Comparison of the predation rate of freshwater cyclopoid copepod species on larvae of the mosquito Culex pipiens

The predation rates of six copepod species: Acanthocyclops robustus G.O. Sars, Eucyclops neumani Pesta, Macrocyclops albidus Jurine, Mesocyclops longisetus Thibaud, Metacyclops grandis Kiefer and Metacyclops mendocinus Wierzejski (Copepoda: Cyclopidae) on mosquito larvae, Culex pipiens Linnaeus (Diptera: Culicidae) were assessed. Experiments consisted of 24-h incubations of one copepod and 10 larvae without extra food at 16 degrees C and 26 degrees C. Nine replicates were considered for each species and temperature. Predation rates (larvae per copepod per day) were: M. mendocinus (1.8), M. grandis (3.1), E. neumani (3.8), A. robustus (3.8), Ma. albidus (6.1) and Me. longisetus (7.0). There was a significant effect of both species and temperature on predation: all species experienced higher predation at 26 degrees C than at 16 degrees C, except for A. robustus whose predation rate was similar at both temperatures. These observations are consistent with previous results that point to Macrocyclops and Mesocyclops genera as important larval predators and suggest the need for field trials to evaluate the response of Ma. albidus and Me. longisetus under natural conditions in Uruguay.

Unexpected mechanical bileaflet valve thrombosis in mitral position: what is better to do, re-replacement or thrombolysis

BACKGROUND AND AIMS

The longevity of the mechanical heart valve prosthesis is an advantage when compared with its biological counterpart, although the former carries a risk of thrombosis depending on valve design, materials and host-related interface; therefore, a patient with a mechanical valve prosthesis, particularly in mitral position, is at risk for systemic thromboembolism even when properly anticoagulated.

PATIENTS AND METHODS

We report a case of a 60-year-old woman who underwent a mitral valve replacement with a St. Jude Medical (SJM) standard bileaflet mechanical heart valve.

RESULTS

On the twelfth post-operative day a primary thrombosis with blockage of the anterior valve leaflet occurred.

CONCLUSIONS

Aware of the risk of recurrent thromboembolism in this special clinical framework and possible cerebral bleeding in case of thrombolysis, we replaced the prosthesis with a new biologic porcine valve, the SJM Biocor.

Congenital coronary artery anomalies as an important cause of sudden death in the young

Unlike sudden cardiac death in adults and elderly people, sudden cardiac death in young people (< or =35 years) is often triggered by nonatherosclerotic coronary artery disease, either acquired (arteritis, spontaneous dissection) or congenital in origin. In particular, congenital coronary artery malformations were reported as the cause of 5%-35% of sudden death in the young, and a wide range of abnormalities including anomalous origin, course, or both were described.

Arrhythmogenic right ventricular cardiomyopathy: current diagnostic and management strategies

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease of unknown etiology characterized by the peculiar right ventricular (RV) involvement. Distinctive pathologic features are myocardial atrophy and fibro-fatty replacement of the RV free wall, and clinical presentation is usually related to ventricular tachycardias with a left bundle branch block pattern or ventricular fibrillation leading to cardiac arrest, mostly in young people and athletes. Later in the disease evolution, progression and extension of RV muscle disease and left ventricular involvement may result in right or biventricular heart failure. The diagnosis of ARVC may be difficult because of several problems with specificity of ECG abnormalities, different potential etiologies of ventricular arrhythmias with a left bundle branch morphology, assessment of RV structure and function, and interpretation of endomyocardial biopsy findings. Therefore, standardized diagnostic criteria have been proposed by the Study Group on ARVC of the European Society of Cardiology. According to these guidelines, the diagnosis of ARVC is based on the presence of major and minor criteria encompassing electrocardiographic, arrhythmic, morphofunctional, histopathologic, and genetic factors. Since the assessment of sudden death risk in patients with ARVC is still not well established, there are no precise guidelines to determine which patients need to be treated and what is the best management approach. The therapeutic options include beta-blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator (ICD). The ICD is the most effective safeguard against arrhythmic sudden death. However, its precise role in changing the natural history of ARVC by preventing sudden and nonsudden death needs to be evaluated by a prospective study of a large series of patients. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In cases of refractory congestive heart failure, patients may become candidates for heart transplantation.

