Atrial fibrillation following chemotherapy for stage IIIE diffuse large B-cell gastric lymphoma in a patient with myotonic dystrophy (Steinert’s disease)

The authors describe the unusual association between diffuse B-cell gastric lymphoma and myotonic dystrophy, the most common form of adult muscular dystrophy, and sudden atrial fibrillation following one cycle of doxorubicin-based chemotherapy in the same patient. Atrial fibrillation or other cardiac arrhythmias are unusual complications in patients treated with chemotherapy. The cardiac toxicity intrinsically associated with the aggressive chemotherapy employed could function as a triggering factor for the arrhythmia in the predisposed myocardium of this patient.

Lone atrial fibrillation: more than meets the eye

Doxorubicin has been used as a chemotherapeutic agent for over 30 years. Its cardiac toxicity has been known for over 20 years. In recent years, delayed-onset cardiac toxicity has been described as yet another cardiac complication of doxorubicin and other anthracyclines. The following case is felt to represent such an example.

Management of patients with persistent chest pain and ST-segment elevation during 5-fluorouracil treatment: report about two cases

5-Fluorouracil, a widely used drug in cancer treatment, is known to have cardiotoxic effects: chest pain with ECG changes, arrhythmias, arterial hypertension or hypotension, myocardial infarction, cardiogenic shock and sudden death have been described in the literature. Coronary artery vasospasm is the pathogenetic mechanism hypothesized in most cases, but mechanisms other than myocardial ischemia had been advocated in some patients. The approach to the patient with persistent chest pain, despite therapy and persistent ST-segment elevation mimicking an acute myocardial infarction, has not been well addressed, and the appropriate diagnostic and therapeutic pathways have not yet been defined. We present our experience regarding 2 patients treated with 5-fluorouracil and referred to our coronary care unit because of prolonged chest pain (in one case with clinical evidence of hemodynamic impairment) and persistent ST-segment elevation, in whom an acute myocardial infarction was suspected. One patient was treated with systemic fibrinolysis, and coronary angiography was performed 6 days later; the other was submitted to urgent coronary angiography shortly after admission. In both cases the ECG and echocardiographic abnormalities were transient and normalized within a few days, the serum markers of myocardial necrosis were persistently in the normal range and the coronary artery trees were normal. The diagnostic and therapeutic approach to patients with this unusual clinical presentation is also discussed.

Age-related sensitivity to nicotine for inducible atrial tachycardia and atrial fibrillation

The influence of nicotine in modulating vulnerability to atrial tachycardia and fibrillation (AT/AF) remains ill defined. The isolated hearts of six young (2–3 mo) and six old (22–24 mo) male Fischer 344 rats were Langendorff perfused at 5 ml/min with oxygenated Tyrode solution at 37°C, and the whole heart was also super-fused with warmed oxygenated Tyrode solution at 15 ml/min. Nicotine prolonged the interatrial conduction time and effective refractory period that were significantly ( P < 0.05) higher in the old than in the young rats in a concentration-dependent manner. Nicotine had a biphasic effect on burst atrial pacing-induced AT in both groups, increasing it at 10–30 ng/ml while decreasing it at 50–100 ng/ml ( P < 0.01). Nicotine at 10–100 ng/ml increased burst atrial pacing-induced AF in the young rats but suppressed it in the old rats ( P < 0.01). Optical mapping showed the presence of multiple independent wavefronts during AF and a single periodic large wavefront during AT in both groups. Nicotine, at concentrations found in the blood of smokers (30–85 ng/ml), exerts biphasic effects on inducible AT/AF in young rats and suppresses it in the old rats by causing high degrees of interatrial conduction block.

Acute coronary syndrome: potassium, magnesium and cardiac arrhythmia

BACKGROUND

Cardiac arrhythmia is often present in patients with acute coronary syndrome (ACS) and may be due to the electrolyte imbalance.

