Report on G4-Med, a Geant4 benchmarking system for medical physics applications developed by the Geant4 Medical Simulation Benchmarking Group

BACKGROUND

Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, micro- and nanodosimetry, imaging, radiation protection, and nuclear medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing.

AIMS

To respond to these needs, we developed G4-Med, a benchmarking and regression testing system of Geant4 for medical physics.

MATERIALS AND METHODS

G4-Med currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the prebuilt Geant4 physics lists are tested. The tests included in G4-Med are executed on the CERN computing infrastructure via the use of the geant-val web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes.

RESULTS

This paper describes the tests included in G4-Med and shows the results derived from the benchmarking of Geant4 10.5 against reference data.

DISCUSSION

Our results indicate that the Geant4 electromagnetic physics constructor G4EmStandardPhysics_option4 gives a good agreement with the reference data for all the tests. The QGSP_BIC_HP physics list provided an overall adequate description of the physics involved in hadron therapy, including proton and carbon ion therapy. New tests should be included in the next stage of the project to extend the benchmarking to other physical quantities and application scenarios of interest for medical physics.

CONCLUSION

The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.

Vardenafil and Weaning from Inhaled Nitric Oxide: Effect on Pulmonary Hypertension in ARDS

We report a 66-year-old patient with refractory pulmonary hypertension secondary to ARDS who was being treated with inhaled nitric oxide. Enteral vardenafil (phosphodiesterase-5 inhibitor) was tried at two different doses (10 mg and 5 mg), in order to wean the patient from nitric oxide. The higher dose decreased pulmonary pressure but caused systemic hypotension and the drug was discontinued. Subsequently, a 5 mg dose of vardenafil decreased pulmonary pressure without hypotension. Pulmonary hypertension was controlled using vardenafil 10-15 mg divided in 2-3 daily doses. This therapy allowed nitric oxide withdrawal, weaning from mechanical ventilation and discharge from ICU.

Vardenafil acted in synergy with inhaled nitric oxide, permitted nitric oxide reduction and discontinuation and proved to be effective as a single, long-term treatment for pulmonary hypertension.

Carbon ion fragmentation effects on the nanometric level behind the Bragg peak depth

In this study, fragmentation yields of carbon therapy beams are estimated using the Geant4 simulation toolkit version 9.5. Simulations are carried out in a step-by-step mode using the Geant4-DNA processes for each of the major contributing fragments. The energy of the initial beam is taken 400 MeV amu(-1) as this is the highest energy, which is used for medical accelerators and this would show the integral role of secondary contributions in radiotherapy irradiations. The obtained results showed that 64% of the global dose deposition is initiated by carbon ions, while up to 36% is initiated by the produced fragments including all their isotopes. The energy deposition clustering yields of each of the simulated fragments are then estimated using the DBSCAN clustering algorithm and they are compared to the yields of the incident primary beam.

Comparison of GEANT4 very low energy cross section models with experimental data in water

PURPOSE

The GEANT4 general-purpose Monte Carlo simulation toolkit is able to simulate physical interaction processes of electrons, hydrogen and helium atoms with charge states (H0, H+) and (He0, He+, He2+), respectively, in liquid water, the main component of biological systems, down to the electron volt regime and the submicrometer scale, providing GEANT4 users with the so-called "GEANT4-DNA" physics models suitable for microdosimetry simulation applications. The corresponding software has been recently re-engineered in order to provide GEANT4 users with a coherent and unique approach to the simulation of electromagnetic interactions within the GEANT4 toolkit framework (since GEANT4 version 9.3 beta). This work presents a quantitative comparison of these physics models with a collection of experimental data in water collected from the literature.

METHODS

An evaluation of the closeness between the total and differential cross section models available in the GEANT4 toolkit for microdosimetry and experimental reference data is performed using a dedicated statistical toolkit that includes the Kolmogorov-Smirnov statistical test. The authors used experimental data acquired in water vapor as direct measurements in the liquid phase are not yet available in the literature. Comparisons with several recommendations are also presented.

