Oral Albuterol Treatment in Three Pediatric Patients with Bradycardia: A Novel Therapy

Clinically significant bradycardia is an uncommon problem in children, but one that can cause significant morbidity and sometimes necessitates implantation of a pacemaker. The most common causes of bradycardia are complete heart block (CHB), which can be congenital or acquired, and sinus node dysfunction, which is rare in children with structurally normal hearts. Pacemaker is indicated as therapy for the majority of children with CHB, and while early mortality is lower in postnatally diagnosed CHB than in fetal CHB, it is still up to 16%. In young children, less invasive transvenous pacemaker systems can be technically challenging to place and carry a high risk of complications, often necessitating surgical epicardial pacemaker placement, which usually entails a median sternotomy. We report three cases of pediatric patients referred for pacemaker implantation for different types of bradycardia, treated at our institution with oral albuterol with therapeutic results that avoided the need for surgical pacemaker implantation at that time.

[Regularity of prescriptions for sick sinus syndrome based on latent structure combined with association rules]

This study aims to mine the regularity of traditional Chinese medicine(TCM) prescriptions for sick sinus syndrome(SSS) and provide a reference for clinical syndrome differentiation and treatment. The relevant papers were retrieved from CNKI, Wanfang, VIP, and SinoMed with the time interval from inception to January 31, 2023. The relevant information from qualified papers was extracted to establish a library. Lantern 5.0 and Rstudio were used to analyze the latent structure and association rules of TCMs with the frequency ≥3%, which combined with frequency descriptions, were used to explore the rules of TCM prescriptions for SSS. A total of 192 TCM prescriptions were included, involving 115 TCMs with the cumulative frequency of 1 816. High-frequency TCMs include Aconiti Lateralis Radix Praeparata, Ginseng Radix et Rhizoma, Glycyrrhizae Radix et Rhizoma, Astragali Radix, and Salviae Miltiorrhizae Radix et Rhizoma. The high-frequency medicines mainly had the effects of tonifying, releasing exterior with pungent-warm, and activating blood and resolving stasis. The analysis of the latent structure model yielded 13 hidden variables, 26 hidden classes, 8 comprehensive cluster models, and 21 core prescriptions. Accordingly, the common syndromes of SSS were inferred as heart-Yang Qi deficiency, heart-spleen Yang deficiency, heart-kidney Yang deficiency, Yang deficiency and blood stasis, both Qi and Yin deficiency and blood stasis, and Yin and Yang deficiency. The analysis of association rules predicted 30 strong association rules, among which Ginseng Radix et Rhizoma-Aconiti Lateralis Radix Praeparata had the highest support. SSS is a syndrome with Yang deficiency and Qi deficiency as the root causes and cold, phlegm, and stasis as the manifestations. The clinical treatment of SSS should focus on warming Yang and replenishing Qi, which should be supplemented with the therapies of activating blood and resolving stasis, warming interior and dissipating cold, or regulating Qi movement for resolving phlegm according to the patients' syndromes.

[Reflex syncope-or more? : Ictal asystole!]

A 59-year-old male patient was admitted for possible reflex syncope following loss of consciousness during urination. During the visit, a malaise with unconsciousness occurred. Holter ECG at that time showed increasing sinus bradycardia with transition to a junctional escape rhythm (30/min); in addition, there were several sinus pauses > 2.0 s (the longest almost 10 s). This malaise occurred again during routine EEG, when a focal epileptic seizure on the right fronto-temporal with sinus bradycardia after 15 s was documented. Thus, the diagnosis of ictal asystole was made, anticonvulsant therapy was started, and a cardiac pacemaker was implanted.

Yixin-Fumai granules improve sick sinus syndrome in aging mice through Nrf-2/HO-1 pathway: A new target for sick sinus syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Yixin-Fumai granules (YXFMs)-composed of Ginseng quinquefolium (L.) Alph. Wood, Ophiopogon japonicus (Thunb.) Ker Gawl, Schisandra arisanensis Hayata, Astragalus aaronsohnianus Eig, Salvia cryptantha Montbret & Aucher ex Benth, and Ligusticum striatum DC-are compound granules used in traditional Chinese medicine to increase heart rate and thus treat bradyarrhythmia. It may be effective in treating sick sinus syndrome (SSS).

AIM

To observe the effect of YXFMs on aging-induced SSS in mice and explore whether this effect is related to the Nrf-2/HO-1 signaling pathway.

MATERIALS AND METHODS

Mice with a significant decrease in the heart rate due to natural aging were selected to construct an SSS model. After the mice were administered YXFMs, the damage to their sinoartrial node (SAN) was assessed through electrocardiography, Masson's trichrome staining, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Dihydroethidium staining and immunofluorescence staining were used to assay reactive oxygen species (ROS) content and HCN4, respectively. Moreover, to observe the effects of YXFMs in vitro, the HL-1 cell line, derived from mouse atrial myocytes, was used to simulate SAN pacemaker cells, with H₂O₂ used as the cellular oxidative stress (OS) inducer. 2,7-Dichlorodihydrofluorescein diacetate staining was used to assay ROS content, whereas immunofluorescence staining and Western blotting were used to elucidate the related protein expression. Finally, mice were injected the Nrf-2 inhibitor ML385 to reversely verify the effects of YXFMs.

RESULTS

In our in vivo experiments, YXFMs significantly inhibited aging-induced SSS, shortened the R-R interval, increased heart rate, alleviated fibrosis, reduced apoptosis rate and ROS content, and promote HCN4 expression in the SAN. In our in vitro experiments, YXFMs significantly inhibited H₂O₂-induced cell peroxidation damage, promoted Nrf-2 activation and nuclear metastasis, increased HO-1 expression- thereby inhibiting ROS accumulation-and finally, upregulated HCN4 expression through the inhibition of histone deacetylase 4 (HDAC4) expression and its nuclear metastasis. Finally, injection of the Nrf-2 inhibitor ML385 after YXFMs administration inhibited their protective effect in the mice.

CONCLUSION

Here, we elaborated on the relationship between aging-induced SSS and the Nrf-2/HO-1 pathway for the first time and proposed that YXFMs improve SSS via the Nrf-2/HO-1 axis. Specifically, YXFMs promoted Nrf-2 activation and plasma-nuclear transfer to enhance HO-1 expression via the Nrf-2/HO-1 axis. This inhibited OS and reduced ROS accumulation in the SAN, and then, through the ROS/HDAC4 axis, reduced HDAC4 expression and plasma-nuclear transfer. Thereby, the OS-induced HCN4 loss in the SAN was inhibited-improving the function of I_f channel and thus producing SAN protection effect against SSS and improving the heart rate and R-R interval. In the future, we plan to use bioinformatics analysis technology to execute the next step of our research, namely to determine the effect of isolated, purified components of YXFMs in SSS, to increase its efficiency and reduce the toxicity of YXFMs.

