WHATíS NEW IN VETERINARY CARDIOLOGY
By Larry Tilley, D.V.M.
Veterinary cardiology is unique because there is a vast array of equipment to assist in a diagnosis. It is also important to recognize that cardiac disorders are quite common I both the dog and cat. The cardiac diseases that are present include congenital heat defects and also acquired cardiac disease. The small canine breeds are quite prone to diseases of the mitral valve which have an effect on left-sided heart function. Large breeds are quite prone to cardiomyopathy (a heart-muscle disorder). Both of these conditions can lead to eventual left-sided heart failure. This can result in breathing problems, exercise intolerance, and even fainting. Cats are quite prone to various forms of cardiomyopathy, especially one abnormality that causes a thickening of the heart muscle.
The heart is a dynamic structure with electrical phenomena that can be measured. The rapidly developing technology available in veterinary cardiology makes analyzing the heart easier for veterinarians. The following is an update and current overview of just some of the recent advances in veterinary cardiology:
The eletrocardiogrm (ECG) is a test used to assess the condition of the heart. The ECG is used mainly to evaluate the status of the heartís conduction system. The machine which records this electrical activity is called an electrocardiograph. An electrocardiogram is indicated for the following reasons:
1) An abnormally slow or fast heart rate on listening to the heart;
2) An irregular rhythm detected on listening to the heart or feeling the pulses;
3) Signs of heart diseases such as coughing, fluid retention, exercise intolerance, and fainting;
4) and before surgical procedures, especially in older animals.
Performing an electrocardiogram is quite simple. A number of electrical wires are attached to the petís skin. The electrocardiograph simply detects electrical activity from the petís heart. The procedure takes no longer than five minutes.
Echiocardiography is a non-invasive procedure (there is no discomfort and no need to give anesthesia) that allows the cardiologist to view the heart and determine structure and function. New machines now have computerized cardiac programs that allow the entering of the cardiac measurements such as the wall thickness, the size of the chamber, and the motion of the actual valves. These machines can also measure the velocity and direction of blood flow through the heart and great vessels. The majority of the specialists in specialty practices have this equipment.
Measuring Blood Pressure
Hypertension is common in man, but this condition wasnít always considered a possibility in dogs and cats. But, studies show that up to 40% of cats older than 12 years of age have hypertension. The blood pressure should be evaluated for animals with heart enlargement, animals with kidney disease, and especially animals with acute visual problems (blindness). The procedure for recording blood pressure is quite easy and involves no special restraint or anesthesia.
Pacemakers in Veterinary Medicine
Yes, pacemakers can be done in the dog and cat. Just last year, I implanted pacemakers in two dogs from Albuquerque that had fainting episodes. The pacemakers were donated and we were able to do this surgical procedure without having the high cost often present I the human field. A pacemaker consists of two major components: the pulse generator and the electrode wire. The pulse generator is a small battery-operated device that sends out pulse signals and takes over the work of the heartís own electrical circuit system. It is connected to the heart by a special electrode wire. A pacemaker is indicated if the heartbeat is very slow, irregular, or very fast. Pacemakers have now been used for years in veterinary medicine.
With the availability of a phone line, computer an a fax machine, the veterinary practitioner can have a cardiologist or any specialist, literally thousands of miles away, in his/her practice to diagnose animals in heart failure and recommend drugs and dosages. By using e-mail and the fax machine, the doctor can transmit ECG data to get a diagnosis an therapy. Veterinary schools and veterinarians are now focusing on prevention as well as new therapeutic measures for heat disease. With telemedicine, veterinarians are now constantly adapting what is successful in the human field and applying the same concepts in animals.
New Advances in Cardiac Sugery?
Animals with congenital valve abnormalities may benefit from surgery or actually a new technique called balloon valvuloplasty. The most common cardiac defect that can be corrected in veterinary medicine is called PDA, which is an abnormal connection between two of the large vessels, the aorta and pulmonary artery. A number of these procedures are done on a yearly basis. A new procedure for treatment of valve obstruction is passing a balloon catheter into a vessel and to then position the balloon over the abnormal valve. The balloon is then inflated to break down the stricture. This non-surgical procedure has been quite successful so far, and many universities and referral hospitals are now offering this technique.
Recent Advances in Continuing Education
Continuing education is a major focus of my life. The best way to learn about the heart is to have a patient on the exam table with a cardiologist standing next to you. CD-ROM technology offers the next best method of teaching. CD-ROM simulated cardiology clinics lead the user through various cases. You an actually see the animal fainting and hear the sounds of the heart as you learn about heart disease. Studies show that the level of retention of knowledge is 70% for CD technology versus 5% from an actual lecture. I have produced three CD-ROM cardiology programs and a CD-ROM internal medicine textbook. Here in New Mexico, we are quite fortunate to have veterinarians providing the highest quality of veterinary care. Veterinarians I New Mexico are constantly acquiring the new technology available, and attending numerous continuing education seminars throughout the county. I recognized a long time ago that keeping up with all the advances in veterinary medicine can be frustrating for the practitioners. You sometimes almost feel guilty about going home in the evening. The biggest impact of new technology and the increased population of specialists is that the profession is able to offer better medicine; animals are living longer; pet owners are happier; and the practitioner can go home with a smile on his/her face.
Dr. Larry Tilley is a veterinarian and the owner of VetMed, a veterinary specialty consulting service based in Santa Fe.
This article first appeared in the Winter/Spring 1997 issue.
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