RESULTS

The authors have assessed the compatibility of experimental data with GEANT4 microdosimetry models by means of quantitative methods. The results show that microdosimetric measurements in liquid water are necessary to assess quantitatively the validity of the software implementation for the liquid water phase. Nevertheless, a comparison with existing experimental data in water vapor provides a qualitative appreciation of the plausibility of the simulation models. The existing reference data themselves should undergo a critical interpretation and selection, as some of the series exhibit significant deviations from each other.

CONCLUSIONS

The GEANT4-DNA physics models available in the GEANT4 toolkit have been compared in this article to available experimental data in the water vapor phase as well as to several published recommendations on the mass stopping power. These models represent a first step in the extension of the GEANT4 Monte Carlo toolkit to the simulation of biological effects of ionizing radiation.

[Pulmonary hypertension in autoimmune rheumatic diseases]

OBJECTIVE

Pulmonary hypertension is a severe and rapidly progressive disease, particularly frequent in patients with rheumatic diseases. The aims of this study were the following: to determine the prevalence of pulmonary hypertension in Italian patients with autoimmune rheumatic diseases, and to evaluate if the presence of a rheumatic disease in general, or of a specific autoimmune rheumatic disease, is a risk factor for the development of pulmonary hypertension.

PATIENTS AND METHODS

One hundred and thirteen Italian patients with connective tissue diseases (105 females, 8 males), aged 19 to 83 yrs, entered the study. Fifty-one had systemic sclerosis (SSc): 49 were females, 2 males, aged 34 to 83 yrs; 41 had limited cutaneous SSc, 8 diffuse cutaneous SSc, and 2 SSc sine scleroderma. Thirty-three patients had systemic lupus erythematosus (SLE): all but one were females, their age ranged from 19 to 82 yrs. Twenty-five had rheumatoid arthritis (RA): 21 females, 4 males, aged 26 to 45 yrs. Three females and one male, 51-77 yrs, had mixed connective tissue disease (MCTD). Systolic pulmonary arterial pressure (SPAP) was assessed by Doppler echocardiography.

RESULTS

Twenty three patients had pulmonary hypertension, which was more frequent in MCTD than in SLE (75% vs 6.1%, p=0.0002) or in AR (20%, p=0.0313). Pulmonary hypertension was more frequent in SSc than in SLE (25.5% vs 6.1%, p=0.0028) and in limited than in diffuse SSc (21.6% vs 3.9%). SPAP was significantly related to age (r=0.35, p=0.0275), with patients with pulmonary hypertension older than patients with normal SPAP (66+/-13 vs 52+/-16 yrs, p=0.0003).

CONCLUSIONS

These data show a significant association between pulmonary hypertension and autoimmune rheumatic diseases. Therefore, pulmonary hypertension assessment seems mandatory, at least in MCTD and SSc. However, more studies are needed to clarify the relationship between age and pulmonary hypertension and to verify whether the low prevalence of pulmonary hypertension we found in our SLE patients is related or not to their lower age.

Thromboembolic risk in atrial flutter. The FLASIEC (FLutter Atriale Società Italiana di Ecografia Cardiovascolare) multicentre study

AIMS

Patients with atrial flutter are believed to be at lower risk of thromboembolism than patients with atrial fibrillation. However, the incidence of atrial thrombi and the need for anticoagulation in patients with atrial flutter is not well established.

METHODS AND RESULTS

A prospective observational multicentre study was undertaken to assess the frequency of atrial thrombi and spontaneous echocontrast and the prevalence for aortic complex atherosclerotic lesions in a cohort of unselected patients with atrial flutter. We evaluated 134 patients (102 male, aged 70+/-9 years); exclusion criteria were history of atrial fibrillation, rheumatic mitral valve disease and mitral mechanical prosthesis. The median of atrial flutter duration was 33 days. Twelve patients had been taking warfarin for more than 7 days. One hundred and twenty-four patients (94%) underwent a transoesophageal echocardiogram, which revealed left atrial appendage thrombi in two patients (1.6%) and right atrial thrombi in one patient (1%). At least moderate left atrial echocontrast was found in 16/124 patients (13%). Complex atherosclerotic aortic plaques were detected in 10 patients (8%). Atrial flutter conversion was attempted in 93/134 patients (69%). At the 1-month follow-up, two patients experienced a thromboembolic event following restoration of sinus rhythm.