"Preventive" pacing in patients with tachy-brady syndrome (TBS): Confirming a common practice

AIMS

Many tachy-brady syndrome (TBS) patients, are implanted a permanent pacemaker (PPM) to allow continuation of anti-arrhythmic drug (AAD) therapy to maintain sinus rhythm. Many of these PPM's are implanted as a preventive measure, in absence of symptomatic bradycardia. Our primary aim was to evaluate pacing use among these patients and find predictors for PPM use. Our secondary aim was to appreciate the portion of these patients who progress to permanent atrial fibrillation (AF).

METHODS

Retrospective study of TBS patients implanted a PPM as preventive measure, dividing cases into defined categories regarding highest percent atrial and ventricular pacing documented in PPM clinic visits during 3 year follow-up (F/U) period. Patients' baseline characteristics and AAD therapy were compared between cases with a major (>90%) pacing use and cases with <90% pacing use to find predictors for pacing use. Multivariable logistic regression was applied to identify independent variables associated with major pacing use.

RESULTS

Our study included 119 TBS patients. Most (86.5%) TBS patients had a moderate (>50%) pacing use and 58% had a major pacing use. Significant association was found between pre-implant severe sinus bradycardia (<40 bpm), first degree atrioventricular block and amiodarone treatment to major pacing use on univariate analysis and severe sinus bradycardia was significantly associated with major pacing on multivariate analysis as well. Only minority (16.8%) of TBS patients progressed to permanent AF during the study F/U period.

CONCLUSION

Our study reveals most TBS patients succeed to maintain sinus rhythm using an AAD with a significant pacing use, suggesting preventive PPM implantation might be advantageous in these cases. Pre-implant severe sinus bradycardia (<40 bpm) is a possible predictor for major pacing use in this population.

[Cilostazol and sick sinus syndrome]

Here we present the case of a 60-year-old patient with sinus node disease (NSS), symptomatic with dizziness and angor. The electrocardiogram showed episodes of sinus pauses with nodal escapes. During hospitalization, pending the placement of a definitive pacemaker, cilostazol (100 mg every 12 hours orally) was indicated, observing an increase in heart rate 48 hours after starting the medication, and the disappearance of sinus pauses in the 24 hours Holter. Our objective has been to show that cilostazol can be useful in patients with SNN, although long-term chronotropic effects of this treatment has yet to be evaluated.

Renal failure, shock, and loss of pacemaker capture: A case of flecainide intoxication

Flecainide intoxication is a severe intoxication that can lead to cardiogenic shock. We report on a 68-year-old female patient, who presented with a flecainide intoxication in the setting of renal failure. She was managed with invasive supportive therapy at the ICU and infusion of sodium bicarbonate and intravenous lipid emulsion (ILE, intralipid 20%), after which she made a complete recovery.

Hyperthyroidism and sick sinus syndrome, a rare but challenging association: A study of three cases

Hyperthyroidism is usually associated with sinus tachycardia or supraventricular tachyarrhythmias, but rarely with dysfunction of the sinus node or other conduction disturbances. Evidence of bradyarrhythmia in patients with hyperthyroidism is clinically relevant, but the fact that several drugs with negative chronotropic effects (beta-blockers and calcium channel antagonists) are frequently used in the management of these patients must be taken into account. In the presence of sick sinus syndrome (SSS) or other conductance disturbances, therapy with agents that delay the activity of sinus node or atrioventricular conduction can lead to extreme bradycardia with syncope. In this paper, aspects of diagnosis and therapy in three patients with SSS and hyperthyroidism, admitted in the Clinic of Endocrinology or/and Cardiology of the County Hospital, Timisoara, have been presented.

Hyperthyroidism and sick sinus syndrome, a rare but challenging association: A study of three cases

Hyperthyroidism is usually associated with sinus tachycardia or supraventricular tachyarrhythmias, but rarely with dysfunction of the sinus node or other conduction disturbances. Evidence of bradyarrhythmia in patients with hyperthyroidism is clinically relevant, but the fact that several drugs with negative chronotropic effects (beta-blockers and calcium channel antagonists) are frequently used in the management of these patients must be taken into account. In the presence of sick sinus syndrome (SSS) or other conductance disturbances, therapy with agents that delay the activity of sinus node or atrioventricular conduction can lead to extreme bradycardia with syncope. In this paper, aspects of diagnosis and therapy in three patients with SSS and hyperthyroidism, admitted in the Clinic of Endocrinology or/and Cardiology of the County Hospital, Timisoara, have been presented.

Fetal and Neonatal Arrhythmias

Cardiac arrhythmias are an important aspect of fetal and neonatal medicine. Premature complexes of atrial or ventricular origin are the main cause of an irregular heart rhythm. The finding is typically unrelated to an identifiable cause and no treatment is required. Tachyarrhythmia most commonly relates to supraventricular reentrant tachycardia, atrial flutter, and sinus tachycardia. Several antiarrhythmic agents are available for the perinatal treatment of tachyarrhythmias. Enduring bradycardia may result from sinus node dysfunction, complete heart block and nonconducted atrial bigeminy as the main arrhythmia mechanisms. The management and outcome of bradycardia depend on the underlying mechanism.

[Intraoperative asystole in a patient with concealed sick sinus syndrome: a case report]

We report a patient with concealed sick sinus syndrome who developed intraoperative bradycardia and asystole. An 81-year-old man was scheduled to undergo total gastrectomy under general and epidural anesthesia. There was no history of syncope, and preoperative 12-lead ECG showed normal sinus rhythm. Anesthesia was induced with propofol and remifentanil, maintained with sevoflurane, remifentanil and thoracic epidural infusion of lidocaine, fentanyl and levobupivacaine. Bradycardia was detected on ECG 110 minutes after the start of surgery. Intravenous atropine (0.5 mg, repeated up to a total dose of 1.5 mg) was ineffective in restoring a normal heart rhythm. Ten minutes later, the ECG changed to asystole lasting for about 15 seconds. Regular chest compression and intravenous administration of dopamine (5 microg x kg(-1) x min(-1)) resulted in successful recovery of sinus rhythm. Postoperative ECG showed sinus rhythm. The final diagnosis by a cardiologist was concealed sick sinus syndrome. Many anesthetic agents have some effects on the cardiac conduction system. Remifentanil may have played a role in the development of asystole in this patient. The existence of concealed sick sinus syndrome should be kept in mind even in patients who show no clinical abnormalities on preoperative assessment.

