Pulmonary vein to pulmonary artery ratio in healthy and cardiomyopathic cats.

INTRODUCTION/OBJECTIVES: Recognition of congestive heart failure (CHF) in dyspnoeic cats is crucial for correct intervention. The pulmonary vein (PV) to pulmonary artery (PA) ratio (PV/PA) has been proposed as an index that might help discriminate dogs suffering from CHF but has never been studied in cats. We sought to determine reference intervals for various PV and PA variables in healthy cats. We then examined these variables in cats with subclinical and clinical cardiomyopathies to determine their diagnostic utility in identifying CHF. ANIMALS, MATERIALS AND METHODS: We took a sample of 114 cats: 51 healthy cats, 32 subclinical cardiomyopathy affected cats and 31 cardiomyopathic cats with CHF. PV and PA were measured at the minimal and maximal diameters using M-mode images obtained from a modified right parasternal long axis view. The aorta (Ao) and left atrium were measured using two-dimensional imaging employing the right parasternal short axis view. RESULTS: median PVmin/PAmin value in healthy cats was approximately 0.51 and the PVmax/PAmax value was 0.67. The median distensibility value of the vessels was 23% for ΔPA and 41% for ΔPV. Cats with CHF had higher PVmin/PAmin, PVmax/PAmax, PVmin/Ao, PVmax/Ao values and a smaller ΔPV value compared to subclinical and healthy cats (p < 0.0001). When evaluating the diagnostic performance of these variables (in cardiomyopathic cats), PVmin/PAmin and PVmin/Ao values had higher accuracy compared to the LA:Ao value when identifying cats with CHF. CONCLUSIONS: Our study provides reference values for PV and PA variables in cats. Moreover, PV/PA variables were better factors than LA:Ao for discriminating cardiomyopathic cats with and without CHF.

Right ventricular outflow tract fractional shortening: an echocardiographic index of right ventricular systolic function in dogs with pulmonary hypertension.

OBJECTIVES: To create reference intervals for right ventricular outflow tract fractional shortening (RVOT-FS) in healthy dogs and examine diagnostic performance of this index in dogs with pulmonary hypertension (PH). In addition, we examine the impact of myxomatous mitral valve disease (MMVD) without PH on RVOT-FS. ANIMALS, MATERIALS AND METHODS: The study population included 52 healthy adult dogs, 51 dogs with MMVD but without PH, and 51 dogs with PH. This is a prospective study. Complete echocardiographic evaluations were performed on all dogs. Right ventricular outflow tract fractional shortening was obtained by two-dimensional guided M-mode recordings from the right parasternal short axis view. Right ventricular outflow tract fractional shortening was evaluated in healthy dogs of various breeds, and reference intervals were generated. We examined the effect of PH on RVOT-FS with receiver operating characteristic analysis and evaluated the effect of MMVD on RVOT-FS in dogs without PH. Intraobserver and interobserver reproducibility was calculated. RESULTS: Healthy dogs had RVOT-FS > 44%. Right ventricular outflow tract fractional shortening values of healthy dogs and MMVD dogs without PH did not differ (p=0.84). In dogs with PH, RVOT-FS decreased with increasing tricuspid regurgitation velocity (p<0.0001). Pimobendan use in dogs with PH increased RVOT-FS as PH worsened. Right ventricular outflow tract fractional shortening was acquired with clinically acceptable intraobserver and interobserver reproducibility. CONCLUSIONS: Right ventricular outflow tract fractional shortening is a novel, easy applicable, and repeatable index for evaluating RV systolic function. Studies comparing this index with common echocardiographic indices used to assess RV function in dogs are needed.

Left atrial deformation and phasic function determined by two-dimensional speckle-tracking echocardiography in dogs with myxomatous mitral valve disease.

INTRODUCTION: Left atrial (LA) function can provide useful information in dogs with myxomatous mitral valve disease (MMVD). Recently, we have demonstrated the feasibility of measuring LA longitudinal deformation using speckle-tracking echocardiography (STE) to estimate LA function in healthy dogs. Whether LA strain and strain rate variables provide additional information about LA function and clinical cardiac status in dogs with MMVD remains unexplored. ANIMALS: Ninety-six client-owned dogs of different breeds with MMVD were prospectively enrolled. METHODS: LA longitudinal deformation was evaluated in each dog by STE and different STE variables were used to assess LA function. RESULTS: No STE variables differed between American College of Veterinary Internal Medicine Stage B1 and B2 dogs but were lower in Stage C dogs. Peak atrial longitudinal average strain < 27.9%, left-atrial-to-aortic ratio > 2.2 and peak atrial contraction average strain < 7.25% discriminated symptomatic MMVD dogs by receiver operating characteristic analysis with sensitivity and specificity of 100% and 100% (95% confidence interval [CI] 91-100%), 92% (95% CI 78-98%) and 98% (95% CI 87-100%), 100% (95% CI 91-100%) and 95% (95% CI 83-99%), respectively. In 12 dogs with similar left-atrial-to-aortic ratio, peak atrial longitudinal average strain and peak atrial contraction average strain differentiated dogs with subclinical disease from those with congestive heart failure (CHF). CONCLUSION: Dogs with MMVD in CHF appear to have lower LA longitudinal strain and strain rate variables compared with dogs with subclinical disease. Further studies are needed to establish if our initial findings can provide useful information for the diagnosis, treatment, and prognosis of dogs with MMVD.

