Background
Supraventricular tachycardias (SVTs), despite having various anatomical substrates and pathophysiological mechanisms, frequently show similar electrocardiographic presentations.
Objectives
...To locate and characterize atrial deflections (ADs) on 12‐lead electrocardiograms in dogs with sustained rapid SVT and assess the utility of different electrocardiographic variables in differentiating types of tachycardia.
Animals
Ninety‐two dogs with orthodromic atrioventricular reciprocating tachycardia, 17 with atrial flutter, 33 with focal atrial tachycardia recorded and confirmed by electrophysiological study, and 40 dogs with sinus tachycardia.
Methods
Atrial deflection position on the 12‐lead surface electrocardiogram was assessed according to the sequence of intracardiac activation. Its features were evaluated together with the relationship between AD and QRS complex interval (AD‐R) and QRS complex and AD interval (R‐AD).
Results
Orthodromic atrioventricular reciprocating tachycardia was characterized by an AD‐AD interval of 213 ± 30 ms, mean electrical axis (MEA) of AD of −90 (−90/−78)°, R‐AD interval of 75 (65‐80) ms, and R‐AD/AD‐R of 0.54 (0.45‐0.64). Atrial flutter was characterized by an AD‐AD interval of 199 ± 57 ms, MEA of 76° (72/81), R‐AD of 120 (72‐144) ms, and R‐AD/AD‐R of 0.81 (0.63‐1.13). Focal atrial tachycardia was characterized by an AD‐AD interval of 270 ± 38 ms, MEA of 49 (−72/76)°, R‐AD of 160 (120‐200) ms, and R‐AD/AD‐R of 1.45 (0.92‐1.67). Sinus tachycardia was characterized by an AD‐AD interval of 292 ± 31 ms, MEA of 66° (52/73), R‐AD of 215 (192‐222) ms, and R‐AD/AD‐R of 2.68 (2.25‐3.08).
Conclusions and Clinical Importance
Analyzing AD on 12‐lead electrocardiogram is helpful in differentiating the most common SVTs in dogs.
Idiopathic pericarditis (IP) and pericardial mesothelioma (PM) are causes of pericardial effusion in dogs. Pericardiectomy can be a definitive treatment in the case of idiopathic pericardial effusion ...or a short-term intervention for mesothelioma. The aim of the present study was to investigate which histopathologic parameters are correlated with clinical outcomes in a cohort of dogs that underwent pericardiectomy. The histopathological findings of 22 IPs and 5 PMs were compared with clinical and survival data and the immunohistochemical characterization of immune cells (CD3, CD79α, Iba1). In IP, the mesothelium was lost in 20 cases, reactive in 9, atypical in 3, and mesothelial papillary hyperplasia (MPH) was observed in 4 cases. Numerous macrophages were found in both IPs and PMs especially at the superficial layer of the pericardium. T lymphocytes were observed in mild to moderate numbers and were more numerous than B lymphocytes in both IPs and PMs. MPH was correlated with the quantity of lymphoplasmacytic infiltrate in the superficial layer, inversely related to the thickness of the pericardium, and associated with a longer overall survival. Pericardial fibrosis was present in 19 out of 22 IPs and in all mesotheliomas and was correlated with increased time from initial presentation and pericardiectomy and lymphoplasmacytic infiltrate in the deep zone. Pericardial thickness was correlated with the amount of lymphoplasmacytic and macrophagic infiltrate in the deep zone. Mesothelioma was associated with an increased number of pericardiocentesis procedures before pericardiectomy and with the presence of macrophages in the superficial pericardial layer, edema, fibrin, and hemorrhage. Disease-free interval and overall survival were significantly shorter in patients with mesothelioma compared with IP.
