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Biomedical subjects

G B Mancini

Publications and source records attributed to G B Mancini.

At least 91 records · Page 5Linked to original sources
PubMed1990

Determination of coronary flow reserve by parametric imaging.

Nine mongrel dogs were instrumented with electromagnetic flow probes (EMF) to measure coronary blood flow through the left anterior descending (LAD) and left circumflex (LCx) coronary arteries at rest and after maximal coronary vasodilation (1 mg/kg/min adenosine). Relative coronary blood flow was determined by parametric imaging in the left posterior oblique projection using digital subtraction angiography (DSA). Transmural myocardial perfusion of the LAD and LCx beds was determined with tracer-labeled microspheres. Coronary flow reserve (maximal coronary blood flow divided by resting blood flow) was calculated under control conditions and after constriction of the proximal LAD or LCx by a screw occluder. Heart rate decreased significantly from 140 beats/min at rest to 122 beats/min after adenosine (p less than 0.001) and from 134 (rest) to 120 beats/min (adenosine; p less than 0.05) after coronary constriction. Peak systolic pressure was kept constant with an aortic constrictor. Left ventricular end-diastolic pressure increased significantly from 18 mm Hg at rest to 23 mm Hg (p less than 0.05) after coronary constriction. At baseline, coronary flow reserve was 4.2 with DSA, 3.8 with EMF, and 3.7 with microspheres; after coronary constriction, it was 2.6 (DSA), 1.9 (EMF), and 1.5 (microspheres) (all p less than 0.001 versus baseline). Coronary blood flow showed a good correlation between EMF and microspheres (r = 0.87, p less than 0.001), with a standard error of estimate (SEE) of 0.78 ml/g/min. Coronary flow reserve also showed a good correlation between EMF and microspheres (r = 0.82, p less than 0.001), with an SEE of 0.93. There was a moderate correlation between EMF and DSA (r = 0.68, p less than 0.001), with an SEE of 1.35 (40% of mean coronary flow reserve). The correlation coefficient between microspheres and DSA was 0.54 (p less than 0.01), with an SEE of 1.46 (39% of mean coronary flow reserve). The mean difference (accuracy) and standard deviation of difference (precision) were 0.2 +/- 1.0 between EMF and microspheres, -0.1 +/- 1.4 between EMF and DSA, and -0.6 +/- 1.7 between microspheres and DSA. We conclude that determination of coronary flow reserve by parametric imaging is associated with large variations that are greater than variations also inherent in the two reference techniques. Parametric imaging allows relatively accurate assessment of coronary flow reserve (small mean difference), but precision is low (large standard deviation of mean differences).(ABSTRACT TRUNCATED AT 400 WORDS)

Angiography, Digital Subtraction↗
PubMed1990

[Humeral fractures with paralysis of the radial nerve].

Forty fractures of the humerus associated with radial nerve palsy were reviewed after an average follow-up of 11 years. Early exploration of the radial nerve and internal fixation of the fracture was performed in 20 patients, while the other 20 patients were treated by closed reduction and immobilization in a plaster cast. In four patients of the latter group the radial nerve did not recover and a delayed exploration was performed. In each treatment group functional recovery of the radial nerve was observed in 16 patients (80%). On the basis of these results the authors suggest treating fractures of the humerus with radial nerve palsy by closed reduction. If there is no evidence of spontaneous recovery within 3-4 months, an exploration of the radial nerve should be performed.

Adolescent↗
PubMed1990

[The results of a resection intervention in isolated fractures of the radial head].

The results of radial head excision were studied in 33 patients with isolated fracture of the radial head. The follow-up period ranged from 1 to 19 years (mean 9.5 years). Overall results were excellent or good in 25 patients (76%) and fair or poor in 8 patients (24%) with functional limitation of the elbow. Range of motion was greatly limited in those patients who had a myositis ossificans or a radio-ulnar synostosis. Periarticular ossifications were observed in 17 elbows (54%) and subluxation of the inferior radio-ulnar joint in 20 wrists (60%). Excision of the radial head is the treatment of choice for comminuted isolated fractures of the radial head, even if in some patients limited elbow function should be expected.

Adolescent↗
PubMed1989

Radionuclide left ventricular contractile indices and their relationship to heart size in dogs.

