An ARG403GLN beta-myosin heavy chain gene mutation identified in an Italian family with hypertrophic cardiomyopathy; description of clinical features of the family members.
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Biomedical subjects
Publications and source records attributed to L Mangiardi.
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A case of hypertrophic obstructive cardiomyopathy in a patient with Turner syndrome is reported. The most frequently associated cardiac anomalies are coarctation of the aorta and bicuspid aortic valve. Hypertrophic cardiomyopathy has never been reported in this syndrome but is frequent in Noonan syndrome. In these two conditions the phenotype may be indistinguishable but the cariotype is different: normal in Noonan and 45X in Turner syndrome. Our patient had the typical somatic features, and the cariotype was 45X in all examined cells. A familial form of hypertrophic cardiomyopathy was excluded by the normal clinical examination of other members of the family. The presence of hypertrophic cardiomyopathy also in Turner syndrome and the recent localization on the long arm of the chromosome 12 of the gene for Noonan syndrome might postulate a common pathogenesis of the two syndromes.
M-mode and two-dimensional echocardiographic images were obtained using the planimeter method in the short axis view and calculated by Doppler-derived pressure half-time in 24 patients with mitral stenosis before and after surgical commissurotomy and posterior annuloplasty. The diameter of the mitral valve annulus was measured in the standard long axis view and in the apical four-chamber view using two-dimensional echocardiography. Preoperatively, the mitral annulus was dilated in all patients as a consequence of left atrial dilation. This could be one of the factors causing residual regurgitation after surgical mitral commissurotomy. However, more data are needed to demonstrate that annuloplasty can prevent the development of mitral regurgitation after surgery.
The spontaneous beat-to-beat variability of the ventricular repolarization duration was investigated in 21 healthy subjects (age 25-71 years; mean, 40 years) during the basal state in a recumbent position. For each subject, approximately 1,000 consecutive cycles were analyzed with an automated technique. The time series of the RR, QT, and RT intervals generate histograms that approximate normal distributions and have mean standard deviations of 57.0 ms, 5.4 ms, and 4.3 ms, respectively. Spectral analysis was used to detect rhythmical oscillations in these time series. The power spectra densities of both heart rate and ventricular repolarization during show peaks in the same frequency bands: low frequency (0.05-0.12 Hz) and high frequency (0.2-0.4 Hz). The power distribution between these two bands observed in the ventricular repolarization duration spectra was found to be the reverse of that in heart rate spectra (p less than 0.005).
Several authors have reported aortic dissection in Marfan's syndrome with familial incidence. Cases of dissecting aortic aneurysms have likewise been described in families whose members had severe systemic arterial hypertension. We report 4 cases of familial aortic aneurysm, 3 of whom had a dissection, in the absence of Marfan's phenotype but with histologic findings and genetic transmission similar to those previously described as formes frustes of Marfan's syndrome.
It is well known that radiation therapy to the anterior mediastinum may induce lesions of all cardiac structures. The pericardium is most frequently involved, but atrioventricular conduction disorders, cardiomyopathy, coronary stenosis may also be produced. Aortic, mitral and tricuspid lesions have been described. However, clinical evidence of pulmonic valve involvement has not been reported. Only at necropsy has fibrotic thickening of the pulmonic cusps occasionally been found. We report a case of infective endocarditis of the pulmonic valve in a 53-year-old patient who had undergone thoracic radiation therapy for Hodgkin's disease 31 years previously. Four years prior to the endocarditis he had also been submitted to myocardial revascularisation for critical lesions of the left main and right coronary ostia, and to aortic valve replacement because of stenosis and insufficiency. At that time, the pulmonic valve was fibrotic on echo examination. It is noteworthy that, of all the cardiac valves, the infective process involved only the pulmonic one, which is seldom the target of an infection. To our knowledge this is the first case of bacterial endocarditis of a heart valve that had been previously damaged by radiation therapy.
An intracavitary electrophysiological study was carried out on 103 patients with Wolff-Parkinson-White (WPW), 23 symptomatic patients had documented episodes of atrial fibrillation, 54 symptomatic patients had atrioventricular reentrant tachycardias, and 26 asymptomatic. Patients were examined for the relation between spontaneous atrial fibrillation and atrial vulnerability, defined as the possibility to induce sustained (greater than 1 minute) episodes of atrial fibrillation with a stimulation protocol excluding atrial bursts. Atrail fibrillation induction was attempted by single and double atrial extrastimuli during pacing at two different cycle lengths and incremental atrial pacing. Sustained atrail fibrillation was induced in 65% of the patients with spontaneous atrial fibrillation, and in 13% of the symptomatic patients with documented episodes of atrioventricular reentrant tachycardias and in 15% of the asymptomatic patients (P less than 0.0005). Atrial vulnerability was higher in patients with spontaneous atrial fibrillation than in patients without this arrhythmia. No significant difference was observed between symptomatic without atrial fibrillation and asymptomatic patients.
