Treating Congestive Heart Failure

We talked yesterday about big, flabby, weak, stretched out of shape hearts.  These hearts can’t pump blood very efficiently.  The body demands that a certain amount of blood get pumped around every minute on a regular basis — that’s Cardiac Output.  If the heart can’t pump strongly enough to get that done with a normal number of beats per minute, the body may compensate by just having more beats per minute.  That only works up to a point, though.  It’s possible for the heart to beat so fast that it doesn’t have time to fill with blood between heart-beats.  Then you have a pulse deficit, meaning that when you feel the pulse inside the thigh, there aren’t as many pulses as there are heart-beats.  This is bad.  When you can still compensate for the heart’s weakness by increasing heart rate, and tightening down blood vessels to keep pressure up to vital organs, you feel okay. When this isn’t enough to maintain cardiac output, you are de-compensated.  Now you don’t feel good and you can’t tolerate exercise.  Eventually you don’t even have enough capacity to just sit there and breathe, much less eat, sleep comfortably, or exercise.

While there are many different medications available, there just a few basic approaches to helping a patient with a weak, flabby heart.  The analogy I like to use is that of an old horse pulling a loaded wagon up a hill.  When he is having trouble getting the wagon up and over, what can you do?

Step one: find a hill that’s not so steep, or go around.  For our heart patient, that means don’t overdo the exercise.  This is not like someone who has had a heart attack and is exercising to build up the remaining muscle.  With congestive heart failure, overdoing the exercise can put you in a crisis situation.  Another thing that makes the hill steep is being overweight.  Pounds of fat are miles of capillaries (microscopic blood vessels) and more work to do.  Lose the excess weight.

Step two: unload the wagon a little.  Here we’re talking about reducing the circulating volume of fluid.  The reason that you restrict salt intake is that sodium is a very active little molecule in retaining water in the body.  Excess sodium in the diet means excess water retained, which is more load in the wagon.  Diuretic drugs allow the kidneys to let more water escape the body in the urine, again dropping the circulating fluid volume.  If you’ve accumulated fluid in the lungs or abdomen, it helps pull some of that out, too.  Furosemide (a.k.a. Lasix, a.k.a. Salix) is one of the most commonly used diuretic drugs for patients with congestive heart failure.

Step three: quit putting the brakes on the wagon wheel.  When a weak heart allows blood pressure to fall, the body puts an inappropriate defense mechanism into play.  In the wild, animals just don’t live long enough to get this disease.  In the wild, if you’ve got low blood pressure, you’re either bleeding or in shock, with blood vessels dilated and not functioning properly.  The body’s response to this situation is to tighten those blood vessels to stop the leak.  This is a great idea if you’re bleeding.  On the other hand, if your blood pressure is low because your heart is weak, tightening those blood vessels just makes it harder for the weak heart to get its job done.  It’s a lot harder to pump fluid through a soda straw than through an open pipe.  Enalapril (a.k.a. Vasotec, a.k.a. Enacard) is a popular drug used to block this inappropriate body defense response.

Step four: whip the horse. Make that weak, flabby heart work harder.  Digoxin (derived from the older digitalis) has been a standby for many years.  This drug makes the weak muscle contract more forcefully, giving more output per beat, and a slower heart-rate.  Unfortunately, it has a narrow margin of safety.  The right dose makes your heart work more efficiently, but just a little too much makes it worse.  It must be dosed carefully, and tends to be used when the other approaches are not working.

There are certainly other ramifications to this disease, and many other drugs beside those mentioned.  There are also other types of heart disease to which this discussion does not apply. 

I’m no cardiologist.  When I have a patient with severe heart disease, we do our homework.  In addition to listening to his chest, we take X-rays to evaluate heart size and shape, and the condition of the lungs.  An echocardiogram (using the ultrasound) lets us see the heart pumping and valves functioning in real time, and lets us measure how well it is contracting.  Blood tests evaluate the extent of damage to other organ systems.  We also use the Idexx Telemedicine service (formerly Cardiopet).   The clips go on your pet, the telephone goes on the box, and the ECG (electrocardiogram) prints out in New Jersey.  There a specialist inteprets the ECG and the other data we have collected and consults with us on the best way to manage the patient.  Many pets with heart disease can have added years of a good quality of life.

2 thoughts on “Treating Congestive Heart Failure

  1. Jennifer says:

    I unfortunately lost my 14 year old Border Collie yesterday. I am heart broken. She was diagnosed with 2 leaking heart valves and an enlarged heart approx 6 months ago, and was on a great deal of medication. Other than a cough she was generally very well for her age and loved a walk, although she did have a bad infection in November due to fluid on the lungs accumulating, and again went back in December with similar symptoms which was put down to a possible allergic reacton. I was told after her original diagnosis with the leaking heart valves, that I should keep exercising her. We went for a walk yesterday morning and she started to bring up bile. I left her with my Husband and went to get the car. We got her home and to bed, thinking she just needed to rest. She was trying to stand up but would fall over, breathing quickly and heavily and not able to keep her head up all of the time. We could not get her to drink anything and she was foaming at the mouth. It was like she was trying to be ill but nothing was coming back although she seemed out of herself. We were about to contact a vet, but she passed away quickly and I am beside myself. I don’t think we could have got to a vet in time as it was a Saturday so it would have only been on call vets available and we are in a national lock down due to covid making things even more difficult. I am so sad and wish I had never took her out, as she may still be here. We went no further than her normal walk, maybe less as she was collected by car. I’m just trying to make sense of it all. Thank you.

    • Doc says:

      Hello, Jennifer,
      Patients with such advanced congestive heart failure are always at risk of decompensating. They are just on the edge of functional, and it doesn’t take much to put them over the edge. Keeping her in a cage for the rest of her life wouldn’t have been a great life. Taking her for a short walk on a leash shouldn’t be “dangerous”, but sometimes it’s just that last little extra that takes them over the edge. Don’t beat yourself up about this. It sounds likeyou gave her several months that she wouldn’t have had without your commitment and nursing care.

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