Magnetic resonance imaging of athlete's heart: myocardial mass, left ventricular function, and cross-sectional area of the coronary arteries

To evaluate left ventricular myocardial mass and function as well as ostial coronary artery cross-sectional area in endurance athletes, an athlete group of 12 highly trained rowers and a control group of 12 sedentary healthy subjects underwent MR examination. An ECG-gated breath-hold cine gradient-echo sequence was used to calculate myocardial mass, end-diastolic and end-systolic volumes, stroke volume, and cardiac output, all related to body surface area, as well as ejection fraction. A 3D fat-saturated ECG- and respiratory-triggered navigator echo sequence was used to evaluate coronary arteries: left main (LM), left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA). Cross-sectional area was calculated and divided for body surface area. Myocardial mass was found significantly larger in athlete group than in control group (p = 0.0078), the same being for end-diastolic volume (p = 0.0078), stroke volume (p = 0.0055), LM (p = 0.0066) and LAD (p = 0.0129). No significant difference was found for all the remaining parameters. Significant correlation with myocardial mass was found for LM (p < 0.001) and LAD (p = 0.0340), not for LCx and RCA. Magnetic resonance imaging is a useful tool in evaluating the myocardial hypertrophy and function of athlete's heart. Magnetic resonance angiography is a valuable noninvasive method to visualize the correlated cross-sectional area increase of the left coronary artery system.

Three-dimensional, navigator-echo MR coronary angiography in detecting stenoses of the major epicardial vessels, with conventional coronary angiography as the standard of reference

PURPOSE

To test three-dimensional (3D), navigator-echo magnetic resonance (MR) coronary angiography in detecting stenoses of the coronary arteries.

MATERIALS AND METHODS

Forty-two patients (age range, 50-79 years) underwent MR coronary angiography (1.5 T). A navigator-echo sequence was used. Two or three 15% overlapped transverse slabs were acquired. Data were analyzed by readers blinded to conventional coronary angiographic results. On conventional coronary angiograms, coronary arterial stenoses of 50% or greater narrowing were considered significant. On MR coronary angiograms, the major coronary vessels were subdivided into proximal (within 5 cm) and distal (beyond 5 cm) segments, except for the left main vessel. Stenoses of 50% or greater were identified on reformatted multiplanar MR coronary angiograms.

RESULTS

Three MR coronary angiographic examinations were aborted because of patient claustrophobia; 39 of 39 left main, 117 of 117 proximal, and 78 of 117 distal segments were visualized. MR coronary angiography showed a sensitivity of 82% (95% CI: 73%, 91%) and a specificity of 89% (95% CI: 85%, 94%) in overall stenoses identification, of 90% (95% CI: 81%, 99%) and 90% (95% CI: 83%, 96%) for proximal segments, and of 68% (95% CI: 50%, 86%) and 81% (95% CI: 71%, 92%) for distal segments, respectively.

CONCLUSION

Navigator-echo, 3D MR coronary angiography is a promising sequence for assessing coronary arterial stenoses, but further improvements are required for distal segments.

Fc-mediated nonspecific binding between fibronectin-binding protein I of Streptococcus pyogenes and human immunoglobulins

Fibronectin-binding protein I (SfbI) from Streptococcus pyogenes plays a key role in bacterial adhesion to, and invasion of, eukaryotic cells. In addition, SfbI exhibits a considerable potential as mucosal adjuvant and can trigger polyclonal activation of B cells. Here, we report that SfbI is also capable of binding human IgG in a nonimmune fashion. SfbI was reactive with IgG1, IgG2, IgG3, and IgG4 isotypes (type IIo IgG-binding profile). The affinity constant (Kd) of the SfbI-IgG interaction was in the range of 1-2 x 10(-5) M. Further studies demonstrated that the SfbI binding was mediated by the Fc component of the IgG molecule. Experiments performed using purified recombinant proteins spanning different domains of SfbI showed that the IgG-binding activity was restricted to the fibronectin-binding domains, and in particular to the fibronectin-binding repeats. Finally, the presence of recombinant SfbI resulted in an impairment of both phagocytosis of IgG-coated RBCs and Ab-dependent cell cytotoxicity by macrophages. These results demonstrated for the first time that, in addition to its major role during the colonization process, SfbI may also favor bacterial immune evasion after the onset of the infection by interfering with host clearance mechanisms.