Sinus node dysfunction after surgical repair of an atrial septal defect (secundum-type): worth the wait

Sinus node dysfunction after surgical repair of an atrial septal defect is a rather uncommon complication. We report a case of protracted post-operative sinus node dysfunction which was managed successfully by oral theophyllines and 'watchful' waiting. This strategy could avoid placement of a permanent pacemaker in this patient group of younger age.

Effects of theophylline on exercise indices in a patient with chronotropic incompetence

Several investigators have documented the successful use of oral sustained-release theophylline in treating symptomatic bradycardia and sick sinus syndrome. This paper reports a case of chronotropic incompetence in which specific exercise indices, including the chronotropic response index, were used to measure the therapeutic efficacy of theophylline.

Sinus node dysfunction in ATX-II-induced in-vitro murine model of long QT3 syndrome and rescue effect of ranolazine

The aim of this study was to characterize the role of the late Na+ current (I(Na,L)) as a mechanism for induction of both tachy and bradyarrhythmias in murine heart and sino-atrial node tissue. The sea anemone toxin ATX-II and ranolazine were used to increase and inhibit, respectively, I(Na,L). In sixteen hearts studied, exposure to 1-10nM ATX-II caused a slowing of intrinsic heart rate and prolongations of the P-R and QT intervals, the duration of the monophasic action potential, and the sinus node recovery time, accompanied by frequent occurrences of early after depolarisations, delayed after depolarisations and rapid, repetitive ventricular tachy and sino-atrial bradyarrhythmias. ATX-II also slowed sinus node pacemaking, and induced bradycardic arrhythmias in isolated sino-atrial preparations (n=5). The ATX-II-induced alteration of electrophysiological properties and occurrence of arrhythmic events were significantly attenuated by 10 microM ranolazine in intact hearts (n=11) and isolated sino-atrial preparations (n=5). In conclusion, the I(Na,L) enhancer ATX-II causes both tachy and bradyarrhythmias in the murine heart, and these arrhythmias are markedly attenuated by the I(Na,L) blocker, ranolazine (10 microM). The results suggest that I(Na,L) blockade may be the mechanism underlying the reductions of both brady and tachyarrhythmias by ranolazine that were observed during the MERLIN-TIMI clinical outcomes trial.

Recurrent syncope due to carotid sinus hypersensitivity and sick sinus syndrome

Syncope is a sudden and brief loss of consciousness with postural tone. Its recovery is usually spontaneous. There are various causes of syncope including cardiac, vascular, neurologic, metabolic and miscellaneous origins. The tracing is usually time-consuming and costly. The diagnosis of carotid sinus syncope may sometimes be difficult since the symptoms are nonspecific, especially in older persons. Here, we report the case of a 72-year-old woman who sought medical attention at our hospital due to repeated syncope episodes over the previous 5 years. Neurologic examinations showed negative results (including brain computed tomography). Twenty-four-hour ambulatory electrocardiogram monitoring showed atrial and ventricular premature contractions only. Electrophysiologic study disclosed prolonged corrected sinus node recovery time (1,737 ms) with poor atrioventricular conduction. Drop of blood pressure together with sinus bradycardia developed after left side carotid sinus massage. Both carotid sinus hypersensitivity with sick sinus syndrome contributed to this patient's syncope, and after pacemaker placement together with selective serotonin reuptake inhibitor treatment, she was free from syncope thereafter.

[Effect of qiangxin fumai granule contained serum on sinoatrial node cells during Ca2+ overloading induced by simulated ischemia/reperfusion]

OBJECTIVE

To explore the effect of Qiangxin Fumai Granule (QFG, a Chinese herbal preparation for treatment of sick sinus syndrome) contained serum (QFG-S) on sinoatrial node cells during Ca2+ overloading induced by simulated ischemia/reperfusion.

METHODS

Model Ca2+ overloading cells were established on sinoatrial node cells from newborn rats, with deprivation of oxygen and glucose to simulate ischemia and with restoration of them to simulate reperfusion. Cells were divided into 5 groups, those in the normal and model control groups were modeled directly and those in the treated groups were pre-cultured with UMEM containing respective medicines in aerobic environment for 30 mm before ischemia/reperfusion simulation. Cell Ca2+ concentration and morphology were observed by invert microscope and fluorescence spectrophotometer.

RESULTS

Most cells in the model control group revealed cell edema and deformation, even abscission. By HE staining, many minimal vacuole appeared in cytoplasm, with crumpled nuclear membrane, partially damaged. While cells in the QFG-S treated group, either high-dose or low-dose, were attached grew well, with basically smooth and complete membrane and nuclear membrane, normal in size and shape. The intracellular Ca2+ concentration raised significantly after modeling, but it was much lower in the QFG-S treated group than in the model control group (P < 0.01) and it was not changed obviously in the atropine treated group.

CONCLUSION

QFG-S could diminish the injury of cell induced by simulated ischemia/reperfusion, the acting mechanism for treatment of sick sinus syndrome might be related to its effect in relieving Ca2+ overloading and thus protecting cells from injury.

Increased AAI mode pacing threshold after termination of atrial fibrillation by acute administration of disopyramide phosphate

AIMS

We studied changes in atrial pacing threshold after termination of atrial fibrillation (AF) by acute administration of disopyramide phosphate (DP) to elucidate the suitable setting for atrial pacing output before AF termination.

METHODS AND RESULTS

Four patients with sick sinus syndrome implanted with AAI mode pacemakers were examined. Disopyramide phosphate (2 mg/kg body weight) was injected intravenously for termination of a total of eight AF episodes. The maximal pacing threshold after AF termination (5.2+/-0.8 V at 0.45 ms) was significantly higher than that at baseline (1.3+/-0.2 V at 0.45 ms; P<0.01) and the average increment was 433+/-68%. During a period free from AF, an acute administration of DP did not increase the atrial pacing threshold and serum disopyramide levels were not toxic.