AIM

To assess the prevalence and clinical significance of electrolyte imbalance in ACS.

METHODS

Serum potassium and magnesium levels were measured within the first few hours in 204 consecutive patients with ACS admitted to our department over a period of 23 months. Cardiac arrhythmia was documented using continuous ECG monitoring, telemetry or standard ECG.

RESULTS

Hypokalemia was observed in 34% of patients, and was significantly associated with the occurrence of life-threatening ventricular arrhythmias (26% of patients with potassium level <4 mmol/l vs 11.9% of patients with normokalemia, p<0.001). No relationship was found between potassium level and supraventricular arrhythmias or in-hospital mortality. Decreased magnesium serum concentration was found in 22% of patients but was not significantly associated with cardiac arrhythmias or mortality.

CONCLUSIONS

Hypokalemia and hypomagnesemia are often present in patients with ACS. The former is associated with dangerous ventricular arrhythmias. Early assessment of electrolyte serum concentration is needed in order to implement proper supplementation.

Atrial fibrillation in an adolescent--the agony of ecstasy

Ecstasy (MDMA), a popular drug of abuse among teenagers, is thought to be "relatively" safe. A case of atrial fibrillation following the ingestion of ecstasy in a previously well adolescent is presented. Emergency room physicians should consider ecstasy abuse in the differential diagnosis of young patients presenting with atrial fibrillation.

[Development of a porcine experimental model of alcoholic intoxication]

Despite important epidemiologic suggestions that alcohol causes a variety of cardiovascular abnormalitíes, and particularly cardiac arrhythmias, the demonstration of this causal effect in animal models is still lacking. Previous open-chest models, heavily instrumented and using epicardial stimulation have failed to demonstrate such causal effect. We developed a porcine, closed-chest model with sedation, a rigorous control of venous alcohol concentration and endocardial electrical stimulation, in a multidisciplinary framework. In this model, we observed that the infusion of alcohol facilitated atrial tachyarrhythmias. This model is available to study a variety of alcohol effects "in vivo", in a controlled fashion.

Intravenous corticosteroids to reduce gemtuzumab ozogamicin infusion reactions

OBJECTIVE

To assess whether the addition of a brief course of intravenous corticosteroids reduces the incidence of infusion-related adverse events associated with gemtuzumab ozogamicin (GO) administration.

METHODS

One hundred forty-three sequential patients received GO-based therapy for refractory myeloid leukemias: 110 patients received the standard regimen of acetaminophen 650 mg orally with diphenhydramine 50 mg intravenously and 33 patients received the same premedications with methylprednisolone sodium succinate 50 mg intravenous piggyback (IVPB) prior to infusion and repeated 1 hour into the infusion.

RESULTS

Of 110 patients who received GO with standard premedications alone, 32 (29%) had grade 2 or above infusion-related adverse events. In 33 patients who received these premedications with methylprednisolone 50 mg IVPB prior to infusion and repeated 1 hour into the infusion, only 1 (3%) experienced any infusion-related adverse events (p = 0.0009, 95% CI 0.16 to 0.36). There was no significant difference between the patient cohorts in terms of hepatotoxicity, rate of development of hepatic venoocclusive disease, response rates, or infectious complications.

CONCLUSIONS

A brief course of intravenous corticosteroids significantly reduces the incidence of GO infusion-related adverse events.

