Case 13
Primary clinician: Mark D. Kittleson, DVM, PhD, DipACVIM (Cardiology)
Signalment
1.5 year old female English bulldog weighing 18.6 kg ("Daisy")
Presenting Complaint Heart Murmur Syncope
History
Daisy was adopted about five months ago at which time the new owners knew she had been previously diagnosed with a heart murmur.
A couple months ago, Daisy had an episode in which the owner described as beginning with a choking-like action followed by Daisy falling into lateral recumbency. Daisy remained unconscious for about one minute without movement or defecation/urination.
After regaining consciousness, it took Daisy about a day to fully recover to her normal attitude.
A second episode occurred last week while Daisy was going down some stairs. The owner was following behind and tried to help her get off the stairs at which time her front legs buckled under her and she remained unconscious for less than one minute. After this episode, she seemed to perk up immediately after the episode and seemed
unaffected. During this episode, Daisy's tongue went white, her body was cold, and she urinated.
Daisy is fairly active and climbs a long set of stairs to the owner's work everyday without evidence of tiring. She is fed once a day.
Physical Examination
BARH; T=102.4; P=120; R=72; wt=18.6 Kg
Skin clean except for skin fold pyoderma on the nasal region.
There is a small skin mass in the intrascapular lesion.
Teeth clean, ears clean.
Well-fleshed and symmetrical.
Femoral pulse strong, jugular pulse can be seen about 1/3rd up the neck. A V/VI systolic murmur was ausculted at the left heart base.
Stertor was ausculted.
No abdominal abnormalities were palpated.
Mandibular, prescapular, and popliteal lymph nodes were all about 2 cm diameter.
Problems
V/VI systolic left basilar heart murmur Syncopal episodes
Case 13
Thoracic Radiographs DV
Right lateral
This is a fairly typical bulldog chest. although you might think Daisy would have a barrel chest, it's actually narrow on the DV, making the heart look larger than it really is. The diaphragm is pushed far forward, reducing the thoracic cavity space and making the cardiac silhouette look large than it is again. The mediastinum is wide (normal for a bulldog). All in all, pretty mcu impossible to say much about cardiac enlargement. Do you see any bony abnormalities?
Case 13
Electrocardiogram
There are six limb leads and one chest lead (V4 or CV6LU) recorded. The calibration signal is provided. The paper speed is 50 mm/second. \
Quiz
1. There is evidence of enlargement of which chamber?
Left ventricle Right ventricle Left atrium Right atrium
Correct Quiz Quiz
1. There is evidence of enlargement of which chamber?
Left ventricle Right ventricle Left atrium Right atrium Correct Quiz
Score: 100 %
Right!
1. It's right (ventricle).
Case 13
Echocardiograms
Right parasternal long-axis view
Electronic calipers are measuring the thickness of the right ventricular free wall (15 mm). RV - right ventricular cavity; LV - left ventricular cavity; LA - left atrial cavity; RA - right atrial cavity.
Right parasternal short-axis view at the ventricles
Right parasternal short-axis view at the base
The electronic calipers are measuring the orifice size of the pulmonic valve annulus, which is small. RVOT - right ventricular outflow tract; Ao - aorta; MPA - main pulmonary artery.
Quiz
1. The findings on this page are charactersitic of what congenital abnormality?
Principio del formulario
Tricuspid valve dysplasia with pulmonary hypertension Double chambered right ventricle
Pulmonary hypertension due to a right-to-left shunting PDA Pulmonic stenosis
Final del formulario Correct Quiz Quiz
1. The findings on this page are charactersitic of what congenital abnormality?
Tricuspid valve dysplasia with pulmonary hypertension Double chambered right ventricle
Pulmonary hypertension due to a right-to-left shunting PDA
Pulmonic stenosis
Correct Quiz
Score: 100 %
Palloose!And they say your record is spotted but it's obviously as clean as the pure driven snow.
1. Pulmonic stenosis it is and it's at least in part due to annular hypoplasia.
Case 13
Color Flow Doppler Echocardiograms
Right Parasternal Short-Axis View at the Base
This is the same view as the third echocardiogram on the previous page with the aorta in the middle and the right ventricular outflow tract and the pulmonary artery to the right of the aorta (where the color flow Doppler box is located). A color flow Doppler image has been added. This frame was recorded in systole.
Quiz
1. What does this color flow Doppler picture show?
Aliased flow into the main pulmonary artery Pulmonic insufficiency
Turbulent, high-velocity flow across a stenotic pulmonic valve Laminar flow
Correct Quiz Quiz
1. What does this color flow Doppler picture show?
Aliased flow into the main pulmonary artery Pulmonic insufficiency
Turbulent, high-velocity flow across a stenotic pulmonic valve Laminar flow
Correct Quiz
Score: 100 %
Up tight and out of sight!