Dispersion of ventricular depolarization-repolarization: a noninvasive marker for risk stratification in arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

We retrospectively investigated the value of clinical and ECG findings as well as QT-QRS dispersion in predicting the risk of sudden death in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS AND RESULTS

Duration and interlead variability of the QT interval and QRS complex were measured manually from standard ECGs in 20 sudden death victims with ARVC diagnosed at autopsy (group I), in 20 living ARVC patients with sustained ventricular tachycardia (group II), in 20 living ARVC patients with </=3 consecutive premature ventricular beats (group III), and in 20 control subjects (group IV). QT and QRS dispersions were greater in group I (77.5+/-10.6 ms for QT and 45.7+/-8.1 ms for QRS) compared with group II (64.5+/-13.9 ms for QT [P=0.001] and 33.5+/-8.7 ms for QRS [P=0.0004]) and in group II compared with group III (48+/-8.9 ms for QT [P<0.0001] and 28+/-5.2 ms for QRS [P<0.0001]) and group IV (33.5+/-4.8 ms for QT [P<0.0001] and 18.5+/-3.6 ms for QRS [P<0.0001]). Negative T wave beyond V(1) and syncope were statistically more frequent in group I (P=0.02 and P=0.007, respectively). On multivariate analysis, QRS dispersion remained an independent predictor of sudden death (P<0.0001), followed by syncope (P=0.09). In assessing risk of sudden death, QRS dispersion >/=40 ms had a sensitivity and specificity of 90% and 77%, respectively; QT dispersion >65 ms, 85% and 75%, respectively; negative T wave beyond V(1), 85% and 42%, respectively; and syncope, 40% and 90%, respectively.

CONCLUSIONS

QRS dispersion (>/=40 ms) was the strongest independent predictor of sudden death in ARVC. Syncope, QT dispersion >65 ms, and negative T wave beyond V(1) refined arrhythmic risk stratification in these patients.

Sudden cardiac death in young people with apparently normal heart

OBJECTIVE

The aim of the present study was to assess the prevalence of subtle morphologic substrates, clinically unrecognizable, underlying sudden cardiac death (SCD) in young people with apparently normal heart.

METHODS

In the time interval 1979--1998, 273 consecutive cases of SCD in young people (< or =35 years) which occurred in the Veneto Region of Italy were prospectively studied. Following exclusion of extracardiac causes of sudden death, the heart was examined according to a detailed morphologic protocol consisting of macroscopic and histologic examination, including study of the specialized conduction system by serial sections.

RESULTS

At macroscopic examination, 197 SCD victims (72%) had an overt underlying structural heart disease such as cardiomyopathy in 56, obstructive coronary atherosclerosis in 54, valve disease in 32, non-atherosclerotic coronary artery disease in 28, aortic rupture in 13, postoperative congenital heart disease in five, and other disease in nine. The remaining 76 cases (28%) (50 males and 26 females, aged 4-35 years, mean 23+/-5 years) had a macroscopically normal heart. A total of 28 of them (37%) had experienced one or more of the following prodroma: syncope, palpitations or both in 20, ECG abnormalities in 18 and arrhythmias in ten. In 79% of them, histologic examination disclosed concealed pathologic substrates consisting of focal myocarditis in 27 cases, regional arrhythmogenic right ventricular cardiomyopathy, mostly localized to RV outflow tract, in nine, and conduction system abnormalities in 24 (leading to ventricular preexcitation in 18 and heart block in six). In 16 hearts (6%) there was no evidence of structural heart disease even after histologic study.

CONCLUSION

Macroscopic heart features were normal in nearly one-third of young SCD victims. In 79% of them, however, histologic study unmasked concealed pathologic substrates such as focal myocarditis or cardiomyopathy and conduction system diseases. A total of 16 victims (6%) had no evidence of structural heart disease and the mechanism of their SCD remained unexplained.