Diadenosine-5-phosphate exerts A1-receptor-mediated proarrhythmic effects in rabbit atrial myocardium

(1) Diadenosine polyphosphates have been described to be present in the myocardium and exert purinergic- and nonreceptor-mediated effects. Since the electrophysiological properties of atrial myocardium are effectively regulated by A(1) receptors, we investigated the effect of diadenosine pentaphosphate (Ap(5)A) in rabbit myocardium. (2) Parameters of supraventricular electrophysiology and atrial vulnerability were measured in Langendorff-perfused rabbit hearts. Muscarinic potassium current (I(K(ACh/Ado))) and ATP-sensitive potassium current (I(K(ATP))) were measured by using the whole-cell voltage clamp method. (3) Ap(5)A prolonged the cycle length of spontaneously beating Langendorff perfused hearts from 225+/-14 (control) to 1823+/-400 ms (Ap(5)A 50 micro M; n=6; P<0.05). This effect was paralleled by higher degree of atrio-ventricular block. Atrial effective refractory period (AERP) in control hearts was 84+/-14 ms (n=6). Ap(5)A>/=1 micro M reduced AERP (100 micro M, 58+/-11 ms; n=6). (4) Extrastimuli delivered to hearts perfused with Ap(5)A- or adenosine (>/= micro M)-induced atrial fibrillation, the incidence of which correlated to the concentration added to the perfusate. The selective A(1)-receptor antagonist CPX (20 micro M) inhibited the Ap(5)A- and adenosine-induced decrease of AERP. Atrial fibrillation was no longer observed in the presence of CPX. (5) The described Ap(5)A-induced effects in the multicellular preparation were enhanced by dipyridamole (10 micro M), which is a cellular adenosine uptake inhibitor. Dipyridamole-induced enhancement was inhibited by CPX. (6) Ap(5)A (</=1 mM) did neither induce I(K(Ado)) nor I(K(ATP)). No effect on activated I(K(Ado/ATP)) was observed in myocytes superfused with Ap(5)A. However, effluents from Langendorff hearts perfused with Ap(5)A 100 micro M activated I(K(Ado)) by using A(1) receptors. (7) Ap(5)A did not activate A(1) receptors in rabbit atrial myocytes. The Ap(5)A induced A(1)-receptor-mediated effects on supraventricular electrophysiology and vulnerability suggest that in the multicellular preparation Ap(5)A is hydrolyzed to yield adenosine, which acts via A(1) receptors. An influence on atrial electrophysiology or a facilitation of atrial fibrillation under conditions resulting in increased interstitial Ap(5)A concentrations might be of physiological/pathophysiological relevance.

Atrial fibrillation induced by simvastatin treatment in a 61-year-old man

A 61-year-old man developed atrial fibrillation 2 weeks after the administration of simvastatin (5 mg once daily) and recovered to sinus rhythm 3 days after withdrawal of the drug. Electrocardiography had not previously revealed an abnormality except for transient atrial fibrillation and left atrial overloading. Although he has not been given any antiarrhythmic agents, sinus rhythm is being continuously maintained. The timing of the transient atrial fibrillation attack was closely related to the administration of simvastatin. An inhibitory effect of myocardial energy metabolism through ubiquinone synthesis may play a role in the development of atrial fibrillation.

Atrial fibrillation after ondansetron for the prevention and treatment of postoperative nausea and vomiting: a case report

PURPOSE

Even though clinical safety has been established in large studies, ondansetron has been reported to cause adverse cardiovascular events. We present a case of atrial fibrillation in association with ondansetron in the postoperative period.

CLINICAL FEATURES

A 47-yr-old, 81 kg female presented with a benign lump in her left breast for lumpectomy. Her past medical history was unremarkable. Physically she was very active, non-smoker and had no allergies. She underwent the procedure under general anesthesia. She received 4 mg of ondansetron intravenously for postoperative nausea and vomiting prophylaxis at the end of the procedure and an additional 4 mg in the recovery room for nausea. Within 15 min after the second dose she was noted to be in atrial fibrillation that required admission to the hospital and procainamide infusion for conversion to normal sinus rhythm. She did not have any evidence of myocardial ischemia, valvular abnormality or pulmonary embolism.

