patients. One hundred and sixty nine patients without atrial thrombi underwent early cardioversion. Fourteen patients with atrial thrombi (7.6%) underwent a second transoesophageal echocardiogram after a median of 4 weeks of oral warfarin, and cardioversion was performed if clot regression was documented. No patient in our study population had a clinical thromboembolic event at 1 month follow-up (95% C.I. 0-0.016). The immediate success rate of cardioversion was better among patients with atrial fibrillation < 4 weeks duration compared with patients with atrial fibrillation of longer or of unknown duration: 96.6% vs 85%, respectively (P = 0.014). At 1 month follow-up, the percentage of arrhythmia relapses in patients with initially successful cardioversion was similar in the two groups (29% vs 26%, P = ns); thus the initial better outcome in patients with recent-onset arrhythmia was not lost. CONCLUSION: Transoesophageal echocardiography-guided early cardioversion in concert with short-term anticoagulation is safe. This approach permits abbreviation of the overall duration of atrial fibrillation and has a better impact on the maintenance of sinus rhythm for patients in whom the duration of atrial fibrillation is < 4 weeks.

Atrial thrombosis in cardiac amyloidosis: diagnostic contribution of transesophageal echocardiography.

Few cases of atrial thrombosis detected by transesophageal echocardiography (TEE) in cardiac amyloidosis have been reported recently. We present the cases of 3 consecutive patients affected by AL-type cardiac amyloidosis, symptomatic for heart failure and in sinus rhythm. All patients had a cardiac restrictive pattern at Doppler examination. TEE showed left atrial thrombus in 2 patients and biatrial thrombi in 1 patient; conventional transthoracic echocardiography detected only 1 left atrial thrombus. Our experience confirms the association between cardiac amyloidosis and atrial thrombosis, even in sinus rhythm. TEE should be considered to assess thromboembolic risk in all cases of cardiac amyloidosis with severe diastolic dysfunction.

Atrial thrombi resolution after prolonged anticoagulation in patients with atrial fibrillation.

BACKGROUND: Cardioversion of atrial fibrillation in nonanticoagulated patients may be associated with clinical thromboembolism. Prolonged anticoagulation with warfarin before cardioversion of atrial fibrillation produces a marked reduction of cardioversion-related thromboembolism. The benefit of anticoagulant therapy is generally believed to be due to atrial thrombi organization. PATIENTS AND METHODS: Transesophageal echocardiography (TEE) is highly accurate for diagnosis of atrial thrombi and gives the possibility to serially evaluate the effects of anticoagulant therapy. One hundred twenty-three patients with atrial fibrillation lasting longer than 2 days underwent TEE before cardioversion. An atrial thrombus was identified in 11 patients (9%), and was always confined to the left atrial appendage. TEE was repeated after a median of 4 weeks of oral warfarin. Atrial thrombus had completely resolved in 9 of 11 patients (81.8%; 95% CI, 48.2 to 97.7%); in two patients, clot was still present. No patient had clinical thromboembolism between the two TEE studies. CONCLUSIONS: In the population of our study, a prolonged course of warfarin therapy was associated with resolution of atrial thrombi in the majority of patients. According to these data, the mechanism of thromboembolism reduction with 4 weeks of anticoagulation before cardioversion in patients with atrial fibrillation seems to be related mainly to thrombus lysis rather than organization. Due to the possibility of thrombus persistence even after prolonged anticoagulation, follow-up with TEE before cardioversion is necessary to document thrombus resolution.

Severe left ventricular dynamic outflow tract gradient secondary to localized septal hypertrophy and concomitant acute ischaemic parietal dyssynergy.

Localized basal septal hypertrophy (LSH) is usually an incidental echocardiographic finding and, as opposed to asymmetric hypertrophic cardiomyopathy (AHC), is of no clinical significance. We report a case of a patient with LSH who developed a severe left ventricular outflow gradient during acute myocardial ischaemia, apical akinesis and compensatory hyperkinesis of basal parietal segments.

[Fontan's operation: results, immediate and long-term postoperative complications]. / Intervento di Fontan. Risultati, complicanze postoperatorie e a distanza.

The Fontan operation and its modifications can be relatively safely performed in the treatment of many complex congenital heart diseases, such as univentricular heart and tricuspid atresia. The main postoperative complications following the Fontan procedure and the incremental risk factors involved in their development are investigated. Between January 1984 and January 1988 eleven patients (6 females and 5 males), ranging in age from 2 to 15 years (mean age: 7.3 +/- 3.7) and in weight from 10.8 to 50 Kg (mean weight 22.3 +/- 12.7) underwent the Fontan operation in our Department. No hospital death occurred. The mean postoperative stay in the Intensive Care Unit was 6.3 +/- 3.9 days. There were two surgical re-entries for the same patient: cardiac tamponade (the day of operation) and residual atrial septal defect (2 days following the operation). Eight patients had significant signs of venous stasis, with severe hepatomegaly and pleural effusion. The 11 patients discharged were followed-up for a period of between 3 and 48 months (mean follow-up: 26.4 +/- 18). There were 2 cases of recurrent pleural effusion, 10 to 15 days after discharge. One late death occurred 2 years after the Fontan procedure (massive pulmonary embolism after re-operation). Short and medium-term rate of complications is related to increased post-operative values of mean right atrial pressure (greater than 15 mmHg). Mean right atrial pressures greater than 15 mmHg appear to be correlated with Nakata index values less than 250 mm2/m2. The experience reviewed confirms the excellent results of the Fontan operation, as regards survival and functional recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of captopril on cold pressor test responses in normotensive and hypertensive subjects.

The aim of this study was to evaluate the effects of short-term captopril administration on the response to cold pressor testing in normotensive and hypertensive subjects. Cold pressor testing was performed in 15 normotensive subjects and 15 hypertensive patients before and 90 minutes after captopril administration. Blood pressure and heart rate were measured before testing and at one-minute intervals from the beginning of cold pressor testing. Systolic time intervals were also assessed before and after testing. Captopril did not affect pressor responses to cold pressor testing in normotensive subjects or hypertensive patients. Basal heart rate (before testing) did not change, despite the decrease in blood pressure and showed a smaller increase in response to cold pressor testing in normotensive subjects, suggesting that captopril might interfere with arterial baroreflexes. The systolic time intervals were not modified by captopril except isometric contraction time; its basal value was reduced by captopril in both normotensive subjects and hypertensive patients. Cold exposure caused a similar increase in isometric contraction time before and after captopril in normotensive subjects, and the increase in isometric contraction time in hypertensive patients was greater. These findings suggest that captopril did not affect cardiac performance, indeed improving it, at least in basal conditions.