Clinical diagnosis and management strategies in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease, often familial, that is characterized by fibro-fatty replacement of the right ventricular (RV) myocardium. The most common clinical manifestations of ARVC consists of ventricular arrhythmias of RV origin, which may lead to sudden death mostly in young people and athletes, electrocardiograph depolarization/repolarization changes mostly localized to right precordial leads, and global and/or regional dysfunction and structural alterations of the RV. The diagnosis of ARVC may be difficult due to several problems with the specificity of the electrocardiograph abnormalities, the different potential etiologies of ventricular arrhythmias with a left bundle branch morphology, the assessment of the RV structure and function, and the interpretation of endomyocardial biopsy findings. Therefore, standardized diagnostic criteria have been proposed by the Study Group on ARVC of the European Society of Cardiology. According to these guidelines, the diagnosis of ARVC is based on the presence of major and minor criteria encompassing electrocardiograph, arrhythmic, morphofunctional, histopathologic, and genetic factors. Because the assessment of sudden death risk in patients with ARVC is still not well established, there are no precise guidelines to determine which are the patients who need to be treated and which is the best management approach. The therapeutic options include beta blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator. The implantable defibrillator is the most effective safe-guard against arrhythmic sudden death. However, its precise role in changing natural history of ARVC by preventing sudden and nonsudden death needs to be evaluated by a prospective study of a large series of patients. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In case of refractory congestive heart failure, the patients may become candidates for heart transplantation.

Cardiogenic shock due to metastatic cardiac lymphoma: still a diagnostic and therapeutic challenge

Myocardial involvement by metastatic lymphoma progressively leads to severe contractile impairment and fatal outcome. Correct diagnosis is often late due to misleading presentation signs. We report on a case of extensive cardiac involvement of a T-cell thymic lymphoma in a young woman, necessitating emergent extracorporeal membrane oxygenation (ECMO) circulatory support, with satisfactory hemodynamic recovery and subsequent ECMO weaning. Unfortunately, the following clinical course was rapidly fatal. This case seems to confirm that early aggressive instrumental diagnosis is crucial before severe myocardial impairment can prevent any therapeutic option. Extensive use of transesophageal echocardiographic examination and early endomyocardial biopsy are highly recommended.

Right bundle branch block, right precordial st-segment elevation, and sudden death in young people

BACKGROUND

Patients with the ECG pattern of right bundle branch block and right precordial ST-segment elevation may experience sudden death in the setting of either arrhythmogenic right ventricular cardiomyopathy (ARVC) or a functional electrical disorder such as Brugada syndrome.

METHODS AND RESULTS

Among a series of 273 young (</=35 years) victims of cardiovascular sudden death who were prospectively studied from 1979 to 1998 in the Veneto Region of Italy, 12-lead ECG was available in 96 cases. Thirteen (14%; 12 males and 1 female aged 24+/-8 years) had right precordial ST-segment elevation, either isolated (9 cases) or associated with right bundle branch block (4 cases). At autopsy, all patients had ARVC (92%) except one, who had no evidence of structural heart disease. Compared with the 19 young sudden death victims with ARVC and no ST-segment abnormalities from the same series, those with AVRC and right precordial ST-segment elevation included fewer competitive athletes (17% versus 58%; P:=0.03), more often died suddenly at rest or during sleep (83% versus 26%; P:=0.003), and showed serial ECG changes over time (83% versus 0; P:=0.015), polymorphic ventricular tachycardia (33% versus 0; P:=0.016), and predominant fatty replacement of the right ventricular anterior wall (58% versus 21%; P:=0.05),

CONCLUSIONS

Right precordial ST-segment elevation was found in 14% of young sudden death victims with available ECG. It mostly reflected underlying ARVC with predominant right ventricular anterior wall involvement and characterized a subgroup of patients who share with Brugada patients the propensity to die from non-exercise-related cardiac arrest and to exhibit dynamic ECG changes and polymorphic ventricular tachycardia.