CONCLUSIONS

Atrial thrombi and echocontrast, and complex aortic atherosclerotic plaques are relatively uncommon in patients with atrial flutter. Post-cardioversion embolism was observed in two patients in our study population.

[Reporting echocardiography exams with the G8-Cardio ANMCO software]

BACKGROUND

The availability of a common computerized program for echocardiographic study archiving and reporting at national and/or international level could make it possible to standardize the echo reports of different echocardiographic laboratories, and to use the wealth of data thus obtainable with echocardiography, and to exploit its capillary territorial distribution, with the aim of collecting echocardiographic data in a standard format for epidemiological, scientific and administrative purposes.

METHODS

To develop such a software, an ad hoc joint National Association of Hospital Cardiologists and Italian Society of Echocardiography task force worked in conjunction with the Italian Branch of Agilent Technologies to standardize the phraseology of accepted echocardiographic terms and of the quantitative parameters derived from transthoracic and transesophageal echocardiographic examination at rest as well as during exercise and pharmacological stress, and to develop an ad hoc software. This echocardiographic study archiving and reporting program is part of the whole G8-Cardio ANMCO software developed to computerize the whole cardiological chart. The software has been developed by Agilent Technologies to provide a fast, easy-access and easy to use report generator for the non-computer specialist using DBMS Oracle 7.3 database and Power Builder 5.0 to develop a user-friendly interface.

RESULTS

The number of qualitative and quantitative variables contained in the program is 733 for echocardiography at rest, while it depends on the stressor and on the length of the examination for the stress echo (dipyridamole 214-384, dobutamine 236-406, exercise 198-392). The program was tested and refined in our laboratory between November 1999 and May 2000. During this time period, 291 resting and 56 stress echocardiographic studies were reported and recorded in a database. On average, each resting echocardiographic study lasting 10 +/- 4 (range 5-17) min was recorded using 50 +/- 11 (range 33-67) variables and 41,566 bytes of hard-disk memory space. Stress echocardiographic studies, each lasting 7 +/- 5 (range 5-21) min, were recorded using 143 +/- 74 (range 38-194) variables and 38,531 bytes of hard-disk memory space.

CONCLUSIONS

To our knowledge this software represents the first experience of a common computerized program for echo archiving and reporting carried out at national level.

Left ventricular opacification by intravenous contrast echocardiography

BACKGROUND

The present study was undertaken in order to evaluate the efficacy of the intravenous administration of Albunex in obtaining left ventricular opacification and the relationship between left ventricular opacification and pulmonary pressures and cardiac function.

METHODS

Fifty-two adult patients, mostly affected by ischemic heart disease, were enrolled in the study. In 37 of these patients, a complete right heart hemodynamic study was performed after Swan-Ganz catheterization. Albunex was administered in three randomized doses (0.10, 0.15 and 0.20 ml/kg) to all the patients. Left ventricular opacification was assessed both visually and using videodensitometric analysis.

RESULTS

Left ventricular opacification was obtained in 93% of all the injections and an intermediate or strong opacification was obtained in 68%, while absent opacification was observed in 6% of the injections, irrespective of the contrast dose. An incremental opacification efficacy trend was observed from the lower to the higher dose, with an intermediate or strong opacification in 58 and in 77% of 0.10 and 0.20 ml/kg injections, respectively. Irrespective of the contrast dose, an enhancement of the endocardial borders was observed in 61% of the wall segments suboptimally visualized in basal conditions. The endocardial borders enhancement was obtained in 39 and in 79% of segments using the 0.10 and the 0.20 ml/kg doses, respectively. No statistically significant differences were observed between the videodensitometric parameters obtained using the three contrast doses. Finally, a significant relationship was observed between left ventricular opacification parameters and pulmonary pressures and left ventricular functional parameters, irrespective of the contrast doses considered.

CONCLUSIONS

The results we obtained demonstrate the good overall efficacy of Albunex administered intravenously in order to obtain left ventricular opacification in a clinical population of cardiac patients. Moreover, they suggest that the dosage to be used clinically should preferably be at least 0.20 ml/kg, although no significant influence of contrast dosage on videodensitometric parameters has been observed. Finally, irrespective of the contrast dosage, the magnitude of left ventricular opacification appears to be influenced by the hemodynamic status of the patient.

