Why Did Dick Cheney Develop Heart Failure?

Years ago, when I was indoctrinated as a fellow in to American College of Cardiology, Dick Cheney - then a former secretary of state, was the keynote speaker at our commencement ceremony. His keynote speech reflected on what it was like to watch his father die following a massive heart attack, comforted only by morphine, oxygen, bed rest. By then, Mr. Cheney, already a recipient of two bypass operations, made a point to thank the cardiovascular community for helping him.

Many years later, Mr. Cheney's complicated yet remarkable cardiovascular history reads like a social studies timeline - one with heart attacks, arrhythmias, blood clots, and now, congestive heart failure. (Of course, political spin meisters want to make sure we call it "fluid retention" rather than congestive heart failure, since "failure" is not an option when speaking of all things political).

Congestive heart failure is nothing more than an insufficient pumping of blood to meet the body's needs. As a result, the kidneys detect the decreased perfusion pressure and trigger the release of a cascade of hormones to increase the blood pressure to maintain perfusion of the tissues. Some of the hormones help retain fluid in the vascular space. If this fluid becomes too excessive, the fluid can spill into the lung resulting in a sensation of shortness of breath, usually worse when lying flat. One of the main drugs used to fool the kidneys to release the accumulated fluid are diuretics - the most common being furosemide (Lasix).

There are a number of things that may have contributed to the development of Mr. Cheney's heart failure. Since HIPAA knows no bounds with disclosing Mr. Cheney's heart history, we can use this opportunity to tease apart a few possibilities.

First, dead meat don't beat.

It doesn't help that Mr. Cheney has had many heart attacks in the past. With the progressive loss of healthy muscle cells to to the heavy lifting of contraction, the ejection fraction falls. At first, the heart compensates by recruiting other, non-injured segments of heart muscle to take up the slack, but with each successive heart attack, the reserve heart muscle dwindles. Lose enough muscle and the heart must rely on increasing the rate at which if contracts to increase output, but for hearts already with limited blood flow this might lead to futher shortage of oxygen to the heart muscleto When this happens, the heart rate kicks up just a bit to increase cardiac output. If it kicks up too much, the heart can outstrip it's own oxygen supply, resulting in additional injury to the heart. This is part of the reason medication that slow the heart rate (beta blockers) can be helpful adjuncts to preserving heart muscle function and slowing the progression of worstened heart failure.

Second, Mr. Cheney's atrial fibrillation.

The loss of coordinated pumping of the top chambers (atria) just before the lower pumping chambers (ventricles) can lead to 10-20% drop in effective cardiac output in some patients. The irregularity of the heart's rhythm while in atrial fibrillation also causes a loss of coordinated closing of the normally one-way valves that direct the flow of blood through the heart, further compromising the heart's pumping ability. Rate control of atrial fibrillation or the restoration of normal sinus rhythm in the heart are often important adjuncts to the treatment of atrial fibrillation.

Third, is the presence of Mr. Cheney's defibrillator.

Although we do not know for sure, it would not be surprising if many of Mr. Cheney's heart beats are being supplied by his defibrillator's pacemaker feature. Excessive pacing the right ventricle can cause a dis coordinated beating of the lower pumping chambers, resulting in a subtle, but real, fall in cardiac function during paced heart beats compared to beats that are not paced and normally conducted from the top to bottom heart chambers. At some point in the future, Mr. Cheney might benefit, in appropriate circumstances, by adding extra pacing wire to his existing defibrillator system (so-called biventricular pacing) to re-coordinate the contraction process of his heart chambers above and beyond that which can be achieved with medications alone.

Finally, might he have new portions of heart muscle lacking sufficient oxygen?

Not all coronary arteries that might be partially blocked can be revascularized during surgeries or angioplasties. As a result, some segments of heart muscle might not have enough blood flow to maintain proper function, yet have just enough to survive intact. Many of our medications help lower blood pressure to decrease the work the heart has to perform on a beat-to-beat basis, dilate blood vessels to improve coronary blood flow, and work to decrease the negative affects that excessive adrenaline-like compounds can have on the heart's remaining muscle cells. The very fact that his doctors did not feel further invasive procedures were necessary suggests Mr. Cheney's revacularization options are limited at this point.

So given his current setback, what should we expect regarding his prognosis?

Hard to know. But given what I know about the successful management of heart failure these days, I wouldn't count him out quite yet.

