Cardiac involvement in Becker muscular dystrophy.

OBJECTIVES: The purpose of this study was to assess the incidence of myocardial involvement and the relation of cardiac disease to the molecular defect at the deoxyribonucleic acid (DNA) or protein level in Becker muscular dystrophy. BACKGROUND: Dystrophin gene mutations produce clinical manifestations of disease in the heart and skeletal muscle of patients with Becker muscular dystrophy. METHODS: Thirty-one patients underwent electrocardiographic and echocardiographic examination and 24-h Holter monitoring. The diagnosis was established by neurologic examination, dystrophin immunohistochemical assays or Western blot on muscle biopsy, or both, and DNA analysis. RESULTS: Electrocardiographic and echocardiographic findings were abnormal in 68% and 62% of the patients, respectively. Right ventricular involvement was detected in 52%. Left ventricular impairment was observed either as an isolated phenomenon (10%) or in association with right ventricular dysfunction (29%). Right ventricular disease was manifested in the teenagers, and an impairment of the left ventricle was observed in older patients. Right ventricular end-diastolic volumes were significantly increased compared with those in a control group. The left ventricular ejection fraction was significantly lower in older patients than in control subjects or younger patients. Life-threatening ventricular arrhythmias were detected in four patients. No correlations were found between skeletal muscle disease, cardiac involvement and dystrophin abnormalities. In our patients, exon 49 deletion was invariably associated with cardiac involvement. Exon 48 deletion was associated with cardiac disease in all but two patients. CONCLUSIONS: The cardiac manifestation of Becker muscular dystrophy is characterized by early right ventricular involvement associated or not with left ventricular impairment. Exon 49 deletion is associated with cardiac disease.

Fatal paroxysmal supraventricular tachycardia in an infant.

A 37-day-old infant, without associated congenital anomalies, died following a 48-hour episode of supraventricular tachycardia. The histopathologic findings of nodoventricular and fasciculoventricular Mahaim's fibers in a setting of persistent fetal dispersion were consistent with an anatomic substrate for a reentry circuit at the specialized A-V junction.

Complex arrhythmias in a patient with predominantly right ventricular cardiomyopathy.

A 23-year-old man presented with ventricular tachycardia. The electrocardiogram revealed right bundle branch block plus right axis deviation. It also showed frequent episodes of asystole, 2: 1 sinuatrial block and couplets of left bundle branch block morphology. Electrophysiologic study demonstrated sinuatrial entrance block, with an HV interval of 65 msec. It was also possible to induce sustained ventricular tachycardia of left bundle branch block pattern with normal QRS axis. Subsequent investigations were consistent with the diagnosis of right ventricular cardiomyopathy with mild left ventricular involvement.

The relationship between growth of atherosclerotic plaques, variant angina and sudden death.

Clinico-pathological findings are described in two patients with typical variant angina who died suddenly during an ischemic attack. In both cases, detailed pathologic examination of the coronary arteries disclosed severe focal atherosclerosis of the anterior descending coronary artery. The only distinctive histological finding was new intimal proliferation of smooth muscle cells enmeshed within mucoid substance, superimposed on the old fibrous cap of the plaque. These findings agree with experimental and clinical data which suggest that coronary vasospasm may be related to growth of atherosclerotic plaques. This study provides histological evidence that progression of an atherosclerotic plaque may underlie variant angina and sudden death.

Unexpected sudden death during acute myocardial infarction: role of primary electromechanical dissociation.

The causes of death during the acute phase of myocardial infarction were studied in 128 patients. Forty-three of these, who had no clear signs of cardiocirculatory failure, were considered to be cases of sudden and unexpected death. Thirty-two of these patients (74%) had electromechanical dissociation, defined as a sudden disappearance of an effective arterial pressure in the presence of adequate electrocardiographic complexes. Twenty-three patients who had been given this diagnosis were males and 9 females; 53% presented with anterior infarction, 31% with infero-posterior infarction, 3.5% with both anterior and infero-posterior and 12.5% with non-Q wave infarction. A previous episode of infarction was recorded in 31.2% of patients with electromechanical dissociation. Autopsy was performed in 84 patients, 23 of whom died with electromechanical dissociation. Half of the latter cases revealed cardiac rupture (secondary electromechanical dissociation), whereas in the other half death was due to primary electromechanical dissociation. The study stresses the relatively high incidence of this cause of death and the need to differentiate between the two different forms. Although at present the pathophysiology of primary electromechanical dissociation is not completely understood, we believe that recurrence of global or local ischemia may play a more important role than cardiovascular inhibitory reflexes.