Identification of mutations in the cardiac ryanodine receptor gene in families affected with arrhythmogenic right ventricular cardiomyopathy type 2 (ARVD2)

Arrhythmogenic right ventricular dysplasia type 2 (ARVD2, OMIM 600996) is an autosomal dominant cardiomyopathy, characterized by partial degeneration of the myocardium of the right ventricle, electrical instability and sudden death. The disease locus was mapped to chromosome 1q42--q43. We report here on the physical mapping of the critical ARVD2 region, exclusion of two candidate genes (actinin 2 and nidogen), elucidation of the genomic structure of the cardiac ryanodine receptor gene (RYR2) and identification of RYR2 mutations in four independent families. In myocardial cells, the RyR2 protein, activated by Ca(2+), induces the release of calcium from the sarcoplasmic reticulum into the cytosol. RyR2 is the cardiac counterpart of RyR1, the skeletal muscle ryanodine receptor, involved in malignant hyperthermia (MH) susceptibility and in central core disease (CCD). The RyR2 mutations detected in the present study occurred in two highly conserved regions, strictly corresponding to those where mutations causing MH or CCD are clustered in the RYR1 gene. The detection of RyR2 mutations causing ARVD2, reported in this paper, opens the way to pre-symptomatic detection of carriers of the disease in childhood, thus enabling early monitoring and treatment.

Ventricular preexcitation in children and young adults: atrial myocarditis as a possible trigger of sudden death

BACKGROUND

Sudden death (SD) in ventricular preexcitation (VP) syndrome is believed to be the result of atrial fibrillation with rapid ventricular response over the accessory pathway. Previous reports are anecdotal and often lack autopsy validation.

METHODS AND RESULTS

Prevalence and clinicopathological features of VP were investigated in a series of 273 SDs in children and young adults (aged <or=35 years). Site of accessory atrioventricular (AV) connection was predicted by 12-lead ECG. Right and left AV ring together with the sinoatrial and AV septal junction were studied in serial histological sections. Ten patients (3.6%; male, mean age 24+/-7 years) had VP: 8 had Wolff-Parkinson-White (WPW) and 2 had Lown-Ganong-Levine (LGL) syndrome. Six patients had previous symptoms, and SD occurred at rest in all but 1. Pathological substrates of LGL consisted of AV-node hypoplasia and right-sided atrio-Hisian tract, respectively. In the 8 WPW patients, 10 total accessory AV pathways consisting of ordinary myocardium were found (7 left lateral, 2 right posterolateral, and 1 septal). These pathways were close to the endocardium (mean distance, 750+/-530 microm) and 310+/-190 microm thick. In 4 WPW patients (50%), isolated acute atrial myocarditis was found, which was polymorphous in 1 and lymphocytic in 3.

CONCLUSIONS

VP accounted for 3.6% of SD in young people and was not preceded by warning symptoms in 40%. A left accessory pathway was the most frequent substrate, and its subendocardial location supports the feasibility of catheter ablation. Isolated atrial myocarditis may act as a trigger of paroxysmal atrial fibrillation that leads to SD.

Is arrhythmogenic right ventricular cardiomyopathy a paediatric problem too?

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease that is often familial, characterized by arrhythmias of right ventricular origin, due to transmural fatty or fibrofatty replacement of atrophic myocardium. ARVC is usually diagnosed in the clinical setting between 20 and 40 years of age. The disease is seldom recognised in infancy or under the age of 10, probably because the clinical expression of the disease is normally postponed to youth and adulthood. This review focuses its attention to the pediatric age, defined as the period of life raging from birth to 18 years. During this span of life, ARVC is not so rare as previously supposed and can be identified by applying the same diagnostic criteria proposed for the adult. Ventricular arrhythmias range from isolated ventricular arrhythmias to sustained ventricular tachycardia and fibrillation. Children and adolescents with ARVC must be carefully evaluated and followed-up especially when a family positive history is present, taking into account the high probability during this life-period that asymptomatic affected patients become symptomatic or that arrhythmias worsen during follow-up. The recent identification of the first defective gene opens new avenues for the early identification of affected subjects even when asymptomatic.