To identify possible mechanisms to explain differences between the maximum time-varying elastance (Emax) and end-systolic pressure-volume (Ees) slope values calculated with radionuclide angiography and to establish whether they have a relationship to heart size, we studied 16 dogs that were instrumented with micromanometer left ventricular catheters and had red blood cells tagged with technetium-99m for radionuclide angiography. Hemodynamics and radionuclide angiograms were obtained under control conditions and during six additional steady-state loading conditions. Isochronal Emax averaged 7.14 +/- 2.54 mm Hg/ml, while Ees averaged 5.68 +/- 1.88 mm Hg/ml (p less than 0.01), but they were highly correlated (r = 0.95, p less than 0.001). This observation was related to the assumption of linearity when curvilinearity was present and to the important influence of timing on these relationships. The Emax and Ees slope values were compared to dog weight; left ventricular weight, which ranged from 85 to 142 gm (mean 113 +/- 18 gm); and left ventricular end-diastolic volume, which ranged from 15 to 56 ml (mean 29 +/- 10 ml) using multiple regression analyses. The Emax and Ees slope values demonstrated a comparable inverse linear relationship with only left ventricular end-diastolic volume (r = 0.76 and -0.69, p less than 0.001 and p less than 0.01). We conclude that the differences between Emax and Ees slope values calculated with radionuclide angiography are related to the assumption of linearity when curvilinearity is present and to the importance of the timing of systolic events and that both Emax and Ees are comparably related to left ventricular end-diastolic volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Induction of ventricular arrhythmia by high and low osmolarity ionic and nonionic contrast media.

Studies that used prolonged contrast media infusion in canine arteries have generated controversy regarding the arrhythmogenic potential of low osmolarity, nonionic contrast agents. In order to establish the relative safety of these agents in the more typical setting of bolus injections, 4 ml intracoronary bolus injections of Hypaque-76 (n = 54), Iohexol-350 (n = 51), and Iohexol-140 (n = 51) were given in random order to 10 anesthetized, open-chest dogs undergoing programmed cardiac stimulation. Hemodynamics and electrocardiogram were monitored during stimulation, both during and for 2 minutes after the end of contrast infusion. Occurrence of evoked single and coupled premature ventricular contractions and nonsustained ventricular tachycardia did not differ statistically among agents. Sustained ventricular tachycardia (five episodes) and ventricular fibrillation (seven episodes) occurred only after Hypaque-76 injections (p less than 0.002). These results differ from those in studies that use continuous contrast infusion and suggest that low osmolarity nonionic contrast agents are as safe as high osmolarity nonionic contrast media. Both appear safer than ionic contrast material.

Animals↗
PubMed1989

The diastolic hyperemic flow versus pressure relation. A new index of coronary stenosis severity and flow reserve.

The measurement of coronary flow reserve, traditionally calculated as the ratio of maximal hyperemic blood flow divided by basal flow, is difficult to interpret in serial studies because fluctuating hemodynamic parameters may affect either basal or hyperemic flow measurements. To determine the magnitude of this problem and to develop alternative approaches for measuring vascular reserve, 10 anesthetized dogs were instrumented with aortic and inferior vena cava occluders, electromagnetic coronary flow probes, and high-fidelity micromanometers in the left ventricle and aortic root. Coronary flow was measured in the basal state and during maximal hyperemia induced by a steady-state adenosine infusion. Observations were made in the absence of a stenosis and in the presence of two incremental degrees of subcritical stenosis produced by a rigid, external screw occluder. Several parameters of vascular reserve were determined: 1) coronary flow reserve (defined above), 2) mean hyperemic flow divided by mean aortic pressure, 3) mean hyperemic flow divided by the difference between mean aortic pressure and left ventricular end-diastolic pressure, and 4) the slope of the instantaneous relation between diastolic hyperemic flow versus pressure. Each parameter was measured during five steady-state pressure levels achieved by partial occlusion of either the inferior vena cava or the aorta and the levels ranged from 82 +/- 8 mm Hg (mean +/- SD) to 127 +/- 9 mm Hg during hyperemia. All measures of vascular reserve were found to be dependent on hemodynamic parameters such as heart rate and mean aortic pressure. The slope of the instantaneous relation between diastolic hyperemic flow and pressure, however, showed only minimal dependence on heart rate and, in contrast to coronary flow reserve measurements, distinguished between the normal and the two stenotic states. Further, this optimal performance of the hyperemic flow versus pressure slope index was shown in a model in which coronary flow and myocardial work were not independently controlled. This index provides a sensitive and reliable indication of subcritical stenosis severity that may have clinical applications.

