Podcast – Intro to EM: The Patient with Syncope

Welcome to the St Emlyn’s podcast. I’m Iain Beardsell and I’m Simon Carley. Before we get on to talking about syncope, we should probably explain that Simon is currently in a small dark hole somewhere deep inside Virtusta Hospital. We’re doing what we can only describe as guerrilla podcast recording. So there’s a bit of an echo on his end of things, but hopefully, it won’t detract from the content or in any way from what he’s got to say today.

In this induction podcast, we’re going to tackle syncope, the patient with the transient loss of consciousness. First of all, I think we should probably just think about patients who come to us with that familiar presenting complaint of collapsed query cause. So Simon, what do you first think about when you see a patient with that presenting complaint? Collapse query cause because obviously not all of them have had syncope. How do you decide who’s had syncope and who hasn’t?

I think it’s a really good question. When somebody’s had a collapse, which is another way of describing it, I suppose, are we talking about something mechanical where somebody’s fallen over, or have they had some physiological reason for them to actually lose consciousness and hit the deck? It’s really important to think about which one of those you’re going to go down in terms of diagnostic pathways. And I think, in the way that we do with emergency medicine, we should probably think about the worst-case scenario first. For these patients, the worst-case scenario is a transient loss of consciousness rather than a trip over the dog.

Absolutely. And there are a whole bunch of really nasty conditions which can present as a collapse, such as abdominal aortic aneurysms, dysrhythmias, significant blood loss, and neurological events. As emergency physicians, those are what we’re going to look for. Interestingly though, a lot of people will claim that they’ve had a mechanical fall even if they haven’t. We have to be very careful about that when people say they’ve tripped. Did they really? So perhaps the best first way to approach these patients is to assume they’ve had a syncopal episode and try to prove otherwise. Almost a mechanical fall then becomes a diagnosis of exclusion.

Let’s move on to think about syncope and a couple of definitions for it. We’ve said already that it’s a transient loss of consciousness. In my head, I like to think about that as being a transient global hypoperfusion. So for a brief period of time, there’s a lack of blood flow to the brain. This can happen from several different causes, and it’s useful to go back to some physiological basics here. What we’re really saying is that the cerebral perfusion pressure is veering towards zero. As we remember, cerebral perfusion pressure depends on several variables, not least the mean arterial blood pressure. Mean arterial blood pressure itself depends on cardiac output and total peripheral resistance, and cardiac output depends on stroke volume and heart rate. So, if any of those single variables veers towards zero, because of the way the equations work, our cerebral perfusion pressure is going to fall. Each of the causes that we have for syncope is down to one of those physiological variables tending to lower for some reason.

Simon, I guess we should start by thinking about the cardiac causes of syncope, how those perhaps relate to those variables I’ve just talked about, but they’re the things that are going to do for you in the end. Let’s not forget that transient loss of consciousness that persists can probably be defined as something different; we can call that death. It’s important that we think about these cardiac causes first. How do you go about thinking about those?

In terms of cardiac problems, we can think about how the heart works. Either the heart’s not pushing out enough volume, so there’s a stroke volume issue, or there’s a rate problem, so it’s not going fast enough or it’s going too fast, or there’s a problem with blockage, so the blood just can’t get out of the heart. We’ve got structural issues and rhythm issues. Starting with rhythm issues, thinking about our physiology, we’ve got those times when the heart rate becomes much slower, veering towards zero, those bradycardias. What groups of people tend to get those?

People with underlying ischemic heart disease can, those with heart blocks, and people on medications that slow the heart, such as beta-blockers. Those are probably the two biggest groups that we see. This brings us to our most important investigation in the patient with collapse query cause, fall, or syncope—call it what you like—and that’s the ECG. We need to look carefully at the ECG for hints and tips that the patient, who may be in sinus rhythm now, could have at one point gone much slower. There’s a huge amount of information that you can gain from the ECG. There are common things like looking at the rate, any degree of heart block, intraventricular conduction disorders, and the QRS complexes. You’ll pick up some fairly obvious things such as heart blocks. Then there’s some really rare stuff that emergency physicians fear, like Brugada syndrome. So look at the ECG. If the ECG is not normal, and even if it just looks weird, get an expert to have a look at it. These are the worst-case scenarios for our patients with transient loss of consciousness. Their heart may not recover next time if they have another episode.

At my hospital, we have a chocolate bar challenge where the first junior doctor on the team who can spot a bifascicular or trifascicular block in a patient who has had syncope wins a chocolate bar, actually paid for by me. That’s how seriously I take this; I put my hand in my pocket. Look out for bifascicular and trifascicular blocks, and we’ll give you some examples of those on the blog post. We’ve got the heart rate going too slow. We mentioned the heart rate going too fast. Obviously, the stroke volume falls. What are the conditions that you’ve seen causing the heart rate to go fast, leading to a transient loss of consciousness?

