Capillary Density of Skeletal Muscle: A Contributing Mechanism for Exercise Intolerance in Class II–III Chronic Heart Failure Independent of Other Peripheral Alterations

AbstractOBJECTIVESThe study was conducted to determine if the capillary density of skeletal muscle is a potential contributor to exercise intolerance in class II–III chronic heart failure (CHF).BACKGROUNDPrevious studies suggest that abnormalities in skeletal muscle histology, contractile protein content and enzymology contribute to exercise intolerance in CHF.METHODSThe present study examined skeletal muscle biopsies from 22 male patients with CHF compared with 10 age-matched normal male control patients. Aerobic capacities, myosin heavy chain (MHC) isoforms, enzymes, and capillary density were measured.RESULTSThe patients with CHF demonstrated a reduced peak oxygen consumption when compared to controls (15.0 ± 2.5 vs. 19.8 ± 5.0 ml·kg−1·min−1, p <0.05). Using cell-specific antibodies to directly assess vascular density, there was a reduction in capillary density in CHF measured as the number of endothelial cells/fiber (1.42 ± 0.28 vs. 1.74 ± 0.35, p = 0.02). In CHF, capillary density was inversely related to maximal oxygen consumption (r = 0.479, p = 0.02). The MHC IIx isoform was found to be higher in patients with CHF versus normal subjects (28.5 ± 13.6 vs. 19.5 ± 9.4, p <0.05).CONCLUSIONSThere was a significant reduction in microvascular density in patients with CHF compared with the control group, without major differences in other usual histologic and biochemical aerobic markers. The inverse relationship with peak oxygen consumption seen in the CHF group suggests that a reduction in microvascular density of skeletal muscle may precede other skeletal muscle alterations and play a critical role in the exercise intolerance characteristic of patients with CHF

Multimodal non-surgical treatment of a feline tracheal adenocarcinoma

Case summary A 10-year-old, castrated male domestic shorthair cat presented with a 2–3 month history of weight loss, lethargy and coughing. Thoracic radiographs revealed a soft tissue opacity overlying the dorsal trachea from the first rib to second rib and the ventral aspect of the trachea extending from the second rib to approximately the fourth rib. CT confirmed a mass involving the dorsal, right lateral and ventral aspects of the trachea narrowing the lumen and extending from vertebra C7 through T4. Bronchoscopy revealed a partially circumferential irregular and multilobulated tracheal mass, which was biopsied. The histopathological diagnosis was tracheal adenocarcinoma. The cat was treated with a definitive course of external beam radiation therapy (RT; 3 Gy × 18), cytotoxic chemotherapy, a tyrosine kinase inhibitor and palliative RT. The cat remained asymptomatic for 2 months and the mass remained stable radiographically for 11 months after RT. Relevance and novel information With multimodal treatment the cat had a survival time of 755 days. Initial treatment included definitive RT, carboplatin and piroxicam, followed by toceranib phosphate and palliative RT when the mass recurred. This case report describes the first documented use of non-surgical treatment and long-term outcome of tracheal adenocarcinoma in a cat. This case report is an indication that prolonged survival can be achieved with multimodal therapy

The progression of heartworm associated respiratory disease (HARD) in SPF cats 18 months after Dirofilaria immitis infection

Abstract Background Heartworm-associated respiratory disease (HARD) in cats is induced by the arrival and death of immature adult Dirofilaria immitis in the pulmonary system and is indistinguishable from mature adult heartworm infection. Methods A controlled, blind research study investigated the long-term (18 months post infection, PI) consequences of the inflammatory response associated with the death of immature adult heartworms in cats. Three groups of cats, 10 per group, were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated with selamectin (Revolution®; Zoetis) per label directions at 28 days PI and once monthly for 17 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 μg/kg) at 70 days PI, then every 2 weeks for 15 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, 240, 309, 380, and 505 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected. Results The selamectin-treated cats (Group A) and ivermectin-treated cats (Group B) were free of heartworms or heartworm fragments at necropsy. All cats became heartworm antibody positive at some time point in the study except for one cat in Group A. Only cats in Group C (all with adult heartworms) were heartworm antigen positive. The heartworm antibody titer for Group B was highest on Days 110 to 168 and then decreased over time and 50% were serologically antibody negative on Day 240. Eosinophilic bronchoalveolar lavage (BAL) cytology and peripheral eosinophilia were most pronounced on Day 110 in all cats. Randomly distributed myofibrocytes in the lungs of some Group A cats suggest that precardiac larval stages were affecting the lungs. Radiographs in Group B cats demonstrated partial resolution of the initial HARD reaction but chronic myofibrocyte proliferation was histologically evident 18 months after infection. Conclusion HARD was induced by immature adult worm infection with progressive improvement starting 6 to 8 months after infection but histologic lesions were evident in some cats 18 months after infection. The serologic antibody assay was negative in 50% of cats at 8 months and 100% of cats at 18 months post infection. Abnormal radiographic lung patterns continued in a subset of Group B cats for months after heartworm antibody serology and BAL cytology returned to normal

Heartworm-associated respiratory disease (HARD) induced by immature adult Dirofilaria immitis in cats