Animals↗
PubMed1989

Resection of the radial capitellum. Long-term results.

The results of 39 resections of the radial capitellum reviewed after an average of 12 years were excellent or good in 59% of the cases and fair or poor in 41%. The results were better in isolated fractures of the capitellum (excellent or good, 71%) compared with those with associated lesions in the same limb (excellent or good, 44%). A reduction of movement was frequently observed, particularly in pronation and supination, which was limited in 28% of the cases and abolished in 15%. In 4 patients there was a significant increase in cubitus valgus. Arthrosis was present in 45% and periarticular calcification in 74% of the cases. There were 5 cases of radioulnar synostosis and 4 cases of myositis ossificans. Subluxation of the distal radioulnar joint was observed in 26 wrists, 4 of which were painful. The results of resection of isolated fractures may be considered acceptable, while the prognosis of fractures with associated lesions is more unfavourable.

Adolescent↗
PubMed1989

[Surgical treatment of fractures of the neck of the radius in children and adolescents. Review of 24 cases].

At the Orthopaedic Clinic of the University of Perugia from 1973 to 1984, 28 fractures of the neck of the radius were treated with open reduction in children aged between 4 and 15. Follow-up evaluation showed a high percentage of poor results (33.3%) frequently associated with a deficit of pronation and supination. Clinical results were related both to the severity of the displacement and to the radiographic results at follow-up. Open reduction is essential in highly displaced fractures, but it can be avoided in those with minor displacement.

Adolescent↗
PubMed1989

Pharmacologic alterations of the isovolumic index: a study of the effects of isoproterenol, propranolol and verapamil.

The isovolumic index has been proposed as a noninvasive index of left ventricular function which, unlike the traditional systolic time index, incorporates the period of isovolumic relaxation. The responses of the isovolumic index and the systolic time index to three cardioactive drugs (isoproterenol, propranolol and verapamil) were assessed by measurements of ejection time (ET), isovolumic contraction time (IVC) and isovolumic relaxation time (IVR) in 23 dogs instrumented with high fidelity micromanometers and ultrasonic crystals. Isoproterenol infusions resulted in improvements in both the isovolumic and systolic time indices as a result of significant shortening of ET, IVC and IVR. Propranolol infusions caused significant and parallel increases of IVC (P less than 0.01) and ET (P less than 0.05) but failed to cause prolongation of either the systolic time index, defined as (IVC/ET) or deterioration of regional function. A higher propranolol dose caused significant increases in ET, IVC (P less than 0.001) and IVR (P less than 0.05), yet neither the systolic time index or the isovolumic index (IVC + IVR/ET) were prolonged, and regional function remained normal. Verapamil infusion caused an upward, nonsignificant trend in the isovolumic index and no change in the systolic time index. Stepwise multiple linear regression analysis demonstrated a similar load dependency of both indices and a higher inverse correlation of the isovolumic index with fractional shortening. The systolic time index showed a higher dependency on peak positive dP/dt whereas only the isovolumic index showed dependency on the isovolumic relaxation time constant. When altered loading conditions are accounted for, the isovolumic index shows directional changes that reflect changes in peak positive dP/dt, the isovolumic relaxation time constant and regional shortening.

Animals↗
PubMed1988

The effects of dopamine and dobutamine on regional function in the presence of rigid coronary stenoses and subcritical impairments of reactive hyperemia.

Intraluminal stenosing cylinders were inserted in the coronary arteries of open-chest, anesthetized dogs to assess the sensitivity of sympathomimetic infusion for detection of subcritical impairment of reactive hyperemia. Observations were made at rest and during steady-state infusions of dopamine and dobutamine (each 10 micrograms/kg/min) before and after placement of the cylinder. Each stenosis was associated with subcritical impairment of postocclusion reactive hyperemia at rest. The degree of impairment was used to stratify experiments into mild (group A) and moderate (group B) cohorts. In group A, reactive hyperemia was 217 +/- 55 cc/min prior to cylinder placement and 82 +/- 17 cc/min (p less than 0.002) after insertion. In group B, reactive hyperemia was 235 +/- 54 cc/min and 63 +/- 7 cc/min (p less than 0.001) before and after insertion. Both drugs resulted in a significant increase in regional shortening (ultrasonic crystal technique) in the absence of a stenosis. After creation of the stenoses, dopamine continued to cause a significant increase in shortening in both groups, whereas this increase was impaired in group B during dobutamine infusion (14.8 +/- 5.9% at rest vs 21.4 +/- 10.3% during infusion, p = NS). Thus, with subcritical lesions in a single vessel, dobutamine infusion was associated with depressed regional function when reactive hyperemia was impaired by more than 80%.