Transthoracic ultrasound guided balloon dilation of cor triatriatum dexter in 2 Rottweiler puppies.

Balloon dilation was performed in two Rottweiler puppies with cor triatriatum dexter and clinical signs of ascites using transthoracic echocardiographic guidance. The dogs were positioned on a standard echocardiography table in right lateral recumbency, and guide wires and balloon catheters were imaged by echocardiographic views optimized to allow visualization of the defect. The procedures were performed successfully without complications and clinical signs were resolved completely in both cases. Guide wires and balloon catheters appeared hyperechoic on transthoracic echocardiography image and could be clearly monitored and guided in real-time. These two cases demonstrate that it is possible to perform balloon catheter dilation of cor triatriatum dexter under transthoracic guidance alone.

Left atrial deformation and phasic function determined by 2-dimensional speckle tracking echocardiography in healthy dogs.

INTRODUCTION: Feasibility, intra- and inter-observer variability of measuring left atrial (LA) longitudinal strain and strain rate (SR) variables using speckle tracking echocardiography (STE) have not been reported in the dog. Reference intervals for these variables which can be useful to estimate LA function have been provided. ANIMALS: Forty-eight healthy adult dogs. MATERIALS AND METHODS: Left atrial longitudinal deformation was evaluated in each dog by STE, and different combinations of STE variables were used to describe the 3 phases (reservoir, conduit and booster pump phase) of the LA function. RESULTS: Left atrial STE was possible in 40/48 dogs (83%). Strain and SR curves in healthy dogs were characterized, and reference intervals for several strain and SR variables are provided. Intra- and inter-observer variability, expressed as percent difference between observations or observers, was 3.58%-10.8% for indices of the LA reservoir function, 10.48%-15.82% for indices of the LA conduit function and 14.1%-34% for indices of the LA contractile function. Strain rate in early diastole and strain rate at atrial contraction variables were correlated significantly with age. No other relationships (body weight, heart rate or LA size) with any STE variables could be identified. CONCLUSION: Speckle tracking echocardiography provides quantitative measurements of LA longitudinal deformation and can be used to assess LA phasic function in healthy dogs. Further studies of these variables in dogs with cardiac diseases are needed to determine the clinical applicability and utility.

Transesophageal echocardiography as the sole guidance for occlusion of patent ductus arteriosus using a canine ductal occluder in dogs.

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) is usually performed by fluoroscopy alone or together with transesophageal echocardiography (TEE). Transthoracic echocardiography (TTE) guidance has been used for deployment of Amplatz Canine Ductal Occluder (ACDO), but sometimes is limited by suboptimal acoustic windows. Transesophageal echocardiography can overcome such issues and provides higher image resolution at the level of the great vessels. OBJECTIVES: To determine if TEE without fluoroscopy could be used to successfully perform ductal occlusion for the treatment of PDA in dogs. ANIMALS: Twenty client-owned dogs with PDA. METHODS: A prospective consecutive case series of PDA occlusion was performed using only TEE guidance. Dogs were positioned in right lateral recumbency and the TEE probe was positioned to visualize the descending aorta, PDA, and pulmonary artery. The guide wire, long introducer sheath, and ACDO were imaged by TEE to direct deployment. RESULTS: Ductal occlusion was performed successfully without need for fluoroscopy and without complications in 19 dogs. One dog required a second larger ACDO because of embolization of the first device 18 hours after positioning. CONCLUSIONS AND CLINICAL IMPORTANCE: We have demonstrated that TEE monitoring without concurrent fluoroscopy can guide each step of transcatheter ACDO embolization thereby providing an alternate method of visualization for this procedure. Use of TEE alone can reduce radiation exposure or is an option when fluoroscopy is not available, and, therefore, should be evaluated in a larger case series to better assess procedural failure rates.