-Wes

Dick vs. Bill

Bill Clinton gets chest pain, hits the hospital, gets a few stents and, voilà, is back at work. A veritable poster child for stents. No doubt JNJ stock climbed on the news.

On the flip side today: Dick Cheney gets chest pain, hits the hospital, and (I'll bet) he stays a while.

What do you mean, Dr. Wes? Can't cardiologist magically fix everything? Do a cath! Give him a stent! Cardiology is so slam bam thank you ma'am, isn't it? Heck, he's got an ICD! He's the bionic man!

Cardiology is easy until it isn't.

No doubt Mr. Cheney has had impecable cardiovacular care. But despite that care, after three bypasses, a history of atrial fibrillation, deep venous thrombosis, a cardiomyopathy that requires a defibrillator or two, and scores of medications to stabilize the angina - you've suddenly got a tough case. One thing's for sure, a re-do bypass is pretty much out of the question (he probably has limited vascular conduits left to borrow).

For the treating cardiologists hoping for an obvious target to angioplasty, I wouldn't be surprised the "target" vessel will not be so obvious to determine after his angiogram today. Look for a nuclear scan tomorrow to figure which wall of his heart is affected (yes, Congress, he'll get one of those all-too-often ordered i-m-a-g-i-n-g studies!). Then look for either a risky angioplasty atempt to improve his symptoms or a (more appropriate) "tuning" of his medication regimen that will take time.

Bill vs. Dick: it's not about Democrats vs. Republicans. Rather, it's about the multifasceted care required of the same disease in two different patients that demonstrates nicely how health care for the individual will never be adequately managed through cookbook means.

-Wes

Cheney Has Afib Again

Just heard Vice President Dick Cheney had another arrhythmia - seems his atrial fibrillation has kicked in again. Since he's probably already on warfarin for his deep venous throboses, if he ate breakfast, they might administer Ibutilide to pharmachologically cardiovert him, or if he was without food for a sufficient period of time, consider cardioversion.

-Wes

Addendum 1300 CST - From politico.com: "Later this afternoon, the vice president will visit George Washington University Hospital for an outpatient procedure to restore his normal rhythm." Translation: He'll go to the hospital four hours after his last meal, be sedated, then have his defibrillator shock him back to normal rhythm, be monitored briefly, then return to the Vice Presidential mansion.

Vice President Cheney Gets Atrial Fibrillation

Well, it was bound to happen.

Take a man with significant coronary artery disease, a prior history of more than enough cardiac bypass operations, a weakened heart muscle that requires an automatic defibrillator, and a prior deep venous thrombosis (blood clot) in his leg and what to you get? An almost inevitable likelihood that he will develop a heart rhythm disturbance, too.

It seems Vice President Dick Cheney has suffered another common complication of a weakened heart: atrial fibrillation (afib).

Atrial fibrillation, characterized by an irregular heart rhythm disturbance in the upper chambers of the heart (atria), becomes symptomatic in a variety of ways:

• It can made the lower chambers of the heart (ventricles) race too fast
• It can cause an uncomfortable irregularity of the heart rhythm that can be disturbing to the individual (called "palpitations")
• It can reduce the efficiency of the pumping action of the heart, making people feel more short of breath or perhaps develop a slight cough (as the above article suggests)
• Or, commonly, it can be completely silent and not cause any symptoms.

But by far and away the main concern with afib in someone like Mr. Cheney is its propensity to increase his risk of stroke. Fortunately for Mr. Cheney, however, this risk was minimized because he was probably taking warfarin (Coumadin®) for treatment of the earlier blood clot in his leg. More ominously, however, the presence of his persistent cough may have represented congestive heart failure (where fluid backs up into the lungs) caused by the reduced efficiency of his heart to pump blood in this rhythm.

Afib that occurs in someone who already has an automatic defibrillator presents additional therapeutic challenges. In defibrillator patients, if afib causes the heart to race too fast, the heart rate could exceed the rate limit in the defibrillator's pre-programmed settings that helps it separate normal from abnormal heart rates. If the lower chamber (ventricular) rate exceeds this limit, then the device might detect the rhythm as excessive, charge, and deliver a shock to attempt to correct the rhythm. If the shock encompasses the upper chambers sufficiently, it can restore the atrial fibrillation rhythm back to normal. If not, the lower chambers can be driven progressively faster by the upper chambers again, and additional shocks could occur. To prevent this, rate control medications (such as beta blockers) are an important therapeutic strategy.

