Biomedical subjects
Publications and source records attributed to Michael R O'Grady.
Despite many advances in he diagnosis and treatment of DCM, it continues to be an important cause of cardiovascular morbidity and mortality in large-breed dogs. In the coming years, it is hoped and anticipated tht further discoveries will be made in the areas of etiology, therapy, and assessment of prognosis, ultimately with a view to having a greater impact on the clinical management of these cases.
OBJECTIVE: To determine the cardiopulmonary response to romifidine (RO) in the dog with or without prior or concurrent administration of glycopyrrolate. STUDY DESIGN: Randomized, cross-over experimental study. ANIMALS: Six (three male, three female) cross-bred dogs weighing 23 +/- 2.4 kg. METHODS: Two-dimensional guided M-mode echocardiography was performed in conscious dogs simultaneously with measurement of systolic arterial blood pressure (SBP) and heart rate (HR). Dimensions of the left ventricle (LVID), interventricular septum (IVS), and left ventricular free wall (LVFW) were obtained in systole (S) and diastole (D). Amplitude of motion (Amp) of the IVS and LVFW were also measured. From these, measures of wall stress (WS) and fractional shortening (FS) of the left ventricle were derived. Baseline echocardiographic measurements were recorded, following which one of the five treatments was administered. Glycopyrrolate (G) 0.01 mg kg-1, or saline (S) 0.5 mL, was administered IM as pre-medication (Gp or Sp), or G was administered concurrently (Gc) with romifidine (RO). Treatments were: T1, Sp + RO (40 micro g kg-1); T2, Gp + RO (40 micro g kg-1); T3, Sp + RO (120 micro g kg-1); T4, Gp + RO (120 micro g kg-1); and T5, Sp + Gc +RO (120 micro g kg-1). Romifidine or RO + Gc was administered SC 20 minutes after pre-medication (time 0), and further measurements were taken 10, 20, 30, 60, and 90 minutes after RO. RESULTS: Echocardiographic indices of cardiac systolic function (LVID-S, FS, Amp-LVFW) and HR were decreased in RO-sedated dogs (p < 0.0001). The magnitude of change in cardiac indices was least with low-dose RO. At most sampling times, high-dose RO produced significantly more alteration in cardiac indices. Systolic blood pressure increased in all treatment groups, with the greatest increases in those groups receiving G. Glycopyrrolate significantly increased HR; however, cardiac indices were further reduced. Wall stress significantly increased, with a more dramatic increase in groups receiving G. CONCLUSIONS: Indices of LV systolic function were reduced in RO-sedated dogs in a dose-related manner. Glycopyrrolate further reduced these indices and dramatically increased measurements of wall stress in dogs sedated with RO. CLINICAL RELEVANCE: Use of low-dose RO minimizes cardiac dysfunction; however, it should still be used cautiously in dogs with cardiomyopathy or heart failure. The routine use of G is not recommended to alleviate the bradycardia associated with RO in conscious dogs.
BACKGROUND: Primary infundibular stenosis is a rare congenital defect in which the right ventricle is divided into a proximal "high-pressure" chamber and a distal "low-pressure" chamber. The condition can be misdiagnosed as ventricular septal defect or valvular pulmonic stenosis and the disease severity underestimated. The purpose of this study was to provide a detailed clinical and echocardiographic description of this anomaly in a series of dogs. HYPOTHESIS: Several anatomic forms of infundibular stenosis exist. High resolution two-dimensional echocardiography could differentiate 3 gross anatomic substrates. Knowledge of the anatomy of the obstructing lesion could influence options for corrective interventions. ANIMALS: Thirteen dogs examined at the Ontario Veterinary College teaching hospital from 1994 to 2005 with an ultrasound diagnosis of subpulmonic stenasis. METHODS: A retrospective review was made of case records from 1994 to 2005. RESULTS: Thirteen dogs were identified as having primary infundibular stenosis, with apparent increased prevalence in Golden Retrievers (8/13, 62%) and Siberian Huskies (3/13, 23%). Three types of infundibular lesions were identified by ultrasound in 11/13 dogs: a fibrous diaphragm (6), fibromuscular (4), and muscular obstruction (1). Two dogs with a fibrous diaphragm underwent direct surgical dilation without the use of cardiopulmonary bypass or inflow occlusion, resulting in substantial reduction of the severity of stenosis. CONCLUSION AND CLINICAL IMPORTANCE: Accurate determination of the severity of the stenosis and the anatomy of the obstructing lesion are important in devising a treatment strategy. Recognition of the fibrous diaphragm by echocardiography identifies a subset of dogs potentially amenable to surgical dilation without the need for cardiopulmonary bypass.