CONCLUSION

The 5-hydroxytryptamine 3 receptor (5-HT(3)) antagonist ondansetron has been reported to cause myocardial ischemia, supraventricular and ventricular tachycardia. Postulated mechanism includes inhibition of Bezold-Zarisch cardiac reflex and coronary vasoconstriction. Inhibition of 5-HT(3) receptors in the heart could lead to unopposed action of other serotonin receptors leading to atrial fibrillation or other tachyarrhythmias described in the literature.

Nicotine gum-induced atrial fibrillation

A 39-year-old man with no prior history of atrial fibrillation was hospitalized with atrial fibrillation and a rapid ventricular rate. For the 7 months before presentation, he had been chewing nicotine polacrilex gum on his own. The week he first developed palpitations, he was chewing more than 1 piece of nicotine Polacrilex gum per hour during work. His diagnostic work-up during hospitalization found no cause for atrial fibrillation. He was cardioverted to sinus rhythm. At 6-month follow-up, he had not renewed chewing nicotine polacrilex gum, was in sinus rhythm, and had no history of palpitations. The temporal relation between more frequent gum usage and the excessive consumption of nicotine polacrilex chewing gum with a probable high serum nicotine level at the time the patient developed his first episode of atrial fibrillation suggests a causal relationship.

Widening of the excitable gap and enlargement of the core of reentry during atrial fibrillation with a pure sodium channel blocker in canine atria

BACKGROUND

This study aimed to assess the effects of pilsicainide, a pure sodium channel blocker, on electrophysiological action and wavefront dynamics during atrial fibrillation (AF).

METHODS AND RESULTS

In a newly developed model of isolated, perfused, and superfused canine atria (n=12), the right and left endocardia were mapped simultaneously by use of a computerized mapping system. AF was induced with 1 to 5 micromol/L acetylcholine. The antifibrillatory actions of pilsicainide on AF cycle length (AFCL), refractory period (RP), conduction velocity (CV), excitable gap (EG), and the core of the mother rotor were studied. The RP was defined as the shortest coupling interval that could capture the fibrillating atrium. The EG was estimated as the difference between the AFCL and RP. At baseline, multiple wavefronts were observed. After 2.5 microg/mL infusion of pilsicainide, all preparations showed irregular activity, and AF was terminated in 2 preparations. The AFCL and RP were prolonged, and CV was decreased significantly. The EG was widened (147%; P<0.01), and the core perimeter was increased (100%; P<0.01). Increasing the dosage either terminated AF (6 preparations) or converted to organized activity (ie, atypical atrial flutter) (4 preparations). On the maps, all "unorganized" AFs were terminated with the excitation of the core of the mother rotor by an outside wavefront, whereas in preparations with atrial flutter, pilsicainide did not terminate its activity.

CONCLUSIONS

Widening of the EG by pilsicainide facilitates the excitation of the core of the mother rotor, leading to the termination of AF. In some experiments, pilsicainide converts AF to persistent atrial flutter.

Atrial fibrillation in pregnancy associated with oral terbutaline

BACKGROUND

Terbutaline has direct effects on the cardiac conduction system, but when used to treat preterm labor it is rarely associated with clinically significant cardiac arrhythmias. Commonly used drug references did not list atrial fibrillation as a complication of terbutaline, and our literature search found only one case of atrial fibrillation that occurred with parenteral administration.

CASE

A 30-year-old gravida 1 carrying a twin gestation at 35 weeks was taking 2.5 mg oral terbutaline four times daily for premature labor. She developed atrial fibrillation and was ultimately treated by chemical cardioversion with procainamide to restore normal sinus rhythm.

CONCLUSION

This is the first report of atrial fibrillation during pregnancy associated with oral terbutaline. Atrial fibrillation should be added as a complication of oral terbutaline therapy.

Reduction of the internal atrial defibrillation threshold with balanced orthogonal sequential shocks

INTRODUCTION

The aim of this study was to determine the atrial defibrillation threshold (ADFT) of a first shock across the standard right atrium (RA) to distal coronary sinus (dCS) configuration followed by a second shock along the atrial septum with a standard sequential waveform (the second shock leading edge equaled the first shock trailing edge) and a balanced sequential waveform (the leading edges of both shocks were equal).