Effect of sample volume location on Doppler-derived transmitral inflow velocity values in 288 normal subjects 20 to 80 years old: an echocardiographic, two-dimensional color Doppler cooperative study

The aims of the study were to evaluate in a population of 288 normal subjects 20 to 80 years old (1) the normal values of the indexes of the mitral flow velocity pattern measured either at the tips of the mitral leaflets or at the annulus; (2) whether there was a significant difference between the values obtained at the tips compared with those measured at the mitral annulus; (3) the correlation with aging between the indexes measured in the two different positions; and (4) whether certain physiological variables have different effects on diastolic function measured in the two different positions. The highest values were always measured at the tips of the mitral leaflets (p < 0.05); only atrial filling fraction, E acceleration time, and E deceleration velocity had higher values when measured at the level of the annulus (p < 0.05). The A-wave peak velocity had the same mean value when measured at both the tips and at the annulus. A significant difference in the correlation between parameters measured at the tips of the mitral leaflets with age and at the annulus (with age) was observed for the following parameters: (1) peak E velocity, E integral, total integral and E acceleration showed better correlation with age when measured at the annulus (p < 0.02); (2) peak A velocity and A integral showed better correlation with age when measured at the tips of the mitral leaflets (p < 0.001). Multivariate analysis showed that age was the variable that had the most influence on diastolic function parameters; heart rate had less influence on the diastolic function indexes.

RITED (Registro Italiano Test Eco-Dobutamina): side effects and complications of echo-dobutamine stress test in 3041 examinations

AIM

The aim of the study was to report the incidence and clinical meaning of side-effects caused by echo-dobutamine testing in a large population and to evaluate any possible correlation between dobutamine dose and side-effects.

METHODS

The study population consisted of 3041 patients enrolled from January 1994 to August 1995 at 63 centers participating in the Italian Register of Echo-Dobutamine Testing (Registro Italiano Test Eco-Dobutamina, RITED). The four major indications were myocardial infarction older than one month (40.4%), recent myocardial infarction (22.7%), coronary artery disease without a history of myocardial infarction (10.8%) and suspected coronary artery disease (19.3%). Dobutamine was administered in a peripheral vein at 5, 10, 20, 30, 40 micrograms/kg/minute + atropine 1 mg in four divided doses of 0.25 mg/minute.

RESULTS

Severe complications were asystole, which went as high as 6" in one patient, and ventricular fibrillation in two patients. The clinical side-effects were headache (2.5%), hypotension (2.2%), nausea (1.7%), bradycardia (1.4%), palpitations (0.5%), tremors (0.3%), dyspnea (0.2%), paresthesia (0.2%) and hypertension (0.2%). Atrial arrhythmia was recorded in 10.6% of patients, while ventricular arrhythmia was recorded in 26.5%. The percentage of supraventricular and ventricular repetitive arrhythmia did not increase with dosage. The cumulative incidence of supraventricular and ventricular repetitive arrhythmia, considered as an interruption criteria, was 6.6% and 5.9%, respectively.

CONCLUSIONS

Echo-dobutamine stress test seems to be a very safe and reliable test for unmasking myocardial ischemia or viability in known or suspected coronary artery disease. It has been shown to be widely applicable in clinical practice for outpatients as well, as long as a protected environment is available.

Pulmonary venous flow velocity patterns in 143 normal subjects aged 20 to 80 years old. An echo 2D colour Doppler cooperative study