CONCLUSION

The increased atrial pacing threshold observed after AF termination cannot be explained by the action of DP alone. However, our results suggest that atrial pacing output should be set at the maximum value before DP is administered to induce AF termination in patients with AAI pacemaker-dependent bradyarrhythmias.

Chronotropic Effect of the Antithrombotic Agent Cilostazol in a Patient with Sick Sinus Syndrome and Syncope

In this case report we describe an 80-year-old man with sick sinus syndrome (SSS) who developed syncope attacks. The diagnosis of SSS was based on electrocardiographic evidence of markedly prolonged sinus arrests associated with syncope attacks while in hospital. The patient was given cilostazol, an anti-thrombotic agent that selectively inhibits cyclic nucleotide phosphodiesterase type 3, at a dose of 100 mg twice daily. The syncope attacks ceased, and an electrocardiogram obtained 1 week after the start of cilostazol administration showed no evidence of sinus arrest. The outcome of this case suggests that cilostazol may be useful in patients with syncope attacks due to SSS, although the long-term chronotropic effects of cilostazol need to be evaluated.

Clinical characteristics of hypervagotonic sinus node dysfunction

BACKGROUND

Sinus node dysfunction (SND) is caused not only by intrinsic sinus node disease, but also by the extrinsic factors. Among the extrinsic factors, autonomic imbalance is most common. Symptomatic SND usually requires permanent pacemaker therapy. However, the clinical characteristics and patient response to medical therapy for hypervagotonic SND have not been properly clarified.

MATERIALS AND METHODS

Thirty two patients (14 men, 18 women, 51 +/- 14 years) with hypervagotonic SND were included in this study, but those patients who had taken calcium antagonists, beta-blockers or other antiarrhythmic drugs were excluded. Hypervagotonic SND was diagnosed if the abnormal electrophysiologic properties of the sinus node were normalized after the administration of atropine (0.04 mg/kg).

RESULTS

The presenting arrhythmias were 16 cases of sinus bradycardia (50.0%), 12 of sinus pause (37.5%), 3 of sinoatrial block (9.4%) and 1 of tachy-bradycardia (3.1%). Nine (28.1%) patients had hypertension, 7 (21.9%) smoked, 2 (6.3%) had diabetes mellitus, and 1 (3.1%) had hypercholesterolemia. Among the patients, 3 had no remarkable symptoms, 13 had dizziness, 7 had syncope, 3 had weakness and 6 had shortness of breath. Twenty five (78.1%) patients were treated with theophylline, 1 patient with tachy-bradycardia syndrome was treated with digoxin and propafenone, and 6 (18.8%) were treated with no medication. During the 43 +/- 28 month follow-up, 25 patients remained asymptomatic, but 6 who took no medication developed mild dizziness. One patient needed permanent pacemaker implantation owing to recurrent syncope despite of theophylline treatment.

CONCLUSION

These results show that hypervagotonic SND has a benign course and most of the patients can be managed safely without implanting a pacemaker. (Ed note: I like the abstract. It is short and direct, as it should be.)

Efficacy of steroid therapy for pacing failure in a patient with chronic myocarditis

A 66-year-old man had a progressive increase in the pacing threshold over a one-year period, resulting from chronic myocarditis. Following steroid therapy, the pacing threshold decreased and became stabilized, and was accompanied by a decrease in the serum creatine kinase, cardiac myosin light chains and pro-collagen III peptide values, but cardiac function did not improve. Endocardial biopsy showed that there was no progression in the fibrosis. The pacing failure improved, but the cardiac function did not. It was believed that the steroid therapy suppressed the progression of the inflammation and fibrosis caused by the chronic myocarditis.

[Psychosomatic ratios and their correction in the autonomic dysfunction of the sinus node]

The study was undertaken to examine the ratio of mental to somatic disorders in patients with autonomic sinus nodal dysfunction (ASND) and the capacities of correction of revealed disorders with the atypical benzodiazepine drug clonazepam. Thirty-two patients with ASND were examined. The diagnosis of ASND was verified by 24-hour ECG monitoring and transesophageal atrial pacing, by performing autonomic cardiac block with atropine and obsidan. In addition to physical examination, heart rhythm variability was studied during relaxed and intensive wake; psychological studies using the conventional tests were conducted, and autonomic disorders were explored by means of original scored somatic, hyperventilation) questionnaires. After examination, the patients received a 1.5-to-2-month course of therapy with clonazepam in a daily dose of 1.5-2 mg. The study has revealed that clinical symptomatology in ASND is greatly determined by psychosomatic disorders. ASND was marked by anxious depressions in combination with inadequate peripheral (to a greater extent, sympathetic) neurovegetative exposures with the simultaneous activation of cerebral ergotropic effects. The use of clonazepam in ASND greatly improved its clinical picture, by eliminating, in the overwhelming majority of cases, clinical symptoms, including rhythm and conduction disturbances that are characteristic of ASND.

[Effect of mexidol on efficacy of traditional therapy of sick sinus syndrome in adolescents]

ECG data obtained with a Holter monitor in a group of 90 adolescent patients with vegetovascular dystonia and sick sinus syndrome (SSS) showed that mexidol, intravenously instilled in a daily dose of 2-4 mg/kg over a period of 10 days in combination with a standard neurometabolic scheme results in the development of a therapeutic effect in 93-100% of patients with clinical-ECG variants I and II of the disorder. In most cases, both clinical state and ECG quality were improved and the functional capacity of myocardium was increased. Repeated courses of mexidol administration increased efficacy of the ambulatory SSS treatment on the average by 20%.

Intrinsic sinus and atrioventricular node electrophysiologic adaptations in endurance athletes

OBJECTIVES

In the present study, we evaluated sinus and atrioventricular (AV) node electrophysiology of endurance athletes and untrained individuals before and after autonomic pharmacologic blockade.

BACKGROUND

Endurance athletes present a higher prevalence of sinus bradycardia and AV conduction abnormalities, as compared with untrained individuals. Previous data from our laboratory suggest that nonautonomic factors may be responsible for the longer AV node refractory period found in well-trained athletes.

METHODS

Six aerobically trained male athletes and six healthy male individuals with similar ages and normal rest electrocardiograms were studied. Maximal oxygen uptake (O(2)max) was measured by cardiopulmonary testing. The sinus cycle length (SCL), AV conduction intervals, sinus node recovery time (SNRT), Wenckebach cycle (WC) and anterograde effective refractory period (ERP) of the AV node were evaluated by invasive electrophysiologic studies at baseline, after intravenous atropine (0.04 mg/kg) and after addition of intravenous propranolol (0.2 mg/kg).

