Electrocardiography-gated cardiac CT angiography can differentiate brachycephalic dogs with and without pulmonary valve stenosis and findings differ from transthoracic echocardiography.

Pulmonary valve stenosis (PS) is one of the most commonly diagnosed congenital heart defects in dogs. Currently, transthoracic echocardiography (TTE) is the standard modality used to evaluate PS. Image acquisition by TTE can be challenging in some brachycephalic breeds of dogs. The use of echocardiographic-gated CT angiography (ECG-gated CTA) in veterinary medicine is limited. This retrospective method comparison study investigated right and left ventricular outflow diameters by sedated ECG-gated CTA and unsedated TTE in 14 brachycephalic dogs with PS and 12 brachycephalic dogs without PS. Measurements of ventricular outflow structures were made in early systole and end diastole for both modalities and then compared for significance between systolic and diastolic phases, as well as between the two modalities. Ratios of the pulmonary trunk diameter to the aorta at different locations (aortic valve, aortic annulus, and ascending aorta) and in different planes (transverse, sagittal) were compared between dogs with PS and without PS, as well as within dogs, by both TTE and ECG-gated CTA. Transthoracic echocardiography and ECG-gated CTA both detected significantly greater pulmonary trunk to aorta ratios in dogs with PS at all aortic locations (P < 0.05). Pulmonary valve to aortic valve ratios were significantly smaller in dogs with PS (P < 0.05). Pulmonary trunk to aorta and pulmonary valve to aorta ratios were achieved with good anatomic detail using ECG-gated CTA. Ratios of the pulmonary trunk and pulmonary valve relative to the aorta may be useful to evaluate for PS using a modality that is underutilized for cardiac assessment.

Extreme tetralogy of Fallot in a dog.

A four-month-old female Labrador retriever was brought to the Tokyo University of Agriculture and Technology Animal Medical Center for examination of its main symptoms of cough, tachypnea and exercise intolerance. Upon examination, the dog was found to have cyanosis and inadequate growth. Echocardiography revealed tetralogy of Fallot. Cardiac catheterization confirmed that the main pulmonary artery was completely occluded and that blood flowed from the aorta to the pulmonary artery. Accordingly, the animal was diagnosed with extreme tetralogy of Fallot.

Size and shape of right heart chambers in mitral valve regurgitation in small-breed dogs.

BACKGROUND: The contribution of right heart (RH) chamber enlargement to general heart enlargement seen on thoracic radiographs in mitral regurgitation (MR) is not known. OBJECTIVES: To determine the size and shape of the RH chambers in normal dogs and dogs with varying degrees of MR. ANIMALS: Fifty-four privately owned dogs: 13 normal, 41 with varying degrees of MR including 25 with congestive heart failure (CHF). METHODS: Archived first pass radionuclide angiocardiograms were used to produce static images of the RH and left heart (LH) chambers. Indexes of size and shape of the RH and LH chambers were related to severity of MR determined by heart rate-normalized pulmonary transit time (nPTT), vertebral heart scale (VHS), and clinical status. RH shape was measured by a circularity index of RH short axis/long axis. RESULTS: A 2nd degree polynomial fit best described the ratios; RH/LH dimension to nPTT (R(2)= 0.62) and to VHS (R(2)= 0.43), RH/LH area to nPTT (R(2)= 0.64) and to VHS (R(2)= 0.58), all P < .001. RH circularity was decreased in CHF, P < .001. In CHF, the RH chambers of 16 dogs were both flattened and enlarged, whereas 9 had convex septal borders. CONCLUSIONS: RH chambers are not significantly dilated in dogs with mild to moderate MR without CHF. In CHF, RH chambers enlarge and also may be compressed by the LH chambers. Pulmonary hypertension probably is present in some dogs with CHF. Increased sternal contact is not a useful sign of right-sided heart dilatation in MR.

Echocardiographic and angiographic comparison of ductal dimensions in dogs with patent ductus arteriosus.