Tachydysrhythmias are interesting because some patients present to the ED still in their tachydysrhythmias. They arrive in VT, fast AF, or SVT, which are pretty easy to diagnose because it’s right there on the ECG. The tricky ones are those who’ve had a transient tachydysrhythmias before they came to the hospital, and now the ECG is normal or near normal. In these cases, you look for things like Wolff-Parkinson-White syndrome, long QT intervals, and other pre-VT type events. A careful look at the ECG is crucial. It’s also key to emergency medicine and to our syncopal patients: ask for a detailed history. Patients with a cardiac cause for their collapse often present with familiar histories. They may have palpitations before blacking out. This is very predictive of a cardiac cause. They usually get very little warning but recover quickly. This quick recovery is crucial as their blood pressure needs to improve rapidly to prevent prolonged hypoperfusion. A good history, examination, and ECG should help diagnose cardiac causes of syncope in about three-quarters of the patients who have them. A thorough history is vitally important.

We’ve got the cardiac causes thinking about rhythm, but we also mentioned some structural issues. What are the structural things you’re looking for? Valvular disease, such as significant aortic stenosis, or any other valvular problem that restricts cardiac output, can be significant causes. Pulmonary embolism can also cause collapse due to obstruction in the pulmonary circulation. Although not a primary cardiac issue, it’s worth mentioning in passing. The cardiac causes of syncope are crucial to identify because they can be life-threatening. We’ve discussed why they happen, with the heart going too slow or fast, and structural causes affecting stroke volume and cardiac output. A detailed history, examination, and ECG help diagnose these in most patients. Always consider ruling out cardiac issues, especially in elderly patients presenting with a mechanical fall.

Next, let’s think about epilepsy in this picture. It’s not transient global hypoperfusion, but we need to consider it as a differential. Classical epileptic grand mal seizures can usually be differentiated based on history, witness reports of epileptic movements, or clues like tongue biting, patterns of injury, or loss of bladder control. These aren’t always present, though. There’s a group of patients who are regularly misdiagnosed, either as having epilepsy when it’s cardiac or vice versa. Always consider if you’re on the right path with each patient. For instance, a young girl diagnosed with epilepsy multiple times before her sister was diagnosed with long QT syndrome following similar symptoms highlights the crossover between these disorders. Even abnormal movements aren’t always due to epilepsy; they can occur with cardiac events. Take an excellent history and get a good description of the event.

In those cases, I describe it as a reflex anoxic seizure—patients with a drop in oxygenation having reflex shaking movements. We see this especially in children with breath-holding events leading to blackout and shaking. History is everything, and even a post-ictal period isn’t always indicative of epilepsy. I had a patient with a 20-minute post-ictal period, initially suspected of seizure, but an ECG revealed long QT syndrome, leading to cardiology admission. Cardiac collapse can mimic post-ictal confusion.

We’ve discussed cardiac and seizure disorders, even though seizures aren’t classic syncope. Another major cause of transient loss of consciousness is postural hypotension. The big one here is drugs. Many people are on medications causing postural hypotension, a common ED presentation. This can be diagnosed by recreating the circumstances of posture change and observing symptoms, sometimes more reliable than blood pressure measurements. Elderly patients on multiple medications often present with this issue, and evidence supports stopping unnecessary medications.

Interestingly, an automatic blood pressure machine might not pick up postural hypotension accurately. Symptomatic presentation, even with normal blood pressure readings, requires investigation. We also consider specific reasons for postural hypotension: in older men, it’s often linked to abdominal aortic aneurysm; in younger women, it could indicate ectopic pregnancy. These can be straightforwardly ruled out with ultrasound.

We’ve discussed major causes like cardiac issues, seizures, and postural hypotension, including necessary tests like ECGs and ultrasounds. Now, let’s talk about simple fainting or vasovagal episodes. It’s very much allowed and a relief when it’s not a sinister cause. A detailed history and ruling out serious causes is key. Vasovagal episodes typically present with lightheadedness and dizziness due to triggers like anxiety or emotional distress. Always safety-net these patients, especially if it’s their first episode or if they are elderly.

For older patients, a first vasovagal episode at 70 is unlikely to be benign. Conditions like new migraines or renal colic in elderly patients are also rare and require thorough investigation. Always ensure that elderly patients presenting with fainting or collapse are carefully evaluated for underlying serious conditions.

Simon, when suspecting a cardiac cause, do all patients get admitted? No, especially younger patients with identifiable causes like Wolff-Parkinson-White syndrome can often be managed as outpatients. However, most will require admission, monitoring, and specialist opinion. Suspect cardiac syncope needs a senior emergency physician’s review and likely consultation with cardiology.

We’ve covered the key aspects of managing patients presenting with collapse query cause, emphasizing ruling out syncope first and considering other life-threatening conditions. Always consult with seniors for a thorough review, carefully examine ECGs, and take detailed histories. Additional learning points and examples are available on our blog.

Finally, Simon, is there anything else? We haven’t discussed decision rules for collapse, like the San Francisco Syncope Rule. Decision rules are challenging due to diverse pathologies, and while they can aid decisions, they aren’t replacements for thorough medical evaluations. Emergency medicine is about asking the right questions and doing focused examinations and investigations. It’s vital to consult seniors, review ECGs carefully, and listen to patients’ histories.

We hope you’ve found this podcast useful. Please share your cases and examples with us. There’s even a St Emlyn’s chocolate bar for the first patient who can email us an anonymized ECG showing bifascicular or trifascicular block. Take care, enjoy your emergency medicine, and we’ll speak to you soon. Have fun!