[Verapamil-responsive ventricular tachycardia in small children: a case report and review of the literature]. / Tachicardia ventricolare verapamil-sensibile nel piccolo bambino: descrizione di un caso e revisione della letteratura.

A case of verapamil-responsive incessant ventricular tachycardia in a 4-year-old girl is reported. Oral verapamil alone failed in maintaining stable sinus rhythm. With association of oral verapamil and betablockers (nadolol) the patient remained asymptomatic without recurrence of ventricular tachycardia over a follow-up of 1 year. In case of failure of monotherapy with verapamil or betablockers alone, an association of both can be effective and safe also in pediatric age. Radiofrequency catheter ablation should be reserved, especially in pediatric age, only to patients with impaired ventricular function who are not responsive to medical therapy.

Effects of long-term vasodilator therapy in patients with carotid sinus hypersensitivity.

BACKGROUND: In patients affected by carotid sinus hypersensitivity, long-term vasodilator therapy might increase the risk of syncopal episodes by reducing systolic blood pressure and venous return to the heart. METHODS AND RESULTS: Thirty-two patients (mean age 73 +/- 9 years; 20 men) who met all the following criteria were included: (1) one or more episodes of syncope occurring during long-term (>6 months) treatment with angiotensin-converting enzyme inhibitors, long-acting nitrates, calcium antagonists, or a combination of these; (2) a positive response to carotid sinus massage, defined as the reproduction of spontaneous syncope in the presence of ventricular asystole > or =3 seconds or a fall in systolic blood pressure > or =50 mm Hg; (3) negative workup for other causes of syncope. The patients were randomly assigned to continue or to discontinue use of vasodilators; carotid sinus massage was repeated 2 weeks after randomization. By the end of the study period, the baseline values of systolic blood pressure were significantly different between the 2 groups of patients both in supine (P=.01) and upright (P=.03) positions. Syncope had been induced by carotid sinus massage in 81% of patients in the "on-vasodilator" group and in 62% of patients in the "off-vasodilator" group (P=.21). The cardioinhibitory reflex was of similar magnitude in the 2 groups, being found in 50% of the patients in each group, with a maximum ventricular pause of 7.1 +/- 2.7 and 6.7 +/- 1.8 seconds, respectively. The percentage decrease of blood pressure did not differ between the 2 groups, even if, in absolute values, the baseline difference of blood pressure roughly persisted for the duration of the test. In consequence of that, the rise of blood pressure to similar values was delayed approximately 30 seconds in the "on-vasodilator" group and took more than 2 minutes to return to baseline values. CONCLUSIONS: In patients affected by carotid sinus hypersensitivity, chronic vasodilator therapy does not have a direct effect on carotid sinus reflexivity, although the delayed recovery of pretest blood pressure values could indirectly potentiate the severity of the clinical manifestations of the syndrome. The persistence of hypotension for a longer time after the end of the massage suggests that vasodilators cause an impairment of compensatory mechanisms.

Pheochromocytoma crisis caused by contemporary ergotamine, caffeine, and nimesulide administration.

Pheochromocytoma is a rare tumor that secretes excess catecholamines. Pheochromocytoma crises may be precipitated by the use of several drugs. This article describes the case of a patient affected by pheochromocytoma in whom multiple organ failure developed after contemporary administration of ergotamine, caffeine, and nimesulide. The patient recovered completely long after surgical intervention.

[Unstable angina in coronary intensive care units without hemodynamics: is admissible a strategy limiting the indications for coronarography?]. / Angina instabile in UTIC senza emodinamica: è ammissibile una strategia che limiti le indicazioni alla coronarografia?

In coronary care units (CCU) without cardiac catheterization facilities, coronary angiography is rarely carried out when a successful medical treatment in the acute phase of unstable angina has been obtained. However, the unstable angina still has an uncertain prognosis when the remission of pain is obtained with drugs. This study presents a follow-up of 147 consecutive patients (aged 66.8 +/- 10.4 years) admitted to our CCU in 1991 and 1992 for unstable angina; 33 of them (22.4%) were in Braunwald class I. 2 (1.4%) in class II and 112 (76.2%) in class III. The patients were treated according to the usual therapy protocols and class III patients received i.v. heparin. In selected cases we used thrombolysis (10 patients) and intra-aortic balloon pump (5 patients). During hospitalization 1 patient died (0.7%), 5 patients (3.4%) suffered an acute myocardial infarction and 9 patients (6.1%) had angina. Stabilization of unstable angina was achieved in 132 patients (89.9%): in 113 (76.8%) during the first 48 hours, and in 19 (12.9%) later. Coronary angiography was carried out in non-stabilized patients and in 46 (34.8%) of the 132 with successful treatment (Group I). Eighty-six patients, without indication to coronary angiography were discharged in medical therapy (Group II). During the follow-up (mean of 15.0 +/- 9.0 months) Group I 10 patients (18.2%) had cardiac events (death, myocardial infarction, or recurrent angina) vs 26 of Group II (p < 0.05). In Group I coronary angiography together with clinical criteria of high risk allowed the identification of candidates to coronary revascularization (61.8% of Group I patients while). These data show that the initial success of treatment during the acute phase of unstable angina should not be considered as a favourable prognostic index. Coronary angiography appears to be indicated for clinical evaluation and therapeutical decision.

