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STRAIGHT TALK FROM A CARDIOLOGIST

Dr. Michael B. Fowler, M.B., F.R.C.P
Stanford Heart Transplant Clinic
Stanford Medical School


Few patients with heart failure fully appreciate the pivotal role that sodium restriction plays in the severity of their symptoms, ability to avoid hospitalization, sleep without a sensation of drowning, or even survive. Those individuals who understand the role of sodium, and who adjust their diets to control their sodium intake at consistently low levels frequently experience a dramatic improvement in general well being.

I have known many patients whose heart failure symptoms were recurrent and so severe that they were advised to undergo heart transplantation, yet these same patients improved with sodium restriction to a degree that removed the requirement for heart transplantation. One individual in particular designed his own diet, one that brought his daily sodium intake to under 500 mg, and had a profound impact on his ability to survive without overt heart failure symptoms. His diet change helped him avoid being wait listed for heart transplantation.

Heart failure, from any cause, is characterized by symptoms that result from retention of sodium (salt is the biggest culprit). Sodium is used by the body to regulate fluid status. In all circumstances that lead to heart failure, sodium (and with it water) tends to be retained. In some individuals this may only be apparent at the time of additional stress to the heart. These stresses may include lack of blood carrying oxygen - leading to angina; change in heart rhythm; intercurrent illnesses, such as flu; or when the dietary sodium intake is especially high - such as with pizza.

The majority of individuals with heart failure (and many with hypertension) have to combat a constant tendency to retain sodium. Those individuals are generally treated with diuretic drugs. Commonly used diuretics are furosemide (Lasix), bumetanide (Bumex), and (Demadex), or in some patients who are allergic to the sulphydryl group in other diuretics edecrin acid (edecrin). Other individuals, such as those diagnosed with hypertension, are given a less potent diuretic (usually of the thiazide group).

All diuretics (or 'water pills') work by increasing the amount of sodium removed from the blood stream by the kidneys. This causes an increase in the volume of urine causing the excess sodium (salt) and water, which characterizes heart failure, to be removed. Most diuretics also cause potassium to be lost, an undesirable side effect often requiring potassium supplementation and/or the use of special potassium retaining diuretics spironalactone (aldosterone) or triamterene.

The amount of sodium loss achieved by a diuretic is largely dependent on the dose of the drug and how often it is taken. The required dose of diuretics is strongly influenced by the dietary sodium intake, although an individual's diuretic requirement in heart failure also varies widely depending on other factors including the tendency to retain sodium, and the individual sensitivity to the actual diuretics (drugs to remove sodium) being given.

It follows that restricting sodium to a constant low level of ingestion is a crucial component to finding and maintaining the correct dose and type of diuretics. Too high a dose of diuretics will have a patient susceptible to dehydration and light headedness particularly when the dietary sodium intake falls. More common a problem is that even high dose diuretics may be incapable of removing all the sodium ingested by an individual who does not keep to a carefully regulated and restricted sodium intake. This will result in recurrent episodes of salt and water retention resulting in excess breathlessness, or abdominal bloating and possible ankle swelling.

Conversely individuals who remove all "added sodium" from their diet, added by them or "others" during food processing, will provide the best possible environment to achieve the maximal improvement in symptoms and reduced risk of hospitalization that can be achieved with the correct dose of diuretics. These individuals will also create the clinical stability that is required to achieve the correct doses of other drugs, especially ACE inhibitors and beta-blockers required to exert the maximal favorable impact on the natural history of the condition of heart failure.

Symptoms & Adverse Effects of Sodium in Heart Failure
  1. Unable to breathe
  2. Bloating (fluid weight gain)
  3. Short of breath lying flat
  4. Waking in the night short of breath
  5. Having to sleep with extra pillows
  6. Abdominal bloating
  7. Ankle swelling
  8. Increased diuretic requirements
  9. Loss of potassium
  10. "Refractory" sodium retention
  11. Thirst
  12. Excess water drinking
  13. Low concentration of sodium in the blood
Benefits of Low Sodium
  1. Stable diuretic dose requirement
  2. Stable potassium replacement
  3. Allows optimal dose of other drugs which improves the risk of major adverse events
  4. Usually results in reduced fat intake (important especially in coronary artery disease or in overweight individuals)
Patients with heart failure, especially those who have been treated with diuretics (drugs which work by removing sodium from the body), or who take diuretics every day will benefit from restricting their sodium to the few milligrams per day found in food consisting of/or prepared from fresh ingredients. Little hardship need follow this important aspect of living well and as long as possible with heart failure.

Some patients who have previously had the dose of diuretics increased to deal with recurrent episodes of decompensated heart failure may become dehydrated and run the risk of reduced kidney function or lightheaded spells (or even blackouts) if they abruptly reduce their sodium intake from previously high levels. Patients should discuss these issues with their physicians before making large changes to their sodium intake and ensure they report adverse changes to their doctor. In general be creative with your cooking ideas and have fun, even if you have a "salt tooth," you can lean to prefer low-sodium food just by eating it. Within 2 months your tastes should adjust and you won't miss the salt.

Low-sodium foods taste delicious! Removing salt can bring out flavors that may have been hidden by the salt.

About Dr. Michael B. Fowler
Dr. Fowler is a leading researcher in the medical field of congestive heart failure (CHF). He has been with Stanford Heart Transplant Clinic since 1982 where he has been involved in research leading to the use of new beta-blockers such as carvedilol (Coreg), and low-sodium diets to help improve the quality of life, as well as the survival rate for those who develop congestive heart failure.





Fowler on CHF