Neurally mediated syncope (NMS) is the clinical manifestation of the vasovagal reflex activation. Prognosis of this type of syncope is reported as "benign", mainly on the basis of the results of the ...Framingham study, in which the incidence of mortality, cardiovascular and cerebrovascular events did not differ from that of the control population. However, in this study NMS starting in young age and that starting in advanced age were investigated together, but some elements suggest that we are dealing with two different clinical entities, even if the efferent pathways of the reflex circuit appear to be the same. While it is largely accepted that NMS starting in young age is a manifestation of a non-pathological trait, some lines of evidence suggest that NMS starting in old age is the expression of a pathological process of the autonomic nervous system, up to now not well defined from the nosological point of view: (i) onset in old age per se, (ii) absence of triggers, which means "abnormal activation" (pathological) of the vasovagal reflex, (iii) frequent overlap with situational syncope, carotid sinus hypersensitivity, orthostatic or post-prandial hypotension and other dysautonomic symptoms, and (iiii) it appears to be the human homologue of a recently described syncope starting in dogs in advanced age; in other words, humans and dogs seem to suffer from the same disease. On the basis of these considerations, in future studies the prognostic significance of NMS starting in old age should be investigated separately. At present, the prognosis of NMS, in relation to hard events, remains undefined in the elderly.
Introduction
The aim of the study was to describe the electrocardiographic features of ventricular pre-excitation (VPE) patterns characterized by the presence of delta (δ) wave, short P-δQRS ...interval, wide δQRS complexes in dogs with right-sided accessory pathways.
Animals, materials and methods
Twenty-six dogs with a confirmed accessory pathways (AP) via electrophysiological mapping were included. All dogs underwent a complete physical examination, 12-lead ECG, thoracic radiography, echocardiographic examination and electrophysiologic mapping. The AP were located in the following regions: right anterior, right posteroseptal, right posterior. The following parameters were determined: P-δQRS interval, δQRS duration, δQRS axis, δQRS morphology, δ-wave polarity, Q-wave, R-wave, R’-wave, S-wave amplitude, and R/S ratio.
Results
In lead II, the median δQRS complex duration was 82.4 (IQR 7.2) and the median P-δQRS interval duration was 54.6 (IQR 4.2) msec. The median δQRS complex axis in the frontal plane was: + 68° (IQR 52.5) for right anterior APs, − 24 ° (IQR 24) for right postero-septal APs, − 43.5 ° (IQR 27.25) for right posterior APs (P = 0.007). In lead II, the polarity of the δ wave was positive in 5/5 right anterior APs and negative in 7/11 postero-septal APs and 8/10 in right posterior APs. In precordial leads of all dogs, R/S was
≤
1 in V1 and > 1 in all leads from V2 to V6.
Conclusion
Surface electrocardiogram can be used to distinguish right anterior APs from right posterior and right postero-septal ahead of an invasive electrophysiological study.
A 5-year-old English Bulldog was presented for acute onset of syncope and fatigue caused by sustained ventricular tachycardia with left bundle block morphology and inferior axis. This arrhythmia had ...the electrocardiographic features of a ventricular tachycardia arising from the right ventricular outflow tract (RVOT), as described in an experimental canine model and in people. Since a RVOT aneurysm was identified by echocardiography, a segmental form of arrhythmogenic right ventricular cardiomyopathy (ARVC) was suspected. Gross examination of the heart confirmed the bulging of the RVOT and histological examination of the ventricular myocardium revealed segmental involvement of the RVOT with transmural fibro-fatty degeneration. To the authors' knowledge, this is the first reported case of AVRC in an English Bulldog and the first example of segmental AVRC described in the dog.
To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block.
ECGs of 36 dogs with third-degree AV block and no ...identifiable structural heart diseases.
Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited.
A Ta wave was detectable in all dogs for at least 1 ECG lead. The Ta wave had negative polarity in leads I, II, III, and aVF and positive polarity in leads aVL and aVR, with a mean electrical axis of -114.26°. Mean duration and mean amplitude of the Ta wave in lead II were 140.2 milliseconds and -0.09 mV, respectively, with the ratio for the Ta-to-P wave duration of 2.3 and the ratio of Ta-to-P wave amplitude of -0.35. Significant correlations were found between the Ta wave duration and duration of the P-Ta interval, Ta wave amplitude and the ECG lead, Ta wave duration and body weight, and duration of the P-Ta interval and atrial rate. Measurements of the Ta wave were repeatable.
Measurements of the Ta wave in dogs with third-degree AV block were repeatable. The values for the Ta wave reported here can be used as reference values for dogs with AV conduction disturbances and an echocardiographically normal atrial size. Further studies are needed to validate these results in dogs with structural heart diseases.