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) is a minimally invasive treatment option in dogs. Device selection based on appropriately acquired PDA dimensions and morphology can minimize procedural complications, including minimizing residual ductal flow and inappropriate embolization. HYPOTHESIS: Transesophageal echocardiographic (TEE) derived minimum ductal diameter measurements would most accurately reflect angiographic measurements. Color Doppler (CD) TEE and transthoracic echocardiographic (TTE) ductal measurements would overestimate two-dimensional (2D) measurements. ANIMALS: Fifteen client-owned dogs with PDA. METHODS: PDA dimensions obtained with angiography, 2D and CD TTE, 2D and CD TEE from the right and left views were prospectively evaluated. RESULTS: PDA dimensions were measured by using TEE most closely approximated angiographic measures. CD TTE and TEE frequently overestimated angiographic measures of minimum ductal diameter. TEE accurately identified a type III (tubular) PDA morphology in 1 dog. Fourteen of 15 dogs were determined to have hemodynamically significant reductions in left to right shunting documented by a first-pass nuclear angiocardiographic ratio of pulmonary to systemic blood flow < or = 1.2 and trivial (n = 3) to no (n = 11) CD TTE flow at approximately 1 month after PDA occlusion. CONCLUSIONS: TEE provided accurate anatomic information regarding PDA morphology and closely approximated angiographic ductal dimensions while aiding in both coil deployment and confirmation of intra-operative ductal closure.

An experimental study of apico-aortic valved conduit (AAVC) for surgical treatment of aortic stenosis in dogs.

A new valved conduit was developed using a canine aortic valve. The bioprosthetic valve was fixed with glutaraldehyde and epoxy compound (Denacol-EX313/810). A vascular graft composed of ultra-fine polyester fiber (10 mm in diameter, 200 mm in length) was used. Four dogs underwent apico-aortic valved conduit (AAVC) implantation and aortic banding (bypass group, BG), while another 4 dogs underwent aortic banding without AAVC implantation (control group, CG). Cardiac catheterization and angiocardiography were performed for assessment of hemodynamics 2 weeks and 6 months after surgery. Left ventricular systolic pressure, left ventricular end-diastolic pressure and the left ventricular-aortic pressure gradient differed significantly (P<0.01) between the BG and CG dogs. Left ventricular angiocardiography showed patency of the valved conduit in all the BG dogs. Echocardiography was performed before and 2, 4 and 6 months after surgery, and showed that while pressure overload caused concentric myocardial hypertrophy in the CG dogs, the left ventricle dilated eccentrically in the BG dogs. Furthermore, relief of left ventricular pressure overload by AAVC was maintained.

Increased pulmonary transit times in asymptomatic dogs with mitral regurgitation.

Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood volume (PBV) to stroke volume ratio (PBV/SV). It is an index of cardiac performance. To determine the effect of compensated mitral regurgitation (CMR) and decompensated mitral regurgitation (DMR) caused by valvular endocardiosis on the index nPTT, we measured nPTT by first-pass radionuclide angiocardiography and ECG in 13 normal dogs, 18 dogs with CMR, and 13 dogs with DMR. PTT was measured as time between onset of appearance of activity at the pulmonary trunk and the left atrium. In the normal dogs, the relationship between PTT and mean R-R interval (mRR) was PTT = 4.08 x mRR + 0.15 (R2 = 0.71). Normal nPTT was 4.4 +/- 0.6 (SD) (range. 3.6-5.3). in CMR, 6.3 +/- 1.6 (SD) (range, 4.0-9.7). and in DMR, 11.9 +/- 3.4 (SD) (range, 8.0-18.8). The differences among all groups were significant. Heart rates were 110 +/- 22 bpm in normal dogs, 111 +/- 20 in dogs with CMR, and 144 +/- 18 in dogs with DMR (P < .001 for difference between DMR group and normal and CMR groups). Increased nPTT in CMR indicates preclinical heart pump dysfunction. Heart rate-normalized pulmonary transit times may be a useful index of heart function in mitral regurgitation.

First-pass nuclear angiocardiography in the evaluation of patent ductus arteriosus in dogs.

First-pass nuclear angiocardiography (FPNA) was performed in 5 normal dogs and in 19 dogs with left-to-right shunting patent ductus arteriosus (PDA). Affected dogs were evaluated before and after an occlusion procedure (surgical ligation or transarterial coil embolization). Two methods of analysis were used to evaluate the pulmonary time-activity curves and assess the magnitude of the shunt. One method involved the calculation of a simple count ratio (C2:C1). The other method used gamma variate modeling to estimate the ratio of pulmonary to systemic blood flow (QP:QS). Values for normal dogs (mean +/- SD) were C2:C1 = 0.39 +/- 0.11 and QP:QS = 1.10 +/- 0.03. Values for affected dogs were C2:C1 = 0.59 +/- 0.17, QP:QS = 2.01 +/- 0.46 before intervention and QP:QS = 1.21 +/- 0.17, C2:C1 = 0.42 +/- 0.12 after intervention. Both methods detected significant differences between normal and affected dogs (QP:QS, t-test, P < .001; C2:C1; t-test; P = .018) and between affected dogs pre- and postocclusion (QP:QS. paired t-test, P < .001; C2:C1, paired t-test, P = .002). However, QP:QS was a better separator of normal from affected animals. First-pass nuclear angiocardiography, by the gamma variate method, may be a useful, adjunct diagnostic test in evaluation of animals with left-to-fight shunting PDA, particularly in animals with residual shunting after an occlusion procedure.