RESULTS

Athletes had a significantly higher O(2)max as compared with untrained individuals. The SCL was longer in athletes at baseline, after atropine and after the addition of propranolol for double-autonomic blockade. The mean maximal SNRT/SCL was longer in athletes after atropine and after propranolol. The WC and anterograde ERP of the AV node were longer in athletes at baseline, after atropine and after propranolol.

CONCLUSIONS

Under double-pharmacologic blockade, we demonstrated that sinus automaticity and AV node conduction changes of endurance athletes are related to intrinsic physiology and not to autonomic influences.

Development of heart failure in bradycardic sick sinus syndrome

Mounting evidence shows that elevated resting sinus rate is an independent predictor of cardiovascular morbidity and mortality in the general population, in elderly subjects, and in patients with myocardial infarction or hypertension. Therefore, a rather slow sinus rate appears to be a protecting factor acting through several mechanisms. The present contribution focuses on the relationship between sinus rate and heart failure. Its major objectives are to discuss whether in patients with heart failure a rather slow heart rate is advisable and whether a sinus bradycardia secondary to sinus node dysfunction can facilitate the development of heart failure. It has been reported that among patients with left ventricular dysfunction, increased sinus rate was a predictor of cardiovascular death at univariate analysis; however, a multivariate analysis to verify whether sinus rate was an independent predictor of mortality was not performed. Randomized trials carried out by utilizing beta-blockers or amiodarone in patients with heart failure showed that heart rate reduction by these drugs was a marker of their ability to reduce mortality. However, beta-blockers and amiodarone have additional pharmacological effects which interfere with the disease substrate. So, at present, though the results of these trials show that a rather slow sinus rate is advisable, we do not know whether in patients with heart failure sinus rate represents an independent predictor of mortality as in patients with myocardial infarction or hypertension and whether the reduction of sinus rate per se is beneficial. The results of the recent randomized THEOPACE trial showed, for the first time, that in a patient population with symptomatic sinus bradycardia (sinus rate < 50 b/min), an increase in heart rate, induced by DDD pacing or oral theophylline, reduced the incidence of overt heart failure. Therefore, sinus bradycardia seems to play a role in the genesis of heart failure. In a post-hoc analysis of the results of this trial it emerged that in the control (not treated) group, the subjects with sinus bradycardia more prone to develop heart failure were those of old age, about 80 years, with organic heart disease and severe chronotropic incompetence. However, this conclusion needs further validation.

[Cilostazol increased heart rate with improvement of activity of daily living in an elderly patient with sick sinus syndrome]

An 86-year-old man had a history of hypertension and had been treated with calcium antagonist but no medications that could reduce heart rate. As a 12-lead electrocardiogram showed sinus bradycardia, complete right bundle branch block and left anterior fascicular hemiblock on his first visit to our hospital on January 1998, he was admitted to our hospital for further examination and treatment. A 24-hour Holter electrocardiogram demonstrated a total number of 74,182 heartbeats per day with pauses (> 2.0 sec) of 187/day. Overdrive atrial pacing study and His bundle electrogram revealed a prolonged corrected sinus node recovery time (5.820msec at a stimulation rate of 130/min) and H-V conduction time (80msec) with normal A-H conduction time, respectively. We diagnosed these abnormalities as sick sinus syndrome (Rubenstein II). His activity of daily living score was 30 points by the Barthel index on the day of admission. Oral administration of orciprenaline sulfate (30 mg/day), a beta-adrenoceptor agonist, was initially chosen rather than implantation of a cardiac pacemaker to increase his heart rate since he did not have any symptoms due to bradycardia and he did not give us an informed consent for the implantation. Orciprenaline sulfate, however, failed to increase total heartbeats (73,079/day). Then, oral cilostazol (100 mg/day), a phosphodiesterase III inhibitor, was administered. After two weeks of the regimen total heart beats were increased (85,642/day) with no pauses. The increase in heart rate resulted in the improvement of his activity of daily living (Barthel index: 55 points). Cilostazol could be the first line medication for elderly patients with bradyarrhythmia in whom implantation of cardiac pacemaker is not absolutely indicated.

[Amiodarone-induced bilateral optic atrophy--a case report]

We report a case of visual loss and bilateral papilloedema under therapy with the antiarrhythmic substance amiodarone, which is used in treatment of refractory and life-threatening supraventricular and ventricular cardial tachyarrhythmias. After excluding intracranial hypertension, local tumors and an inflammatory genesis we consider this case to be an amiodarone-induced toxic opticusneuropathy. Amiodarone, a diiodated benzofuran derivative, is a cationic amphiphilic drug, which is able to cause ceratopathy and neuropathy. The rarely described and less known opticusneuropathy caused problems in differential diagnosis. A brief review about current knowledge of pathophysiology, differential diagnosis and course of illness is presented.

Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome

BACKGROUND

It has been claimed that patients with sick sinus syndrome have an increased risk of developing AV block, but this has never been assessed prospectively. The aim of the present study was to evaluate in a prospective trial AV conduction during the long-term follow-up of patients with sick sinus syndrome.

METHODS

Two hundred twenty-five consecutive patients with sick sinus syndrome and intact AV conduction were randomized to undergo single-chamber atrial pacing (110 patients) or single-chamber ventricular pacing (115 patients). Follow-up after 3 months and then yearly included measurement of the PQ interval and, in patients with atrial pacemakers, determination of the atrial stimulus-Q intervals at pacing rates of 100 and 120 bpm. The occurrence of AV block in the atrial group was recorded. During follow-up (mean, 5.5+/-2.4 years), there was no change in PQ interval in either group and no change in atrial stimulus-Q intervals or Wenckebach block point in the atrial group. Four of 110 patients in the atrial group developed grade 2 to 3 AV block that required upgrading of the pacemaker (0.6% per year). Two of these 4 patients had right bundle-branch block at pacemaker implantation.

CONCLUSIONS

AV conduction, estimated as PQ interval and atrial stimulus-Q interval at atrial pacing rates of 100 and 120 bpm and the Wenckebach block point, remains stable during long-term follow-up. Thus, treatment with single-chamber atrial pacing is safe and can be recommended to patients with sick sinus syndrome without bundle-branch block.

