Interventional cardiology for the criticalist

Objective – To review indications, procedures, and prognosis for common cardiovascular emergencies requiring intervention in small animals. Etiology – Pericardial effusion, symptomatic bradycardia, and heartworm‐induced caval syndrome are examples of clinical scenarios commonly requiring intervention. Pericardial effusion in small animals occurs most frequently from cardiac neoplasia, idiopathic pericarditis, or congestive heart failure. Indications for temporary pacing include transient bradyarrhythmias, ingestions resulting in chronotropic incompetence, and emergency stabilization of critical bradyarrhythmias. Caval syndrome results from a large dirofilarial worm burden, pulmonary hypertension, and mechanical obstruction of right‐sided cardiac output with resultant hemolysis and organ dysfunction. Diagnosis – The diagnosis of pericardial effusion is suspected from signalment and physical findings and confirmed with cardiac ultrasound. Symptomatic bradycardias often present for syncope and definitive diagnosis derives from an ECG. Caval syndrome is diagnosed upon clinical, hematologic, and ultrasonographic evidence of severe heartworm infestation, cardiovascular compromise, and/or mechanical hemolysis. Therapy – Pericardial effusion is alleviated by pericardiocentesis in the emergency setting, though may require further intervention for long‐term palliation. Temporary transvenous pacing can be performed emergently to stabilize the symptomatic patient with a bradyarrhythmia. Dirofilariasis leading to caval syndrome requires urgent heartworm extraction. Prognosis – The prognosis for pericardial effusion is dependent upon the underlying etiology; the prognosis for cardiac pacing is favorable, and the prognosis for caval syndrome is grave if untreated and guarded to fair if heartworm extraction is performed.     

Corneal ulceration in a dog following exposure to the defensive spray of a walkingstick insect (Anisomorpha spp.)

Objective – To describe a case of corneal ulceration in a dog resulting from ocular exposure to the defensive spray of a walkingstick insect (Anisomorpha spp.). Case Summary – A 4‐year‐old, male Chihuahua in southeastern Louisiana presented to an emergency veterinary hospital approximately 20 hours after it was witnessed to have come in close proximity to a walkingstick insect. Within seconds of approaching the insect, the dog yelped, jumped backwards and developed lacrimation, blepharospasm, and periocular swelling of the left eye. Upon presentation, the dog was found to have blepharospasms and miosis of the left eye. Fluorescein stain was applied to the affected eye and diffuse corneal uptake of stain was noted. A diffuse superficial corneal ulceration was diagnosed and treated supportively with ocular flushing, topical antibiotics, ocular lubrication, and a 1% solution of ocular atropine, as well as systemic nonsteroidal anti‐inflammatory agents. Clinical signs resolved 10 days after injury. New or Unique Information Provided – While most species of walkingstick insects are considered harmless, certain species in the southeastern United States have the ability to spray defensive venom at their predators. Upon ocular exposure to the venom, the victim may experience intense pain followed by blurred vision, conjunctivitis, keratitis, and corneal ulceration. To date, there is only 1 previous reported case of ocular exposure to walkingstick venom in a dog although both children and animals may be at higher risk for ocular exposure due to their curious nature and proximity in size to the insect. Superficial corneal and conjunctival damage can occur following direct exposure to the defensive chemical spray of the Northern and Southern Twostriped walkingstick insects found in the southeastern United States and may be considered a differential diagnosis in cases involving diffuse corneal ulceration.     

Clinical Technique: Dorsal Ovariectomy in Rodents

Dorsal ovariectomy is a quick and simple procedure to perform on rodent patients. This procedure can be used to both prevent and treat many common diseases of the female rodent reproductive tract. It has also been shown to prevent mammary and pituitary tumors in rats. Although this article describes how to perform a dorsal ovariectomy in rats, this procedure is applicable for use in other rodent species too.     

