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Biomedical subjects

L Boisante

Publications and source records attributed to L Boisante.

11 recordsLinked to original sources
PubMed1982

Mechanism of paradoxic pulse in bronchial asthma.

To elucidate the mechanism of paradoxic pulse in severe bronchial asthma, we performed hemodynamic studies and measured esophageal pressure in nine patients who had status asthmaticus and clinical paradoxic pulse. Two-dimensional echocardiography allowed simultaneous assessment of cyclic changes in right- and left-heart size throughout the respiratory cycle. Esophageal pressure varied from a markedly negative level during inspiration (-24.4 +/- 6.5 cm H2O) to a positive level during expiration (7.6 +/- 6.0 cm H2O). Competition between right- and left-heart chambers for pericardial space during inspiration was suggested by the reduced left ventricular cross-sectional area at end-systole (-24%, p less than 0.01) and end-diastole (-32%, p less than 0.01), the leftward septal shift, and the increased right ventricular internal diameter at end-systole (42%, p less than 0.01) and end-diastole (40%, p less than 0.001). Competition for filling, however, could not entirely account for the paradoxic pulse, for systemic and pulmonary pulse pressures were almost (within one cardiac cycle) in phase: both were minimal at inspiration and maximal at expiration. The increase in impedance to right ventricular ejection is another major factor reducing left ventricular preload at inspiration. This reduction in preload was shown to be the predominant mechanism for the decrease in left ventricular stroke output at inspiration.

Adult↗
PubMed1982

[Update on the study of true and false left ventricular aneurysms by 2-dimensional echocardiography].

2D echocardiography is a great advance in the study of left ventricular aneurysms. The wide field of visualisation and the numerous planes of examination obtained from different transducer positions allow precise spatial orientation and reliable analysis of regional wall movement. An aneurysm appears as a clear and constant bulge of a segment of left ventricular wall in both diastole and systole. Antero apical aneurysms are the commonest variety. The sensitivity and specificity of 2D echo in the detection of ventricular aneurysms are high. Thrombosis within the aneurysmal bulge may also be detected (33-38%). Pseudo-left ventricular aneurysms are easily identified as a chamber communicating with the ventricle by means of a narrow neck; the width of this neck is the main echocardiographic feature differentiating pseudo and true ventricular aneurysms. 2D echocardiography gives valuable information on the state of the remaining contractile area, an important prognostic factor when surgical resection of the aneurysm is being considered.

Diagnosis, Differential↗
PubMed1981

Influence of positive end-expiratory pressure on left ventricular performance.

Although left ventricular dysfunction is common during ventilatory support with positive end-expiratory pressure (PEEP), the mechanism of this disorder remains unclear. In 10 patients with the adult respiratory-distress syndrome we studied the effects of a stepwise increase in PEEP from 0.to 30 cm H2O on left ventricular output, intracardiac transmural pressures, and two-dimensional echocardiographic measurements of left ventricular cross-sectional area at end-systole and at end-diastole. Increasing PEEP was associated with progressive declines in cardiac output, mean blood pressure, and left ventricular dimensions and with equalization of right and left ventricular filling pressures. The radius of septal curvature decreased at both end-diastole and end-systole, implying a leftward shift of the interventricular septum. At the highest PEEP, blood-volume expansion did not restore cardiac output, although left ventricular transmural filling pressures had returned to base-line values. We conclude that decreased cardiac output during PEEP is mediated by a leftward displacement of the interventricular septum, which restricts left ventricular filling.

Blood Pressure↗
PubMed1981

[Value of continuous electrocardiographic recording using the Holter method in the diagnosis and surveillance of myocardial ischemia].

A series of 80 patients underwent continuous electrocardiography by Holter monitoring (ECG-H) for 24 hours to detect myocardial ischaemia. Fifty five patients were not on anti anginal therapy. The results of ECG-H were compared with those of exercise electrocardiography (ECG-E) (33 cases) and coronary angiography (50 cases). The ECG-H was positive in 31 of 43 patients (72%) with clinical (5 patients) or angiographic (38 patients) signs of ischaemic heart disease. The ECG-H was negative in 11 out of 12 patients (92%) with normal coronary; angiography. The sensitivity and specificity of ECG-H (57% and 92%) were inferior to those of ECG-E (75% and 100%) in the 33 untreated patients undergoing all three investigations. Twenty five recordings were compared with the ECG-E to assess anti anginal therapy. In asymptomatic patients ECG-H showed pathological ST depression in 10 cases, the ECG-E being positive in 1 7 cases. Anginal chest pain was induced on ECG-E in 5 out of 7 cases with a positive ECG-E and negative ECG-H. The lower sensitivity of the ECG-H compared to the ECG-E is related to several factors: 1) the sensitivity of the ECG-E increases with the number of exploratory electrodes; 2) reduced levels of physical activity decrease the sensitivity; in false negative cases the heart rate on ECG-H was only 74 +/- 7% of that corresponding to the threshold of positivity of the ECG-E, compared to 97 +/- 16% of the threshold heart rate in true positives (p less than 0,001); 3) the sensitivity of the ECG-H and ECG-E depends on the severity and distribution of the coronary lesions; false negative results were commoner in single vessel disease (57%) than in double or triple vessel disease (24%) (p less than 0,01). Anginal pain during the test increased the sensitivity to 92%. The specificity of the ECG-H is partially dependent on the recognition of positional variations of the ST segment. These were observed in 10% of cases but were generally easy to distinguish by their beat-to-beat appearances. The satisfactory specificity of the ECG-H in this study is also related to the high incidence of coronary artery disease in the population under study (80%). The predictive value of a positive test (Bayes theorem) was 97%, but that of a negative test was only 41%.

Adult↗
PubMed1980

Two dimensional echocardiographic visualization of ventricular septal rupture after acute anterior myocardial infarction.

In three consecutive cases of ventricular septal rupture after acute anterior myocardial infarction, wide angle two dimensional echocardiography readily visualized the septal defect, permitting the defect to be localized and its size estimated. In addition, negative contrast echoventriculography identified a left to right shunt at the ventricular level. The echocardiographic findings were corroborated by cardiac catheterization data in all patients, by perioperative examination in two and by postmortem findings in one patient. Postoperative echocardiographic studies afforded demonstration of the patch closing the defect. In patients with acute myocardial infarction associated with the sudden appearance of a systolic murmur, two dimensional echocardiography should be performed promptly in order to guide the diagnosis and management of these critically ill patients. In some patients with severe cardiogenic shock, in whom a favorable prognosis depends on rapid treatment, two dimensional echocardiography may allow the patient to be taken to surgery immediately without further study.

Aged↗