Giant P wave in a patient with right ventricular cardiomyopathy.

A P wave of 7.5 mm in lead I and 12.5 in V1 was detected in a 28-year-old man, with a progressive cardiomegaly since the age of 14 years. At last admission he had minor symptoms, and a systolic murmur consistent with tricuspid regurgitation. The electrocardiogram showed an extremely tall P wave and a QRS of a very low amplitude; T waves were inverted on the precordial leads. These ECG features, and subsequent investigations, were consistent with right ventricular cardiomyopathy with massive tricuspid regurgitation, and right atrial abnormality.

[Supraventricular paroxysmal tachycardias. Electrophysiological studies]. / Tachicardie parossistiche sopraventricolari. Studio elettrofisiologico.

Two cases of paroxysmal supraventricular tachycardia are presented. The electrophysiological study has established that in the first patient arrhythmia was induced by an ectopic focus unprotected by entrance block localized in the lower part of the atrium, while in the second patients paroxysms implied the presence of a mechanism of re-entry due to the existence of a Kent bundle. The identification of the electrophysiological characteristics is therefore essential to the proper administration of anti-arrhythmia drugs.

[Incidence of conduction disorders in patients who underwent surgery for hypertrophic obstructive cardiomyopathy]. / Incidenza di disturbi di conduzione in pazienti operati per miocardiopatia ipertrofico-ostruttiva.

Thirteen non-consecutive patients, aging 7 to 61 (average 27) years, underwent left ventricular myotomy-myectomy for a severely symptomatic idiopathic hypertrophic subaortic stenosis (IHSS). In all patients the resting ECG before surgery showed P-R less than 0.18 sec, QRS duration less than 0.11 sec, QRS axis ranging from +10 to +80 degrees. In the immediate post-surgical period 3 patients has complete heart block and 1 had 2nd degree type 2 atrio ventricular block. Lesion was infra-Hisian in 3 patients and intra-Hisian in 1 patient. In the remaining 9 patients an immediate post-surgical left bundle branch block appeared; in 3 out of these patients ECG and an electrophysiologic study documented severe infra-Hisian conduction impairments after an average period of 4 years from surgery. During follow-up 3 patients died suddenly.

[Unusual manifestations of Ebstein's disease in a 53 year old adult. Ebstein's disease in an adult]. / Manifestazioni inusuali della malattia di Ebstein in un adulto di 53 anni. Malattia di Ebstein in un adulto.

B.P., asymptomatic until her fifties, was admitted to hospital because of precordial pain. Her ECG and chest X rays were normal. When 52 she was again admitted, because of congestive heart failure. ECG showed repolarization abnormalities and chest X rays showed marked cardiomegaly. 2d echocardiogram was consistent with right atrial dilatation, dislodged posterior leaflet of the tricuspid valve and marked tricuspid regurgitation; these features were consistent with Ebstein anomaly. The patient was successfully treated by digitalis and diuretics. This case shows that in very rare cases this congenital heart disease can produce its clinical manifestations only late in lifetime.

Bidirectional tachycardia. A sustained form, not related to digitalis intoxication, in an adult without apparent cardiac disease.

In this paper we report the first adult case of an "idiopathic" ventricular bidirectional tachycardia (BT), in a 57 year old woman. The tachycardia, at the time of our observation, was incessant in type and had a slightly irregular frequency of about 140 bpm. BT initiated and terminated abruptly, without any temporal relationship to the preceding RR interval, or the QRS morphology. The interval between the two alternating QRS patterns often varied over a wide range of values. The BT could be interrupted only by overdrive atrial and ventricular stimulation, but promptly reappeared as pacing was discontinued. Therapy with quinidine associated with propranolol was effective on a long term trial. The vectorcardiographic analysis and the electrophysiologic investigation demonstrated a ventricular origin of the BT, localizing its site of origin to common myocardial tissue, probably near the two left hemifascicles. Our data could not elucidate the electrogenetic mechanism of this ventricular arrhythmia, because of its chaotic behavior.