[Right atrial metastasis as an initial clinical manifestation of adenocarcinoma of the colon]. / Metastasi atriale destra come prima manifestazione clinica di adenocarcinoma del colon.

We report the case of a young woman suffering from colonic mucinous adenocarcinoma with the unusual clinical presentation as a right atrial metastasis. The tumor was successfully resected, and after histopathological characterization, the primary lesion was searched for and discovered. The tumor had the clinical appearance and echocardiographic pattern of a pedunculated atrial myxoma. The aspects of echo-patterns useful for differential diagnosis are discussed.

[Efficacy of intravenous and per os propafenone in the ambulatory treatment of recent-onset atrial fibrillation]. / Efficacia del propafenone e.v. e per os nel trattamento ambulatoriale della fibrillazione atriale di recente insorgenza.

Propafenone efficacy in conversion of atrial fibrillation to sinus rhythm has been well documented. In this study we considered propafenone efficacy according to a graduated protocol of administration. Forty-two patients with recent-onset atrial fibrillation, without left ventricular failure, ischemic symptoms and in absence of antiarrhythmical treatment, were treated according to the following protocol: propafenone 1 mg/kg i.v. (5 min) followed, in the non-responder patient group, by a second dose, 0.5 mg/kg i.v. (15 min). Patients with persistent atrial fibrillation received 900 mg/daily of propafenone per os, at home for two days. Thereafter, patients still not restored to sinus rhythm were considered non-responders. Patients who were converted to sinus rhythm received 450 mg daily of the drug (oral administration), at home, as antiarrhythmical prophylaxis, for three months. Thirty-nine patients were converted to sinus rhythm (92.8%), 24 of them after intravenous propafenone (57.2%), and the other 15 (35.6%) after oral administration of the drug. The average heart rate in patients not converted to sinus rhythm with intravenous propafenone was significantly reduced after drug administration, compared to basal values (from 136.4 +/- 18.1 to 107.1 +/- 17.6, p < 0.01), allowing home treatment. No major cardiac effects were observed after infusion, nor after oral administration of propafenone. During a three-month follow-up we observed 3 cases of relapsed atrial fibrillation and 2 discontinued treatments due to minor gastroenteric side effects. In conclusion, propafenone therapy in ambulatory regimen is safe and effective in patients with recent-onset atrial fibrillation. In many patients refractory to IV treatment, further therapeutic success may be achieved following oral propafenone administration.

Propafenone versus amiodarone in field treatment of primary atrial tachydysrhythmias.

Thirty-nine patients with paroxysmal atrial fibrillation or supraventricular tachycardia randomly received amiodarone or propafenone intravenously at home. Fifteen patients received amiodarone and 24 received propafenone; 87.5% of the patients who received propafenone and 40% of the patients who received amiodarone were converted at home to sinus rhythm (P less than .005). The median time of conversion was 10 minutes (range 5 to 35) for propafenone and 60 minutes (range 20 to 130) for amiodarone (P less than 0.005). When either drug failed to terminate atrial tachydysrhythmias at home, the same drug always restored sinus rhythm with subsequent oral treatment during hospitalization. No major side effects were observed after the infusion of either drug. The incidence of minor side effects was not significantly different between the two drugs. Both the drugs are efficacious and safe in the acute management of primary supraventricular tachydysrhythmias. Propafenone showed a greater rapidity of action.

[Significance of QT interval as a premonitory sign of severe ventricular arrhythmia in the early phase of myocardial infarct]. / Valore dell'intervallo QT come segno premonitore di gravi aritmie ventricolari nella fase precoce dell'infarto miocardico.