Abstract Background A controlled, blind research study was conducted to define the initial inflammatory response and lung damage associated with the death of immature adult Dirofilaria immitis in cats as compared with cats developing adult heartworm infections and cats on preventive medication. Methods Three groups of cats were utilized, 10 per group. All cats were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated topically with selamectin (Revolution®; Zoetis) per label directions at 28 days post infection (PI) and once monthly for 8 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 μg/kg at 70 days PI, then every 2 weeks for 5 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, and 240 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected on all cats. Upon completion of the study (Day 245), cats were euthanized and necropsies were conducted. Results Results were analyzed statistically between groups by ANOVA and by paired sample T testing for changes within the group over time. The selamectin-treated cats (Group A) did not develop radiographically evident changes throughout the study and were free of adult heartworms or worm fragments at necropsy. The heartworm life cycle was abbreviated with oral doses of ivermectin (Group B), shown by the absence of adult heartworms or worm fragments at necropsy. The early stage of immature adult worm in Group B cats, however, did induce severe pulmonary airway, interstitial, and arterial lung lesions, revealing that the abbreviated infection is a significant cause of respiratory pathology in cats. Cats in Groups B and C could not be differentiated based on radiographic changes, serologic antibody titers, complete blood count, or bronchoalveolar lavage cytology at any time point throughout the study. Eighty percent of cats in Group A and 100% of cats in Groups B and C became heartworm antibody positive at some time point post infection. Conclusions The clinical implications of this study are that cats that become infected with immature adult heartworms may not develop fully mature heartworms and are only transiently heartworm antibody positive, but do develop Heartworm-Associated Respiratory Disease (HARD)

Increasing the Availability of Automated External Defibrillators at Sporting Events: A Call to Action from the American College of Sports Medicine

ABSTRACT: Given that most sudden cardiac arrests (SCAs) occur outside of a medical facility, often in association with exercise and sporting events, and given that early cardiopulmonary resuscitation (CPR) plus defibrillation is the strongest predictor of survival from SCA, this Call to Action from the American College of Sports Medicine recommends increasing the availability and effectiveness of early CPR plus defibrillation so that the time from collapse-to-first automated external defibrillator shock is less than 3 min

Inverse association of pulse pressure augmentation during exercise with heart failure and death

OBJECTIVE: Resting pulse pressure (PP) is a risk factor for heart failure (HF); however, whether PP augmentation during exercise, a parameter easily obtained from routine treadmill stress testing, is associated with incident HF is unknown. Thus, we aimed to study the relationship between a novel parameter, the pulse pressure stress index (P2SI), and adverse outcomes among adults undergoing clinical exercise stress testing in the Henry Ford Exercise Testing Project. METHODS: The P2SI was calculated as PP at peak exercise divided by resting PP and was analysed continuously and categorically using quartiles. Cox models examined the association between P2SI and adjusted HR (aHR) of incident HF, myocardial infarction (MI) or death. Receiver operating curve (ROC) analyses tested the optimal prognostic cut-point for P2SI. RESULTS: Among 55 524 participants without prior MI or HF, mean (SD) age was 53 (13) years, 51% were men and 29% black. A total of 2516 HF, 1606 MI and 6224 mortality outcomes occurred. Quartile 3 P2SI (2.0-2.4) was chosen as the reference category based on ROC analyses. There was a graded inverse association of low P2SI with excess HF (aHR of 1.3 (95% CI 1.1 to 1.5) for quartile 2 and 1.5 (95% CI 1.2 to 1.8) for quartile 1, p for trend CONCLUSIONS: Poor augmentation of PP with exercise, specifically a P2SI below 2, is a novel and readily quantifiable exercise-based risk feature for HF and death

Effect of heartworm disease and heartworm-associated respiratory disease (HARD) on the right ventricle of cats

Abstract Background Dirofilaria immitis infection occurs in dogs and cats, both of which species are clinically affected by mature adult infections. Cats are uniquely affected by immature-adult infections with an inflammatory pulmonary disease called Heartworm-Associated Respiratory Disease (HARD). D. immitis infection causes pulmonary parenchymal and vascular pathology in the dog and cat. Dogs develop pulmonary hypertension and cor pulmonale, whereas the development of pulmonary hypertension is rare in the cat. D. immitis infection in the dog causes alteration of the right ventricular (RV) extracellular matrix, including a decrease in myocardial collagen. In this study, the RV myocardial changes of cats infected with adult and immature-adult D. immitis were assessed. Methods The cardiopulmonary systems of six groups of SPF cats (n = 9-10 per group) were examined 8 or 18 months after infection with L3 D. immitis. Two groups were untreated and allowed to develop adult HW; two groups were treated with ivermectin starting 3 months post infection, thus allowing HARD but no mature adult heartworms; and two groups were treated with selamectin beginning 1 month post infection, preventing development of L5 or adult heartworms. A group of specific pathogen free (SPF) normal cats was utilized as a negative control (n = 12). Lung pathologic lesions were objectively assessed, and both RV and left ventricular (LV) weights were obtained to calculate an RV/LV ratio. Intramural RV myocardial collagen content was quantitatively assessed. Results RV/LV weight ratios were not different between groups. Negative control cats had significantly greater RV collagen content than all other affected groups (P = 0.032). Analysis of the RV/LV ratios and collagen content revealed no significant relationship (r = 0.03, P = 0.723, respectively). Collagen content had a modest, but significant, negative correlation, however, with both pulmonary vascular pathology (r = −0.25, P = 0.032) as well as the total pulmonary parenchymal and vascular pathology (r = −0.26, P = 0.025). Conclusions Cats infected with mature and immature D. immitis did not develop RV hypertrophy but did demonstrate loss of RV myocardial collagen content. The collagen loss was present at 8 and 18 months after infection in all infected cats. This loss of RV myocardial collagen was correlated with the severity of pulmonary parenchymal and vascular pathology