Protective immune response against Streptococcus pyogenes in mice after intranasal vaccination with the fibronectin-binding protein SfbI

Despite the significant impact on human health of Streptococcus pyogenes, an efficacious vaccine has not yet been developed. Here, the potential as a vaccine candidate of a major streptococcal adhesin, the fibronectin-binding protein SfbI, was evaluated. Intranasal immunization of mice with either SfbI alone or coupled to cholera toxin B subunit (CTB) triggered efficient SfbI-specific humoral (mainly IgG) and lung mucosal (14% of total IgA) responses. CTB-immunized control mice were not protected against challenge with S. pyogenes (90%-100% lethality), whereas SfbI-vaccinated animals showed 80% and 90% protection against homologous and heterologous challenge, respectively. Multiple areas of consolidation with diffused cellular infiltrates (macrophages and neutrophils) were observed in lungs from control mice; the histologic structure was preserved in SfbI-vaccinated animals, which occasionally presented focal infiltrates confined to the perivascular, peribronchial, and subpleural areas. These results suggest that SfbI is a promising candidate for inclusion in acellular vaccines against S. pyogenes.

Streptococcal invasion

The genus Streptococcus consists of large number of species many of which are pathogenic to humans and animals. Although streptococci have long been considered as extracellular pathogens, they are capable of causing serious invasive infections such as necrotizing fasciitis and meningitis. Streptococcal invasion, therefore, has been a focus of many studies in recent years. Streptococci are efficiently internalized by nonprofessional phagocytes and the current research interest has shifted to determine the role of this invasion in the natural infection process. Moreover, characterization of bacterial and eukaryotic components involved in the uptake process might be useful in developing new strategies for combating streptococcal infections.

Magnetic resonance spectroscopy of ischemic heart disease

An overview of the basic knowledge necessary to understand the procedure of Magnetic Resonance Spectroscopy of the myocardium and its most significant applications in the study of ischemic heart disease, is presented, with reference to the personal experience. The chemical shift phenomenon, the main techniques of spectroscopic localization and the general aspects of myocardial 31P and 1H Magnetic Resonance Spectroscopy, including proton decoupling and magnetization transfer, are illustrated. Postprocessing techniques before and after Fourier transform are mentioned. 31P Magnetic Resonance Spectroscopy allows the noninvasive assessment of the metabolism of high energy phosphates, PCr/ATP ratio in particular, in the in vivo myocardial tissue with significant applications in the diagnostic approach to ischemic patients with the support of provocative tests (dobutamine). 1H Magnetic Resonance Spectroscopy allows similar evaluations based on the peak of total creatinine.

Magnetic resonance assessment of coronary artery bypass grafts

The increasingly widespread use of myocardial revascularization by aortocoronary bypass grafts and the frequent need for their angiographic control require noninvasive imaging procedures able to provide reliable information on their performance. After an overview of angiography as gold standard and the different imaging procedures of aortocoronary bypass grafts alternative to MRI, echocardiography, nuclear cardiology, X-ray or electron beam ultrafast CT, main MRI procedures for the study of aortocoronary bypass, are illustrated together with the results of the personal experience as those of navigator echo technique provided with cardiac and respiratory synchronization (91% sensitivity for aortocoronary bypass occlusion and 97% specificity for patency). In the near future, hardware and software refinements, intravascular contrast media and the application to aortocoronary bypass grafts of flowmetric techniques of phase-velocity mapping will enable the evaluation of bypass stenosis and distal coronary arteries as well as a complete functional graft assessment.

Invasion and survival of Streptococcus pyogenes in eukaryotic cells correlates with the source of the clinical isolates

The invasiveness of 96 group A streptococci (GAS) isolates (56 from throat or skin and 40 from blood) were analyzed. GAS invasion strongly correlated with the source of the isolates, whereas no correlation was observed with the Vir type. Isolates from throat or skin exhibited the highest invasion efficiency (57% were between 0.1% and 10%). In contrast, 77.5% of the blood isolates were noninvasive (efficiency <0.01%) and only 7.5% exhibited rates comparable to those of throat or skin isolates (>0.1%). Immunofluorescence studies of 34 selected isolates showed that attachment and invasion are strain-related. Although isolates with high invasiveness usually exhibit high attachment, isolates that showed high attachment and no invasion or poor attachment and efficient internalization were identified. The ability of GAS to invade and survive within eukaryotic cells may provide bacteria a sure niche, in which they are protected against host defense mechanisms or antimicrobial agents favoring their local persistence.

The fibronectin-binding protein of Streptococcus pyogenes, SfbI, is involved in the internalization of group A streptococci by epithelial cells

Streptococcus pyogenes organisms (group A streptococci) are considered to be highly adhesive extracellular pathogens. However, it has recently been reported that S. pyogenes has the capacity to efficiently invade eukaryotic cells. In this study, we demonstrate that the interaction of S. pyogenes fibronectin-binding protein (SfbI) with fibronectin on nonphagocytic HEp-2 cells triggers bacterial internalization. Blocking of the SfbI adhesin by either antibodies against the whole protein or antibodies against the fibronectin-binding domains of SfbI, as well as pretreatment of HEp-2 cells with purified SfbI protein, prevents both S. pyogenes attachment and internalization. Inert latex beads precoated with the purified SfbI protein are ingested by eukaryotic cells, demonstrating that SfbI is per se enough to trigger the internalization process. Experiments performed with a recombinant SfbI domain encompassing the two fibronectin-binding regions of the SfbI molecule demonstrated that these binding regions are essential and sufficient to activate uptake by HEp-2 cells. These results demonstrate that the fibronectin-binding protein SfbI is involved in both S. pyogenes' attachment to and ingestion by HEp-2 cells and contribute to elucidation of the underlying molecular events leading to eukaryotic cell invasion by S. pyogenes.