In order to evaluate the relationship between the length of the corrected QT interval (QTc), calculated according to Bazett's formula, and the incidence of ventricular fibrillation (V.F.) in the early phase of acute myocardial infarction (A.M.I.), the QTc interval was measured in 494 patients (mean age 66.42 +/- 11 years; 357 males and 137 females) assisted by the Mobile Coronary Care Unit of Florence. A.M.I. was anterior in 269 patients, inferior in 177 and non-Q in 34. The QTc interval measured on E.C.G. was recorded within the first hour after the onset of pain in 203 patients and between the first and sixth hour in 291 patients. The QTc interval was also measured in a control group consisting of 96 non A.M.I. patients with no history of coronary artery disease. 43 patients with A.M.I. (8.6%) developed V.F. in the first 24 hours. It was observed that: 1) The QTc interval of patients with A.M.I. was longer than that in patients without A.M.I. (432 +/- 34.18 msec. versus 425.37 +/- 25, p less than 0.02). 2) The QTc interval of patients with A.M.I. who developed V.F. was the same as that of patients with A.M.I. but without V.F., (432.6 +/- 34.18 msec. versus 438.11 +/- 34.13, N.S.). 3) 60.46% of patients with V.F. had a value of QTc less than 440 msec.; the incidence of QTc greater than 440 msec. showed no difference in the groups with or without V.F. (41.86% versus 41.11%). 4) The QTc interval length was greater in anterior than in inferior A.M.I. (435.12 +/- 30.81 msec. versus 429.05 +/- 34.5, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pharmacologic autonomic blockade on atrial electrophysiologic properties in normal subjects and in patients with sinus node disease.

In order to elucidate the influence of autonomic nervous system on atrial electrophysiologic properties, we studied 10 patients with sinus node dysfunction and 10 age-matched normal subjects. In each of them effective and functional refractory periods of the right atrium (near its junction with the superior caval vein) were measured, during atrial pacing (100/min) and using variable current strengths (2, 3, 4, 5, 7, 10, and 15 mA), before and after pharmacologic autonomic blockade (using intravenous propranolol 0.2 mg/kg and atropine 0.04 mg/kg). Mean values of effective and functional refractory periods at each current strength were significantly higher in patients with sinus node disease than in normal subjects both before and after autonomic blockade. Blockade did not significantly modify mean values of effective and functional refractory periods at any current strength, either in patients with sinus node disease or in normal subjects. Furthermore, autonomic blockade did not change the effects of the increase of current strength on atrial refractoriness in either group. We conclude that our data indicate a prolonged refractoriness to be present in patients with sinus node disease even in the absence of influences from the autonomic nervous system. Thus, we can suggest a "primary" involvement of atrial fibers in this pathophysiological condition. Propranolol together with atropine did not induce changes of atrial refractoriness. Indeed, they probably exerted an opposite effect. The effects of the increase of current strength on atrial excitability do not seem to be mediated by autonomic humoral agents.

Anterograde sinuatrial conduction evaluated by sinus node electrogram in atropine blocked retrograde atrial conduction.

Two cases are described where atropine induced the disappearance of reset zone as response to premature atrial stimulation for blocked retrograde atrial conduction. Because of this, sinuatrial conduction time could not be estimated. The sinus node electrogram allowed the direct measurement of sinuatrial conduction and showed a facilitated anterograde conduction through the perinodal fibers after administration of the drug.

Clinical electrophysiological effects of chronic administration of verapamil: the phenomenon of overdrive excitation of junctional pacemaker.

The electrophysiological effects of chronic administration of verapamil were studied in 10 patients with normal sinus node function, who received 160 mg of the drug every eight hours for at least two weeks. Uncorrected and corrected sinus node recovery time, sino-atrial conduction time, effective and functional refractory periods were normal in each case. In three patients, at the cessation of atrial pacing, an overdrive excitation of junctional pacemaker with short lasting A-V dissociation was observed.

Effects of atropine on atrial refractoriness and its dispersion in humans.

To evaluate the influence of atropine on atrial refractoriness and its dispersion, we studied ten subjects with sinus bradycardia who were otherwise healthy. Effective and functional refractory periods were measured at three sites of the right atrium (high, middle, and low in the lateral wall), in sinus rhythm and during atrial pacing (120/min), before and after i.v. administration of 0.04 mg/kg of atropine. Both before and after administration, dispersion of atrial refractoriness was determined from the range of refractory periods measured at the three atrial sites as the longest minus the shortest refractory period. Our data indicate that atropine was able to significantly reduce refractoriness and its dispersion. The study protocol allowed us to exclude the possibility that cycle length played a role. The antivagal effect of atropine seemed to explain our findings, even if the possibility that the drug had a direct effect could not be excluded.

