Magnesium reversal of digoxin-facilitated ventricular rate during atrial fibrillation in the Wolff-Parkinson-White syndrome

The purpose of this investigation was to determine whether pyrophosphate, the anticalculus component of tartar-control dentifrices, exerts antimicrobial activity against oral bacteria commonly found in supragingival plaque. Minimal inhibitory concentrations of pyrophosphate were determined for Streptococcus sanguis, Streptococcus mutans (serotype c), Actinomyces viscosus and Actinomyces naeslundii. All of the bacteria tested were susceptible to pyrophosphate with identical minimal inhibitory concentrations of 0.67% wt/vol (25 mM). Bactericidal kinetics assays revealed that both S. mutans and A. viscosus were killed by pyrophosphate, with the latter being considerably more susceptible. The mechanism of killing was not due to high ionic strength, as comparable controls showed no loss in numbers of viable cells. Brief exposure (two 5-min incubations) of S. mutans to pyrophosphate and sodium dodecyl sulfate caused pronounced inhibition of growth over the 24-h test period. Under the constraints of the conditions used, these studies indicate that pyrophosphate and sodium dodecyl sulfate can substantially inhibit the growth of oral bacteria. These compounds may affect the oral microflora of patients who routinely use tartar-control dentifrices and mouthrinses.     

Atrial fibrillation and coronary disease

OBJECTIVE: To study the incidence of atrial fibrillation in patients (pts) with angiographic coronary artery disease and its relation with clinical and angiographic parameters. DESIGN: Retrospective study. SETTING: Six hundreds consecutive pts, submitted to diagnostic coronary angiography, performed in Hemodynamic Laboratory of Santa Marta Hospital (from 88/04/03 to 90/05/04). MATERIAL AND METHODS: From six hundreds pts were excluded 43 because they had also valvular heart disease and/or minimal coronary artery lesions. Two groups were considered: Group I-pts with atrial fibrillation (n = 7) and Group II-pts in sinus rhythm (n = 549). We evaluated the following parameters: age, sex, clinical history, basal ECG, cardiac enlargement in chest X-ray, angiographic score of LVF, left ventricular diastolic pressure (LVDP), ventricular aneurysm, mitral regurgitation and number of vessels disease. RESULTS: We only found significant statistically differences between the two groups concerning the following parameters: a) age-mean age was superior in group I (Group I-64.2 +/- 8.2 versus 56.3 +/- 9.6), the number of pts older than 60 years in group I was 75% vs 33.8% in group II (p < 0.02); b) heart failure-the incidence was superior in group I, 37.5% vs 9% in group II (p < 0.03); c) cardiac enlargement in chest X-ray-75% pts of group I vs 22% of group II (p < 0.002); d) moderate to severe mitral regurgitation-25% of pts in group I vs 5% of pts of group II (p < 0.05). CONCLUSIONS: Atrial fibrillation is an unusual rhythm in pts with angiographic coronary artery disease. Its presence is related with age, clinical evidence of heart failure, cardiac enlargement and moderate to severe mitral regurgitation.     

Abnormal Q waves in Wolff-Parkinson-White syndrome. Incidence and clinical significance

Between January 1970 and January 1975 the diagnosis of Wolff-Parkinson-White syndrome was entertained in 44 patients. Thirty-one (70%) of these patients had negative sigma-deflections (Q waves) on one or more electrocardiographic leads, thereby simulating a pattern of myocardial infarction (Mi). Fifteen patients (34%) were initially referred with an erroneous diagnosis of Mi based on the presence of Q waves. In nine of these 15 patients, the referring diagnosis was Mi plus ventricular preexcitation; in six, the diagnosis of ventricular preexcitation was overlooked entirely. The incidence of misdiagnosis (34%) was exactly the same as that reportly by Wolff and White approximately 30 years ago. Erroneous diagnosis of Mi can be virtually eliminated by normalizing the QRS complex by premature stimulation of the atrium during the effective refractory period of the accessory pathway.     

Atrial fibrillation with neonatal pulmonary lymphangiectasia

A female infant born at 28 weeks' gestation was found to have mild hydrops foetalis. Initial echocardiography showed a structurally normal heart. During the first week of life, episodic atrial tachycardia with 1:1 or 2:1 conduction was seen, requiring therapy with digoxin. The infant remained ventilator dependent, with a persistent, chylous pleural effusion which contained a preponderance of lymphocytes. Congenital pulmonary lymphangiectasia (CPL) was confirmed histologically. Worsening episodes of atrial tachycardia, including episodes of atrial fibrillation, were further investigated and a repeat echocardiogram revealed thickening of the entire right atrial wall. The cardiac findings of a thickened right atrial wall with the histological signs of myocarditis were thought to be the cause of paroxysms of atrial fibrillation, an extremely rare arrhythmia in the neonatal period. To the authors' knowledge there have been no previous reports of CPL in association with the cardiac abnormalities described herein.     

Atrial fibrillation: new management strategies

The main goal of therapy in atrial fibrillation is to restore sinus rhythm, if this is possible, to avoid adverse hemodynamic, electrical, and embolic consequences. The restoration of sinus rhythm is urgent if the patient is unstable. In a stable patient, if the duration is shorter than 48 hours and an atrial thrombus is unlikely, then sinus rhythm can be restored after initial rate control. If the duration of atrial fibrillation is more than 48 hours, the embolic risk may be significant, and anticoagulation will be required for 2 to 4 weeks before an attempt at cardioversion. In patients in whom sinus rhythm cannot be restored or maintained, the goal of therapy is rate control and reduction of embolic risk unless the risk of anticoagulation outweighs its benefit. In difficult cases, rate control may be accomplished with AV nodal ablation and pacemaker implantation or with one of the surgical procedures described above with varying degrees of normalization of the physiology. Although not included in this flow chart, we do not advocate episodic intermittent therapy for patients with infrequent episodes of atrial fibrillation because this could be potentially dangerous and may place the patient at a higher risk for developing proarrhythmia.     

Radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome

OBJECTIVE: To report on the experience with radiofrequency catheter ablation of accessory atrioventricular pathways in patients with Wolff-Parkinson-White syndrome in terms of the duration of fluoroscopy exposure to the patient and the operator and the effect of accessory-pathway location and operator experience on the success rate. DESIGN: Retrospective review. SETTING: Tertiary care university hospital. PATIENTS: Two hundred consecutive patients with Wolff-Parkinson-White syndrome who underwent radiofrequency catheter ablation between September 1990 and June 1992. INTERVENTIONS: Electrophysiologic study and radiofrequency catheter ablation. MAIN OUTCOME MEASURES: Success rate, duration of fluoroscopy, complications and long-term follow-up. RESULTS: Of the 224 accessory pathways in the 200 patients 135 were left free wall, 47 posteroseptal, 32 right free wall and 10 anteroseptal. The overall success rate increased from 53% in the first 3 months of the study period to 96% in the last 3 months. The success rate depended on the location of the accessory pathway. The duration of fluoroscopic exposure decreased from 50 (standard deviation [SD] 21) minutes in the first 3 months to 40 (SD 15) minutes in the last 3 months (p < 0.05). Complications occurred in 3.5% of the patients; they included hemopericardium, cerebral embolism, perforation of the right atrial wall, air embolism in a coronary artery and hematoma at the arterial perforation site. None of the complications resulted in death. CONCLUSIONS: With experience, radiofrequency catheter ablation of accessory pathways can have an overall success rate of more than 95% and a complication rate of less than 4%. Such rates make this procedure suitable for first-line therapy for patients with Wolff-Parkinson-White syndrome.