[Atrial desynchronization induced by Valsalva's maneuver in a patient with reciprocating supraventricular tachycardia and Wolff-Parkinson-White syndrome]. / Desincronizzazione atriale indotta da manovra di Valsalva in un paziente con tachicardia sopraventricolare reciprocante e sindrome di WPW.

A 22 years old man with ventricular preexcitation syndrome due to a left accessory pathway, was admitted because of orthodromic reciprocating tachycardia, 205 bpm in frequency. The patient was invited to perform a Valsalva Maneuvre, and at its ending, the tachycardia degenerated into atrial fibrillation (AF) associated with high ventricular rate, reverted to sinus rhythm by D.C. shock. The electrophysiologic study documented a left lateral by pass tract, with an anterograde refractory period of 230 msec. AF was inducible and had a minimal RR interval of 220 msec. Vagal stimulation, induced at the end of Valsalva maneuvre, probably caused dispersion of atrial refractorines and intraatrial reentry, converting the orthodromic tachycardia into atrial fibrillation.

[Vectorcardiographic analysis of late potentials]. / L'analisi vettorcardiografica dei postpotenziali.

We analyzed by high amplification vectorcardiography the morphology of the QRS ending loop and the ST segment of patients with previously recorded Lown 4A, 4B ventricular arrhythmias and the healthy subject. Eight patients were affected by ischemic heart disease and 7 by arrhythmogenic right ventricular dysplasia. All had some irregularities at the end of the QRS or in the ST segment, on the standard ECG. The VCG showed one or more of these three morphologies: complete or incomplete ring, rapidly inscripted isodi-triphasic potentials, sinusoidal irregularities. In the 20 healthy subjects, the loop corresponding to the last 30 msec of the QRS, till the end of the afferent portion of T, was regular, without any particular morphology. We think that these aspects could be related to delayed fragmentation of the ventricular depolarization.

Right ventricular dysplasia: a familial cardiomyopathy?

268 preselected subjects were extensively studied and the diagnosis of right ventricular dysplasia (RVD) was made in 108 living and 18 deceased patients, 35% of cases being familial. Subsequently we studied 72 subjects from nine families in which a case of sudden death had occurred with the autoptic diagnosis of RVD. In 42 out of 72 cases the autoptic (11 patients), clinical-echocardiographic (30 patients) and haemodynamic (15 patients) data supported the diagnosis of RVD. In all but one deceased patient, death was sudden, while in all the living family members we observed ventricular arrhythmias, mostly with left bundle branch block morphology. Both manifest and concealed forms were documented with polymorphic presentation and with clinical-pathologic findings similar to the non-familial RVD cases. This study confirms the presence of a familial form of RVD that is probably more frequent than previously thought. Preliminary data seem to indicate an autosomal dominant inheritance with incomplete penetrance and variable expression.

Prolonged cardiac arrest and complete AV block during upright tilt test in young patients with syncope of unknown origin--prognostic and therapeutic implications.

The purpose of this study was to define the history and prognosis of 12 patients (8 males, 4 females) with syncope of unknown origin (5 to 15 episodes), who developed prolonged asystole or complete AV block during the upright tilt test (UTT). The mean age (+/- SD) of the patients was 29 +/- 7.4 years, and all had normal neurological and cardiological findings on evaluation. These patients were selected from a larger group of 92 cases with positive UTT out of a total of 136 subjects who were referred for recurrence of syncope. Neither clinical nor autonomic nervous system evaluation distinguished these 12 patients from those with positive UTT. Following UTT, therapy was initiated and consisted of transdermal scopolamine in four, disopyramide in two, and beta-blockers in four patients. During follow-up (mean, 17 +/- 5.4 months), four patients had recurrences but none experienced episodes of life-threatening syncope. These patients do not show an enhanced risk of sudden death, and drug therapy seems to improve their clinical course. Only long-term follow-up would correctly identify a subgroup at higher risk.