Five dogs were presented to our institution for fatigue caused by an incessant supraventricular tachycardia. In all dogs, an ECG on admission showed a narrow QRS complex tachycardia with a median ...ventricular cycle length of 220 ms (range 180–360 ms), and a positive atrial depolarization identifiable in the ST segment following the previous QRS complex. There was a 1:1 atrioventricular conduction ratio in all but one dog, which presented with 2:1 atrioventricular block. Electrophysiologic studies identified the underlying arrhythmogenic mechanism as a right atrial macro-reentrant tachycardia with two distinct isthmic areas: right septal (RS) in three dogs and right atrial free wall (RAFW) in two dogs. Linear radiofrequency catheter ablation was performed during tachycardia in all dogs at the identified isthmic area, which acutely blocked the macroreentrant circuit. At 18-month follow-up, 3 dogs (1 with RAFW isthmus and 2 with RS isthmus) showed no recurrence of the arrhythmia on Holter monitoring. One dog with RS isthmus showed recurrence of the supraventricular tachycardia 15 days post-ablation, and 1 dog with RAFW isthmus presented with persistent atrial fibrillation 2 months post-ablation.
OBJECTIVE: To describe the use of contrast‐enhanced ultrasonography (CEUS) for the detection of active renal hemorrhage in a dog with spontaneous kidney rupture resulting in hemoperitoneum. CASE ...SUMMARY: A 9‐month‐old, sexually intact male Boxer dog presented for acute collapse, abdominal pain, and tachycardia. Physical examination findings were consistent with hypovolemia and acute abdomen. B‐mode ultrasonography revealed peritoneal effusion and a right kidney mass. Subsequently, a CEUS study was performed on the right kidney, which demonstrated active hemorrhage from that kidney resulting in both hemoretroperitoneum and hemoperitoneum. At exploratory surgery, ultrasonographic findings were confirmed and a right nephrectomy was performed. Histopathology demonstrated severe parenchymal alterations along with the presence of nematode larvae. Fecal and urine testing for the presence of parasitic ova were negative. Identification of the larvae was inconclusive. At 30 days postoperatively, repeat B‐mode ultrasound and clinicopathologic testing was unremarkable. The dog was alive at 1 year postsurgery with no ill effects. NEW OR UNIQUE INFORMATION PROVIDED: To the authors’ knowledge, this is the first report of CEUS for the detection of active hemorrhage from a kidney resulting in hemoretroperitoneum and hemoperitoneum in a dog. Although rare, the finding of nematode larvae within the renal parenchyma may have been the cause of kidney rupture. Importantly, surgical removal of the kidney was curative. Benign processes causing kidney rupture such as parasitic infestation should be considered in the working diagnosis as related to geographical location.
To evaluate the diagnostic value of an implantable loop recorder (ILR) in dogs with unexplained syncope.
Prospective case series.
12 dogs with recurrent unexplained syncope.
An ILR was surgically ...inserted in a pocket created in the subcutaneous tissues of the left hemithorax of each dog. The ILRs were programmed for manual and automatic activation, and event analysis and programming were performed at 3-month intervals and after each syncopal episode.
The ILR was manually activated in 7 of 12 dogs at least once within 45 to 218 days (median, 120 days) after implantation. Four dogs had syncopal episodes associated with sinus tachycardia followed by sinus bradycardia and asystolic pauses. Two dogs had ventricular tachycardia, and 1 dog had sinus node dysfunction with prolonged sinus arrest that coincided with loss of consciousness and falling. Four dogs had no additional syncopal episodes after implantation of the ILR. In the remaining dog, the owner was unable to activate the ILR during the only syncopal episode observed for that dog after ILR implantation. In all 12 dogs, analysis of ECG traces after automatic activation of recording revealed normal cardiac rhythms.
Data gained after manual activation of an ILR provided valuable diagnostic and prognostic information in almost all dogs with unexplained syncopal episodes by confirming or disproving an association between syncope and arrhythmias. However, detection of disturbances in cardiac rhythm after automatic activation did not appear to improve the diagnostic value for an ILR implanted in dogs.
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