Aberrant branch of the bronchoesophageal artery resembling patent ductus arteriosus in a dog.

An anomalous shunt between the bronchoesophageal artery and pulmonary artery was diagnosed in a 1-year- old, 3.5 kg female Miniature Dachshund by selective contrast angiography. A cardiac murmur had been observed in the dog during examination at another hospital. The machinery murmur was auscultated at the left side of the base of the heart. Although thoracic radiography revealed mild cardiomegaly, the characteristic findings of patent ductus arteriosus (PDA), including as aortic arch enlargement and pulmonary artery enlargement were not observed. Echocardiography demonstrated shunting of blood flow presumably from the arterial duct at the pulmonary artery carina. Based on the above findings the case was diagnosed as PDA. Angiocardiography was performed to confirm the diagnosis in preparation for surgical treatment, but later we confirmed that the shunt vessel was not PDA, but apparently a branch of the bronchoesophageal artery. The shunt vessel was branching in a complicated manner and shunted to the pulmonary artery.

Left ventricular outflow tract to left atrial fistula associated with endocarditis in a dog.

A one-year-old, intact male, 28-kg, mixed-breed dog developed neurological episodes consistent with emboli. An acquired III/VI holosystolic heart murmur was ausculted in the mitral area, and valvular endocarditis with pulmonic and aortic insufficiency were noted at echocardiographic examination. An abnormal communication (i.e., fistula) between the left ventricular outflow tract (LVOT) and the left atrium adjacent to the mitral valve annulus was noted with Doppler imaging and confirmed with angiography. Infective valvular endocarditis was confirmed based on two of three blood cultures being positive for Staphylococcus intermedius. In humans, a sequela to infective endocarditis of the aortic or mitral valve, or both, is rupture of the mitral-aortic intervalvular fibrosa, resulting in a communication between the LVOT and the left atrium. This is the first report of this sequela in the dog.

Dilated coronary sinus in a dog with persistent left cranial vena cava.

This paper describes the electrocardiographic, echocardiographic (two-dimensional, M-mode, contrast and Doppler) and non-selective angiocardiographic features in a 3 year old female Beagle with dilated coronary sinus due to persistent left cranial vena cava. Negative P waves in leads III and aVR and a positive P wave in lead aVL were seen. Echocardiographically, a hypoechoic circular structure was seen between the left atrium and the pericardium in the area where the coronary sinus is located. A velocity pattern with two peaks was obtained, one systolic with velocity = 0.44 +/- 0.05 m/sec and the other diastolic with velocity = 0.27 +/- 0.01 m/sec. By M-mode echocardiography, at level of the aorta and the left atrium, a linear structure was identified between the left atrium and the pericardium; this structure was characterized by phasic movements of the anterior wall during the cardiac cycle. Following a left cephalic vein injection of saline, bubbles were seen within the coronary sinus; when saline was injected into the right cephalic vein, bubbles were also seen within the coronary sinus and right atrium and ventricle. Non-selective angiocardiography confirmed a dilated coronary sinus with persistent left cranial vena cava. The right cranial vena cava was absent. The dog was clinically normal and the unusual vessel was an incidental finding.

Dyserythropoiesis, polymyopathy, and cardiac disease in three related English springer spaniels.

A polysystemic disorder was observed in three related English Springer Spaniel dogs that demonstrated regurgitation from an early age, slowly progressive temporal muscle atrophy with partial trismus, and less pronounced generalized skeletal muscle atrophy. All dogs exhibited moderate dyserythropoietic anemia, polymyopathy with megaesophagus, and varying degrees of cardiomegaly. The prevalence, etiology, underlying pathomechanism, and possible mode of inheritance remain to be elucidated.

Cardiopulmonary values in dogs with artificial model of caval syndrome in heartworm disease.