In order to find out the normal values and to evaluate the effects of age, heart rate, sex, and haemodynamic and standard echocardiographic parameters on pulmonary venous flow velocity obtained by the transthoracic approach. Doppler pulmonary venous flow parameters were measured in 143 healthy subjects aged from 20 to 80 years. Doppler pulmonary venous flow parameters which had the best correlation with age were: the peak velocity of the systolic wave (r = 0.39) and its integral (r = 0.5), the peak velocity of the diastolic wave (r = -0.6) and its integral (r = -0.44); the systolic (r = 0.68) and diastolic fractions (r = -0.68); the systolic/diastolic peak velocity ratio (r = 0.73) and the systolic/diastolic integral ratio (r = 0.7). The atrial reversal wave did not correlate with age; the atrial reversal wave was more difficult and probably less reliable to measure than the systolic and diastolic waves. The correlations of pulmonary venous flow parameters with mitral flow parameters were also examined. This study showed that, in healthy subjects, despite an increase in the early and atrial waves from the annulus to the tips of the mitral leaflets, there is a similar association between pulmonary venous flow and mitral flow measured at the annulus or at the tips of the mitral leaflets. The intra-observer reproducibility of all the pulmonary venous flow parameters considered were found to be excellent. Moderate inter-observer variability was observed for the systolic, diastolic and atrial reversal wave peak velocities and integrals; however, the systolic/diastolic ratio improved the precision of the measurements. Multivariate analysis showed that age is the principal determinant of the Doppler parameters of pulmonary venous flow: heart rate, sex, body surface area, the size of the left atrium in systole and the left ventricular ejection fraction all influence the Doppler parameters of pulmonary venous flow, even if only slightly.

Echocardiographic follow-up in patients with mild to moderate mitral stenosis: is a yearly examination justified?

The result of this study showed that echocardiographic and Doppler parameters in patients with mild to moderate mitral stenosis did not undergo any major changes over a relatively long observation period, reflecting the substantial stability of the valve disease process. Thus, unless such patients experience clinical deterioration, a yearly echocardiographic examination appears to be unjustified.

Measurement of mitral valve area in mitral stenosis: four echocardiographic methods compared with direct measurement of anatomic orifices

OBJECTIVES

This study sought to compare the mitral valve areas of patients with rheumatic mitral valve stenoses as determined by means of four echocardiographic and Doppler methods with those obtained by direct anatomic measurements.

BACKGROUND

There has been no systemic comparison between Doppler-determined valve areas and the true anatomic orifice in a single cohort.

METHODS

In 30 patients with mitral stenosis, the mitral valve areas determined by two-dimensional echocardiographic planimetry, pressure half-time, flow convergence region and flow area were compared with the values directly measured on the corresponding excised specimen by means of a custom-built sizer.

RESULTS

The correlation coefficient was r = 0.95 (SE 0.06, p < 0.0001) for two-dimensional planimetry; r = 0.80 (SE 0.09, p < 0.0001) for pressure half-time; r = 0.87 (SE 0.09, p < 0.0001) for flow convergence region; and r = 0.54 (SD 0.1, p < 0.002) for flow area. Two-dimensional echocardiographic planimetry, pressure half-time, flow convergence region and flow area overestimated the actual anatomic orifice by > 0.3 cm2 in 2, 1, 6 and 0 patients, respectively, and underestimated it by > 0.3 cm2 in 0, 4, 1 and 8 patients, respectively.

CONCLUSIONS

Mitral valve areas determined by two-dimensional planimetry, pressure half-time and proximal flow convergence region reliably correlated with size of the anatomic orifice. The flow area method provided a less reliable correlation.

[Multiplane transesophageal echocardiography. The experience with 250 patients]

BACKGROUND AND OBJECTIVES

Multiplane transesophageal echocardiography provides countless tomographic planes through an angle of 180 degrees, thus overcoming the restriction encountered even with biplane transesophageal echocardiography. However, the incremental diagnostic value and clinical usefulness of this technique over biplane transesophageal echocardiography has not been extensively studied.

STUDY POPULATION AND METHODS

In order to evaluate its advantages over biplane imaging, 250 patients (129 male, 121 females) aged 14-86 years, underwent multiplane transesophageal echocardiography. Indications for the study were the following: source of embolism in 83 patients, suspected prosthetic dysfunction in 58 patients, valvular disease in 46 patients, congenital heart disease in 30 patients, aortic disease in 17 patients, intra- or paracardiac masses in 11 patients, and other reasons in 5. All the patients underwent an initial comprehensive diagnostic assessment using only the transverse (0 degree) and longitudinal (90 degrees) plane as the biplane imaging technique. "Off-axis" tomographic sections through the full 0 degree to 180 degrees angle were subsequently obtained by means of the gradual electrical rotation of the transducer. The echocardiographic information obtained by rotating the transducer was then compared to that obtained by biplane imaging to determine whether the additional information provided by "off-axis" sections a) carried diagnostic data; b) were to be considered useful but not diagnostic; or c) irrelevant.

