Clinical Activities & Procedures
Physical Examination and Consultation
All examinations begin with the owner and animal in an examination room. First, the reason for the animal's visit, the history of the problem, and any previous evaluation or treatment is discussed. This is followed by a cardiac physical examination. The examination may include examination of the animal's mouth or eye membrane color, the large veins in the neck, the palpable heartbeat on the chest, and the arterial pulse, but always includes listening carefully to the heart and lungs. In addition to a resident-in-training and/or faculty doctor, 4th (final) year veterinary students are involved in every examination as part of their 2 week clinical training in cardiology. Following the examination, the probable diagnosis or most common possibilities are discussed, as well as the choices of additional recommended diagnostic techniques. Most evaluations can be completed in a few hours, after which a second meeting with the owner is held to discuss the findings and recommendations. Any questions from an owner or agent are discussed, and a written summary of findings and recommendations are provided. If the animal was referred by a primary care veterinarian, they are notified of the visit by telephone as well as a written summary of the examination results and treatment recommendations. One of our goals is to involve the owner in all discussions and decisions and to help educate them and have them understand all available options for treatment.
Blood Pressure Recording
Although arterial hypertension (high blood pressure) is not as common in animals as it is in humans, arterial pressure is measured routinely in many patients, especially those with other medical conditions known to be associated with high blood pressure (kidney disease, thyroid or adrenal gland disease, etc.), and in patients where high blood pressure may be suspected from an echocardiogram. The technique is very similar to that used in humans, involving an inflatable cuff placed around a limb and a monitor to detect flow in the artery within the cuff. Proper technique is critical and the patient must be as relaxed as possible. Dogs and cats with high blood pressure may be prescribed some of the same blood pressure lowering drugs that are used in humans.
Cardiac Catheterization and Intervention
In some patients it may be necessary to perform more invasive procedures for diagnosis and treatment of a heart condition. In the cardiac catheterization & intervention lab, catheters are inserted into blood vessels of anesthetized patients and are guided through the heart using fluoroscopic radiography.
Pressure and other data may be recorded in the various heart chambers and adjacent blood vessels, and contrast dye visible to the fluoroscope can be injected to outline the heart chambers and large blood vessels to identify defects. Shown below is a left ventricular angiogram from a normal dog and one from a young dog with a small hole between the two ventricular chambers (ventricular septal defect or VSD). Most animals come to the cath lab, however, for one of 3 common interventional procedures performed to correct or improve certain specific heart conditions:
- Catheter Closure of a Congenital Septal-type Defect
- Balloon Dilation of Obstructive Defects
- Cardiac Pacemaker Implantation for Slow Heart Beats
A resting electrocardiogram (ECG or EKG) is performed on many animals with heart disease. The ECG is a graphic recording of electrical potentials that develop on the external surface of the body as a result of the electrical activity of the heart. Every heart beat begins with an electrical signal that is conducted through the heart and stimulated the heart muscle to contract. Because the normal pattern of initiation and conduction through the heart is consistent from beat to beat, the normal pattern on the body surface is also consistent. The ECG is used primarily to evaluate and identify the electrical heart rhythm and to identify abnormal beats (arrhythmias) or abnormally conducted beats (heart block, bundle branch block). It is the only way to rapidly identify such electrical abnormalities, which may cause an abnormally rapid, slow, or irregular heart beat and pulse.
In some patients, symptoms may be intermittent, or an abnormal heart rhythm (arrhythmia) may occur at irregular intervals. To better correlate an arrhythmia to reported symptoms, a continuous loop-type recorder may be used. The recorder (shown at left) is attached to electrodes on the animal and continuous senses a loop of the ECG. When the suspected symptom is observed, the owner presses the Record button and the device digitally captures several minutes of the ECG for subsequent examination. In other patients, it may be important to assess the frequency and severity of an arrhythmia throughout the day. In these cases, a continuous ambulatory ECG recorder (Holter monitor) is used to digitally capture the ECG for 24 to 48 hours. The system is attached to the animal as shown below, and the pet is sent home. At the completion of the recording, the owner mails the vest and recorder back for analysis. The ECG stored on a small flash memory card in the recorder is transferred to a computer for analysis. Computer software is used to evaluate the recording and provide a summary of heart rate and the type and frequency of any abnormal beats.
Echocardiography (Ultrasound Imaging)
An echocardiogram (cardiac ultrasound or sonogram) is a sonar image of the heart and adjacent large blood vessels (great vessels). It is the principal non-invasive technique that allows a cardiologist to directly examine the anatomy and mechanical function of the heart. In most small animals, the examination is performed with the pet lying on a padded table that allows the imaging transducer to be directed upward from below the table. In large animals (horses, etc.) the examination is performed with the animal standing. Most animals can be examined with no or only very mild sedation, and there is no discomfort associated with the examination. The two-dimensional (2D) image allows a subjective evaluation of the walls, chambers, and valves, as well as the measurement of specific dimensions (chamber size, wall thickness) and indexes of the function of the ventricular chambers. The color Doppler image shows the direction and speed of blood flow throughout the heart and great vessels, and is very sensitive for identifying leaks in the 4 heart valves (see example below), abnormal movement of blood between the left and right sides of the heart, and obstructions to normal blood flow.
The UC Davis Cardiovascular Surgery Program was started in 2008 under the leadership of Dr Leigh Griffiths. Open heart surgery has been offered in veterinary medicine for approximately 20 years. Although many of the procedures have been shown to be curative in dogs, the relatively high risk associated with the procedure has hindered open heart surgery from becoming a routine procedure in veterinary medicine. We believe that no fundamental reason exists which would prevent open heart surgery from becoming as successful in dogs as it currently is in humans. The risks associated with open heart surgery in dogs are largely due to the relative inexperience of open heart surgery teams, and low case numbers performed in veterinary open heart surgery programs. It is well established from the literature in human patients, that with case numbers below 100-200 per year, success rates drop dramatically regardless of the skill or dedication of the open heart surgical team. In veterinary medicine, no institution has yet managed to perform more than 25 cases per year, and we believe that this alone likely has a direct bearing on current success rates. Thus, the long term goal of the UC Davis open heart surgical program is to gradually grow the program to the point where greater than 100 procedures per year can be accommodated, at which point the true success rate for open heart procedures in dogs will become evident. The infrastructure required to achieve this goal is substantial, and although the program is self funding, additional financial support from client donations will inevitably increase the rate at which program goals can be achieved. The donations section of the website details the giving opportunities available for your support of the program. We greatly appreciate all of our clients and donors efforts in supporting the program, and are committed to offering the potential for a brighter future to beloved dogs with heart disease.