Chronotropic effects of cilostazol, a new antithrombotic agent, in patients with bradyarrhythmias

Whether phosphodiesterase inhibitors increase the heart rate in patients with bradyarrhythmias is not known. We attempted to determine whether the oral phosphodiesterase inhibitor cilostazol exhibits beneficial chronotropic effects in patients with symptomatic bradyarrhythmias. Twenty patients comprising eight with bradycardic atrial fibrillation, eight with sick sinus syndrome, and four with Wenckebach-type atrioventricular block, whose 24-h total heart-beat count was < or =70,000 beats and whose maximal RR interval was > or =2.5 s, were enrolled. Holter recordings (24-h) were made before and 2 weeks after oral daily administration of 200 mg of cilostazol. Cilostazol increased the 24-h total heart-beat count from 77,429 +/- 11,168 to 107,981 +/- 13,536 (95% confidence interval, 24,605-36,497; p < 0.0001), the minimal heart rate from 33 +/- 9 47 +/- 13 beats/min (95% confidence interval, 9-19 beats/min; p < 0.0001), and the maximal RR interval from 3,149 +/- 1,018 to 2,087 +/- 601 ms (95% confidence interval, -1,517 to -608 ms; p = 0.0001). Only two patients had headaches as adverse effects. In conclusion, cilostazol had a beneficial positive chronotropic effect in patients with bradyarrhythmias, especially with bradycardic atrial fibrillation and sick sinus syndrome.

Relation between bradycardia dependent long QT syndrome and QT prolongation by disopyramide in humans

BACKGROUND

Recent molecular biological investigations have identified abnormal genes in familial forms of long QT syndrome, but in bradycardia dependent acquired long QT syndrome, no such genetic abnormality has yet been identified.

OBJECTIVE

To investigate the relation between the responses of QT interval to pacing change and to disopyramide.

METHODS

This study included 13 patients with bradyarrhythmia who had undergone pacemaker implantation. The patients were divided into two groups: group I (n = 8), patients with QT prolongation (QT interval > or = 500 ms) during bradycardia; group II (n = 5), patients without QT prolongation (QT interval < 500 ms) during bradycardia. The responses of QT interval caused by the change of pacing rate were determined and compared with the changes of the QT interval after disopyramide administration.

RESULTS

The QT interval in group I was significantly longer than that in group II when the pacing rate was decreased from 110 to 50 beats/min: mean (SD) 451 (16) v 416 (17) ms at 90 beats/min (p = 0.0033), and 490 (19) v 432 (18) ms at 70 beats/min (p = 0.0002), respectively. The QT interval was prolonged significantly by disopyramide in both groups, but the change was more pronounced in group I than in group II: 78 (33) v 35 (10) ms (p < 0.05).

CONCLUSIONS

This study suggests that the patients showing bradycardia dependent QT prolongation are also more markedly affected by disopyramide and that abnormal potassium channel may be the underlying mechanism.

[The use of Cordanum in combination with Corinfar-Retard for the treatment of ectopic arrhythmias in the sick sinus syndrome in patients with ischemic heart disease]

38 patients with ischemic heart disease (IHD) and sick sinus syndrome (SSS) received combined therapy with nifedipine (Corinfar-Retard) and talinolol (Cordanum). The former drug had a positive chronotropic effect on the heart, the latter's chronotropic effect was slightly negative. All the patients had sinus bradycardia and ectopic arrhythmia which needed therapeutic correction: supraventricular and ventricular extrasystoles, fibrillation paroxysms or/and atrial flutter, paroxysmal supraventricular tachycardia, ventricular tachycardia. Cordanum was given in a dose 50 mg twice a day, Corinfar-Retard 20 mg twice a day for 16 days. 30 patients responded to the treatment. In addition to good subjective response, episodes of extrasystoles, paroxysms, flutter and fibrillation occurred much less frequently. Side effects resulted in the treatment discontinuation in 3 patients.

Sotalol for atrial tachycardias after surgery for congenital heart disease

Atrial tachycardias, in particular atrial flutter after surgery for congenital heart disease, is associated with a high mortality. Treatment with various antiarrhythmic drugs and/or antitachycardia pacemakers is not very successful. Sotalol, a Class III drug, has shown to be a promising drug in adults with atrial tachycardias. However, the experience with sotalol in children after surgery for congenital heart disease is limited. Therefore, we describe our results here. Between December 1990 and February 1997, 26 children with atrial tachycardias, most of them with atrial flutter or fibrillation (n = 20), after surgery for congenital heart disease were treated with sotalol orally. The age of the children at the start of treatment was 7.5 +/- 5.8 years (mean +/- SD). The time interval between surgery and the start of atrial tachycardia ranged from 1 day to 14.3 years (3.8 +/- 3.8 years). Conversion to sinus rhythm was achieved in 16 out of 22 hemodynamically stable children with a dosage of 4.0 +/- 1.6 mg/kg per day. The six children without sinus rhythm on sotalol and four hemodynamically unstable patients were treated prophylactically with sotalol after DC cardioversion for their tachycardias. Two children complained of mild transient fatigue. Heart rate decreased during therapy (95 +/- 33 vs 81 +/- 21 beats/min; P = 0.01). QTc-intervals did not change. Proarrhythmias such as torsades de pointes were not encountered. Two children with a preexistent sick sinus syndrome showed aggravation of bradycardia and needed pacemaker implantation. The percentage of children with a recurrence-free interval of 1 and 2 years was 96% and 81%, respectively, for all atrial tachycardias, and 92% and 66% for atrial flutter. The recurrences of atrial tachycardias during the follow-up period, which ranged from 0.1-6.1 years (2.5 +/- 1.8 years) could be treated with only an increase of the dosage of sotalol in all but one patient. We conclude that sotalol is an effective drug for the treatment and prevention of atrial tachycardia in children after surgery for congenital heart disease.

Radiofrequency ablation of accessory pathways associated with congenital heart disease

The coexistence of significant congenital cardiac disease with accessory pathways is not uncommon, and presents a number of issues for clinical management. These issues include the propensity of such patients to have poorly tolerated tachycardia; the difficulties in choosing appropriate medical management given potential problems with preexisting sinus node disease, poor contractility, and the possibility of proarrhythmia; the need to seriously consider ablation prior to, or at the time of, intracardiac repair of congenital cardiac defects; and finally, the difficulties that complex anatomy may pose to the interventional electrophysiologist. Definitive management requires expertise both in electrophysiology and in pediatric cardiology. Success can usually be achieved with a careful, anatomically precise approach, combined with imagination and persistence. Because of the difficulties with medical management, catheter ablation may be the most attractive modality for control of accessory pathway tachycardia in this patient population.