Clinical profile and long-term follow-up of 37 families with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVES

We sought to define the clinical picture and natural history of familial arrhythmogenic right ventricular cardiomyopathy (ARVC).

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy is a myocardial disease, often familial, clinically characterized by the impending risk of ventricular arrhythmias and sudden death.

METHODS

Thirty-seven ARVC families of northeast Italy were studied. Probands had a histologic diagnosis of ARVC, either at autopsy (19 families) or endomyocardial biopsy (18 families). Protocol of the investigation included basal electrocardiogram (ECG), 24-hour ECG, signal-averaged ECG, stress test and two-dimensional Doppler echocardiography. Invasive evaluation was performed when deemed necessary.

RESULTS

Of the 365 subjects, 151 (41%) were affected, 157 (43%) were unaffected, 17 (5%) were healthy carriers, and 40 (11%) were uncertain. Mean age at diagnosis was 31+/-13 years. By echocardiography, 64% had mild, 30% had moderate, and 6% had severe form. Forty percent had ventricular arrhythmias, 49 were treated with antiarrhythmic drugs, and two were treated with implantable cardioverter defibrillators. Sport activity was restricted in all. Of the 28 families who underwent linkage analysis, 6 mapped to chromosome 14q23-q24, 4 to 1q42-q43, and 4 to 2q32.1-q32.3. No linkage with known loci was found in four families and 10 had uninformative results. During a follow-up of 8.5+/-4.6 years, one patient died (0.08 patient/year mortality), and 15 developed an overt form of ARVC.

CONCLUSIONS

Arrhythmogenic right ventricular cardiomyopathy is a progressive disease appearing during adolescence and early adulthood. Systematic evaluation of family members leads to early identification of ARVC, characterized by a broad clinical spectrum with a favorable outcome. In the setting of positive family history, even minor ECG and echocardiographic abnormalities are diagnostic.

Spontaneously occurring arrhythmogenic right ventricular cardiomyopathy in the domestic cat: A new animal model similar to the human disease

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary myocardial disease of incompletely resolved pathogenesis and is a largely unappreciated cause of sudden death in the young.

METHODS AND RESULTS

Clinical features of 12 domestic cats with ARVC (7 male; 1 to 20 years old, mean 7.3+/-5.2 years) were right-sided congestive heart failure (n=8), supraventricular tachyarrhythmias (n=5), ventricular tachycardia (n=3), polymorphic ventricular arrhythmias (n=6), and right bundle-branch block (n=5). ARVC was suspected in all 8 cats examined with echocardiography by marked enlargement of the right ventricle (RV) and right atrium and tricuspid regurgitation. Eight died of cardiovascular disease and 4 died of noncardiac conditions. At autopsy, hearts of ARVC cats were characterized grossly by moderate-to-severe RV cavity enlargement and wall thinning (n=12) and apical aneurysm formation (n=6). Histology demonstrated pronounced RV lesions in all 12 ARVC cats, including marked myocardial injury (myocyte death and atrophy) and repair (fibrous and/or fatty replacement). Injury and repair were also evident in the left ventricle (LV) in 10 cats, and 2 had involvement of both atria. Myocarditis was present in 10 of the 12 ARVC cats. Apoptosis was detected in 9 ARVC cats (mean apoptotic index, 28+/-23% RV, 21+/-19% LV, and 17+/-15% ventricular septum) but not in controls.

CONCLUSIONS

In the common domestic cat, we identified a clinically relevant cardiomyopathy that closely mimics ARVC in humans. This unique feline model of human disease will be relevant to defining pathogenesis and investigating mechanisms responsible for disease progression in ARVC.