Animals↗
PubMed1988

The effects of acute ischemia on the isovolumic index.

The isovolumic index is the ratio of the duration of isovolumic contraction (IVC) and relaxation (IVR) divided by ejection time (ET), and has been proposed as a more sensitive descriptor of ventricular performance than the systolic time index, which ignores the period of isovolumic relaxation. To determine the effects of acute ischemia on these indices, IVC, IVR, and ET were measured in seven open-chest dogs instrumented with high-fidelity micromanometers and ultrasonic crystals and subjected to a 10-second period of coronary occlusion. Fractional shortening was significantly impaired (18.4 +/- 6.9% vs 1.9 +/- 7.3%, p less than 0.001) during coronary occlusion. ET was unaffected by the brief ischemia, whereas IVC time showed directional shortening that attained statistical significance (55 +/- 7 msec control vs 50 +/- 6 msec, p less than 0.01) at 8 to 10 seconds. IVR time was prolonged by occlusion, significantly so at 6 to 8 seconds (72 +/- 26 msec control vs 88 +/- 22 msec, p less than 0.01) and at 8 to 10 seconds (81 +/- 19 msec, p less than 0.05). The systolic time index showed no deterioration during ischemia, whereas the isovolumic index did not show directional prolongation. Assessment of IVC, IVR, and ET at the time of the maximal change in the isovolumic index revealed significant changes of IVC and IVR (each p less than 0.05 vs control), though ET and the systolic time index were unchanged. Through incorporation of IVR, the isovolumic index was more sensitive to acute brief ischemia than the systolic time index.

Animals↗
PubMed1988

Radionuclide determination of the relationship between left ventricular contractile state and ejection fraction.

To determine whether the relationship between various measures of left ventricular (LV) contractile state and ejection fraction (EF) is linear in man, we studied 30 patients during right atrial pacing over a range of loading conditions. With the use of micromanometer LV pressures and radionuclide LV volumes, pressure-volume (P-V) loops were generated for each loading condition. Then isochronal, instantaneous P-V data points were obtained by linear regression analysis to attain the maximum slope (Emax) of these time-varying isochrones. Other measures of LV end systole were also used to calculate end-systolic P-V relations in a similar fashion, and indirect P-V relations were obtained from the linear regression analysis of brachial artery peak pressure vs minimum LV volume data points. When the slopes of these LV contractile measures were compared to the radionuclide LV EFs, the linear correlation coefficients ranged from 0.53 to 0.67. After natural log transformation of the LV contractile state and EF data, the correlation coefficients for the polynomial curve fits ranged from 0.80 to 0.88. When the correlation coefficients for the polynomial curve fits of the natural log transformed data were compared to those for the linear regression analyses of the raw data, significant improvements were evident (p less than 0.05). Thus the relationship between various measures of LV contractile state and EF obtained with radionuclide angiography is best approximated by a complex, curvilinear relationship that is due, in part, to the wide range of LV contractile states within the relatively narrow normal range of LV ejection fractions.

Adult↗
PubMed1988

Quantitative regional curvature analysis: a prospective evaluation of ventricular shape and wall motion measurements.