RESULTS

Additional diagnostic information was obtained in 24 out of the 250 patients (9.6%), including the source of embolism in 9 patients, mitral insufficiency in 6 patients, bicuspid aorta in 2 patients, aortic endocarditis in 2 patients, mitral prosthetic dysfunction in 4 patients and complex congenital heart disease in 1 patient. Additional useful but non-diagnostic information was obtained in 162 patients (64.8%). These data mainly allowed a more comprehensive assessment of the cardiac abnormality, enhancing confidence in the transesophageal diagnosis. Finally, data considered to be irrelevant were found in 64 patients (25.6%).

CONCLUSIONS

The present study indicates that the wide range of tomographic planes provided by multiplane transesophageal echocardiography allows a more comprehensive evaluation of cardiac diseases and makes an accurate diagnosis possible in a significant number of cases.

Left ventricular diastolic parameters in 288 normal subjects from 20 to 80 years old

Left ventricular diastolic indexes are influenced by several variables. In order to evaluate the relationship of these indexes to age, heart rate, sex and to standard echo parameters, 288 normal subjects aged from 20 to 80 years, divided into six age groups, underwent a two-dimensional colour Doppler examination. Doppler examination was performed from the apical four chamber view to evaluate transmitral flow; isovolumic relaxation time (IVRT) was measured from an apical five chamber view. In order to obtain a sufficient number of subjects for an adequate statistical analysis, seven hospitals were involved in the study. Univariate analysis showed that age influences the peak velocity of the E (r = -0.46) and A waves (r = 0.46), the E/A ratio (peak velocities) (r = -0.69), the A wave integral (r = 0.48) and the E/A integral ratio (r = -0.57), the early and late filling fractions (r = -0.48 and r = 0.51 respectively), and the E wave deceleration (r = -0.43) and deceleration time (r = 0.36). In subjects older than 70 years an inversion of the E/A wave ratio was observed. Multivariate analysis confirmed that age has an important influence on left ventricular diastolic indexes but also demonstrated that heart rate has a significant influence. Sex, ejection fraction (EF), and the dimensions of the mitral annulus and the left ventricular posterior wall had less influence on left ventricular diastolic indexes. The mean values of E and A wave acceleration, deceleration and peak velocity were used to depict left ventricular filling morphology in various age groups for three different heart rate values. The conclusions of the study, are: (1) normal left ventricular diastolic parameters were obtained as mean values at seven different hospitals (2) when evaluating left ventricular diastolic function parameters it is important to take into account age and heart rate; E/A inversion in older subjects should be considered the normal mitral flow pattern.

Transthoracic high-frequency echocardiographic detection of atherosclerotic lesions in the descending portion of the left coronary artery

To assess the ability of transthoracic high-frequency two-dimensional echocardiography to detect atherosclerotic lesions in the descending portion of the left coronary artery, 30 consecutive patients with suspected coronary artery disease underwent two-dimensional echocardiographic examination 24 to 96 hours before coronary angiography. The descending portion of the left coronary artery was arbitrarily divided into a mid segment (the portion of the coronary vessel embedded in the anterior interventricular sulcus) and an apical segment (the portion turning around the cardiac apex into the posterior interventricular sulcus). The mid segment was imaged in 24 and the apical segment in 25 of the 30 patients for a total of 49 out of 60 segments (82%). Comparison of the echocardiographically visualized segments with the corresponding angiographic segments indicated that a correct echocardiographic diagnosis of significant stenosis was made in 11 out of 12 segments. There were no false positive results. Thus the sensitivity and specificity of high-frequency transthoracic echocardiography in the detection of significant stenosis in the imaged segments were 92% and 100%, respectively. Compared with angiography, additional information concerning the status of the arterial wall, the presence of calcific plaques, and the cross-sectional extent of the obstructive lesions was obtained by echocardiography in eight patients.

