A little lesson in cardiac physiology

If something doesn't seem right, trust your instincts.


A geriatric golden retriever presented to a colleague at my hospital for a sudden collapse.    Diagnostics confirmed that "Frank" was bleeding into his abdomen from an abnormal area of his spleen.  In medical terms, this condition is called hemoabdomen  About 2/3 of cases of hemoabdomen from a splenic mass are malignant, and about 1/3 can be a result of benign causes.  The most common malignancy is hemangiosarcoma, which is a very aggressive and poorly treatable form a cancer.  Read the above link if you would like more information.

My colleague and the clients discussed the only two reasonable options for Frank, which included either stabilization and emergency splenectomy (removal of the spleen to halt blood loss), or euthanasia.   His family elected to go forward with the emergency surgery.

Frank received a blood transfusion, and was stabilized for surgery.  His spleen was removed, and surgery was relatively uneventful.   After surgery, Frank transferred to the care of his primary daytime veterinarian.

Frank returned to us while I was on shift, about 36 hours later. In the interim, Frank had been sent home from the daytime clinic.  He was lethargic and refusing to eat, and his family had noted that his heart had been racing all day.  A recheck exam at his daytime clinic that same morning revealed a heart rate of 190 beats per minute.  Their primary care doctor discharged Frank, in hopes that it would 'go away,' per the clients recollection.  The family knew that something was not right, however did as they believe they were told and took Frank home.  The family monitored Frank's heart rate throughout the day, counting the number of beats in 15 seconds and multiplying by 4.  Around 2pm, they called their regular doctor with an update; the heart rate remained high.  They were instructed to wait at home.  Around 5pm, they called again and their daytime clinic recommended that they come immediately to see the emergency hospital.

As Frank entered the hospital, we immediately knew something was wrong.  His heart rate was a dangerous 220bpm, his pulses were poor, and his capillary refill time was prolonged. An IV catheter was placed, an an ECG immediately performed.  Frank was suffering from ventricular tachycardia, a dangerous rhythm which requires immediate treatment with anti-arryhthmics.  I immediately administered IV lidocaine, and consulted with the clients regarding Frank's current status.

The positive news is that ventricular beats and this type of arrhythmia is usually a transient complication of splenic surgery (in this case, ventricular tachycardia/VPCs have many, many other causes).  It is not understood why this occurs, but with treatment, ventricular rhythm disturbances commonly resolve within 24-48 hours after surgery.

One part of my job that I enjoy most is client education.  While Frank was receiving his initial lidocaine and a mini-blood panel was pending, I took the time to give the clients a brief lesson in cardiac physiology.

The heart consists of four chambers.  Two chambers are called the atria, which receive blood as it returns from the lungs and the body.  The other two chambers are the ventricules, which pump blood forward to the lungs, where oxygen is replenished, and to the body, which provides life-sustaining oxygen and removes wastes, such as carbon dioxide.  In order to organize this complicated organ, electrical activity in a normal heart starts in a specific location near the atria (called the sinoatrial node), and travels along a sophisticated pathway towards the ventricles.  This organized progression of electrical activity allows the heart to function as a unit, and for blood to move in an organized, forward fashion.  A normal ecg beat looks something like this:

wikimedia, public domain image

On the other hand, a ventricular beat originates in the ventricles, and is an unorganized, haphazard movement of electrical activity through the heart. A ventricular beat / rhythm looks something like this:

Borrowed from http://www.vetgo.com/cardio/concepts/concsect.php?sectionkey=5

Ventricular beats resulting in high heart rates become dangerous when the heart can no longer act as an effective pump, starving the body's tissues of life-sustaining oxygen.  Excessively high heart rates (>170-180bpm), poor pulses, pale gums, or weakness are all indications that anti-arrythmic therapy is needed.

The clients immediately knew that this heart rate was present 8 hours ago at their daytime clinic.  Frustrated, they asked me the question that we all were wondering --

 "Why wasn't this treated this morning? Why weren't we transferred to your care sooner?" The family looked at each other in exasperation. "We knew something wasn't right."

Unfortunately, I couldn't answer this question for them.  "I'm not sure," I said. "You'll have to talk to your veterinarian to ask them for specifics. I wasn't there, and I can't guess or assume at why specific medical decisions were made.  What I can tell you is that Frank needs to stay with us tonight for monitoring, lidocaine, and hopefully, he'll resolve this rhythm disturbance in 12-24 hours."


Morale of the story: If things don't seem right, get a second opinion.  Even the world's best doctor/veterinarian is never able to achieve 100% accuracy.  Second opinions save lives.