Biomedical subjects
Publications and source records attributed to H Geschwind.
Angiography was used to diagnose atrial septal aneurysm in a 46-yr-old man suffering from recurrent pulmonary emboli, who had normal venograms of his lower extremities. This case demonstrates the usefulness of searching for sources of emboli other than deep venous thrombosis, but illustrates the limits of two-dimensional echocardiography in diagnosing atrial septal aneurysm.
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Nd-NAG laser carried by optical fibres 0.2 mm diameter was used in experimental studies to recanalize obstructed human cadaver arteries. Successful perforation of atheromatous plaques was obtained in all cases with a power of 12 W and a duration of exposure of 30-50 s provided that blood and not saline was used. The arterial wall was protected from injury by coaxial position of the optical fibre that was inserted into an inflated balloon catheter, and by circulating blood that cooled the system. The feasibility of guiding these devices in man was demonstrated in femoral and coronary arteries.
The energetic costs of post-extrasystolic potentiation (PEP) were assessed by evaluating left ventricular function and coronary blood flow in 16 patients with different forms of cardiac disease during cardiac catheterisation under basal conditions and sustained coupled right ventricular pacing. The coronary blood flow was measured by thermodilution techniques with sampling in the aorta and coronary sinus to measure O2 concentration, glucose, and plasma lactate and catecholamine levels. Parameters of LV function were calculated from data obtained from biplane left cineventriculography. During PEP, the ejection fraction increased from 0.48 +/- 0.8 to 0.62 +/- 0.22, the mean velocity of circumferential fibre shortening from 0.79 +/- 0.37 to 1.12 +/- 0.45 circ/s (p less than 0.001) and systolic work from 97 +/- 46 to 139 +/- 67 g/m2 (p less than 0.05). Coronary blood flow increased from 176 +/- 60 to 305 +/- 155 ml/min; myocardial oxygen consumption per potentialized beat rose from 0.15 +/- 0.07 to 0.50 +/- 0.33 ml/beat (p less than 0.001) whilst cardiac efficiency fell from 19.1 +/- 8 to 9.2 +/- 4% (p less than 0.001). PEP was associated with increased myocardial noradrenaline secretion (-3.1 +/- 31.5 ng/min under basal conditions to 30.2 +/- 42.8 ng/min, p less than 0.05). Therefore, the inotropic effect of PEP imposes a high metabolic demand and is associated with increased myocardial noradrenaline secretion.
Effects of laser radiation on atherosclerotic plaques were evaluated in vitro and in vivo. Necropsy artherosclerotic femoral and coronary arteries were submitted to a laser beam. Arteries were perfused by saline or blood solution and a silicone fibro-optic system was placed near the plaques through a balloon dilatation catheter. After laser radiation (20 to 40 W, 2 to 10 seconds) angiograms and histologic sections were obtained. Aorta of 20 atherosclerotic New Zealand rabbits was exposed in dry condition to a CO2 laser beam (2-4 W, 0,2 second). After reinstatement of blood flow, animals were sacrificed from 24 hours to 3 weeks for microscopical examination. In vitro studies showed a significant recanalisation of the thrombosed arteries under blood flow but not under saline solution. Histologically the laser radiation produced a crater surrounded by thermal intimal damage and decollated calcified plaques. In vivo studies showed the healing process: no perforation, no aneurysm, no thrombosis occurred. After 24 hours the crater was filled with a non extensive thrombus, on the first week the thrombus contained phagocyte cells and on the third week, the endothelial damage was completely healed. These results suggest that laser radiation may be effective to recanalize totally occluded arteries in human.
The sensitivity of basal hemodynamic data and the value of those observed during exercise in the diagnosis of severe mitral stenosis (MS) were investigated by comparing the results under basal conditions and during dynamic exercise with the operative findings in 55 patients with pure MS, aged between 18 and 73 years (average, 43 years), 29 with mild stenosis (Group I) and 26 with severe stenosis (Group II). Under basal conditions, mean pulmonary capillary pressure (PCP) was significantly higher in Group II than in Group I (15.7 +/- 4.4 mm Hg compared to 12.2 +/- 3.5 mm Hg, p less than 0.01). The same difference was observed in mean pulmonary arterial pressure: Group I, 18.2 +/- 5.4 mm Hg; Group II: 23.0 +/- 6.1 mm Hg, p less than 0.01; but cardiac and systolic indices were comparable in the two groups. On exercise, only PCP (Group I: 29.6 +/- 6.8; Group II: 34.7 +/- 4.9 mm Hg) and systolic index (Group I: 39.9 +/- 10.0; Group II: 33.4 +/- 8.2 ml/m2) were significantly different (p less than 0.01). Pulmonary capillary and arterial pressures rose in the same proportion in the two groups on exercise but systolic index fell in severe MS (-4 p. 100) and rose in mild MS (+30 p. 100) (p less than 0.001). The formulae for calculating mitral valve surface area only give discriminating results between the two groups when the hemodynamic data on exercise are used.(ABSTRACT TRUNCATED AT 250 WORDS)
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The surgical indications in aortic regurgitation (AR) depend on the functional performances of the left ventricle (LV) and its reactions to the chronic volume overload. The relation between patient symptomatology and the hemodynamic data in isolated chronic AR were studied by correlating parameters obtained at catheterisation and biplane left cineventriculography under basal conditions and post-extrasystolic potentialisation (PEP) with the NYHA functional classification of 51 patients with AR. Fifteen patients were in Class I, 26 in Class II, 10 in Class III and none in Class IV. The mean regurgitant fraction (0,55 +/- 0,15), cardiac index (3,1 +/- 0,7 1/min/m2) and left ventricular end diastolic pressure (LVEDP) (14 +/- 7 mmHg) were comparable in the 3 classes of patients. Three significant differences were observed between Class I and Class III: --The LV ejection fraction was significantly lower (I = 0,53 +/- 0,13; II = 0,50 +/- 0,39; III = 0,42 +/- 0,17, p less than 0,04). --The LV end systolic volume was significantly higher (I = 88 +/- 48; II = 90 +/- 31; III = 138 +/- 68 ml/m2, p less than 0,02). --The myocardial mass was significantly greater (I = 168 +/- 57; II = 204 +/- 94; III = 291 +/- 128 g/m2, p less than 0,003). Under basal conditions, this was the only parameter distinguishing asymptomatic from symptomatic AR. The increase in LV ejection fraction during PEP was similar in all 3 groups, as was the increase in LVEDP (+36 p. 100). The LV systolic pressure of the potentialised complex was the only parameter which distinguished Class I and Class III patients.
