A QTc of 512 ms, a Surgeon's Office That Already Said 'Cleared,' and a Lunch Break
You work in a preoperative clinic. A 34-year-old woman is being evaluated before elective laparoscopic cholecystectomy. She takes ondansetron as needed and was started on citalopram 40 mg by her primary care provider two weeks ago. Her potassium is 3.3 mmol/L. Her resting 12-lead ECG at 25 mm/s and 10 mm/mV shows sinus rhythm at 76, PR 0.16 seconds, QRS 0.09 seconds, and a QT of 0.44 seconds measured by the machine; the machine's QTc reads 512 ms. The anesthesiologist is in the operating room, the surgeon's office has already told the patient she is 'cleared,' and the ordering nurse practitioner is at lunch until 13:00. It is 11:40. The patient is asymptomatic at rest but mentions two episodes of 'feeling fluttery' yesterday afternoon.
1. How do you verify the QTc, and what do you conclude about the machine's value?
Read the worked answer
Measure it yourself rather than transcribing the machine's number. Pick a lead with a clean T-wave ending - usually lead II or V5 - and measure from the beginning of the QRS to the point where the T wave returns to baseline, excluding any separate U wave. Average across three to five consecutive beats and use the same lead for future comparisons.
Then do the correction by hand at this rate. Heart rate 76 means RR = 60/76 = 0.79 seconds, and the square root of 0.79 is about 0.889. Bazett: QTc = QT divided by the square root of RR = 0.44 / 0.889, which is roughly 495 ms. The machine's 512 ms probably comes from a slightly different QT or a different beat selected; both numbers are prolonged, and both are above the 460 ms threshold used for women and close to the 500 ms mark that carries higher risk. At a rate of 76, Bazett is a reasonable correction; the correction is least reliable at fast rates, which is not the situation here.
So the finding is real, not a machine glitch: a prolonged QTc in a patient on citalopram plus ondansetron with a potassium of 3.3 and two episodes of palpitations. Note that verifying and reporting the measurement is inside your scope; deciding what it means for the surgery is not.
2. It is 11:40, the nurse practitioner is at lunch until 13:00, and the surgeon's office has already told the patient she is cleared. What is your reporting chain and escalation?
Read the worked answer
A QTc near 500 ms with palpitations, hypokalemia, and two QT-prolonging drugs does not wait 80 minutes for a lunch return. Escalate now.
- Call the covering provider named on the order or the unit roster. If none is listed, call the charge nurse or nursing supervisor and ask who is covering.
- Also notify the preoperative anesthesiology service, since the 'cleared' message came from the surgical office and the patient may otherwise proceed on that basis.
- Report the facts, not a diagnosis: 'Sinus at 76, QT 0.44 s, QTc about 495 to 512 ms, potassium 3.3, on citalopram and ondansetron, reports two episodes of palpitations yesterday.'
- Obtain a read-back of the values and record the name, time, and read-back.
What you do not do: tell the patient she is cleared, tell her she is not cleared, cancel or delay the case yourself, or tell her she is at risk of a dangerous arrhythmia. Those are provider decisions and provider conversations. If she is preparing to leave before anyone responds, say that the provider needs to review a finding on her ECG before the surgery and keep her comfortable while you keep escalating; document any attempt and any departure.
3. What exactly goes in the documentation, and what do you say to the patient in the meantime?
Read the worked answer
Documentation (objective, time-stamped): date and time of the study; indication (preoperative evaluation); relevant medications (citalopram 40 mg, ondansetron); potassium 3.3; heart rate 76, PR 0.16 s, QRS 0.09 s; QT 0.44 s and QTc calculated by Bazett at approximately 495 ms, with the machine's 512 ms noted as well; the lead used for measurement and the paper speed and gain; the patient's report of two episodes of 'feeling fluttery' yesterday, quoted; 'Reported to Dr. ___ at 11:52, read-back confirmed'; the escalation attempts and any unanswered calls; the education given.
Trap to avoid: writing an interpretation such as 'long QT syndrome,' 'torsades risk,' or 'surgery should be cancelled.' Those are clinical conclusions. Describe, measure, report, and record - that is the technician's contribution, and it is a substantial one.
What to say to the patient: 'The doctor will review one of the measurements on your ECG before your surgery. If you feel faint, dizzy, or your heart races before then, tell me right away.' That is honest, non-alarming, and does not pre-empt the provider's decision. Keep the original tracing in the record; do not alter or reprint over it.