How COPD Affects the Heart

COPD stresses the cardiovascular system in several ways, increasing the heart's workload. One stress is increased heart rate, a response to two different situations: the intense anxiety often accompanying COPD, plus limits on the amount of oxygen the lungs can supply. And with severe chronic bronchitis, the heart's right side eventually weakens from contracting too hard for too long to pump blood through the lungs' constricted blood vessels.

COPD is also associated with more frequent premature ventricular contractions, often called PVCs, meaning that the heart's ventriclesthe two large chambers that propel blood to the lungs and to the rest of the bodyare contracting out of their normal sequence. In fact, severe COPD with hypoxia often changes the heart's normal electrical pattern even in people with no signs of heart disease.

These cardiovascular stresses can become proportionately more dangerous when the heart's oxygen supply has been reduced by a combination of COPD and ischemic heart disease. It can be hazardous, therefore, to withhold bronchodilator medication, or to use ineffective doses, through the misplaced fear of harmful cardiac side effects.

How COPD Medications Affect the Heart

Beta-receptor Stimulators: Because early bronchodilatorssuch as epinephrine and ephedrinenonselectively stimulate both alpha- and beta-receptors, they constrict blood vessels. This in turn increases blood pressure, heart rate, and the force of the heart's contractions. Because of this substantial increase in the heart's workload, these drugs are contraindicatedmeaning "should not be used"for patients with any kind of cardiovascular problem.

A better choice would be one of the newer beta-2 selective bronchodilators: terbutaline, salbutamol {albuterol), fenoterol, and metaproterenol. Not only do they add little to the heart's workload, but their vasodilatation side effect lowers blood pressure. This makes them a particularly effective and appropriate choice for the COPD patient with high blood pressure.

Theophyllines: Theophylline and its derivatives are well known both for their potent cardiovascular and central nervous system side effects, and for their narrow therapeutic range (there is little ground between the minimally effective and toxic levels). Both of these characteristics require particular caution if a theophylline preparation must be used to treat a COPD patient who has a cardiovascular problem.

Considerable care must be taken to ensure the lowest dose that is still effective for treatment so that cardiovascular side effects are avoided as much as possible. And because some heart conditionssuch as congestive heart failurecan dramatically slow the rate at which theophylline is removed, blood theophylline levels must be monitored even more frequently than usual in these patients. Toxic levels of theophylline are associated withamong other thingsrapid heart rate and arrhythmias.

Anticholinergic Agents: Western physicians have used anticholinergic drugs (atropine is the most well known) to treat asthma for about 200 years. Recent advances in understanding the effects of acetylcholine on the respiratory system have indicated that anticholinergic drugs can also help COPD patients. This is to the immense benefit of those who also suffer from cardiovascular problems.

The reason? Ipratropium bromidean atropine-like drugis a relatively specific bronchodilator. And it is remarkably free of side effects because it is poorly absorbed across the airways. Beyond this, combining ipratropium bromide along with a beta-2 agonist or theophylline sometimes permits reducing the other drug's dosage.

Steroids: Steroids can be important in treating some COPD patients. There is an unavoidable side effect, however, that is potentially dangerous in the presence of cardiovascular disease. Steroids increase the amount of salt retained in the body, causing water retention, which then raises blood pressure and increases the heart's workload. Of the oral steroids, methylprednisolone causes the least salt retention. Still, blood pressure must be regularly monitored, with careful adjustment of both diuretic and blood pressure-reducing medications.

For some patients, an aerosolized bronchodilator plus a steroid can be a reasonable alternative to a theophylline-plus-beta-stimulator combination, as long as blood pressure increases can be prevented.

So, when a patient has both COPD and a complicating cardiovascular problem, ipratropium bromide is a helpful bronchodilator and has no negative cardiovascular side effects. It can be augmented by an inhaled beta-2 selective drug such as salbutomol. For the COPD patient whose cardiac problemsuch as high blood pressuredoes not involve arrhythmias, theophylline can be added to the menu. If theophylline is contraindicated, but the other nonsteroid medications cannot open the airways adequately, then an oral steroid should be considered. In this case, special monitoring and therapeutic attention must be given to water retention and resulting blood pressure changes.

Regarding cardiac medication, beta-blockers should belong to the beta-1 selective group (metorpolol, atenolol) to avoid constricting the airways. Or a calcium blocker can be used. Avoid both cholinergic and anticholinergic drugs.