Gadolinium inhibits mechanoelectrical transduction in rabbit carotid baroreceptors. Implication of stretch-activated channels.

Gadolinium (Gd3+) has been shown to prevent mechanoelectrical transduction believed to be mediated through stretch-activated channels. We investigated the possible role of Gd(3+)-sensitive channels in mediating baroreceptor activity in the carotid sinus of rabbits. Baroreceptor activity induced by a ramp increase of carotid sinus pressure was reduced significantly during exposure to Gd3+. The inhibition was dose-related and reversible, and was not associated with alteration of carotid sinus wall mechanics as the pressure-strain relationship was unaffected. Veratrine triggered action potentials from single- and multiple-baroreceptor fibers when their response to pressure was inhibited by Gd3+. This suggests that the effect of Gd3+ on baroreceptors in the isolated carotid sinus was specific to their mechanical activation. The results suggest that stretch-activated ion channels sensitive to Gd3+ may be the mechanoelectrical transducers of rabbit carotid sinus baroreceptors.

Protein-losing enteropathy complicating the Mustard procedure.

Protein-losing enteropathy is a reported complication of several cardiac diseases. Recently we encountered a patient with protein-losing enteropathy acquired as a late surgical complication of the Mustard procedure. An obstructed superior vena caval conduit was repaired surgically and the enteropathy was resolved.

Ruptured ductus arteriosus. Aneurysm in an infant. Report of a survivor.

The diagnosis of a large ductus arteriosus aneurysm was made in a 3 1/2-month-old infant by cardiac catheterization following massive hemoptysis. Prompt surgical correction accounted for the patient's survival. Differential diagnosis of an intrathoracic mass should include a ductus arteriosus aneurysm even in the newborn period.

LOCALIZATION OF ANGIOTENSIN II RESPONSES IN THE TROUT CARDIOVASCULAR SYSTEM

The renin/angiotensin system (RAS) is a tonic anti-drop regulator of arterial blood pressure in many teleosts. In trout, angiotensin II (ANG II) has no direct constrictor effect on large arteries or veins and the identity of specific cardiovascular pressor effectors is unknown. Potential targets of angiotensin activation were examined in the present experiments using perfused organs and isolated tissues from the rainbow trout Oncorhynchus mykiss. Perfused gill (arches 2 and 3), perfused skeletal muscle-kidney (via the dorsal aorta; PDA) and perfused splanchnic (via the celiacomesenteric; PCM) circulations vasoconstrict in response to salmonid ANG II in a dose-dependent manner. ANG II was significantly (P¾0.05) more potent in the PCM than in the PDA, and both preparations were more responsive than the gills: pD2=8.0±0.20 (10) for PCM; pD2=7.5±0.07 (13) for PDA; pD2=6.9 ±0.21 (8) for gill arch 3; pD2=6.7±0.23 (8) for gill arch 2; mean ± s.e.m. (N), respectively. Salmonid angiotensin I (ANG I) also produced a dose-dependent constriction of the PDA and PCM. Angiotensin converting enzyme (ACE) activated nearly 100 % of ANG I to ANG II in a single pass through the PDA, whereas PCM conversion was estimated to be less than 10 %. Inhibitors of adrenergic constriction partially prevented ANG II responses in the PDA but did not affect PCM responses. ANG II did not affect paced rings of ventricular muscle in the presence of high or low [Ca2+] or epinephrine concentrations, nor did it have any inotropic or chronotropic effects in the in situ perfused heart. Red blood cell swelling was unaffected by ANG II. Similarly, the effects of ANG II on gut, urinary bladder and gall bladder smooth muscle were negligible or non-existent; thus, an increase in splanchnic resistance due to extravascular compression can be discounted. These results indicate that, in trout, the systemic microcirculation is the major cardiovascular effector of angiotensin-mediated pressor responses. In addition, the RAS has little direct effect on non-vascular smooth muscle or the heart. From an evolutionary perspective, the initial site of direct systemic RAS action appears to be the vascular microcirculation.

Partial inflow occlusion: a neglected technique for treating troublesome aortic leaks.

Most cardiac surgeons occasionally encounter troublesome bleeding from an ascending aortic site and are aware of the potential difficulties associated with repairing this complication. Partial inflow occlusion, as described below, is a simple method of depressurizing the aorta to facilitate suture placement after cardiopulmonary bypass.

Acute radial nerve compression following routine venipuncture in an anticoagulated patient.

Venipuncture is a commonly used modality for therapeutic monitoring in patients on anticoagulant therapy. The antecubital fossa provides an easily accessible site with low associated morbidity. A case report of an acute complete radial nerve compression neuropathy that developed after antecubital venipuncture in a patient on anticoagulant therapy is presented.

Left atrial appendage aneurysm: correlation of noninvasive with clinical and surgical findings: report of a case.

Congenital left atrial appendage aneurysm is rarely diagnosed on the basis of an abnormal cardiac silhouette. Patients with a left atrial appendage aneurysm often present with symptoms of systemic emboli or supraventricular arrhythmias. A patient with left atrial appendage aneurysm was diagnosed by correlation of two noninvasive techniques echocardiography and radionuclide scintiscanning. Angiography was confirmatory and aneurysmectomy was successfully performed.

Periarticular bone sites associated with traumatic injury: false-positive findings with In-111-labeled white blood cell and Tc-99m MDP scintigraphy.

The authors evaluate the reliability of combined indium-111-labeled white blood cell (WBC) and technetium-99m methylene diphosphonate (MDP) bone scan interpretations at sites of suspected periarticular osteomyelitis with radiographic evidence of adjacent traumatic arthropathy. A review of all orthopedic patients who underwent In-111 WBC-Tc-99m MDP scintigraphy over a 7-year period revealed a subset of 32 such cases that also included results of bone-biopsy cultures. Twenty-eight patients had a history of traumatic intraarticular injury, and four had periarticular fracture malunion or nonunion. Compared with intraoperative culture results, blinded In-111 WBC-Tc-99m MDP scan interpretations included four true-positive, 17 true-negative, and 10 false-positive results, and one false-negative result. The predictive values for positive and negative scans were 28% and 94%, respectively. A high prevalence of false-positive In-111 WBC-Tc-99m MDP scans may occur at periarticular sites of patients with associated traumatic arthropathy. This reduces the specificity of this technique for osteomyelitis, making culture confirmation of positive scans necessary. A negative scan is highly predictive of negative culture results at these sites.