METHODS AND RESULTS

In nine sheep atrial fibrillation was induced with acetyl-beta-methylcholine and burst pacing. A catheter was placed with electrodes in the dCS, proximal coronary sinus (pCS), and RA. A J-shaped catheter was positioned with an electrode at Bachmann's bundle (BB) while another catheter was positioned with an electrode in the superior vena cava (SVC). The ADFTs of six single- and dual-pathway configurations were determined with single, standard sequential, or balanced sequential shocks. The ADFT of the RA-->dCS configuration (0.86 +/- 0.27 J, 159 +/- 29 V, 2.42 +/- 0.36 A) was significantly reduced when followed by an SVC-->pCS (0.58 +/- 0.17 J, 112 +/- 20 V, 1.64 +/- 0.39 A) or a BB-->pCS shock (0.64 +/- 0.16 J, 119 +/- 18 V, 1.81 +/- 0.38 A) with standard sequential shocks. With balanced sequential shocks, the peak voltage and current ADFTs were further significantly reduced (85 +/- 11 V and 1.24 +/- 0.21 A for second shock SVC-->pCS, and 93 +/- 13 V and 1.38 +/- 0.27 A for second shock BB-->pCS).

CONCLUSION

The ADFT of the standard RA-->dCS shock is significantly reduced when followed by a second shock along the atrial septum delivered between electrodes in the pCS and either SVC or BB and ADFT is further reduced with balanced sequential shocks.

Increased vulnerability to inducible atrial fibrillation caused by partial cellular uncoupling with heptanol

We hypothesized that partial cellular uncoupling produced by low concentrations of heptanol increases the vulnerability to inducible atrial fibrillation (AF). The epicardial surface of 12 isolated-perfused canine left atria was optically mapped before and after 1-50 microM heptanol infusion. At baseline, no sustained (>30 s) AF could be induced in any of the 12 tissues. However, after 2 microM heptanol infusion, sustained AF was induced in 9 of 12 tissues (P < 0.001). Heptanol >5 microM caused loss of 1:1 capture during rapid pacing, causing no AF to be induced. AF was initiated by conduction block across the fiber leading to reentry, which broke up after one to two rotations into two to four independent wavelets that sustained the AF. Heptanol at 2 microM had no effect on the cellular action potential duration restitution or on the maximal velocity rate over time of the upstroke. The effects of heptanol were reversible. We conclude that partial cellular uncoupling by heptanol without changing atrial active membrane properties promotes wavebreak, reentry, and AF during rapid pacing.

[Transient atrial fibrillation induced by adenosine in a patient with atrial tachycardia]

The administration of adenosine during atrial tachycardia usually terminates the arrhythmia or induces AV block and makes the diagnosis clear. We present a patient with atrial tachycardia in which the administration of adenosine induced a transient atrial fibrillation (AF). A continuous transition between both arrhythmias was observed and the original tachycardia persisted after the termination of the AF. This proarrhythmic effect may be due to the adenosine-mediated shortening of the atrial refractory periods, which produces a decreased wavelength of the reentry circuits and the potential coexistence of several wave-fronts in the atria, favoring the development of AF. The recognition of this uncommon effect is important, since the repeated administration of increasing doses of adenosine may induce sustained AF.

Epicardial foci of atrial arrhythmias apparently originating in the left pulmonary veins

INTRODUCTION

Epicardial potential sources of atrial arrhythmias, such as the ligament of Marshall, are in close proximity with, and electrically connected to, the left superior pulmonary vein. Ectopic activity arising from these areas may be difficult to differentiate from ectopy that, according to endocardial only mapping, originates in the left superior pulmonary vein. We hypothesized that in patients with paroxysmal atrial fibrillation (AF) apparently originating in the left pulmonary veins, mapping through the distal coronary sinus might identify possible epicardial locations of the arrhythmogenic focus.