Bacteria involved in the blockage of biliary stents and their susceptibility to antibacterial agents

Endoscopically inserted stents are used for the palliation of obstructive jaundice, but infections and blockage of these stents by biliary sludge and bacterial biofilm may develop, presenting major complications. To analyze which bacteria are involved in this process, 25 biliary stents were examined. Eighty-one microorganisms were isolated: 59 gram-negative bacteria (54 Enterobacteriaceae and 5 Pseudomonas aeruginosa), 19 gram-positive bacteria (all Enterococcus spp.), and 3 Candida albicans. The Enterobacteriaceae were sensitive to netilmicin (100%), imipenem (98%), ciprofloxacin (96%), cefotaxime (69%), and piperacillin (57%), whereas Enterococcus spp. were sensitive to imipenem (79%), piperacillin (75%), ciprofloxacin (63%), and ampicillin (58%). The unpredictable aetiology and high rates of antibiotic resistance suggest that bacteriological monitoring is mandatory to avoid treatment failures in these patients.

Right ventricular dysplasia as a generalized cardiomyopathy? findings on magnetic resonance imaging

The aim of our study was to define cardiac morphological and functional abnormalities of right ventricular dysplasia by magnetic resonance imaging. Twenty-two healthy volunteers (age, 37.7 +/- 14.2 years) free of cardiac or respiratory diseases (group I) and 12 patients (age, 41.9 +/- 15.8 years) with clinical, electrophysiological and cineangiographic diagnosis of right ventricular dysplasia (group II) underwent magnetic resonance imaging at 0.2 Tesla. End-diastolic diameter, trabecular disarray and segmental wall motion abnormalities were evaluated for the right ventricle as were adipose replacement and fractional shortening for both ventricles. The right ventricular end-diastolic diameter was significantly enlarged in group II (P = 0.0023). Right ventricular trabecular disarray was mild in two group I subjects, and moderate in seven and massive in five group II patients. Right ventricular systolic bulges were found in seven group II patients, aneurysms in five. Excellent agreement was found between magnetic resonance imaging and cineangiography for bulges, aneurysms and tricuspid regurgitation (P < 0.0001). On spin-echo images, signal hyperintensities, due to adipose replacement, were found in 44 cardiac regions in group II: right ventricular outflow tract (12), sub-tricuspid posterobasal region (8), right ventricular apex (9), right ventricular anterior wall (6), interventricular septum (4), left ventricular lateral wall (4), left ventricular apex (1). Significant signal-to-noise ratio differences were found between group II abnormal areas and group I myocardial tissue for the right (P < 0.0001) and left ventricles (P = 0.0006). Fractional shortening in the right and left ventricles were significantly reduced in group II (P = 0.0002 and P = 0.00016, respectively). Magnetic resonance imaging can be considered a very useful diagnostic tool for the detection of features typical of right ventricular dysplesia, such as adipose replacement, trabecular disarray, bulges and aneurysms and provides useful information about cardiac function and regional wall motion. It indicates that left ventricular involvement occurs in a significant fraction of patients, and suggests that right ventricular dysplasia may be a generalized cardiomyopathy.

[Retrospective study of 135 cases of lung neoplasms diagnosed between 1983 and 1993]

The authors expose the results of a retrospective study concerning 135 cases of neoplasia diagnosed by their Department between 1983 and 1993. The patients' age, their sex, their consume of tobacco, their survival from the moment of the diagnosis have been considered in the study. Likewise the clinical instrumental researches and their reliability, the different incidence of the examined pathology in the first and in the second part of the period considered. It is emerged from the collected data, that also in our territory there is an increasing tendency in the incidence of lung neoplasia, a generally short survival after the diagnosis, a strong prevalence of smokers among those people affected from the disease, the difficulty of an early diagnosis due to scarce specificity of the commonest symptoms. The final auspicious is that a more incisive diligence in prevention and significant progresses in clinical pharmacological research may determine a notable reduction of the incidence of such a dramatic pathology.