The purpose of this study was to examine the relation between spontaneous atrial fibrillation and the induction of atrial tachyarrhythmias during electrophysiologic study in patients with Wolff-Parkinson-White, with and without atrial fibrillation. Intracavitary electrophysiologic study was performed on 115 patients, 27 with spontaneous atrial fibrillation (group 1), 57 symptomatic due to AV re-entrant tachycardias, without spontaneous atrial fibrillation (group 2) and 31 asymptomatic (group 3). Induction of atrial fibrillation was attempted by using single and double atrial extrastimuli during atrial pacing at 2 different cycle lengths and by incremental atrial pacing (protocol A). When atrial fibrillation was not obtained, atrial bursts were added (protocol B). Atrial fibrillation or flutter were induced in 81% of group 1.54% of group 2 and 55% of group 3 patients (p less than 0.05), using protocol A. They were induced in 100, 75 and 71%, respectively (p = 0.01), with protocol B. Considering only sustained (greater than 1 minute) episodes, atrial fibrillation or flutter were induced in the three groups with protocol A in 74, 33 and 32% of the patients, respectively (p less than 0.001). The difference in the three groups was even greater when atrial fibrillation was considered separately from atrial flutter. The reason for this was that atrial fibrillation was induced in two thirds of group 1 patients, while only about 15% of patients without spontaneous atrial fibrillation had this arrhythmia induced. Our results suggest that the induction of sustained atrial fibrillation is a useful parameter to separate Wolff-Parkinson-White patients with from those without spontaneous atrial fibrillation. Due to the low specificity of the analysis of the shortest R-R interval during induced atrial fibrillation for the identification of the patients at risk of sudden death, the induction of sustained atrial fibrillation could be proposed as an additional parameter. This would improve the specificity of electrophysiologic study.
Noninvasive stress and pharmacologic tests with procainamide and propafenone were studied as methods to identify patients with Wolff-Parkinson-White syndrome (WPW) who would otherwise be judged at risk of sudden death on the basis of electrophysiologic criteria: the shortest RR interval during induced atrial fibrillation less than or equal to 250 ms or accessory pathway anterograde effective refractory period less than or equal to 250 ms. Sixty-five patients were studied. Twenty-four patients fulfilled the electrophysiologic risk criteria (group A) and 41 patients fulfilled none of these criteria (group B). Persistence of preexcitation during stress test showed a sensitivity of 96% and a specificity of 17% to identify group A patients; its positive predictive value was 40% and negative predictive value 88%. With both procainamide and propafenone tests persistence of preexcitation identified group A patients with a sensitivity of 96% and a specificity of 51%; their positive and negative predictive value were, respectively, 53 and 95%. Stress and pharmacologic tests have good sensitivity and negative predictive value, but low specificity and positive predictive value.
A case is reported of congenital long QT interval associated with fixed 2:1 atrioventricular block. The bradycardia was detected at 16 weeks of gestational age. The atrioventricular block was due to an extremely delayed ventricular repolarization. Early detection of bradycardia in fetal life and the demonstration of a normal positive correlation between QT duration and ventricular rate suggest that, in this case, the syndrome may be due to an anomaly of the myocardial cells rather than to imbalance of the sympathetic nervous system.
A case of intravenous amiodarone induced QT-interval prolongation and ventricular arrhythmia of the torsade de pointes type is described: the arrhythmia developed in the presence of hypokalemia. The efficacy of lidocaine in suppressing this type of arrhythmia is reported. The electrophysiologic effects of intravenous and oral amiodarone administration are compared.
Eighteen patients (11 women and 7 men) with Ebstein's anomaly recognized in adult age (18-55 years, mean 31.5) were followed in our Department for 3-13 years (mean 7 years). Echocardiographic and cardiac catheterization studies were performed in the majority. Clinical and echocardiographic findings were evaluated in the follow-up period. During the first assessment mild cyanosis was present in 14 cases. Nine patients were in NYHA class I, 6 in NYHA class II, 2 in NYHA class III and 1 in NYHA class IV. Eleven patients complained of palpitations. A Wolff-Parkinson-White (WPW) syndrome was present in 4 cases. At cardiac catheterization, done in 14 patients, a moderate-severe tricuspid regurgitation was found in 7 patients. In 8 cases there was a mild right-to-left shunt at atrial level. During the follow-up period there was 1 sudden death. In all patients with the WPW syndrome, the symptoms were well controlled by medical treatment. Systemic embolism was a major complication in 3 patients (all with patent foramen ovale and right-to-left shunt). During the follow-up period surgery was performed in 3 patients for a worsening of the tricuspid incompetence. Good early and late results were obtained in all 3 patients. The clinical conditions remained stable in the other 14 cases. Seven women out of 11 had 1 or more pregnancies (all together 14 pregnancies). In conclusion, in our experience Ebstein's anomaly diagnosed in adult life is a benign and stable disease, particularly if the patient is asymptomatic; surgical correction must be performed if the patient becomes symptomatic either because of paradoxical embolism or because of worsening of the tricuspid regurgitation.