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To determine the relationship between functional classes (NYHA) and hemodynamics in patients (pts) with chronic aortic insufficiency, indices of left ventricular (LV) function derived from hemodynamic and biplane left cineventriculographic data were compared with the clinical status in 51 AI pts, including 15 pts in class I, 26 pts in class II and 10 pts in class III. Regurgitant fraction (0.55 +/- 0.15 mean +/- SD), cardiac index (3.1 +/- 0.7 l/mn/m2) and LV end-diastolic pressure (14 +/- 7 mmHg) were of the same order of magnitude in 3 classes patients. A significant correlation was evidenced between functional classes and 1/LV ejection fraction (0.53 +/- 0.13, 0.50 +/- 0.39, 0.42 +/- 0.17 in class I, II, III pts, respectively, p less than 0.04), 2/LV end-systolic volume (88 +/- 48, 90 +/- 31, 138 +/- 68 ml/m2 in class I, II and III pts, respectively p less than 0.02), 3/ and LV mass (168 +/- 57, 204 +/- 94, 291 +/- 128 g/m2 in class I, II and III pts respectively, p less than 0.003). Only the latter parameter could discriminate symptomatic from asymptomatic AI pts.
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19 cases of endomyocardial fibrosis were studied. Angiocardiography localises the site of fibrosis and seems to be the best diagnostic method. All cases in this series had left ventricular involvement which resulted in changes of the silhouette (square, polylobulated or deformed like the shape of a heart on a playing card) and of the ventricular contour (smooth, lacunar or "doubled"). Ten patients had mitral incompetence. The ejection fraction was normal in 8 patients but significantly reduced in the series as a whole (EF = 0,56, p less than 0,05). 15 patients had right ventricular involvement. Apart from the smooth contour of the anterior wall, the only abnormality in the mild cases, the most suggestive feature was an amputation of the ventricular apex, giving rise to a ventricular appearance of a narrow, akinetic (apart from the infundibular region) tube. The catheter data demonstrated the haemodynamic changes due to the fibrosis. A constrictive syndrome was observed in all the severe poorly tolerated cases. This was not apparent under basal conditions in milder cases. The value of pharmacodynamic testing and endomyocardial biopsy in cases where the diagnosis is uncertain should be stressed. The results of resection of the fibrosis and valvular replacement in severe cases depend to a large extent on the degree of myocardial involvement.
To assess accurately left ventricular function (LVF) in patients with aortic regurgitation (AR pts), isometric exercise (IE) was used in association with postextrasystolic potentiation (PESP) during diagnostic heart catheterization including left cineventriculography in 16 pts with pure moderate or severe AR. The results were compared with those observed in 8 control pts (C pts). IE resulted in a significant increase in heart rate by 15 p. cent and in an increase in mean aortic pressure by 29 p. cent (p < 0.001). During IE, LV end diastolic pressure (EDP) remained unchanged in C pts and in 6 AR pts whereas this value was increased by 49 p. cent (p < 0.01) in 7 AR pts without a significant change in LV end diastolic volume. Ejection fraction (EF) was decreased in each AR pt (mean 14 p. cent; p < 0.001) and remained unchanged in C pts. A negative correlation was evidenced between the decrease in EF and the increase in LVEDP (r = 0.76). PESP resulted in a increase in EF in both C pts and AR pts (+ 25 and + 29 p. cent respectively; p < 0.001). PESP under IE resulted in a lower increase in EF than PESP under basal conditions (+ 19 and + 24 p. cent respectively) mainly due to the increase in after load provided by IE. Dynamic investigation of the LVF in AR pts is a physiological method of investigation easy to perform which may assess both LV contractile reserve and cardiac reserve. Such a method of investigation may help to select AR pts for surgery.
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