So what usually happens next?

First, the White House really doesn't want or need this publicity. So the most logical step will be to convert Mr. Cheney's heart rhythm back to normal quickly. Provided he is on adequate anticoagulation, this could be performed right away, often using his defibrillator to restore his atrial rhythm to normal (an "internal" cardioversion) while sedated. If unsuccessful, a more conventional "external" cardioversion could be performed by applying a jolt of electricity across his chest to reset the heart rhythm - much like one hits "Alt-Ctrl-Del" on a PC to reboot it (sorry, I digress...) If these methods are objectionable to Mr. Cheney, pharmachologic cardioversion with a medication like ibutilide (Corvert®) could also be attempted. By restoring the rhythm back to normal quickly, Mr. Cheney loses his star power before the media and gets back to his business as Vice President. And as predicted, it's already been done.

Long-term, there will be a discussion if Mr. Cheney should remain on an anti-arrhythmic medication. This will most likely depend on the severity of symptoms he experienced with his afib. If the symptoms were deemed severe enough, he might placed on a medication to attempt to maintain normal atrial rhythm. The efficacy of these anti-arrhythmic medications are at best about 60% effective long-term at maintaining normal rhythm after one year. On the other hand, if his symptoms were minimal, then a rate-control medication (i.e., beta blocker) coupled with anticoagulation might be the better long-term option.

It would seem unlikely that Mr. Cheney would opt for primary catheter ablation of his atrial fibrillation right now, especially given the inherent risks to the procedure, but should the medicines prove ineffective at managing his symptoms, or if his atrial fibrillation rates prove difficult to control with medications alone, then catheter ablation might offer some effective therapeutic options.

No matter how you cut it, though, this rhythm disturbance is likely to be a recurrent problem for Mr. Cheney. Hopefully, its effects can be minimized with close management and follow-up.

-Wes

Cheney to Have Routine Defibrillator Change

Vice President Dick Cheney is to have his implantable cardiac defibrillator (ICD) battery changed. Actually, he'll have the whole device changed, with the exception of the leads - those will likely be re-used. It is a common misconception by patients needing an ICD battery change that only the battery is changed. The battery is housed with the capacitors and computer logic circuitry in one hermetically-sealed titanium can, to which the leads that extend to the heart are attached with small fixation screws. As such, the whole defibrillator can will be exchanged in a smae-say procedure.

It has not been publically discussed if Vice President Cheney has had some heart failure, or how much he uses his device to pace his heart. No doubt his doctors have considered if his device should be upgraded to a biventricular pacing defibrillator which can "resynchronize" and re-coordinate the heart's muscular contraction to improve symptoms of heart failure, since this would be an ideal time to do so while his device is exposed.

But usually with politicians eager to make light of the circumstances at hand, they usually opt for as little as possible (i.e., get in and get out) to minimize possible risks and media exposure. Hopefully, this will be the right decision.

As to which device he'll receive? Since he's had Medtronic devices previously, it's likely he'll receive a Virtuoso ICD this time around (which is a dual-chamber ICD that can be interrogated wirelessly). If his doctors should decide to upgrade his device to a biventricular ICD, then it would likely be with a Concerto ICD.

-Wes

Dick Cheney's Deep Venous Thrombosis

Look for a pair of these compression stockings on Vice President Dick Cheney's leg soon. He was reportedly diagnosed with a deep venous thrombosis (DVT) today and will likely be treated with low molecular weight heparin (enoxaparin) shots twice daily for several days, followed by warfarin therapy. His family has been understandably tight-lipped about these details of his therapy.

Given his history of a weakened heart muscle from coronary artery disease, multiple vein harvestings to procure conduit for his bypasses (yes, he's had more than one), the repair of a popliteal artery aneurism behind his knee, coupled with his significant travel history, he really was a set-up for this occurence. If he was my patient, I'm not sure I'd just treat this for "a couple of months" with anticoagulants as the article suggests because I doubt his risk factors for DVT will subside. Others agree.

But spokeswoman Lea Anne McBride's statement that "He'll maintain his regular schedule. He feels fine." might not be such bad advice after all, since there have been some studies that have suggested that early ambulation speeds recovery in patients with DVT.

-Wes

Image credit.