Hypertrophic cardiomyopathy and sudden death in the young: pathologic evidence of myocardial ischemia

The mechanism underlying cardiac arrest in patients with hypertrophic cardiomyopathy (HC) is intriguing. In the clinical setting, myocardial ischemia has long been incriminated, particularly in the young. Among 274 cardiovascular sudden deaths in the young (< or = 35 years), 19 (7.0%), 14 males and 5 females, median age 23 years, had HC. Familial occurrence of HC was ascertained in 3 (16%). SD occurred on effort in 6 (31%). Previous syncope occurred in 5 and palpitations in 3. Basal electrocardiogram (ECG) was abnormal in 7 of 8 available cases. Hypertrophy was septal asymmetric in 14. Gross examination showed large isolated or multiple septal scars in 11 (58%); at histomorphometry, the mean percent area of fibrosis of the septal myocardium was 18.6 +/- 6. Four showed a deep intramyocardial course of the left anterior descending coronary artery. At histology, myocardial disarray involved 30 +/- 16% of the septal myocardium; evidence of acute-subacute myocardial necrosis was present in 14 (74%), 1 of them with a regional acute myocardial infarction. By comparing hearts with (n = 11) and without (n = 8) areas of scar-type fibrosis, we found a statistically significant difference in terms of age (25.5 +/- 5.4 v 15.5 +/- 12.4 years, P = .04), septal thickness (25.4 +/- 5.4 v 15.4 +/- 4.9 mm, P < .001), percent increase of septal thickness versus normal value for age and sex (46.2 +/- 15 v 25.2 +/- 13.6%, P < .01) and mean score of small vessel disease (1.7 +/- 0.4 v 1.2 +/- 0.4, P = .04). Linear regression analysis showed a positive correlation of percent area of replacement fibrosis with septal thickness (P = .01) and with mean score of small vessel disease (P < .01). In conclusion, our pathologic findings of ischemic damage, either acute-subacute or in the form of fibrotic scars, support the clinical evidence that ischemia occurs in the natural history of HC and may contribute to life-threatening electrical instability.

No detection of enteroviral genome in the myocardium of patients with arrhythmogenic right ventricular cardiomyopathy

AIMS

Despite the evidence of familial occurrence, chromosomal gene mapping, and apoptosis as a mechanism of myocyte death, the aetiopathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC) remains speculative. Because of the frequent histological finding of focal inflammatory infiltrates, the hypothesis of an infective myocarditis aetiology has been put forward. The aim of this investigation was to test this hypothesis. The presence of enteroviruses was investigated by a highly sensitive and specific molecular technique.

METHODS

Endomyocardial tissue samples from 20 patients with ARVC (11 male, nine female; mean age, 40 years; SD, 16) and 20 control subjects with other cardiac diseases were analysed using reverse transcription and nested polymerase chain reaction (PCR). Myocardial samples obtained from four patients with enteroviral myocarditis and coxsackie B3 virus infected cells were used as positive controls.

RESULTS

Endomyocardial biopsy was diagnostic for ARVC in all patients: myocardial atrophy was seen, with less than 45% residual myocytes. Foci of inflammatory infiltrates were seen in four biopsies, and the cells were identified by immunohistochemistry as mainly T cells. All samples, from both patients with ARVC and subjects with other cardiac diseases, were negative for enteroviral genome by means of nested PCR.

CONCLUSION

These findings indicate that enteroviruses are not involved in the aetio-pathogenesis of ARVC. Future molecular studies should investigate the presence of other infective agents, as well as their possible role in triggering apoptosis.

Clinical profile of congenital coronary artery anomalies with origin from the wrong aortic sinus leading to sudden death in young competitive athletes

OBJECTIVES

The purpose of this study is to characterize the clinical profile and identify clinical markers that would enable the detection during life of anomalous coronary artery origin from the wrong aortic sinus (with course between the aorta and pulmonary trunk) in young competitive athletes.

BACKGROUND

Congenital coronary artery anomalies are not uncommonly associated with sudden death in young athletes, the catastrophic event probably provoked by myocardial ischemia. Such coronary anomalies are rarely identified during life, often because of insufficient clinical suspicion. However, since anomalous coronary artery origin is amenable to surgical treatment, timely clinical identification is crucial.

METHODS

Because of the paucity of available data characterizing the clinical profile of wrong sinus coronary artery malformations, we reviewed two large registries comprised of young competitive athletes who died suddenly, assembled consecutively in the U.S. and Italy.