[The right bundle branch blocks with posterior loop (author's transl)]. / I blocchi di branca destra con ansa dorsalizzata

The AA. have analysed 39 VCG which show terminal slowed down forces definitely directed towards the right and the back. It is presumed that such electrical patterns have to be classified amongst defects which deal with right intraventricular conduction. Both the ECG and UCG test have been classified in groups: some of them simulating BFA, others BFP. An analysis of the different developing ways of the vectorial loops has been made. The AA. think that in some cases the particular direction of the terminal forces could be compatible with an isolated and zonal right conduction defect in the posterior region of the right ventricle. In other cases the coexisting electrical pathology of the left ventricle is likely to be responsible for it. At the end the distinguishing diagnostic criteria of the ECG are discussed.

[Reliability of premature atrial stimulation in the study of sinoatrial conduction time (author's transl)]. / Attendibilita' della stimolazione atriale prematura nello studio del tempo di conduzione senoatriale

Premature atrial stimulation was carried out in 32 patients, and for each stimulus the basic cycle (A1A1), test cycle (A1A2), and the return cycle (A2A3) were analyzed. When A2A3 was plotted as the function of A1A2, a biphasic pattern, characterized by a slope phase followed by a "plateau", was observed in 25 subjects. Sinoatrial conduction time (SACT) was calculated using the Strauss method, which assumes that in the plateau A2A3 = A1A1 + SACT. Sinus arrhythmia was also determined in order to evaluate its importance in altering the results of premature atrial stimulation: it should be pointed out that when arrhythmia was marked it was impossible to calculate sinoatrial conduction time. An inverse correlation between A1A1 and the calculated SACT and between A1A1 and A2A3/A1A1 in the plateau was also demonstrated. The reliability of SACT obtained by premature atrial stimulation is discussed in relation to the results obtained and the data found in the literature.

[Electrophysiological demonstration of more structures in the atrioventricular node (author's transl)]. / Evidenziazione elettrofisiologica di piu' strutture nel nodo atrioventricolare.

Three types of atrioventricular nodal conduction curves, relating A1A2 to H1H2, generated with atrial extrastimulus technique, are known. The first type is smooth, suggesting the homogeneous structure of A-V node. The second type, with abrupt increase in H1H2 response over a critical range of A1A2 coupling intervals, suggests the presence of fast and slow A-V nodal pathways. We have found in five patients the third tipe of A-V conduction curve, giving evidence of an intranodal final common pathway, distal to the fast and slow A-V nodal pathways. The thyrd type of curve enables us to know also some alectrophysiological properties of final common pathway. Indeed we have defined effective and functional refractory periods of fast, slow and final common pathways as far as we can in this type of curve. Paced heart rate variations and atropine medications have led the third type of A-V conduction curve to change into the second type in three cases, into first type in one case. These changes of A-V nodal conduction curves are related to different influence of cardiac cycle lenghts and autonomic nervous system on refractory periods and conduction velocity of the outlined intranodal structures.

[Electro-vectorcardiographic behavior of right bundle branch block in endocardial cushion defects. Its probable relation to the so-called left anterior fascicular hemiblock]. / Comportamiento electro-vectorcardiográfico del bloqueo de rama derecha del haz de His en el defecto de los cojines endocárdicos. Su probable relacion con el llamado hemibloqueo fascicular anterior izquierdo.

We have investigated the possible ECG signs of incomplete Left Anterior Hemiblock (LAH). As an experimental model we chose the endocardial cushion defect, which is proved to have a ventricular activation correspondent to different degrees of LAH due to the particular disposition of the AV node and the His bundle. The VCG of 50 patients with endocardial cushion defect were divided into 5 groups according to the entity of the left and superior deviation of the maximum left vector. Comparison with the ECG signs shows that: a) minimal degrees of LAH occur with simple counterclockwise rotation of the frontal loop without a significant left axis deviation; b) there is no linear correlation between the importance of the left axis deviation and the signs of left ventricular activation asincronism. We conclude that, with the exception of this particular congenital heart disease, minimal LAH degrees can only be suspected on the basis of a counterclockwise VCG frontal loop, because the ECG diagnosis is possible only when the left axis deviation becomes important.