[Effects of oral amezinium metilsulfate in patients with sick sinus syndrome]

The effects of amezinium metilsulfate (Risumic) were studied in patients with sick sinus syndrome. Four males and 11 females with clinical symptoms were treated with 0.5 mg/kg for 1 to 40 weeks. In all patients, the length of sinus pause observed during 24-hour Holter monitoring was longer than 2.0 sec, and/or the sinus node recovery time in the electrophysiologic study was longer than 2.0 sec. The effects were evaluated by Holter monitoring and standard electrocardiography. The total number of heart beats every 24 hours by Holter monitoring were significantly increased from 78,917 +/- 15,983 (mean +/- SD) to 85,753 +/- 17,849 beats after the treatment. The length of the sinus pause was significantly decreased from 3.89 +/- 1.24 to 2.36 +/- 1.45 sec. Patients with sinus node recovery time of less than 5.0 sec showed the effects especially clearly. The total number of premature ventricular contractions was decreased from 530 +/- 767 to 123 +/- 182 beats. The PQ, QRS and QTc intervals did not change. Only diastolic pressure was slightly increased. Clinical symptoms disappeared in almost all patients and the clinical courses were favorable. Amezinium metilsulfate, which stimulates the intrinsic sympathetic nervous system, increased total heart beat and shortened sinus pause in patients with sick sinus syndrome. Few side effects, such as arrhythmogenecity or increase of blood pressure were observed. These results show that amezinium metilsulfate is useful in the treatment of patients with sick sinus syndrome, if the disease is not so severe as to require implantation of a cardiac pacemaker.

[Experiences in therapy of bradycardic cardiac arrhythmias in childhood with ipratropium bromide]

Ipratropiumbromid is used in adults for a variety of bradyarrhythmias. In contrast this therapy has not yet been established in childhood, where symptomatic bradyeardias are less frequent. Since Ipratropiumbromid has less side effects (especially concerning the central nervous system) and a longer half time than atropin, we investigated the efficacy of Ipratropiumbromid in 12 children (mean age 7.2 yrs.) in the course of 2 1/2 years. We found a significant increase of the minimal and mean heart rate in Holter-Eeg-recordings. Only in 7 of 12 patients we obtained a sufficient therapeutic effect. In one patient we had to terminate the therapy because of side effects. In two patients with atrioventricular block and two children with higher degree sinus node dysfunction could be removed only by implantation of a pacemaker. In another case we observed the proarrhythmical effect of Ipratropiumbromid. Summarizing we think, that the therapy with Ipratropiumbromid may be useful in symptomatical supranodal bradyarrhythmias in childhood in regard of side effects.

[A case of idiopathic orthostatic hypotension manifesting sick sinus syndrome due to sympathetic nervous dysfunction]

A 67-year-old woman with idiopathic orthostatic hypotension was presented. The patient started to experience faintness on standing since 1993. During a physical examination, her systolic blood pressure fell from 148 to 50 mmHg on standing. Blood pressure responses to the mental arithmetic test and hyperventilation stress were normal. However, cold pressor test failed to increase blood pressure. These observations, with the finding that phase IV response on Valsalva's maneuver was absent, indicate afferent sympathetic nervous dysfunction. Peripheral neuropathy including diabetes mellitus and involvement of central nervous system such as multiple system atrophy were excluded. Holter ECG examination revealed a 3.9 second sinus arrest and bradycardia (total beats 88901/day). the blunted responses of the heart rate to atropine as well as isoproterenol further suggested the presence of sick sinus syndrome. Amezinium administration significantly improved her orthostatic hypotension and eliminated sinus arrest. These findings indicate that sympathetic nervous dysfunction could account for at least a part of the sick sinus syndrome in this patient.

Coronary dilating effects of intracoronary nicorandil. Comparison with isosorbide dinitrate

Although nicorandil, N-(2-hydroxyethyl) nicotinamide dinitrate, is a nitrate ester, its cardiovascular action differs from that of nitrate compounds in several aspects. In this quantitative angiographic study, the acute coronary dilating effect of intracoronary nicorandil (0.25, 0.50, 1.0 mg) was compared with that of isosorbide dinitrate (ISDN; 1.0 mg) in 46 patients with or without ischemic heart disease (IHD). Dose-dependent right coronary dilating action was observed by intracoronary administration of nicorandil without any adverse effects. The same degree of right coronary dilation was achieved by the intracoronary application of equivalent doses of ISDN. We conclude that intracoronary administration of nicorandil is beneficial for the supportive treatment of IHD during coronary artery investigation and intervention without the risk of severe systemic hypotension.

[Treatment of arrhythmias in the elderly]

The disorders of cardiac rhythm in the elderly are frequent and important since they are generally less tolerated than in young patients. Sinus bradycardia is one of the most common disorder of cardiac rhythm; symptomatic sinus bradycardia will be treated by pacemaker insertion in most cases. Atrial fibrillation is frequent in the elderly and often poorly tolerated; the aim of therapy is to restore sinus rhythm and prevent recurrences. In order to avoid strokes (emboli), old patients, with chronic atrial fibrillation should be submitted to low-level anticoagulation. Elderly patients may also suffer from supraventricular and ventricular premature beats which should be treated if they present some degree of malignancy.

Treatment of atrial fibrillation. Recommendations from a workshop arranged by the Medical Products Agency (Uppsala, Sweden) and the Swedish Society of Cardiology

Atrial fibrillation may be paroxysmal or chronic. The paroxysmal form presents in the form of attacks of short duration but may last for up to 3-4 days. Episodes of atrial fibrillation of longer duration are considered as chronic. The diagnosis is made by ECG.

Clinical observation on treatment of bradyarrhythmia with Chinese herbal medicine

This paper reports on treatment of 62 cases of bradyarrhythmia with Fu Ben Zeng Mai Tang, a decoction of herbal medicine which has the effect of warming and tonifying the heart and kidney, reinforcing qi and improving blood circulation. The result indicates that it is effective for quickening the heart rhythm, improving the symptoms and regulating the function of sinoatrial node. It is also good for regulating the function of endocrine and the immune and nervous system. This therapy was compared with Western medicine in the treatment of 24 cases.

