Prevention of hypertensive crises in rats induced by acute and chronic norepinephrine excess.

Calcium Channel Blockers (CCBs), competitive α-adrenoceptor blockers, and phenoxybenzamine (POB) are used for preoperative treatment of pheochromocytomas. We analyzed the protection from hypertensive crisis provided by these drugs during acute and chronic norepinephrine excess. To ensure adaptive changes during chronic norepinephrine (NE) excess, we continuously exposed male Wistar rats to NE for 3 weeks (osmotic pumps). Afterwards, blood pressure (BP) was continuously measured while NE boli (0-1000 µg/kg, i. v.) were administered before and after antihypertensive treatment in anesthetized and catheterized rats. A single dose of urapidil (10 mg/kg), nitrendipine (600 µg/kg) and POB (10 mg/kg) lowered BP from 212 ± 12 mmHg by 52 ± 7%, 31 ± 9%, and 50 ± 6%, respectively. With NE boli a maximum BP of 235 ± 29, 240 ± 30 and 138 ± 3 mmHg was measured in urapidil, nitrendipine, and POB treated animals (p<0.05). The number of hypertensive episodes (delta BP >30 mmHg) was 3 (3), 1.5 (0-3), and 0 (0-1) (p<0.05). Because of inferiority, urapidil was excluded from further testing. Chronically NE exposed rats were treated with POB (10 mg/kg/d), nifedipine (10 mg/kg/d), or vehicle for 7 days. Marked BP elevations were observed at baseline (167 ± 7, 210 ± 7 , and 217 ± 7 mmHg, p<0.01) and maximum blood pressure was 220 ± 32, 282 ± 26, and 268 ± 40 mmHg (p<0.001) with NE boli. Further stabilization was achieved combining POB pretreatment with a continuous nifedipine infusion, which effectively prevented BP elevations during NE excess. POB was the most effective drug used in monotherapy, but BP stabilization was superior using a combination of POB pretreatment with a continuous nifedipine infusion in this model.

Postcardiac injury syndrome following radiofrequeny ablation of atrial flutter.

We report the case of a 64-year-old woman who was admitted to our hospital for radiofrequency ablation of isthmus-dependent counterclockwise atrial flutter. Following an initially uncomplicated right atrial linear isthmus ablation that was associated with conversion of atrial flutter to sinus rhythm and evidence of complete isthmus block, the patient developed a small pericardial effusion, a marked and recurrent left-sided pleural effusion, and had significantly elevated inflammatory markers. After an extensive diagnostic work-up which excluded infectious, malignant and thromboembolic causes of the effusions, a diagnosis of postcardiac injury syndrome was made and the patient was treated with oral corticosteroids and nonsteroidal anti-inflammatory drugs. Over a treatment period of 2 months there was complete resolution of the pericardial and left-sided pleural effusions and normalization of inflammatory markers. Postcardiac injury syndrome is a rare complication of radiofrequency ablation that is characterized by signs of pericardial, pleural and pulmonary parenchymal inflammation.