[Comparison of Narula's technic of direct and estimated sinoatrial conduction at increasing rates in normal subjects]. / Comparaison chez le sujet normal du temps de conduction sino-auriculaire mesuré directement et estimé par la technique de Narula à fréquences croissantes.

Twenty eight normal subjects in sinus rhythm underwent direct measurement of sinoatrial conduction time (SACTD) by sinus node potential recordings (SNP) and indirect evaluation by Strauss (SACTS) and Narula's methods (SACTN) using the extrastimulus technique. Stimulation in Narula's method was undertaken at three different rates, 3, 6 and 9 beats per minute faster than the spontaneous rate of the subject (SACTN3, SACTN6, SACTN9). The mean values (+/- SD) were as follows: SACTD 84 +/- 18, SACTN3 85 +/- 29, SACTN6 96 +/- 33, SACTN9 101 +/- 36. The mean value of the SACTD was significantly lower than that of the SACTN9 (p less than 0,01) but there were no significant differences between SACTD and SACTN3 and SACTN6. The three values of the SACTN were closely related to each other but not to the values of the SACTD.

The effects of atropine on sinoatrial conduction time directly measured from sinus node electrogram. A comparison with results furnished by indirect methods.

The effects of atropine on sinoatrial conduction time (SACT) measured directly (SACTD) from the sinus node electrogram (SNE) were investigated in 15 patients with normal sinus node function. A comparison was undertaken with the results furnished by indirect methods which employ premature (SACTS) and asynchronous atrial stimulation (SACTN) to calculate SACT. In the control state SACTD was 92.5 +/- 16.4 ms, SACTS 78.2 +/- 22 ms, and SACTN 97.9 +/- 32.2 ms. After atropine SACTD was 70.6 +/- 15.6 ms (P less than 0.0005), SACTS 46.7 +/- 14.3 ms (P less than 0.0005) and SACTN 43.1 +/- 12.7 ms (P less than 0.0005). Mean percent decreases of SACTN (51.6 +/- 21) and SACTS (37.4 +/- 18) were statistically greater than that of SACTD (23.5 +/- 13.3) (P less than 0.0005 and P less than 0.01 respectively). While the reduction of SACTS and SACTN was greater than that of sinus cycle length (SCL) (29.2%), SACTD showed a reduction significantly less than that of SCL (P less than 0.005). Thus, SNE recording confirms that atropine induces a shortening of SACT in normal patients, but significantly less than that indicated by indirect methods.

Aging and atrial electrophysiologic properties in man.

In order to assess the influence of age on atrial electrophysiologic properties, we studied 17 normal subjects, whose ages were homogeneously distributed between 17 and 78 years, measuring in each of them effective (ERP) and functional (FRP) refractory periods at 3 sites of the right atrium (high, middle and low in the lateral wall) at the same driven frequency (120/min). Twice threshold stimuli of 2 msec duration were applied. Dispersion of atrial refractoriness was measured as the longest minus the shortest refractory period. A significant direct correlation was observed between age and dispersion of atrial refractoriness (of ERP: r = 0.75, P less than 0.001; of FRP: r = 0.82, P less than 0.001). Moreover, age showed a significant direct correlation with refractoriness at high right atrium (ERP: r = 0.66, P less than 0.01; FRP: r = 0.76, P less than 0.001), but did not correlate with that at the other two sites. We suggest that ageing modifies atrial refractoriness in a non-uniform manner inducing a progressive increment of dispersion of atrial refractoriness. The impression is that a slow but continuous process takes place from juvenility to old age.

[Evaluation of sinoatrial conduction time by recording the sinus node potential. Comparison with indirect methods of evaluation]. / Evaluation du temps de conduction sino-auriculaire par enregistrement du potentiel du noeud sinusal. Comparaison avec les méthodes indirectes d'évaluation.

A method of recording the sinus node potential (SNP) has recently been introduced in clinical electrophysiology. The sinoatrial conduction time can now be measured directly (SACTD) as the interval between the onset of the SNP and the onset of atrial activation. We measured the SACTD in 16 normal subjects and in 7 patients with sinus node dysfunction. These values were compared with those obtained by the indirect methods of Strauss et al (SACTS) and Narula et al (SACTN). In normal subjects the SACTD ranged from 50 to 130 ms (average 84,4 +/- 22,35); the SACTS, from 55 to 160 ms (92,9 +/- 29,3), and the SACTN from 70 to 175 ms (113,2 +/- 28,8). In patients with sinus node dysfunction the SACTD ranged from 200 to 290 ms (227 +/- 32,5), the SACTS, from 52 to 198 ms (111,8 +/- 59,3) and the SACTN from 89 to 251 ms (142,3 +/- 63). No significant difference was observed between normal and pathological subjects using the indirect methods of evaluation. However, the SACTD method showed a very significant difference between the two groups (p less than 0,0005) with no overlap. No correlations were observed between the values obtained by the indirect and direct methods of measuring SACT.

