Block of potassium currents in guinea pig ventricular myocytes and lengthening of cardiac repolarization in man by the histamine H1 receptor antagonist diphenhydramine.

Treatment with second generation histamine H1 receptor antagonists has been associated with lengthening of the Q-T interval and proarrhythmia. Similarly, lengthening of the Q-T interval has been reported in patients after overdosing with diphenhydramine (DPH), a first generation agent. Therefore, our study was designed 1) to assess effects of DPH on cardiac repolarization and 2) to characterize effects of the drug on major voltage-dependent cardiac K+ currents. First, we noticed that oral administration of DPH at usual dosages to healthy volunteers or to patients (prior to angioplasty) was associated with prolongation of the Q-Tc interval. Although this effect was modest in most individuals, Q-Tc was increased more than 20 ms in 7 of 20 patients. Second, we noticed that exposure of isolated guinea pig hearts to DPH 10(-5) M caused a lengthening of monophasic action potential duration. This effect was potentiated by the combined perfusion of other K+ channel blockers such as indapamide. Finally, experiments performed with the patch-clamp technique demonstrated unequivocal block of the rapid component of the delayed rectifier (IKr) by DPH; however, IC50 determined for block of IKr (3 x 10(-5) M) is approximately 40-fold greater than plasma concentrations of the drug measured at usual dosages (7 x 10(-7) M). Consequently, in agreement with the long-term clinical use of the drug, prolongation of cardiac repolarization should be minimal in most patients at usual dosages but may be observed with overdosing. Nevertheless, caution remains since excessive lengthening of cardiac repolarization may occur after administration of DPH with other drugs due to 1) concomitant block of other ionic currents or 2) pharmacokinetic interactions leading to toxic concentrations of DPH.

Intrapulmonary artery and intrabronchial migration and extraction of a fragment of J-shaped atrial pacing catheter.

A fragment of a fractured Telectronics Atrial Accufix 330-801 lead asymptomatically perforated the adjacent bronchus and was detected on routine chest X-ray. The metallic fragment was located by chest CT scan and bronchial fluoroscopy to lie between the right lobar bronchus and the pulmonary artery, confirming bronchial perforation. The foreign body was removed without complication by direct visualisation with rigid bronchoscopy.

[Intrabronchial migration and extraction of a fragment of an Accufix J-shaped atrial pacing catheter]. / Migration intrabronchique et extraction d'un fragment de guide J d'une sonde auriculaire Accufix.

The authors report a case of exteriorisation and migration of a fragment of a J-shaped atrial Accufix Telectronix (Stimarec Class IV) responsible for a bronchial penetration without clinical repercussion. A systematic control chest X-ray detected this complication. The position of the metallic fragment was determined by chest CT scan and bronchial fibroscopy between the inferior right lobar bronches and artery confirming bronchial perforation. Rigid bronchoscopy with direct visualisation enabled extraction of the foreign body without complications.

[Unexplained pulmonary edema: demonstration of obstruction to pulmonary venous return by transesophageal echocardiography. Apropos of 4 cases]. / Oedèmes pulmonaires inexpliqués: mise en évidence d'une gêne au retour veineux pulmonaire par échocardiographie transoesophagienne. A propos de quatre observations.

The usual causes of pulmonary edema are left ventricular dysfunction, mitral valve disease or left atrial myxoma. Obstruction to pulmonary venous drainage is a rare and unrecognised diagnosis which should be considered when the usual investigations are unproductive. The authors report four cases in which transesophageal echocardiography showed pulmonary edema to be due to compression of one or more pulmonary veins by a mediastinal mass (2 cases), by the false lumen of dissection of the aorta (1 case) and postoperative stenosis of the pulmonary veins (1 case). These cases underline the diagnostic value of this technique which rapidly provides diagnostic information with privileged visualisation of the pulmonary veins and abnormalities of acceleration of blood velocities in the Doppler mode due to obstruction.

[Angiosarcoma of the pericardium. Apropos of a case]. / Angiosarcome du péricarde. A propos d'un cas.

Malignant primary cardio-pericardial tumours are rare and difficult to diagnose because of the diversity of their clinical expression. The authors report a case of pericardial angiosarcoma and review the literature, underlining the value of new non-invasive imaging techniques in the diagnosis and surgical approach to obtaining histological confirmation. Magnetic resonance imaging is a valuable tool in this context as it allows scanning of the tumoral extension in all spatial planes and the visualisation of the haemorrhagic signs of malignancy the pericardial effusion related to this pathology.