Disappearance of complete atrioventricular block after chemotherapy for malignant lymphoma: a case report.

A 77-year-old man with malignant lymphoma presented with dizziness and exertional dyspnea. Physical examination revealed marked bradycardia (36 beats/min). Twelve-lead electrocardiography showed complete atrioventricular block with narrow QRS escape beats. Gallium scintigraphy demonstrated significant abnormal uptake in the heart. Transesophageal echocardiography showed a thick interatrial septum with increased echogenecity. He underwent chemotherapy under external temporary pacing with a suspected diagnosis of complete atrioventricular block secondary to cardiac invasion of malignant lymphoma. Atrioventricular conduction progressively improved and the complete atrioventricular block disappeared. He is currently well and has required no cardiac pacing for 6 months. We conclude that complete atrioventricular block may be reversible in some patients with malignant lymphoma, even in the elderly.

Nitrate tolerance: hemodynamic effects of intravenous isosorbide dinitrate after sustained oral isosorbide dinitrate administration.

To determine whether hemodynamic effects of isosorbide dinitrate (ISDN) diminish and disappear during sustained administration, nine patients with recent myocardial infarction received 10 mg of ISDN intravenously before and 1, 4, 12, 24, and 48 weeks after sustained oral administration of 20 mg of the slow-release form of ISDN four times daily. Blood pressure always decreased after intravenous ISDN; the decrease tended to be diminished when preceded by oral ISDN, but no further attenuation in blood pressure was noted. The decrease in blood pressure was associated with consistent and nonsignificant increases in heart rate after intravenous ISDN. Plasma ISDN levels were not affected by prior oral ISDN. Plasma isosorbide 2-mononitrate and isosorbide 5-mononitrate levels were consistently higher when preceded by oral ISDN. The results suggest that the hemodynamic and metabolic properties of ISDN are preserved even after sustained therapy.

Pacing failure due to markedly increased stimulation threshold 2 years after implantation: successful management with oral prednisolone: a case report.

In a 53-year-old male who had undergone transvenous permanent pacing, intracardiac potential reduced progressively over a 2-year period and exit block developed, while the stimulation threshold was markedly increased. After oral prednisolone for 5 months, the stimulation threshold reduced gradually along with an increase in intracardiac potential, culminating in no recurrence of exit block for the ensuing 2 years. The clinical course suggests that progressive reduction in intracardiac potential may have presaged the late development of exit block, and that oral prednisolone may be a therapeutic approach for the restoration of ventricular capture even 2 years after implantation.

Periodic occurrence of premature atrial beats inducing alternation during supraventricular tachycardia in a case of pre-excitation syndrome.

During orthodromic atrioventricular reciprocating tachycardia (AVRT) in a patient with pre-excitation syndrome, 2:1 to 9:1 cycle length alternation was observed. The alternation was induced by the development of premature atrial beats (PABs) recurring in every three to ten AVRT beats. An electrophysiologic study revealed that: 1) PAB developed periodically during atrial/ventricular tachy-pacing (at a rate of 140-170 times/min), during atrial/ventricular extrastimulus study, and during electrically induced AVRT. 2) The PAB had a constant coupling interval to the preceding atrial complex, probably an atrial echo beat, and was associated with no His bundle or ventricular deflection. 3) An intensive search failed to reveal any third ventriculo-atrial conduction pathway. The PABs may have been induced by intra-atrial reentry or by triggered activity in the atrium.