Sinus Node Sparing Hybrid Thoracoscopic Ablation Outcomes in Patients with Inappropriate Sinus Tachycardia (SUSRUTA-IST) Registry.

BACKGROUND: Medical treatment of inappropriate sinus tachycardia (IST) remains suboptimal. Radiofrequency sinus node (RF-SN) ablation has poor success and higher complication rates. OBJECTIVE: We aimed to compare clinical outcomes of the novel SN sparing hybrid ablation technique with those of RF-SN modification for IST management. METHODS: This is a multicenter prospective registry comparing the SN sparing hybrid ablation strategy with RF-SN modification. The hybrid procedure was performed using an RF bipolar clamp, isolating superior vena cava/inferior vena cava with the creation of a lateral line across the crista terminalis while sparing the SN region (identified by endocardial 3-dimensional mapping). RF-SN modification was performed by endocardial and/or epicardial mapping and ablation at the site of earliest atrial activation. RESULTS: Of the 100 patients (hybrid ablation group, n = 50; RF-SN group, n = 50), 82% were women, and the mean age was 22.8 years. Normal sinus rhythm and rate were restored in all patients in the hybrid group (vs 84% in the RF-SN group; P = .006). Hybrid ablation was associated with significantly better improvement in mean daily heart rate and peak 6-minute walk heart rate compared with RF-SN ablation. The RF-SN group had a significantly higher rate of redo procedures (100% vs 8%; P < .001), phrenic nerve injury (14% vs 0%; P = .012), lower acute pericarditis (48% vs 92%; P < .0001), permanent pacemaker implantation (50% vs 4%; P < .0001) than did the hybrid ablation group. CONCLUSION: The novel sinus node sparing hybrid ablation procedure appears to be more efficacious and safer in patients with symptomatic drug-resistant IST with long-term durability than RF-SN ablation.

Electron microscopic study of canine Babesia gibsoni infection.

Canine babesiosis is a tick-borne parasitic disease caused by the intraerythrocytic parasites, Babesia canis and Babesia gibsoni. A lethargic, weak, American Staffordshire Terrier (pit bull) dog, which had regenerative, normocytic, normochromic anemia, was shown by polymerase chain reaction analysis to be infected with B. gibsoni. Transmission electron microscopy of ethylenediamine tetraacetic acid-treated blood disclosed many well-preserved, intraerythrocytic babesia trophozoites. Four morphologic forms of babesia trophozoites are described (small spheres, small rods, irregular forms lacking pseudoinclusions, and large spheres having pseudoinclusions) and are compared with intraerythrocytic forms of B. canis and B. gibsoni described in other light and electron microscopic studies of in vivo and in vitro Babesia infections. This is the first detailed transmission electron microscopic study of canine B. gibsoni-infected red blood cells in North America.

Multiple animal intoxications associated with Carolina jessamine (Gelsemium sempervirens) ingestions.

Neurological signs characterized by marked progressive weakness and convulsions culminating in death were observed in 3 goats over a 24-h period. Affected animals were in a group of 5 goats confined toa fenced paddock: a domestic goose within the paddock was also found dead. Present in the same paddock, but unaffected, were 2 other goats and an adult cow. Five days prior to the animals' deaths, the owner had trimmed the surrounding brush and had thrown the cuttings into the enclosure. Post mortem examination of 2 of the dead goats and the goose revealed reduced muscle mass and fat stores, serous atrophy of adipose tissue, and reduced gastrointestinal contents, which included numerous leaves identified as Carolina jessamine (Gelsemium sempervirens). Histologic lesions included mild diffuse neuronal degeneration and cerebellar Purkinje cell loss in all animals with mild multifocal vacuolation of brainstem and cerebral white matter in 1 goat, and myofiber atrophy with perimyseal fibrosis in the goose. Preexisting malnutrition and lack of adequate alternative forages likely resulted in ingestion of Carolina jessamine and subsequent toxicosis. To our knowledge, this is the first reported case of Carolina jessamine toxicosis in goats and geese.

Thymic hematoma in juvenile dogs associated with anticoagulant rodenticide toxicosis.

Ten cases of thymic hematoma in young dogs (9-24 weeks of age) were reviewed. Anticoagulant rodenticide toxicosis was confirmed in 5 cases. Histologically, hemorrhage caused variable expansion of thymic lobules and interlobular septa. The medulla appeared to be the primary site of hemorrhage. In areas of severe hemorrhage, normal lobular architecture was lost and lymphocytes were admixed in the hemorrhagic exudate. Vasculitis, necrosis of capillaries, and degeneration of the capsule were observed in infarcted areas. In 2 cases, angiofibroplasia indicated a longer interval between onset of thymic hemorrhage and death. The lesions are similar to those in 5 cases of idiopathic thymic hemorrhage. Appropriate samples were not available for anticoagulant rodenticide analysis in 3 of these 5 idiopathic cases. Lesions in confirmed cases of anticoagulant rodenticide toxicosis also are compatible with published descriptions of idiopathic and spontaneous thymic hemorrhage, but are inconsistent with normal thymic involution. Analysis for anticoagulant rodenticides is indicated in cases of thymic hematoma when an obvious cause is not detected at necropsy.