Today was stressful, exhausting, and incredibly rewarding.
A couple of weeks ago, my anesthesia partner and I performed our pre-op physical exam on our spay patient. While obtaining a heartrate, his forehead crinkled up and he got a look on his face. He stood up and said, "I think I hear a murmur. Listen and tell me what you think."
When I put my stethoscope to her chest, initially everything sounded perfectly normal. I didn't hear any murmur, but then, all of a sudden, there was a dropped beat. I waited until it had happened a few times before I assured myself that it was definitely a dropped beat and not a respiratory sinus arrhythmia. For the non-medical types in the audience, a RSA is when your heart speeds up and slows down while inhaling and exhaling. It's due to stimulation of the vagus nerve, which runs through the diaphragm. That's not what this was. The heart was not speeding up and slowing down, the rate was steady but every so often there would suddenly be a beat that went completely missing. And then during that time I thought I was hearing a third heart sound - likely what my partner was referring to as a murmur. But I didn't think it was a murmur, because it wasn't constantly present.
I told him that I definitely heard the third heart sound he was referring to, and that I thought she also had dropped beats. We called over a clinician and presented our findings to him. At this point I was thinking that she might have a 2nd degree AV block, but I didn't want to say it out loud because I'm a chickenshit about being wrong. The clinician, though, after listening to her, said he didn't hear anything abnormal. In his defense, it was very loud in that room and the dropped beats were very intermittent with no regular rhythm to them. It's very possible he didn't hear one in the 15 seconds that he listened to her chest. We figured we were just being hyperactive vet students and diagnosing zebras that are actually horses. In this case, an AV block instead of a simple respiratory sinus arrhythmia.
Today, in surgery, as soon as we got our patient hooked up to an ECG it was there, plain as day. Every 9-11 beats there was a P wave with no corresponding QRS. Dropped beats. A second degree AV block. BOOM! My partner and I high fived each other. We had totally diagnosed this just by listening to the patient's cardiac sounds two weeks prior and had a clinician tell us we were wrong. We should have listened to our gut, because we would have been more prepared for what happened next. During surgery her 2nd degree AV block degraded to a 3rd degree, with dropped beats every 2-3 heartbeats and VPCs all over the place (ventricular premature contractions are where the ventricles are desperately trying to compensate for a completely screwed up heart rate by initiating their own contractions instead of waiting for a signal from the SA node). She wound up on a lidocaine continuous rate infusion and she's staying in the intensive care unit overnight for monitoring.
As frightening and stressful as that was, I am over the moon right now. This is what we live for in vet school. That moment when a few of the puzzle pieces that you've been collecting seemingly at random suddenly snap together in a moment of pure, clear clinical understanding.