Observations on changes in intermittent claudication after the administration of creatine phosphate.

A study was carried out in 13 patients with stabilized occlusive arterial disease to assess the effect of treatment with creatine phosphate (800 mg/day for 12 days) on walking distance to onset of disabling pain and on haemodynamic parameters (Winsor Index and calf arterial blood flow after ischaemia). Before treatment, patients had daily exercise for 12 days on a treadmill to plateau walking distance increase due to exercise. The results showed a further significant increase in walking distance after treatment, and a significant increase in peak reactive hyperaemia in all but 2 patients. The possible mechanisms of the effects of creatine phosphate are discussed.

Measurement of the sinoatrial conduction time using direct recording of sinus node electrogram. Preliminary study in normal subjects and comparison with the indirect methods.

Sinus node electrogram is characterized by a smooth, low-frequency upstroke slope beginning before P wave and followed by a rapid deflection that results from initial atrial activity. Sinoatrial conduction time (SACT) can be measured directly (SACTD) from the sinus node electrogram as the interval from the onset of the upstroke slope to the onset of atrial activation. In our laboratory the values found in 20 patients with normal sinus node function ranged between 50 and 130 msec (mean 86.5 +/- 21.3). We compared SACTDs with those obtained by three indirect methods using the atrial premature stimulation technique (Strauss method) or the asynchronous pacing (Narula/Raviele method). In this part of the study were included 15 patients presenting A3A4 = A1A1 (i.e. without a depression of the sinus node) in the zone of reset and A2A3 greater than A1A1 (i.e. positive SACTs) when Narula/Raviele method was employed. No correlation was observed between directly measured and indirectly estimated SACTs. On this last point opposite conclusions have been drawn by the few papers published until now. The discrepancy may be explained by the different incidence on the study populations a) of the various factors determining the return cycle length b) of the measurement errors in SACTD.

[Atrial refractoriness and its dispersion in different physiopathologic conditions]. / La refrattarietà atriale e la sua dispersione in differenti condizioni fisiopatologiche.

Previous studies have demonstrated a prolonged and non-uniform atrial refractoriness in patients with both sinus node dysfunction and supraventricular tachyarrhythmias. However, they have not been able to define separately the influence on atrial electrophysiologic properties of isolated "bradycardia", of sinus node dysfunction and of supraventricular tachyarrhythmias. Therefore we have measured the effective and functional refractory periods at three different sites of the right atrium (high, middle and low lateral wall) in 16 normal subjects (N), in 9 patients with chronic asymptomatic sinus bradycardia (AB), in 9 patients with sinus node dysfunction but without evidence of supraventricular tachyarrhythmias (SSS) and in 10 patients with paroxismal atrial fibrillation (PAF). The study was performed both in sinus rhythm and during atrial pacing (120 beats/min) utilizing twice threshold stimuli. Dispersion of atrial refractoriness (D) was determined from the range of refractory periods measured at the three different atrial sites as the longest minus the shortest refractory period. Refractoriness at the high site of the lateral wall (parasinusal zone), mean values of the refractory periods obtained at the three atrial sites, and dispersion were compared among the three groups. Refractoriness at the two rates (sinus rhythm and 120 beats/min) was also compared. During sinus rhythm SSS, AB and PAF showed a significantly higher refractoriness than N, while only SSS and PAF showed increased D. Atrial pacing reduced refractoriness but not D in all groups. At the same driven frequency refractoriness of SSS and AB, and D of SSS and PAF were still significantly higher than those of N. Finally, it is noteworthy that during paced rhythm, single values of mean refractoriness of SSS did not correspond with those of N. In conclusion, our data suggest that: 1) sinus node dysfunction and supraventricular tachyarrhythmias exert an independent influence on atrial electrophysiologic properties; 2) the presence of a less homogeneous recovery of atrial excitability should be considered as a possible concause in the genesis of atrial fibrillation; 3) chronic isolated sinus bradycardia seems to be characterized by a longer atrial refractoriness and not by an increased D; 4) contrary to results obtained in animal subjects, there does not seem to be a relation between D and cycle length in man.