The noise stopped me in my tracks. It had no business being there. This visit was supposed to be a routine wellness exam for a 34-year-old woman who felt fine. She was here in my office only at the insistence of her mother, who was concerned that her daughter hadn't been paying sufficient attention to her health. The patient, a Hollywood talent agent, had a thoroughly unremarkable medical history.
I leaned over her, resting my stethoscope on the front of her chest, and listened to the lub-dub of her heart, thumping its reassuring, monotonous way up into my ears. But I heard something else: a mechanical whooshing that was pulsing in rhythm with her heartbeat. I listened some more. The sound was distinct from her heartbeat, of that I was certain. It sat somewhere in the background, like the thrum of a ship's engines below decks. Amid familiar heart tones and breath sounds, this alien, machinelike noise had emerged and claimed my attention.
In 20 years of internal medicine practice, I have listened to a lot of chests and picked my way through a host of murmurs, rubs, honks, and whistles—some musical, some coarse, some loud, some soft. A handful among the cacophony were trivial, but others were the acoustic signatures of serious abnormalities that demand attention. In the latter category are so-called machinery murmurs, whose rumbling noises can be heard throughout the contractions and relaxations of each heartbeat. They are heard mostly in association with congenital heart problems, such as those that occur in "blue babies."
In rare cases, machinery murmurs can be a complication of knife wounds to the chest.
I looked at my patient. She wasn't blue, and she hadn't been stabbed. Although I didn't have a name for it, I knew the sound was out of place. Straightening back up, the head of my stethoscope poised in midair, I pondered where to go next. Were my ears playing tricks on me? It was not a rhetorical question.
Several weeks earlier I had stepped out of my morning shower with what I thought was water trapped in my left ear. Vigorously shaking my head didn't help, and I resigned myself to letting the water evaporate, confident that it would soon clear. But it didn't. Making rounds at the hospital, I tried to respond to an overhead page. I picked up the phone and found as I pushed one button after another that all the lines were dead. Then it struck me. I switched the telephone handset to the other ear and, sure enough, there was the dial tone—on every line. I'd gone deaf in my left ear. Little more than two hours had passed since I'd stepped into the shower with two good ears.
Tests revealed that I had a sensorineural hearing loss in the left ear, which meant that the nerve conducting electrical impulses from my ear to my brain had died that Sunday morning. Why? It could have been caused by a virus with a taste for nerve tissue, or perhaps a microvascular event, a tiny stroke, had damaged my acoustic nerve. I had no way of knowing. Neither did anyone else. There is no treatment or therapy.
My home, my children's voices, the highway—everything sounded different to me. I had to relearn my world, including my professional world. Although I continued to work, I felt uncertain of my abilities. I had lost hearing in my left ear, but the hearing in my right ear was fine. Still, I triple-checked everything I did. Over two decades I had built a reputation for being a solid diagnostician. Was I about to see that slip away?
Now, weeks later, with my hearing half gone, I stood in front of my patient, stethoscope in hand, wondering how a healthy young woman could be walking around with what sounded like a machinery murmur in her heart. I examined her electrocardiogram and saw that it was textbook normal. Things were not adding up.
When I mentioned the noise to her, to my surprise she said, "Oh, that? That's been there since I was a teenager. My old doctor heard it, and he sent me to see a cardiologist about 10 years ago. The heart guy listened to me and told me not to worry about it."
"Really?" I thought. Reassuring, I suppose, but hardly satisfying.
I decided to listen again, to see what I had missed the first time around. With my stethoscope back on her chest, I heard that aberrant noise once more, then moved my stethoscope around to her back. It didn't take long to find it. The machinery noise was there too. Some heart murmurs can radiate to the back, but was this noise coming from her heart? I started walking my stethoscope, lifting it and replacing it, inch by inch, up her spine. The noise not only followed the movement but grew louder.
By the time I reached the back of her neck, the pulsing whoosh had become intense. I focused on the carotid arteries, two large conduits lying on either side of the throat that carry blood up to the brain. I considered the possibility that a blockage in one of these big vessels was causing a bruit, the noise made by a turbulent flow in a narrowed vessel. From experience I knew that carotid bruits don't often transmit sound from the neck down into the chest, but stranger things have happened. I listened carefully over each carotid. The intensity of the sound there was softer, much softer. No bruits. Her carotids were "clean" and not the source of the noise. I had just one more place left to listen.
Although I felt a little foolish doing so, I placed my stethoscope on the back of her skull, just behind her right ear and—bingo! It was a roar now, louder than anywhere else I had heard it in her body. A relentless, throaty whoosh emanated from beneath the occipital bone. This was the source of the noise, the one that didn't belong in her chest. It wasn't in her chest. It was here, inside her skull. The sound was so intense that it vibrated along the skeleton and transmitted itself into the chest, where the noise had been misinterpreted in the past as an innocent murmur. But there was nothing innocent about this noise.
I understood immediately what I was hearing and knew that I was listening to a killer. My patient had been walking around for decades with an arteriovenous malformation in her head.
Present at or near birth, arteriovenous malformations, or AVMs, are complex tangles of abnormal arteries and veins that can be located in almost any organ in the body, including the brain. Two things need to be understood about these vascular mutants. First, the movement of blood through an AVM is a rapid, turbulent, high-volume flow. Like rapids racing through a narrow canyon, the rush can be noisy.
Second, the walls of the vessels in these tangles are not normal. They have a defective layer and are prone to rupture and bleed. A hemorrhage from one of them in the brain can be devastating, causing severe and sometimes fatal strokes. In fact, stroke is the most common way that AVMs are discovered. While most brain AVMs don't bleed (about one in 1,000 people have one), there is no way to predict whether one will remain quiescent or rupture, destroying a life.
After sharing my suspicions with my patient, I immediately arranged for brain imaging, and she was in the MRI scanner the following morning. By noon I was looking at pictures of an AVM about the size of a walnut on the surface of her right cerebral cortex. I referred her on an urgent basis to a local academic center that does cutting-edge neurovascular research.
Two days later the neuroradiologists took her into their interventional lab, where they threaded a catheter, a thin flexible tube, up into the vessel feeding blood to the malformed network. It was critical that they position the catheter so that it was aimed only at the feeder vessel and not at any vessels supplying blood to normal brain tissue.
Once the catheter was positioned properly, a metallic coil was threaded into the feeder vessel, causing it to clot off. That was it. With the blood supply eliminated, the malformation was now just a tangle of empty vessels. As if the pin had been put back into a grenade, the killer had been rendered harmless. The patient went home that day.
Afterward she went on feeling just as well as she did on her first visit to me. Coming on the heels of my confidence-shaking hearing loss, her case proved a lesson about what it takes to be an effective diagnostician. It's not about having the keenest hearing, the sharpest vision, or the most sensitive fingers. It's about a curiosity that, when coupled with persistence, will do more to unravel a diagnostic conundrum than even the most expensive stethoscope.
H. Lee Kagan is an internist in Los Angeles. The cases described in Vital Signs are true stories, but the authors have changed some details about the patients to protect their privacy.