1. This is high velocity, turbulent blood flow.
Case 13
Spectral Doppler (Continuous Wave)
This is a continuous wave Doppler tracing taken from the dog using a transesophageal probe while the dog was anesthetized. The probe is in the esophagus, dorsal to the heart and the flow is traveling toward the transducer. Hence, the signal is above the line. The continuous wave Doppler cursor has been placed across the right ventricular outflow tract and main pulmonary artery in the turbulent jet. The peak velocity (V) in systole is increased to 5.69 (5.7) meters/second which translates into the pressure gradient (PG) of 129 mm Hg.
There is 60-cycle interference on the ECG trace.
Quiz
1. How severe is this dog's disease?
Mild Moderate Severe
Actually it's normal
Correct Quiz Quiz
1. How severe is this dog's disease?
Mild Moderate
Severe
Actually it's normal Correct Quiz
Score: 100 %
Righteous, brother!
1. A pressure gradient in a dog with pulmonic stenosis over 80 mmHg is generally considered severe.
Case 13
Coronary Artery Echocardiograms
This is a transthoracic echocardiogram that shows one large coronary ostium (arrow). No other ostia could be identified. The ostium is abnormally positioned but appears to be originating from the right coronary sinus.
This is a transesophageal echocardiogram of the dilated main pulmonary artery (PA) showing a coronary artery coursing around the PA. This vessel could be traced back to its origin at the aorta where it again appeared that there was only one ostium. This vessel appeared to course behind the pulmonary artery, between it and the aorta.
At this point the vessel appears to divide.
Case 13
Coronary Artery Angiograms Aortic root injection
The catheter has been advanced from the right carotid artery into the proximal ascending aorta where an injection of a radioiodinated contrast agent has been made. Only one coronary ostium can be seen with all of the coronary branches originating from it. The left anterior descending (LAD) coronary artery is the largest and descends down the front of the heart. The right coronary (RC) artery is seen as the most dorsal artery in this plane and is immediately below the label. It is normal. The left circumflex (LCx) coronary artery is fed by a small branch that appears to course ventrally and then horizontally. It is immediately above the label.
The catheter tip has now been placed selectively in the right coronary ostium and an
injection of contrast agent made. All of the coronary artery branches fill simultaneously. The left anterior descending (LAD) coronary artery can again be seen originating from the right coronary ostium. The right coronary (RC) artery also originates from this ostium and is normal. The left circumflex coronary artery is fed by a small branch that appears to originate from the LAD and from a number of collateral vessels that also originate from the LAD. The upper small branch appears to wrap around a structure, which happens to be the area of the pulmonic valve or just ventral to it.
The only additional thing seen here is what appears to be a circle just caudal to the right coronary ostium. This frame was taken in systole so that the branch that feeds the left circumflex (LCx) coronary artery has moved dorsally (up) making it look like it connects to the right coronary (RC) artery. This is an illusion but does make it look like these arteries are encircling the pulmonic valve region. LAD - left anterior descending
Video clip of aortic root angiogram
Contrast agent was injected into the root of the aorta. Only one coronary ostium leading to a large coronary artery can be seen on the ventral border of the aortic root. The large artery is the left anterior descending coronary artery. Two smaller arteries can be seen coursing backward. The upper one is the right and the bottom one is the left circumflex. The left circumflex initially goes ventrally and then courses caudally. The bend it takes as it goes from coursing ventrally to coursing caudally occurs as it goes around the region of the pulmonic valve.
Video clip of a selective injection of contrast agent into the right coronary ostium
Contrast agent was injected selectively into the right coronary ostium (ventral aspect of aortic root). Similar to the aortic root injection, the contrast first flows into the large left anterior descending coronary artery. It can then be seen coursing around the pulmonic valve region (encircles it) to turn again into the left circumflex coronary artery (lower) and right coronary artery (upper). At the very end you can see contrast (faintly) coming back into the great cardiac vein, immediately above the right coronary artery.
©Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.
Case 13
Event Recorder
In order to determine if an arrhythmia was the cause of Daisy's syncopal events, an event recorder was placed on her. This device is an ECG recording device hooked up to wires and then electrodes which are adhesed to either side of the chest. The recording device is a continuous loop that records about 5 minutes of ECG continuously. For the first 5 minutes the tape (or other medium) is filled with the first 5 minutes of ECG. At 5 minutes and 1 second, the ECG is recorded over the first part of the previous recording. This goes on continuously. Daisy's owner was instructed to depress a button the device when he noticed her having another syncopal event. When he did this, the two minutes before the event was left intact and the device continued to record the ECG for another 3 minutes and then stopped. He did this and when the tape was analyzed there was no evidence of an
arrhythmia that could have caused the syncopal event. All that occurred was some sinus tachycardia right after the event.
Case 13 Diagnosis Quiz
1. What is your primary diagnosis?
Subaortic stenosis Pulmonic stenosis Ventricular septal defect
Normal heart
2. What is causing (or at least associated with) this abnormality?
Coronary artery anomaly Poor nutrition
Hypercalcemia Osteodendritis Correct Quiz
Quiz
1. What is your primary diagnosis?
Subaortic stenosis Pulmonic stenosis Ventricular septal defect Normal heart
2. What is causing (or at least associated with) this abnormality?
Coronary artery anomaly Poor nutrition
Hypercalcemia Osteodendritis Correct QuizScore: 100 %
Cool!
