Electrophysiologic effects of d-sotalol in humans

Sotalol is a beta-adrenergic blocking agent that prolongs the duration of the cardiac action potential in humans, without affecting the upstroke velocity of depolarization. The dextrorotatory isomer, d-sotalol, retains these class III effects, but has little beta-blocking activity in vitro. d-Sotalol has not been studied extensively in humans. The electrocardiographic (ECG) and electrophysiologic effects of d- and d,l-sotalol were therefore assessed in a prospective randomized study of 20 patients. Each patient received either d-sotalol (1, 1.5 or 2 mg/kg body weight) or d,l-sotalol (1 mg/kg) by intravenous infusion. The QT and QTc intervals were prolonged and refractoriness increased in the atrium, atrioventricular (AV) node, His-Purkinje system and right ventricle after both d- and d,l-sotalol. After d-sotalol, the increases in both QT and QTc intervals and in atrial and ventricular effective refractory periods were dose dependent. Highly significant linear correlation was demonstrated between the plasma sotalol level and the change in QT (r = 0.86, p = 0.001) and QTc intervals (r = 0.79, p = 0.002), and between the plasma sotalol level and the effective refractory period of the right atrium (r = 0.75, p = 0.005) and ventricle (r = 0.70, p = 0.025). This study confirms that d-sotalol has effects consistent with class III properties. It demonstrates these effects in humans, and suggests that d-sotalol may prove to be a useful antiarrhythmic agent.     

Vasodepressor reactions after orthotopic cardiac transplantation: Relationship to reinnervation status

Ventricular vagal nerve endings are thought to trigger vasodepressor syncope. Reports of vasodepressor reactions associated with donor bradycardia after cardiac transplantation have led to speculation that vagal reinnervation occurs. We assessed reinnervation status in seven patients 23–36 months (median 24 months) post-transplantation. Heart rate responses to vagal manoeuvres (respiration, Valsalva) and sympathetic stimuli (exercise and injection of tyramine into the coronary artery supplying the sinus node) were measured. All patients underwent 60 min of 60° head-up tilt with foot plate support. During tilt four of the seven had vasodepressor reactions with a fall in mean arterial pressure of 20–90 mmHg. During vasodepression two patients had falls in donor heart rate of 13 and 40% relative to peak heart rate during tilt. These two patients had evidence of functional sympathetic reinnervation. By contrast the two patients without donor bradycardia during vasodepression had only limited or no evidence of sympathetic reinnervation. No patient had consistent evidence of parasympathetic reinnervation as judged by the heart rate response to vagal manoeuvres. Headup tilt can thus produce vasodepressor reactions with donor bradycardia after cardiac transplantation in the absence of consistent evidence of vagal reinnervation. Left ventricular nerve endings may not be the only mediators of tilt-induced vasodepressor reactions in man. Donor bradycardia during vasodepression may reflect sympathetic withdrawal and not vagal reinnervation.     

MEASUREMENTS OF INTERFACE PRESSURE BETWEEN BODY SITES AND THE SURFACES OF FOUR SPECIALISED AIR MATTRESSES

SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.     

Radiology and the Health Policy Agenda for the American People

Eleven radiologists appointed by the major radiological societies participated for the past 5 years in the development of the Health Policy Agenda for the American People. The Agenda is an action plan to address a wide variety of serious problems in medicine. The first phase involved establishment of 159 principles, broad value statements that were the foundation of the project. Phase 2 involved the development of policy proposals on 38 urgent issues for action in medical science; education; health resources; delivery mechanisms; evaluation, assessment, and control; and payment for services. These proposals are summarized in this report. The activities and recommendations of representatives for the field of radiology are described. The Agenda has been released, and an implementation phase has begun. It will likely be of great importance to the practice of radiology over the next decade. Important issues can be addressed by acting with the coalitions that are being formed from among the more than 150 participating organizations.     

Tubal occlusion after inguinal hernia repair. A case report

Midtubal occlusion and infertility occurred subsequent to an inguinal hernia repair. Recognition of the traumatic etiology is important because other causes of midtubal obstruction, such as endometriosis, tuberculosis and adenomatoid tumor of the oviduct, may be considered contraindications to reconstructive surgery. Once recognized, the condition is highly amendable to microsurgical reconstruction.     

Management of symptomatic chronic extra-axial fluid collections in pediatric patients.

The records of 103 pediatric patients having symptomatic chronic extra-axial fluid collections treated at Children's Hospital of Los Angeles from 1977 to 1988 were reviewed. Patients were treated with observation, serial percutaneous needle drainage, drainage through burr holes, drainage into a closed external drainage system, or subdural to peritoneal shunt. If the initial treatment was not effective, additional forms of treatment were instituted. Shunts, ultimately used in 73% of the patients, proved to be the most effective treatment. Of the group with shunts, the extra-axial fluid was unilateral in 20% and bilateral in 80%. In those patients with bilateral effusions, no difference in efficacy of shunts was seen in patients treated with bilateral versus unilateral shunts. Of the 75 patients with shunts, 12% required a shunt revision for progressive or recurrent symptoms. Shunt infections occurred in 3% of the patients, necessitating removal of the shunt and treatment with antibiotics. Eosinophilia in the subdural fluid was associated with shunt obstruction requiring revision. The shunt was never removed in 51% of patients with no untoward effects. This study demonstrates that the most efficacious treatment of symptomatic chronic extra-axial fluid collections in children is a unilateral subdural to peritoneal shunt. The shunt need not be removed after resolution of the fluid collections.