To overcome the assumptions and approximations mandated by the use of traditional wall motion methodologies, a method was recently developed for measuring ventricular shape based on quantitative curvature analysis of ventricular outlines. This study was designed to assess prospectively the performance of this algorithm, to compare it to traditional wall motion measurements (centerline method), and to determine the comparative degree to which each method mimicked the interpretation of wall motion by clinical observers. Semiquantitative visual grading of regional function in 52 patients was performed by four independent observers on two occasions. Anterior, apical, or inferior segments were judged to be normal (0 points) or abnormal (1 point) based on viewing nonrealigned, end-diastolic and end-systolic ventricular silhouettes from cineventriculograms obtained in the 30-degree right anterior oblique projection. Each segment was assigned a collated score ranging from 0 (all observers felt the region was normal on both readings) to 8 (all observers felt the region was abnormal on both readings). Quantitative regional curvature analysis and wall motion analysis (centerline method) were performed. Quantitative shape and wall motion scores correlated equally well with the semiquantitative visual scores. When a visual score of greater than or equal to 4 was used to designate an abnormal segment, both quantitative approaches demonstrated comparable sensitivity, specificity, and concordance rates. Both methods achieved optimal performance when maximum and minimum deviations from normal were recorded. Under these circumstances, the shape analysis demonstrated a greater concordance with the clinical diagnosis than did wall motion analysis (99% vs-93%, p less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1988

Surgical release of the median nerve under local anaesthesia for carpal tunnel syndrome.

Carpal tunnel release was performed under local anaesthesia in 124 wrists of 108 patients. The local anesthetic was injected into the carpal tunnel and into the subcutaneous tissue under the line of the skin incision. A tourniquet was used in all cases. Analgesia was complete in all but six patients. Only one patient had real difficulty in tolerating the tourniquet. In 18 cases the median nerve, when exposed at operation, showed evidence of some damage caused by the needle or by injection of local anaesthetic but, at follow-up, no symptoms or signs related to this damage were found.

Adult↗
PubMed1988

Modification of the centerline method for assessment of echocardiographic wall thickening and motion: a comparison with areas of risk.

The ability of the centerline method to discern regional myocardial risk area was evaluated using two-dimensional echocardiographic measurements and coronary artery occlusion in 16 open chest, anesthetized dogs. The centerline method was modified to allow determination of both wall thickening and wall motion at control and during coronary artery occlusion. End-systolic and end-diastolic echocardiographic images were analyzed at 100 equally spaced points around the centerline of the short-axis view of the left ventricle to determine shortening and thickening abnormalities. In vivo risk regions were assessed by microsphere injection during occlusion, and autoradiographic analysis revealed a mean (+/- SD) circumferential risk area of 37.5 +/- 7.7%. Abnormal function was established by three criteria on the basis of the control values for both fractional shortening and wall thickening: 1) less than 2 SD, 2) less than 95% tolerance limits, and 3) dyskinesia. The criterion of less than 2 SD estimated a risk area of 45.9 +/- 16.7% for fractional shortening and 37.2 +/- 16.8% for wall thickening. Although neither value was significantly different from the actual mean value for the risk region, the results for fractional shortening were greater than for wall thickening (p less than 0.01). The less than 95% tolerance limit method significantly underestimated risk area for both shortening (25.6 +/- 15.1%, p less than 0.05) and thickening (19.1 +/- 12.7%, p less than 0.001), as did analysis by dyskinesia (13.1 +/- 12.1% for shortening, p less than 0.001; 20.6 +/- 12.1% for thickening, p less than 0.01). Thus, modification of the centerline method allowed determination of both fractional shortening and wall thickening from echocardiographic images.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

A comparison of 35 mm cine film and digital radiographic image recording: implications for quantitative coronary arteriography. Film vs. digital coronary quantification.

To assess potential differences in the intrinsic properties of image recording media and their impact on quantitative coronary arteriography, we used an automatic quantitative arteriography computer program to analyze cine film and digital radiographic images of a radiographic arterial phantom. The phantom consisted of a lucite plate with precision-drilled lumena ranging from 0.5 to 5.0 mm in diameter. Film images were digitized at 2048 X 2048 pixel resolution, and digital radiographic images were acquired at 512 X 512 and 1024 X 1024 resolution. Arterial geometric diameter, percent diameter stenosis, densitometric relative cross-sectional area, and densitometric percent area stenosis were measured. All three techniques were equivalent in measuring diameters with a high degree of overall accuracy (R greater than .992). All methods overestimated diameters below 1.0 mm. Both 512 X 512 and 1024 X 1024 digital images were superior to film for densitometric measurement of relative area (R = .995 vs. R = .940, P = .0032). We conclude that automated analysis of digital radiographic images yields results that are similar in geometric precision but greater in densitometric precision than film analysis.

Cineradiography↗