Xamoterol in sinus node disease

A pharmacological alternative to pace-maker implantation would be useful in some patients with sinoatrial disorder particularly since the single lead ventricular system usually fitted has disadvantages. Xamoterol, a cardioselective beta-receptor partial agonist, has been shown to increase heart rate both in animals and in man. We, therefore, studied the effects of Xamoterol in patients with sinoatrial disease in a double blind, cross-over trial in 10 patients. Mean heart rates and number and duration of pauses were compared during the treatment phases of the trial with Holter monitoring. Mean heart rates were significantly increased between 01:00 h and 05:00 h (P < or = 0.02) and between 05:00 h and 09:00 h (P < or = 0.01) on Xamoterol. The number of sinus pauses were eliminated or reduced on Xamoterol in six patients, but there was an increased frequency in three patients. Xamoterol, therefore, does increase the heart rate and reduce the number of pauses in sinoatrial disorder, but only in some patients.

Effects of oral theophylline on sick sinus syndrome

OBJECTIVES

We sought to determine the effect of theophylline on cardiac pauses in sick sinus syndrome.

BACKGROUND

Sick sinus syndrome, a relatively benign condition, is usually treated with pacemaker implantation without any proved effectiveness. Thus, an appropriate pharmacologic therapy would be useful.

METHODS

Theophylline (200 to 400 mg/day for 1 month) was initially administered orally to 17 patients with sick sinus syndrome, which is manifested by sinus pauses of > 2.5 s. Eleven of the 17 patients subsequently received theophylline for an additional 8 to 37 months. Twenty-four-hour Holter recordings were obtained before treatment, at the end of 1 month of treatment and then at 6-month intervals.

RESULTS

Theophylline decreased the frequency of sinus pauses from 256 +/- 230 to 23 +/- 62 pauses per 24 h and decreased the duration of the longest pauses from 4.7 +/- 1.8 to 2.2 +/- 0.97 s after 1 month of treatment. Subjective symptoms associated with cardiac pauses disappeared in 16 of 17 patients. Ventricular premature beats increased in frequency but did not last longer than two beats. Three patients experienced adverse effects. Nine of the 11 patients receiving long-term treatment had a good outcome, but 2 patients required a pacemaker because of the reappearance of long sinus pauses.

CONCLUSIONS

The results suggest that oral theophylline may be beneficial for the treatment of patients with sick sinus syndrome.

[The effects of pharmacological autonomic blockade on the conduction system in patients with and without sinus node dysfunction]

Electrophysiological studies were performed in 26 patients with sick sinus syndrome (SSS) and 12 controls before and after pharmacologic autonomic blockade (PAB) with propranolol (0.15 mg/kg) and atropine (0.04 mg/kg). Sinus cycle length (SCL) shortened significantly after PAB in both groups. PA and HV intervals did not change after PAB. AH interval shortened and Wenckebach period increased after PAB in SSS group. Maximum corrected sinus node recovery time shortened in the control group but did not change in the SSS group after PAB. Calculated sinoatrial conduction time shortened after PAB in both groups. Refractory periods of the atrioventricular (AV) node and the ventricle shortened significantly, but those of the atrium did not change after PAB. Linear relations existed between the change of SCL and the change of AH interval and of the Wenckebach period. These results suggested that the autonomic nervous system had the same effects on the sinus and the AV nodes in patients with SSS, and that parasympathetic tone was predominant on the sinus node, the perinodal tissue and the AV node under resting conditions.

Comparison of effects of propranolol versus pindolol on sinus rate and pacing frequency in sick sinus syndrome

Beta blockers in patients with sick sinus syndrome (SSS) may prevent supraventricular arrhythmias, systemic hypertension and myocardial ischemia, but may cause excessive depression of sinus node function. In 8 patients with SSS and a permanent pacemaker, the effect of chronic oral pindolol on sinus rate and pacing frequency was compared with that of propranolol in a double-blind crossover trial. In all patients the pacemaker was programmed to a rate of < or = 50 beats/min. Holter monitors, obtained at baseline and on each drug, were used to calculate peak ambulatory sinus rate, number of paced beats per day, maximal number of paced beats per hour, and percentage of hours with paced beats. The peak sinus rate with pindolol therapy was 24% higher than with propranolol (p = 0.001). During pindolol therapy, the number of paced beats per day and maximal paced beats per hour were reduced 54% (p = 0.04) and 61% (p = 0.02), respectively, compared with propranolol. Patients with SSS who require beta-blocker therapy for tachycardia, systemic hypertension or angina pectoris may have less bradycardia when treated with pindolol rather than propranolol. Beta blockers like pindolol, which cause less sinus node depression, may obviate the need for prophylactic permanent pacemakers in patients with SSS, and may help to prevent chronotropic incompetence and pacemaker syndrome in patients already treated with a VVI device.

Kawasaki disease in an infant with cystic fibrosis

The authors report a case of a 3-month-old infant with a very rare association: cystic fibrosis and Kawasaki disease. The clinical picture is atypical but cardiovascular signs consist of cardiomegaly, sick sinus syndrome and Q waves in D II, D III and AVF. The diagnosis is confirmed by the pathological changes found at the postmortem examination. The patient is the first case of Kawasaki disease reported in Romania.

Clinical effects of oral theophylline in sick sinus syndrome

In 17 patients with symptomatic sinus bradycardia (age: 66 +/- 11 years), a resting electrocardiogram, a 24-hour Holter recording, and a treadmill test were performed both before and after administration of slow-release theophylline (700 mg daily). The drug increased resting heart rate (46 +/- 7 versus 62 +/- 18 beats/min, p less than 0.01), mean 24-hour rate (51 +/- 6 versus 64 +/- 16 beats/min, p less than 0.01), and minimal 24-hour heart rate (36 +/- 6 versus 43 +/- 10 beats/min, p less than 0.05). Cardiac pauses greater than 2.5 seconds were present in four patients during control recording, and disappeared after theophylline. The daily number of premature supraventricular and ventricular beats increased slightly after the drug. Exercise heart rate was higher after theophylline than during the control test (p less than 0.01). Thirteen patients were followed for a period of 17 +/- 3 months. Suppression of symptoms was achieved in 12 patients. Asthenia and easy fatigue were reduced markedly by the drug. During long-term therapy, the sinus rate was similar to that observed at the steady-state evaluation. In 3 of the 17 patients theophylline had to be discontinued because of gastric intolerance (in two at the end of the steady-state evaluation and in one during long-term therapy). These data suggest that oral theophylline can represent an effective therapy in some patients with symptomatic sinus bradycardia.