Value of two-dimensional echocardiography in the identification of pulmonary hypertension in chronic obstructive lung disease

Thirty-three patients suffering from chronic obstructive lung disease (COLD) were submitted to right heart two-dimensional echocardiographic (2D-ECHO) and hemodynamic study. By the subcostal approach, the right ventricle outflow tract including the pulmonary vessels was visualized in 85% of the patients. Most parameters measured on the right ventricle and pulmonary vessels were significantly higher than those recorded in the healthy control group. Very significant correlations were observed between the mean pulmonary artery pressure (PAP) and the following 2D-ECHO parameters: diameter of the pulmonary artery at valve level (r = 0.62; p less than 0.001); supravalvular diameter of the pulmonary artery (r = 0.44; p less than 0.03); diameter of the left branch of the pulmonary artery (r = 0.48; p less than 0.05); diameter of the right branch of the pulmonary artery (r = 0.39; p less than 0.05), and between the PAP and PaO2 (r = -0.66; p less than 0.001). Furthermore, the sensitivity, specificity, and accuracy of 2D-ECHO measurements were calculated to assess the presence of pulmonary hypertension. Overall sensitivity was 65%, specificity 75%, and accuracy 67%. However, by combining the value of PaO2 with that of the pulmonary valve by means of the multiple regression analysis, sensitivity increased to 84% in identifying pulmonary hypertension. Such data demonstrate that the 2D-ECHO study of the right heart in COLD patients has to carefully measure the dimensions of the pulmonary valve and the great pulmonary vessels, as their modification are mainly linked with the presence of pulmonary hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prognostic value of the equivalents of transitory myocardial ischemia evaluated by exercise thallium-201 myocardial scintigraphy in an ambulatory population of 367 patients with a maximum 5-year follow-up]

From 1-1-1981 to 3-31-1985, 367 subjects (227 males and 140 females) were examined by means of TL-201 myocardial scintigraphy for diagnostic purpose. A follow-up period, 5 years maximum, was run in order to assess the prognostic value of the three equivalents of transient myocardial ischemia which can be demonstrated by the test (angina, reversible hypoperfusion, and ST-T segment changes). The end points were myocardial infarction and/or sudden death. Three-hundred fifty-four patients complied (96%). During the observation period 9 severe ischemic events (SIE) occurred: 5 myocardial infarctions and 4 sudden deaths. As far as the predictivity of SIE is concerned, the "t" test for independent samples showed a statistically significant difference between the group of patients with no signs of ischemia and the group with positive scintiscan (p less than 0.05) and with the three equivalents of ischemia all together (p less than 0.05). Moreover, in the sub-group of patients with pathological scintigraphic results the probability for SIE to occur was statistically different in the patients with no hypoperfusion in the region supplied by the anterior descending coronary artery and in those with pathological scintigraphic findings in that region (p less than 0.05). In our opinion, the above data demonstrate the pathological signs noticeable with stress myocardial TL-201 scintiscan to have prognostic value.

[Long-term clinical results after intervention using aorto-coronary bypass]

The survival and symptoms of 294 consecutive patients discharged from the hospital after isolated coronary artery bypass grafting from 1970 to 1975 were evaluated 6 to 10 years after surgery. The actuarial 10 years expectancy of cardiac death as 10.0 +/- 2.4% the non fatal myocardial infarction one was 11.2 +/- 2.8; the yearly probability of severe ischemic event therefore was 2.1%. One year after surgery, 56% patients were free from angina, 31% improved and only 7% symptomatically unchanged. These percentages became 45%, 26% and 13% respectively at the end of the follow-up, thus showing a definite though slight deterioration. Clinical status one year after operation was predictive of further evolution: only 6.2% of the symptom-free patients developed severe ischemic events, as opposed to 20% of the highly symptomatic ones. The actuarially determined curve of recurrence of angina in the patients asymptomatic at the first control shows, after 2 years of steady state, a progressive upslope which reaches 40% by the 7th year and 90% at the 10th year of follow-up. Subgroup analysis indicated that long term prognosis is influenced by the presence of left main stenosis and by perioperative myocardial damage. Clinical results at one year are influenced by completeness of revascularization, graft patency and perioperative myocardial infarction. The tendency of symptoms to recur in patients who are free from angina one year after intervention, is similar in the various subgroups and is adversely influenced only by perioperative myocardial damage. These results show that coronary artery bypass grafting has a true clinical impact, although symptomatic improvement is somewhat temporary.