METHODS AND RESULTS

Forty patients (age 48 +/- 12 years) who underwent catheter ablation for paroxysmal AF were studied by epicardial mapping through the distal, superoposterior coronary sinus. Catheterization of the distal coronary sinus in order to approach the ostium of the left superior pulmonary vein was feasible in 14 of 19 patients with AF originating in the left superior vein (11 patients) or inferior pulmonary vein (3 patients) according to endocardial mapping criteria. In 2 patients, the sole focus of atrial tachycardia/fibrillation was epicardial with earliest activation clearly preceding electrograms recorded at the os of the left superior pulmonary vein or any other endocardial mapping site. Epicardial potentials separated from atrial electrograms were present during sinus rhythm in both patients and during atrial tachycardia in one patient. Catheter ablation through the coronary sinus rendered the arrhythmia noninducible in both patients without abolishing epicardial potentials in one of them.

CONCLUSION

In patients with paroxysmal AF apparently originating from the left superior or inferior pulmonary vein, detailed epicardial mapping through the distal coronary sinus might identify epicardial locations of the arrhythmogenic focus.

Age-dependent atrial remodeling induced by recombinant human interleukin-11: implications for atrial flutter/fibrillation

Recombinant human interleukin-11 (rhIL-11) has been used to alleviate side effects caused by chemotherapy in patients with neoplastic diseases and as an experimental anti-inflammatory agent. Its use in elderly patients has been associated with increased frequency of atrial flutter/fibrillation (AF). The mechanism of the latter phenomenon was studied in a rat model in vivo. Adult and old Fischer 344 rats fed with either normal diet or sodium-restricted diets were treated with rhIL-11 or vehicle (control) (1 mg/kg/day, i.p., 7 days); cardiac electrophysiologic parameters and atrial dimensions were determined. In adult rats, rhIL-11 was without effect, and atrial pacing did not induce AF. In contrast, in old rats, rhIL-11 shortened atrial refractoriness and increased atrial dimensions. Also, atrial pacing induced AF in old rats treated with rhIL-11 more than in controls. These effects of rhIL-11 in old rats were reversed by sodium-restricted diet. It was concluded that rhIL-11 induces age-dependent atrial remodeling manifested by atrial stretch and reduced atrial refractoriness, which favor AF. Na retention is the most likely mechanism underlying this effect of rhIL-11.

Efficacy and safety of sodium phosphate tablets compared with PEG solution in colon cleansing: two identically designed, randomized, controlled, parallel group, multicenter phase III trials

BACKGROUND

Liquid purgatives for cleansing before colonoscopy often are poorly tolerated. A sodium phosphate tablet has been developed to provide equivalent efficacy with better patient tolerance. These 2 studies compare the safety, efficacy, and patient acceptance of the tablet (Visicol) to a polyethylene glycol (PEG) solution in adults undergoing colonoscopy.

METHODS

Two identically designed, randomized, investigator-blinded, multicenter trials were performed. The primary efficacy variable was the overall quality of colon cleansing. Patient tolerance was assessed in terms of compliance with the dosing regimen. Safety assessments included recording of adverse events and changes in biochemical tests, electrocardiogram, and vital signs.

RESULTS

Eight hundred forty-five patients participated in the studies; 420 took sodium phosphate tablets and 425 took a PEG solution. The 2 methods of preparation were equivalent in the overall quality of colon cleansing, cleansing in the right colon, and the frequency of inadequate preparation. Overall cleansing was excellent or good in 84.3% of patients in the tablet group and in 76.7% in the PEG group. Patient compliance was greater in the tablet group. There were also significantly fewer GI side effects in this group.

CONCLUSIONS

Sodium phosphate tablets, compared with PEG solution, produce equivalent colon cleansing, are associated with fewer GI side effects, and are better tolerated by patients.