Arnold A. Stokhof

Transcatheter Closure of Patent Ductus Arteriosus Using Occluding Spring Coils

The purpose of this study is to report our initial experience with the use of spring coils to close the patent ductus arteriosus in the dog. There are few large-patient series reported in the veterinary literature. Coil closure was attempted in 15 dogs (median weight, 6.5 kg; range, 1.2 to 38.7 kg) presenting with a patent ductus arteriosus between May 1997 and May 1999. Arterial catheterization followed by angiography was used to decide if coil placement was adequate. A 5- or 8-mm embolization coil, depending on the angiographic diameter of the ductus, was delivered, with 1 loop in the pulmonary arterial side and the remainder of the coil in the aortic side of the duct. Additional coils were used if a residual shunt was present, and closure was confirmed by aortography. Patients were discharged the day after the procedure. Successful coil closure, without residual shunt on angiography, was achieved in 11 of 13 dogs in which coils were released. In 6 dogs, a coil embolized to the pulmonary artery. Four of these dogs had successful closure with multiple coils, and 2 others had surgery. None of these dogs experienced adverse effects. In 2 dogs with conical patent ductus arteriosus >5 mm in minimal diameter, coil closure was not done. We conclude that the patent ductus arteriosus size and anatomical shape are crucial in deciding whether coil closure is the method of choice. In selected cases, coil closure represents an elegant alternative to surgical ligation. Although pulmonary embolism occurred commonly, it did not cause any obvious clinical problem.

Relationship between atrial fibrillation and primary hypothyroidism in the dog

Atrial fibrillation (AF) and primary hypothyroidism are most often diagnosed in middle-aged and older dogs of large and giant breeds. We hypothesized that the frequency of primary hypothyroidism may be higher in dogs with AF than in those without AF. Two groups were investigated. Group 1 (March 1987-June 1990) consisted of 128 dogs with AF. A thyroid-stimulating hormone (TSH) stimulation test was performed in dogs with a low voltage on the ECG and low uptake of pertechnetate on a thyroid scan. Group 2 (July 1990-July 1991) consisted of both dogs with AF (n = 38) and control dogs (n = 235) in which plasma thyroxine (T4) was measured. If T4 was below 15 nmol/l, a TSH stimulation test was performed. The frequencies of primary hypothyroidism in group 1 (8/128) and in the group 2 AF dogs (3/38) were not different, but were higher than in the control animals (3/235) (P < 0.05). The group 1 and the group 2 AF dogs were found to be comparable, and pooling of the data of the two groups enhanced the significance of the frequency of primary hypothyroidism in dogs with AF versus the control animals (11/166 versus 3/235) (P < 0.01). We concluded that the frequency of primary hypothyroidism in dogs with AF is higher than in the group of control dogs without AF. This may be due to the additional cardiovascular changes accompanying primary hypothyroidism in dogs that already have heart disease.

Scaling of atrioventricular transmission in mammalian species: an evolutionary riddle!

Scaling of AV Transmission.“Scaling deals with the structural and functional consequences of changes in size or scale among otherwise similar organisms.” It plays a key role in all studies on comparative mammalian physiology and morphology. Heart weight is proportionally related to body weight and can be described by a straightforward, so‐called allometric equation. We studied scaling of AV transmission times (PR intervals on the ECG) in 375 mammals of different dimensions and species. Scaling of AV transmission times versus heart length (third root of weight) is statistically best described by a S‐shaped curve. This implies that AV transmission time in mammals is not linearly related to heart length and does not depend solely on the length of the AV transmission system. The AV node fine‐tunes AV transmission times at rest and during exercise in individuals; it protects the ventricles against high‐rate atrial arrhythmias such as atrial fibrillation; and it regulates basal AV transmission times in mammalian species of varying sizes. We call the “how” and “why” of the scaling of AV transmission time in mammals an evolutionary riddle that deserves further study.

ECG of the “Newborn” Mouse (Mus Domesticus) with Specific Reference to Comparative AV Transmission

Comparative AV Transmission. Introduction: The objective of this study was to record the ECG of the smallest living mammal to extend the domain of data for comparative A V nodal electrophysiologic purposes. These data are needed to establish the relationship between the PR interval and heart size in mammalian species of all sizes.

Seven cases of heartworm disease (dirofilariosis) in dogs in the Netherlands

We present here the clinical history, diagnosis, and treatment of seven dogs with dirofilariosis. All dogs were imported into the Netherlands after residing in an area in which dirofilariosis is endemic. In three of these dogs the infection was occult, for the serological test was positive but there was no microfilaraemia. Weight loss, coughing, dyspnoea, and decreased exercise tolerance were the most prominent clinical signs. Two of the dogs had the characteristic electrocardiographic and radiographic signs of enlargement of the right heart. Treatment with thiacetarsamide and ivermectin resulted in complete remission in six dogs. One dog died, presumably as a result of acute renal failure. In the past year (1992-1993) seven cases of canine dirofilariosis were diagnosed, nearly equal to the number in the preceding 10 years (n = 9). This most probably reflects the greater sensitivity of the serological diagnosis of dirofilariosis in comparison with identification of microfilariae in the circulation, but a real increase in the number of dogs with dirofilariosis as a result of growing international traffic of tourists accompanied by pets cannot be excluded.

