1/ Hey #MedTwitter learners!
What is your first reflex when you are faced with sinus tachycardia?
Give fluids, make sure patient is not in overt shock. Most likely.
But what if your sinus tachycardia persists and the exact cause remains elusive? #thread
What is your first reflex when you are faced with sinus tachycardia?
Give fluids, make sure patient is not in overt shock. Most likely.
But what if your sinus tachycardia persists and the exact cause remains elusive? #thread
2/ It is normal to give a fluid bolus when you have sinus tachycardia in the hospital. Sinus tachycardia is commonly a sign of intra-vascular depletion with baro-receptor stimulation and sympathetic nervous system activation. 
3/ In some cases, even after you reached euvolemia, sinus tach persists and is isolated without a clear syndrome to tie it to.
You see an 80ish y.o. admitted with failure to thrive and decreased oral intake. Found to have HR in the 110 bpm range. Previously ~80s. How to treat?
You see an 80ish y.o. admitted with failure to thrive and decreased oral intake. Found to have HR in the 110 bpm range. Previously ~80s. How to treat?
4/ Patient was adequately resuscitated but tachycardia persisted. Rate even ⬆️ to 120s. On clinical survey, there was no evidence of sepsis. Patient had no complaints and denied palpitations. She was not hypoxic. You start listing less common causes of isolated sinus tach.
5/ You order a TSH. It's back at 0.088 but free T4 is normal. Tachycardia persists, rate 120-130 bpm. Patient is resting with no complaints. Next step?
6/ Free T3 is reasonable given the possibility of T3 thyrotoxicosis, but this is unlikely given normal recent TSH and epidemiology of disease.
Medication list only included PPN and folic acid.
Dysautonomia plausible but no parkinsonism, no history of diabetes or neuropathy.
Medication list only included PPN and folic acid.
Dysautonomia plausible but no parkinsonism, no history of diabetes or neuropathy.
7/ The only other abnormality patient had was a slowly downtrending thrombocytopenia over the last few days (194-->137-->100-->83-->67-->58-->47). Anti-PF4 antibodies were negative. No clear etiology (commonly drug-induced) was identified but this finding was puzzling you.
8/ Almost giving up and calling this "inappropriate sinus tachycardia" (diagnosis of exclusion), I re-thought the case and, bothered by this inexplicable "sign", decided to order a D-dimer level. D-dimer came back at 7 (cut-off to R/O PE is 0.5).
9/ My suspicion for PE ⬆️⬆️⬆️. Patient was bedbound, immobile, has sinus tachycardia and an unignorablely high D-dimer level. To show some perspective, Schutte et. al showed that patients with D-dimers >5 almost always had underlying PE (32%), cancer (29%) or sepsis (24%).
10/ Armed by the conviction that stars will align for a diagnosis, I ordered a CT angiogram of the chest. Comes back with "filling defects involving the right main, RUL, RLL and LLL pulmonary artery branches consistent with pulmonary embolism. No evidence of right heart strain."
11/ Suddenly, everything makes sense. Sinus tachycardia not responding to fluids is due to PE. Thrombocytopenia is most likely relative to consumption in the clots. Read this brilliant article on occurrence of ⬇️ platelets with PE and not with DVT.
ncbi.nlm.nih.gov/pubmed/1959389
ncbi.nlm.nih.gov/pubmed/1959389
12/ Patient started on anticoagulation with enoxaparin. Tachycardia slowly subsided and platelet count rebounded to normal.
For the feeling of satisfaction such reasoning exercises bring, I'd do this again and again and again!
For the feeling of satisfaction such reasoning exercises bring, I'd do this again and again and again!
14/ Take-home points:
💓PE is a tricky diagnosis. Sometimes found incidentally. Rarely with full textbook picture. Expect to find it when unexpected. Expect not to find it when highly suspected.
💓Isolated persistent sinus tachycardia could be a sign of PE.
💓PE is a tricky diagnosis. Sometimes found incidentally. Rarely with full textbook picture. Expect to find it when unexpected. Expect not to find it when highly suspected.
💓Isolated persistent sinus tachycardia could be a sign of PE.
💓Think of PE (even without hypoxia) if risk factors and/or no response to fluids.
💓Thrombocytopenia can occur with large PE burden, improves with anticoagulation.
💓Super-high D-dimer levels almost always hide a VTE, cancer or sepsis. Investigate!
💓Thrombocytopenia can occur with large PE burden, improves with anticoagulation.
💓Super-high D-dimer levels almost always hide a VTE, cancer or sepsis. Investigate!
💓IST is a diagnosis of exclusion. Do not jump rapidly to it before exhausting all investigations.
💓Do not beta block an unexplained sinus tachycardia and sleep on it. Could be deleterious.
💓If something doesn't perfectly make sense, think it and re-think it. You'll solve it.
💓Do not beta block an unexplained sinus tachycardia and sleep on it. Could be deleterious.
💓If something doesn't perfectly make sense, think it and re-think it. You'll solve it.