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It is well known that in patients with Wolff-Parkinson-White (W.P.W.) adrenergic activity stimulation induced by exercise or isoproterenol I.V. infusion shortens the anterograde effective refractory period (E.R.P.) of the accessory pathway. Our purpose was to evaluate whether the upright position produces similar changes on the electrophysiologic properties of the accessory pathway and influences reciprocating tachycardias induction. In 18 patients, with W.P.W. syndrome, who underwent electrophysiologic study, we determined the anterograde E.R.P. of the accessory pathway and attempted to induce a reciprocating tachycardia in the supine and in the upright position. In 13 patients (72%) the anterograde E.R.P. of the accessory pathway shortened in the upright position (303 +/- 104 msec vs 331 +/- 123 msec; p less than 0.001); in 4 patients (22%) it was unchanged; in 1 patient was not defined, being inferior to the atrium E.R.P. We were able to induce a reciprocating tachycardia in 3 patients in the supine position, in 6 patients in the upright position. Electrophysiologic testing in the upright position improves the evaluation of the accessory pathway electrophysiologic properties.
As a clinical entity atrioventricular (AV) block due to hypothyroidism is rare. Such a case induced by hypothyroidism complicating long-term therapy with amiodarone in a 45 year old woman with pre-excitation is presented. Electrophysiologic data obtained before and during thyroxine replacement therapy showed that hypothyroidism lengthens the effective refractory period of the atria, AV node, bypass tract and His-Purkinje system (that in the ventricle not being measured); this lengthening resembles the effects of long-term administration of amiodarone. These observations suggest that depressed thyroid function may be protective against arrhythmias but a patient with preexisting conduction system disease may develop AV block. The tendency to develop AV block in a patient who is euthyroid was reduced by bypass tract conduction. These findings are significant not only in monitoring amiodarone effects during chronic prophylactic drug therapy but also in providing further insight into the complex interrelation between the action of the drug and the thyroid hormones on cardiac muscle.
New experimental methods in cellular electrophysiology allowed the identification and characterization of specific "ion channels" in the plasma membrane of cardiac cells in different regions of the heart. Function and implication of the "ion channels" have been considered in 1) the initiation of the heart-beat, 2) the chronotropic and inotropic effects of neurotransmitters (nor-epinephrine-acetylcholine), 3) the action mechanism of the steroid cardioactive drugs, 4) the cardiac repolarization, 5) the physiopathology of several arrhythmias. Moreover clinical data useful for the indirect evaluation of the ion channels function have been pointed out, stressing the ion channels models contribution for the cardiac pathology interpretation, particularly in the cardiac arrhythmias field.
Electrophysiological evidence of dual intrahisian pathways has been shown in a patient with diseased His bundle. The main electrocardiographic features, in this case were: 1). 1:1 A-V conduction with alternating short and long PR intervals; 2). unexpected A-V Wenckebach sequences; and 3). unexpected interruption of Wenckebach sequences by early captures of the ventricles with short and fixed PR intervals. These features were due to the following causes: 1). different E.P. properties of the two pathways producing a shift of conduction from a fast conducting pathway (FCP) to a slow conducting pathway (SCP); 2). a concealed reentry from the SCP into the FCP; and 3). a phase of "unexpected conduction" in the FCP.
The efficacy of amiodarone in the prevention of atrial tachycardia is well recognised. However, there remains some controversy over its use in patients with a basal sinus bradycardia because of the risk of further depression of sinus node function. We studied the effects of acute and chronic amiodarone therapy in 13 patients with paroxysmal supraventricular tachycardia and intercritical sinus bradycardias of between 40 and 50/min. All patients underwent electrophysiological investigation under basal conditions and after 5 mg/kg IV amiodarone. Five patients were excluded from chronic oral amiodarone therapy after IV amiodarone for the following reasons : sinus bradycardia of less than 30/min; sinus node recovery times greater than 2 s; 2nd or 3rd degree sino-atrial block. The other 8 patients were administered oral amiodarone on a long term basis. They were followed up clinically with dynamic ECGs every three months over a period of 1 to 3 years. All symptoms regressed in 6 patients. In one patient, the daily attacks of palpitations decreased to one a week. One patient did not improve. No cases of sino-atrial standstill were observed, although the sinus rate remained unchanged. The results of our study show that amiodarone may be administered for long periods in patients with sinus bradycardia and attacks of paroxysmal supraventricular tachycardia if the dynamic ECG during the waking hours shows a heart rate of no less than 40/min, and if electrophysiological investigations do not show significant depression of sinus node function after acute intravenous administration of the drug.