Survival time in dogs with spontaneous atrial fibrillation related to scintigraphically measured cardiac performance.

In 40 canine patients with spontaneous atrial fibrillation (AF) cardiac performance was measured scintigraphically and correlated with the survival time (ST) following the diagnosis of AF. The parameters used for cardiac performance were heart rate (HR), end-diastolic left ventricular volume (EDV), ejection fraction of the left ventricle (EF), left ventricular regurgitation fraction (RF) and cardiac output (CO). ST varied from 3 days to 780 days. Two groups of animals were distinguished as previously described: group A (EF less than 0.3, n = 26) and group B (EF greater than or equal to 0.3, n = 14). The median ST (90 days) in group A was only weakly significant (p = 0.1) shorter than in group B (150 days). RF was significantly lower in group A than in group B (p less than 0.001). A weak correlation was found between ST and EF (r = 0.28; p = 0.04). It was concluded that the prognosis in the described AF patients is slightly favourable if EF is normal or only moderately reduced.

Radiocardiography in dogs with atrial fibrillation

In 54 of 99 dogs with atrial fibrillation heart function was examined scintigraphically. Data on the ejection fraction (EF), end-diastolic volume (EDV) and regurgitation fraction (RF) are presented. Of these animals 37 had a seriously decreased EF (less than 30%) with a more or less normal RF value, whereas a smaller group (17) had a moderately decreased EF (but greater than or equal to 30%) and a seriously increased RF value. In both groups the EDV was increased.

Congenital Subvalvular Pulmonic Stenosis in a Cat

in thickness and appearance. The junction between normal and thickened epithelium sometimes was necrotic, with some separation from the underlying submucosa (fig. 3, 4). The small intestine had purulent enteritis. One large strongyle was seen. The liver had a mild round-cell infiltration of the hepatic triads. The kidney had the convoluted tubular necrosis usually seen in toxic tubular nephrosis. Other organs and systems had no significant lesions. Leukoplakia has been reported extensively in man [I]. It consists of the formation of abnormal white plaques of keratin on the mucous membrane, or a thickening of the stratum germinativium. It may be the result of chronic irritation, and generally is accepted as a precancerous lesion. Medical pathologists have reported leukoplakia to be most common in the oral cavity, esophagus, vagina and vulva [3], less common in the urinary bladder, ureter and kidney pelvis [2], and occasionally associated with hemorrhoids and rectal lesions [4]. Chronic catarrhal esophagitis may cause leukoplakia [5 ] . Repeated irritation to the esophageal mucosa causes increased thickness of the stratum germinativium, and the increased thickness of the epithelium looks like white plaques.

Evaluation of pulsatile plasma concentrations of growth hormone in healthy dogs and dogs with dilated cardiomyopathy.

OBJECTIVE To evaluate plasma concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-I) in healthy dogs and large-breed dogs with dilated cardiomyopathy (DCM). ANIMALS 8 dogs with DCM and 8 healthy control dogs of comparable age and body weight. PROCEDURES Blood samples for determination of the pulsatile plasma GH profile were collected from all dogs at 10-minute intervals between 8:00 am and 8:00 pm. Plasma IGF-I concentration was determined in the blood sample collected at 8:00 am. RESULTS No significant differences in plasma IGF-I concentrations, basal plasma GH concentration, GH pulse frequency, area under the curve above the zero line and above the baseline for GH, and GH pulse amplitude were found between dogs with DCM and control dogs. CONCLUSIONS AND CLINICAL RELEVANCE Results did not provide evidence for an association between DCM in dogs and a reduction in plasma concentrations of GH or IGF-I. Therefore, reported positive effects of GH administration are most likely attributable to local effects in the heart.

Cardiac changes induced by excess exogenous growth hormone in juvenile miniature poodles

The transient elevated plasma growth hormone (GH) levels that occur at a young age in giant breed dogs may have consequences in adult life. The aim of this study was to investigate whether excess juvenile GH has consequences for cardiac function and morphology. To simulate the naturally occurring juvenile hypersomatotropism in giant breed dogs, elevated plasma GH and insulin-like growth factor-I (IGF-I) concentrations were induced in six miniature poodles (GH dogs) by daily administration of supraphysiological doses of GH starting at 12 weeks of age. Eight miniature poodles of the same age that received vehicle only served as controls. Cardiac anatomy and function were evaluated by echocardiography. After euthanasia at 21 weeks of age, the hearts were examined for weight, myocyte dimensions and collagen fraction. The hearts of the GH dogs had larger atria (+22%), a thicker left ventricular wall (+21%), greater weight (+84%), and their cardiomyocytes were 15% longer, 25% thicker, and 92% greater in volume than those of control dogs. The mean collagen fraction was also higher in the GH dogs (5.6%) than in the controls (3.1%). In conclusion, excess GH in juvenile miniature poodles resulted in myocardial hypertrophy and increased collagen content. These findings are consistent with observations in acromegalic human patients and in rats treated with GH.