Cardiopulmonary values were determined in dogs with an artificial model of heartworm caval syndrome, which was produced by insertion of heartworm-like silicone tubes into the tricuspid valve orifice and right atrium. Fifteen to 25 tubes with some knots were inserted in 6 dogs (knot group), and 7 to 11 tubes (small-number group) or 29 to 37 tubes (large-number group) without a knot in 3 dogs, respectively. After tube insertion, angiographic contrast medium infused into the right ventricle regurgitated to the right atrium in all cases, and the regurgitation was the most severe in the large-number group. On electrocardiographic findings, the atrial and/or ventricular premature beat developed. The height of a- and v-wave of right atrial pressure curves elevated in all groups. The elevation in v-wave was obvious in the large-number group. The pulmonary arterial pressure tended to fall or to elevate slightly, and total pulmonary resistance increased in all groups. The right cardiac output decreased significantly in all cases. The right heart hemodynamics of the model might resemble those in spontaneous cases without disturbed pulmonary circulation.

An open patch-graft technique for correction of pulmonic stenosis in the dog.

An open patch-graft technique for correction of pulmonic stenosis was performed in four dogs. A synthetic patch-graft was presutured to a partial-thickness incision in the right ventricular outflow tract and to the pulmonary artery along its cranial border. The pulmonary artery and right ventricle were incised during venous inflow occlusion, and dysplastic pulmonic valve leaflets were excised. The arteriotomy was closed by suturing the caudal margin of the incision to the patch-graft. The entire procedure was performed during mild hypothermia (30 degrees - 32 degrees C). The mean circulatory arrest time was 5.5 +/- 0.2 minutes. The mean systolic pressure gradient across the pulmonic valve before surgery was 121 +/- 29 mm Hg; after surgery it was 9 +/- 2 mm Hg.

Right ventricular outflow obstruction caused by primary cardiac neoplasia. Clinical features in two dogs.

Obstruction to pulmonary blood flow as a result of neoplasia in the right ventricular outflow tract is described in two dogs. Whereas one dog had exertional syncope and a systolic ejection murmur, the other had signs of congestive failure and hypoxia. In both animals the mass was detected in the right ventricle with two-dimensional echocardiography and confirmed angiographically. Although rare, primary right ventricular neoplasia represents a potentially treatable form of cardiac disease and should be considered as a cause of acquired outflow tract obstruction.

Pulmonic stenosis caused by single coronary artery in dogs: four cases (1965-1984).

Single right coronary artery (CA) associated with pulmonic stenosis was found in 3 English Bulldogs and a Boxer, suggesting a genetic predisposition for the associated anomalies. The left main coronary branch arose from the single right CA, encircled the pulmonic root over hypoplastic pulmonic valves at the level of the obstruction, and appeared to be the primary cause of underlying pulmonic stenosis. Patch-graft surgery to relieve pulmonic stenosis caused death in 1 dog when the unrecognized anomalous CA was served during the procedure. The anomalous left CA was detectable by use of angiocardiography in all 4 dogs and was recognized before surgery in 2 of them. In 1 dog, a right ventricle-to-pulmonary trunk-bridging conduit was implanted to improve outflow from the right side of the heart.

Pulmonary atresia with intact ventricular septum and agenesis of the ductus arteriosus in a pup.

A 7-week-old Wire Fox Terrier was admitted with pulmonary atresia with intact ventricular septum. The right ventricle and tricuspid valve were hypoplastic, and venous return to the right atrium reached the left side through an atrial septal defect. Oxygenation was via hyperplastic bronchial arteries. There was no evidence of the ductus arteriosus. Physical examination, plain and contrast radiography, and electrocardiography were performed. Clinical findings for this combination of defects were similar to those of more common defects (tetralogy of Fallot, patent ductus arteriosus.

The angiocardiographic diagnosis of a persistent truncus arteriosus in a foal.

Persistent truncus arteriosus is a relatively rare cardiac anomaly which is associated with a single large artery arising from the ventricles. An interventricular septal defect is invariably present. The vessel gives origin to the pulmonary trunk, aorta and coronary arteries. A description of the angiocardiographic diagnosis of this condition is given as well as a general review of the relative developmental anatomy.

Right-to-left patent ductus arteriosus with dysplastic left ventricle in a dog.

A 6-week-old Siberian Husky pup had an unusual group of congenital heart anomalies that included a right-to-left patent ductus arteriosus, a small left ventricular chamber and ascending aorta, and a dysplastic mitral valve that may have been stenotic. Anomalies were diagnosed, using cardiac catheterization, angiocardiography, and blood gas determinations. Findings were confirmed by postmortem examination.