Implantable cardioverter-defibrillator in a German shepherd dog with ventricular arrhythmias

This report describes the use of an implantable cardioverter-defibrillator (ICD) in a young German shepherd dog afflicted with inherited ventricular arrhythmias. Proper generator and lead placement was necessary for successful termination of ventricular fibrillation during device testing at the time of implantation. The risks of inappropriate therapy triggered by sinus tachycardia and oversensing of the T wave were controlled by extensive programming of the device. Following spontaneous resolution of the arrhythmia and due to the development of sepsis associated with the device, the ICD was successfully removed.     

NT-proBNP, NT-proANP and cTnI concentrations in dogs with pre-capillary pulmonary hypertension

Objectives

To compare [NT-proBNP], [NT-proANP] and [cTnI] between control dogs with respiratory disease without pulmonary hypertension (PH) and dogs with pre-capillary PH, and to assess the accuracy of [NT-proBNP], [NT-proANP], [cTnI] to predict Doppler-derived peak tricuspid regurgitation (TR) gradient.

Animals

20 dogs. 8 control dogs with respiratory disease with no PH and 12 with pre-capillary PH.

Methods

[NT-proBNP], [NT-proANP] and [cTnI] were compared between the 2 groups and simple linear regression analysis was used to predict peak TR gradients from various blood biomarkers.

Results

Median [NT-proBNP] was higher in the dogs with PH (2011 pmol/L, 274–7713 pmol/L) compared to control dogs (744 pmol/L; 531–2710 pmol/L) (p = 0.0339). [NT-proBNP] was associated with peak TR gradient (R² = 0.7851, p = 0.0001). Median [NT-proANP] did not differ between dogs with PH (1747 fmol/L; 894–2884 fmol/L) and control dogs (1209 fmol/L; 976–1389 fmol/L (p = 0.058). [NT-proANP] was not associated with peak TR gradient (R² = 0.2780, p = 0.0781). Median [cTnI] did not differ between dogs with PH (0.2850 ng/mL; 0.19–1.13 ng/mL) and control dogs (0.2 ng/mL; 0.19–0.82 ng/mL, p = 0.3051). Median [TnI] was not associated with peak TR gradient (R² = 0.024, p = 0.6307).

Conclusions

[NT-proBNP] concentration is significantly higher in dogs with pre-capillary PH when compared to dogs with respiratory disease without PH, and [NT-proBNP] may be useful to predict the severity of estimated PH. Elevations in [NT-proBNP] due to pre-capillary PH may complicate the interpretation of [NT-proBNP] elevations in patients presenting with cardiorespiratory abnormalities. [NT-proANP] and [cTnI] were not elevated in dogs with pre-capillary PH.     

DISCOSPONDYLITIS IN A CAT

The incidence and causative agents of discospondylitis in cats are unknown. This report describes a cat with radiologic changes consistent with discospondylitis and concurrent urinary tract infection. As in dogs, discospondylitis should be the primary rule out for vertebral end plate lysis in cats.     

EVALUATION OF IOHEXOL AS A GASTROINTESTINAL CONTRAST MEDIUM IN NORMAL CATS

The non-ionic, iodinated contrast medium, iohexol (240 mg I/ml) was evaluated as a gastrointestinal (GI) contrast medium in cats. Iohexol, both undiluted and diluted with tap water, was administered via a percutaneous endoscopically-placed gastrotomy (PEG) tube to 4 mature clinically normal cats. The dilution of contrast medium administered was 1:1, 1:2, and 1:3, and doses were 10 ml/kg and 5 ml/kg body weight. All combinations of dilution and dose of iohexol provided adequate visualization of the contrast medium column within the GI tract, and results were not significantly different than those observed using 30% w/v barium sulfate. Dehydration and diarrhea were not observed after contrast medium administration, but vomiting occurred within 15–30 minutes after administration of undiluted iohexol in all experimental cats. Renal opacification did not occur on exposures made through a 2 hour period, and dilution in transit was not apparent.