RESULTS

We reported 27 sudden deaths in young athletes, identified solely at autopsy and due to either left main coronary artery from the right aortic sinus (n = 23) or right coronary artery from the left sinus (n = 4). Each athlete died either during (n = 25) or immediately after (n = 2) intense exertion on the athletic field. Fifteen athletes (55%) had no clinical cardiovascular manifestations or testing during life. However, in the remaining 12 athletes (45%) aged 16 +/- 7, certain clinical data were available. Premonitory symptoms had occurred in 10, including syncope in four (exertional in three and recurrent in two, 3 to 24 months before death) and chest pain in five (exertional in three, all single episodes, < or =24 months before death). All cardiovascular tests were within normal limits, including 12-lead electrocardiogram (ECG) pattern (in 9/9), stress ECG with maximal exercise (in 6/6) and left ventricular wall motion and cardiac dimensions by two-dimensional echocardiography (in 2/2).

CONCLUSIONS

With regard to congenital coronary artery anomalies of wrong aortic sinus origin in young competitive athletes, 1) standard testing with ECG under resting or exercise conditions is unlikely to provide clinical evidence of myocardial ischemia and would not be reliable as screening tests in large athletic populations, 2) premonitory cardiac symptoms not uncommonly occurred shortly before sudden death (typically associated with anomalous left main coronary artery), suggesting that a history of exertional syncope or chest pain requires exclusion of this anomaly. These observations have important implications for the preparticipation screening of competitive athletes.

Pathology and pathogenesis of arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy is a primary heart muscle disease characterized by progressive myocardial atrophy of the right ventricle, with transmural fatty or fibrofatty replacement, either segmental or diffuse, accounting for electrical instability at risk of life-threatening ventricular arrhythmias. It was recently included among cardiomyopathies in the revised WHO classification. The disease was found to be a major cause of sudden death in the young and in athletes of the Veneto Region, Italy. A familial occurrence with autosomic dominant inheritance was then discovered with a prevalence estimated to be 6/10,000 inhabitants and 5 loci have been identified by linkage analysis so far, 2 mapping to chromosome 14 and to chromosome 1, 2 and 3 one each. A recessive form associated with palmoplantar keratosis has also been reported, mapping to chromosome 17. Nonetheless, the specific gene defects as well as the defective coded proteins have not yet been identified. At gross examination, the right side of the heart appears yellowish or whitish as to suggest a fatty or fibrofatty infiltration of the underlying myocardium; the myocardial loss frequently accounts for a parchment like, translucent look of the right ventricular free wall. Aneurysms of the right ventricular free wall, whether single or multiple, were reported in about 50% of cases in a recent pathologic investigation, and are considered a pathognomonic feature of arrhythmogenic right ventricular cardiomyopathy; they are typically located in the inferior, diaphragmatic wall, underneath the posterior leaflet of the tricuspid valve, as well as in the infundibulum and at the apex. Right ventricular enlargement, whether mild, moderate or severe, is a constant feature. Involvement of the left ventricle has been reported in almost 50% of cases. At histology, the pathologic process generally starts from the subepicardium and extends to the endocardium in a wave-front phenomenon. The residual, spared myocytes are located within the subendocardial trabeculae and few myocardial fascicles are scattered throughout the fibrofatty tissue. All stages of myocardial injury and repair are recognizable: acute cell death with sarcolysis and inflammatory infiltrates; subacute damage with "active fibrosis", including dying myocytes, lymphocytes and macrophages, or otherwise adipocytes replacing vanished myocytes; and, eventually, chronic stage with fibrous tissue and adipocytes surrounding residual surviving myocytes. Both the etiology and pathogenesis of arrhythmogenic right ventricular cardiomyopathy are still unknown. In particular, the mechanisms leading to progressive loss of myocardium and fibrofatty replacement are speculative. According to the frequent finding of inflammatory infiltrates at histology, an inflammatory theory has been advanced and infective, toxic or immune mechanisms have been investigated. Recently, apoptosis has been documented both in autoptic and bioptic material, suggesting that recurrent bouts of apoptosis may account for progressive atrophy of the myocardium which is then replaced by fibrofatty tissue. Apoptosis may be triggered by T-lymphocytes.