The coronary subclavian steal syndrome: an uncommon sequel to internal mammary-coronary artery bypass surgery

Coronary subclavian steal syndrome is a possible sequel in patients who have undergone myocardial revascularization with an internal mammary artery. We report a case of this syndrome in a 67-years-old man. In 1990 he underwent a quadruple bypass: aorta-obtuse margin, aorta-right coronary (two sequential), internal artery mammary-descending coronary artery. Three months later he started to have angina pectoris. In April 1992 an aortic arch angiography and a coronary angiography were performed. The examination showed an occlusion of the left subclavian artery at its origin. The artery was opacified countercurrently by the left vertebral artery but the left mammary artery was not opacified. Left coronary angiography showed a very severe disease of left anterior descending coronary artery and retrograde flow through the anastomosis in the left mammary artery. The patient underwent a left common carotid-subclavian artery bypass operation using a 6 mm vascutex graft. Eighteen months later the patient is doing well without angina pectoris and with very little alteration of the perfusion in the left frontal lobe observed by SPECT neuroimaging with a lipophilic tracer (99mTc-HMPAO). We think that the coronary-subclavian steal syndrome can be treated successfully with low risk by means of common carotid-subclavian artery bypass.

[The role of stabilometry in assessing the correlations between craniomandibular disorders and equilibrium disorders]

We examined three groups: 29 patients suffering from balance disorders and craniomandibular disorders but from vestibular disease; 21 patients suffering from balance disorders, craniomandibular disorders and vestibular disease; 26 patients suffering from craniomandibular disorders but not from vestibular disease or balance disorders. All cases were examined by the odontologist and otoneurologist and tested by computerized stabilometry; they were reexamined after six months of therapy by an occlusal stabilization splint. The static analysis of the results show a significative reduction of the postural oscillations in all patients.

[The use of computer-assisted stabilometry in the diagnosis of craniomandibular disorders]

The aim of this study was to evaluate the influence of the cervical region and the stomatognathic system on the balance control. We examined 35 healthy subjects and 201 balance disorder patients; of the 201 patients 60 suffered also from craniomandibular disorders (CMD) and 40 from cervical rachis disease. All cases were tested by computerized stabilometry executed in Romberg position: with closed eyes, retroflexed head and two cotton roles between the dental arches. The results show that cervical rachis disease and stomatognathic dysfunction have a significative influence on the balance control; however, this influence is smaller than that of vestibular disease; moreover, the computer stabilometry allows to measure the degree of ascending or descending correlation between the posture and stomatognathic system.

[Heart involvement in thymic neoformations: the role of magnetic resonance tomography. Experience in 3 cases]

Three paracardiac masses (1 thymic cyst, 2 thymomas) were studied by magnetic resonance imaging (MRI) using spin-echo, multi-echo, and gradient-echo sequences (cine-MR). MRI showed: a pedunculate cystic lesion, typical for thymic origin, in Case 1; cardiac and pulmonary infiltration, and 3 intracardiac metastases, in Case 2; cardiovascular compression but not infiltration, in Case 3. In 3/3 cases MRI was superior to transthoracic echocardiography (TTE), and in 2/2 MRI was superior to computed tomography (CT), not performed in Case 2 (allergy to contrast agents). MRI may be considered the most important technique to evaluate cardiovascular involvement by thymic neoplasms. MRI should be performed after TTE and makes CT unnecessary.

MRI in hypertrophic cardiomyopathy: a morphofunctional study

OBJECTIVE

We compared MRI with two-dimensional echocardiography (2dE) and Doppler echocardiography to determine the diagnostic role of MRI in hypertrophic cardiomyopathy (HCM).

MATERIALS AND METHODS

Twenty-three patients with 2dE diagnosis of HCM were examined with MRI; 12 of 23 patients were also studied by color (cDE) and continuous wave (cwDE) Doppler echocardiography. Morphologic information and diastolic heart wall thickness were obtained by SE sequences; functional study was performed by gradient echo sequences (cine MR).

RESULTS

The correlation between MR, SE sequences and 2dE was better for septal (r = 0.930, p < 0.01) than for posterolateral (r = 0.739, p < 0.01) wall thickness. The assessment of the distribution of the hypertrophy was changed by MR in five cases. Cine MR functional study showed a systolic subaortic signal void (dynamic obstruction) in 12 of 22 patients and a systolic left atrial signal void (mitral regurgitation) in 17 of 22. Systolic wall thickening was studied by cine MR and 2dE in 11 patients: A good correlation was found for septum (0.01 < p < 0.05) and a poor one for posterolateral wall (p > 0.05). The cine MR and cDE turbulence duration in the left ventricle and atrium showed excellent correlation (p < 0.01). Good agreement was found between the duration of subaortic turbulence (cine MR or cDE) and the pressure gradient (cwDE) (p < 0.01 and 0.01 < p < 0.05, respectively) and between cine MR and cDE semiquantitative estimate of the mitral regurgitation (p < 0.01). In all patients with subaortic MR signal void studied with cwDE, a pressure gradient was present.

CONCLUSION

Magnetic resonance imaging can play an important role in the diagnosis of HCM after 2dE-DE.