Case 13
Case Discussion
This dog had severe pulmonic stenosis. You should note that the chest radiographs from this dog were not very helpful. This was primarily because of this dog's chest configuration.
Bulldog chests are always difficult to interpret.
The ECG from this dog was typical of severe right ventricular enlargement. There were deep S waves in leads I, II, and aVF. There was also a very deep S wave in lead V4. You should have also noted in lead II that the P waves were too wide (0.05 seconds) and were notched.
These are typical findings for a dog with left atrial enlargement. Of course, this dog did not have left atrial enlargement so this is a false positive finding. The P wave will also become
wider when the intraatrial conduction system is disrupted. This may explain this finding in this dog.
The echocardiogram from this dog showed that the pulmonic stenosis had at least an annular component since the annulus of the pulmonic valve was markedly reduced in size.
Upon careful examination of the pulmonic valve cusps, a valvular component could also be appreciated (this was not shown).
In many English bulldogs, pulmonic stenosis is of the subvalvular type and is either
associated with or caused by a particular type of coronary anomaly called an R2A coronary artery anomaly (shown below).
In this type of anomaly, there is only one coronary artery ostium that originates from the right coronary artery sinus (RAS). The right coronary artery courses normally back along the top of the right ventricle in the atrioventricular groove. The left coronary artery, instead of originating from the left coronary ostium also originates from the right coronary ostium. To get to the left ventricle it courses cranially over the front of the junction of the right
ventricular outflow tract and pulmonary artery, right at or just below the pulmonic valve region. Immediately in this region is where the stenosis occurs. In "Daisy" the coronary ostium appeared to be similarly placed as in the above diagram. However, it appeared to course between the pulmonary artery and the aorta.
In the past, we have observed sudden death when we tried to do balloon valvuloplasty on English bulldogs with an R2A type of coronary artery anomaly. At postmortem exam, we found that the left coronary artery had been avulsed off of its origin resulting in acute loss of blood supply to the left ventricle. In daisy's case we were as concerned with that happening although we were not 100% sure that we could correctly determine the course of the
coronary arteries. However, even if the left coronary artery went between the pulmonary artery and the aorta, we presumed that inflation of a balloon in this region would cause cessation of coronary flow during the time of balloon inflation. This could also result in catastrophic complications. Consequently, it was decided not to perform balloon valvuloplasty.
The owners primary complaint was the syncopal events the dog was experiencing. The usual rule-outs in this type of dog with this type of disease are a tachyarrhythmia, a bradyarrhythmia, and vasodilation. The tachyarrhythmia could be a supraventricular or a ventricular tachycardia due to the dog's cardiac disease. A bradyarrhythmia could occur secondary to right ventricular mechanoreceptor stimulation and reflex stimulation of vagal efferents to the heart during excitement or with exercise when the right ventricular pressure increased further as the right heart tried to pump more blood. Similarly, mechanoreceptor stimulation could produce a reflex increase in vagal tone to the systemic arterioles resulting in acute vasodilation leading to systemic hypotension. The event recorder showed no arrhythmia during a syncopal episode and so an arrhythmia was ruled out. Consequently, it could be assumed that Daisy was having vasodepressor syncope in which she had acute vasodilation resulting in severe hypotension leading to syncope. The only problem with this theory is that her events were not precipitated by exercise or excitement.
Follow-Up
No treatment was initially prescribed and Daisy was sent home. I talked to the owner again about 6 weeks after her hospitalization. During that time, Daisy had only two more syncopal events. The first one occurred when she was outside in the back yard on a hill where she passed out. The owner said she literally rolled over 3 or 4 times down the hill on to the deck.
She wasn't unconscious very long and recovered quickly. The last one, however, was a different story. That time he was talking to his neighbor in the house when she suddenly fell over. Again, she was white. Her eyes were open but she did not respond. She urinated and defecated during the event. He estimated that the event lasted 3 to 5 minutes. Owners tend to exaggerate this time since it seems so long to them. However, this was at least the fourth event this owner had witnessed and regardless of its true length, it was clearly much longer than the previous events. After this episode, Daisy did not bounce right back. He had to carry her for a while and she did not seem right for a couple of days afterward. He took her in to his veterinarian who noted that the heart rhythm was normal on auscultation. The other observation the owner had was that the other three episodes were preceded by a "gagging"
sound and this one was not. This observation brought one more rule-out into the picture - stimulation of vagal afferents in the pharynx. Consequently, I decided to have a surgeon examine her pharynx to see if there were any particular problems that might be surgically correctable before attempting to treat her medically.
Daisy was examined by our soft tissue surgeons and found to have an elongated soft palate, stenotic nares, and everted saccules. She underwent surgery to correct these abnormalities.
Only one everted saccule was surgically corrected. At the time of the last update (four months following the procedure) she was doing very well and had not had another syncopal event.
