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Pump mechanics · Cardio & Respiratory · INBDE Patient Cases

Cardiac Cycle INBDE Patient Cases

By Dr. Isaac Sun, DDS

9 ADA INBDE-format patient cases on cardiac cycle. Each case is a shared patient box (chief complaint, history, medications, allergies, exam) followed by linked multiple-choice questions with full distractor explanations. Practice the way the real exam is structured.

9 patient cases45 linked questionsADA INBDE formatFull distractor explanations

Nine ADA INBDE-format patient cases on cardiac cycle and hemodynamics in the dental setting: vasovagal syncope after a local anesthetic injection, orthostatic hypotension after a long reclined appointment, heart failure with a reduced ejection fraction and orthopnea, palpitations from systemic epinephrine in local anesthetic, aortic stenosis presenting as a heart murmur, hypertensive left ventricular hypertrophy with a fourth heart sound, supine hypotensive syndrome of pregnancy from inferior vena cava compression, atrial fibrillation with loss of the atrial kick and anticoagulation bleeding risk, and pre-sedation hypovolemia with low preload. Topics include preload, afterload, contractility, stroke volume, ejection fraction, the Frank-Starling relationship, heart sounds, the epinephrine cardiac dose limit, and chair-side positioning.

Case Coverage Map
What each case is testing
Feeling faint and sweaty just after the injection:
Vasovagal syncope, parasympathetic preload drop, legs-up positioning, distinguishing it from anaphylaxis.
Graying out on standing after a long appointment:
Orthostatic hypotension, reduced venous return, diuretic contribution, slow dismissal.
Short of breath when the chair reclines:
Heart failure with low EF, orthopnea and S3, semi-upright positioning, conservative epinephrine.
Racing heart right after the numbing shot:
Transient systemic epinephrine, beta-1 effect, heart rate and filling time, aspiration technique.
A heart murmur mentioned in the health history:
Aortic stenosis, increased afterload, poor tolerance of hypotension, referral and prophylaxis rules.
High blood pressure before a surgical extraction:
Hypertensive LVH, S4 and the atrial kick, epinephrine dose limit, when high BP is an emergency.
Faint and nauseated lying back in late pregnancy:
Supine hypotensive syndrome, inferior vena cava compression, left lateral tilt, second-trimester timing.
An irregularly irregular pulse at the chair:
Atrial fibrillation, lost atrial kick and filling, anticoagulant bleeding risk, local hemostasis.
Fasted too long before sedation and feels weak:
Hypovolemia and low preload, sedation-related vasodilation, volume status, sedation monitoring.
Patient case: Feeling faint and sweaty just after the injection
0 of 5 answered, 0 correct
Patient
Female, 28 years old
Chief Complaint
"I feel sick and sweaty, the room is spinning," she says moments after the injection.
Background and/or Patient History
  • Presented for a routine restoration on tooth #14
  • Very anxious about dental injections
  • Skipped breakfast before the appointment
  • Lightheaded and nauseated within a minute of the local anesthetic
  • No chest pain, no difficulty breathing
Allergies
NKDA
Medications
  • None
Current Findings
  • Pale and diaphoretic, briefly loses consciousness in the chair
  • Pulse 48 bpm and weak
  • BP 84/52
  • Recovers quickly once repositioned
  1. Question 1
    Easy
    What is the most likely cause?
  2. Question 2
    Moderate
    The fall in cardiac output is driven mainly by:
  3. Question 3
    Easy
    The best immediate position for her is:
  4. Question 4
    Moderate
    Which feature most argues against anaphylaxis?
  5. Question 5
    Moderate
    To reduce recurrence at her next visit, the best step is:

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Patient case: Graying out on standing after a long appointment
0 of 5 answered, 0 correct
Patient
Male, 74 years old
Chief Complaint
"I stood up and the room went gray," he says at the end of a long appointment.
Background and/or Patient History
  • Completed a 90-minute crown appointment in a reclined chair
  • Stood up quickly when dismissed
  • Long-standing high blood pressure
  • Dizzy and unsteady on standing, no loss of consciousness
Allergies
NKDA
Medications
  • Lisinopril
  • Hydrochlorothiazide
Current Findings
  • Seated BP 132/80, pulse 78
  • Standing BP 108/66 with lightheadedness
  • Skin warm and dry
  • Symptoms resolve after sitting back down
  1. Question 1
    Easy
    What is the most likely cause?
  2. Question 2
    Moderate
    On standing, the immediate problem is reduced:
  3. Question 3
    Moderate
    Which medication most contributes to this?
  4. Question 4
    Easy
    The best way to dismiss this patient is to:
  5. Question 5
    Hard
    Compared with vasovagal syncope, orthostatic hypotension here is suggested by:

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Patient case: Short of breath when the chair reclines
0 of 5 answered, 0 correct
Patient
Male, 68 years old
Chief Complaint
"I can't lie back, I get short of breath," he says when the chair is reclined.
Background and/or Patient History
  • Presented for extraction of a hopeless molar
  • Known heart failure with an ejection fraction of 30%
  • Sleeps propped on three pillows
  • Mild ankle swelling
Allergies
NKDA
Medications
  • Furosemide
  • Carvedilol
  • Lisinopril
Current Findings
  • Becomes dyspneic when reclined past 45 degrees
  • Pulse 88, BP 118/74, SpO2 96%
  • Soft crackles at both lung bases
  • Audible S3 gallop
  1. Question 1
    Easy
    His inability to lie flat is called:
  2. Question 2
    Moderate
    An S3 in this adult suggests:
  3. Question 3
    Easy
    The best chair position for treatment is:
  4. Question 4
    Moderate
    Regarding epinephrine in local anesthetic, the best approach is to:
  5. Question 5
    Hard
    Why does his low ejection fraction matter for this appointment?

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Patient case: Racing heart right after the numbing shot
0 of 5 answered, 0 correct
Patient
Female, 35 years old
Chief Complaint
"My heart is racing and pounding," she says right after the numbing shot.
Background and/or Patient History
  • Received local anesthetic with 1:100,000 epinephrine for a filling
  • Sudden brief surge of palpitations and shakiness
  • Symptoms began within a minute of the injection
  • No chest pain, no difficulty breathing
Allergies
NKDA
Medications
  • None
Current Findings
  • Pulse briefly 110, then settling
  • BP 130/82
  • Alert and mildly anxious
  • Symptoms fading after a few minutes
  1. Question 1
    Easy
    The most likely explanation is:
  2. Question 2
    Moderate
    The racing heart reflects stimulation of:
  3. Question 3
    Hard
    If her heart rate climbed very high, cardiac output could fall because:
  4. Question 4
    Moderate
    The best immediate step is to:
  5. Question 5
    Moderate
    To reduce this at her next injection, you should:

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Patient case: A heart murmur mentioned in the health history
0 of 5 answered, 0 correct
Patient
Male, 72 years old
Chief Complaint
"My doctor said I have a heart murmur," he mentions during the health history.
Background and/or Patient History
  • Presented for a new-patient exam and cleaning
  • Reports chest tightness and lightheadedness when climbing stairs
  • Told he has a narrowed aortic valve
  • Has not seen his cardiologist in over a year
Allergies
NKDA
Medications
  • Aspirin 81 mg
Current Findings
  • Harsh systolic murmur at the right upper sternal border
  • Pulse 70, BP 122/86
  • No distress at rest
  • Symptoms reproduced by exertion
  1. Question 1
    Moderate
    The murmur and exertional symptoms most suggest:
  2. Question 2
    Moderate
    Aortic stenosis increases left ventricular:
  3. Question 3
    Hard
    Patients with severe aortic stenosis tolerate poorly a sudden drop in:
  4. Question 4
    Moderate
    With exertional chest tightness and an unmonitored murmur, the best step before elective surgical care is to:
  5. Question 5
    Hard
    Antibiotic prophylaxis before dental procedures is indicated mainly for:

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Patient case: High blood pressure before a surgical extraction
0 of 5 answered, 0 correct
Patient
Male, 60 years old
Chief Complaint
"My blood pressure runs high," he says before a surgical extraction.
Background and/or Patient History
  • Presented for extraction of tooth #3
  • Long-standing hypertension
  • Left ventricular hypertrophy noted on a prior echocardiogram
  • Feels well today
Allergies
NKDA
Medications
  • Amlodipine
  • Lisinopril
Current Findings
  • BP 158/94 in the operatory
  • Pulse 76
  • S4 gallop on auscultation
  • No chest pain or shortness of breath
  1. Question 1
    Moderate
    The S4 reflects:
  2. Question 2
    Hard
    Because his ventricle is stiff, filling depends more on:
  3. Question 3
    Moderate
    For a patient with significant cardiovascular disease, the recommended epinephrine limit is about:
  4. Question 4
    Moderate
    With BP 158/94 and no symptoms, the best approach to this elective extraction is to:
  5. Question 5
    Moderate
    Which finding would make you stop and refer urgently instead?

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Patient case: Faint and nauseated lying back in late pregnancy
0 of 5 answered, 0 correct
Patient
Female, 31 years old, 34 weeks pregnant
Chief Complaint
"I feel faint and nauseated lying back," she says during the appointment.
Background and/or Patient History
  • Presented for treatment of a painful cavity
  • Third-trimester pregnancy
  • Symptoms began after reclining flat in the chair
  • Improves when she shifts onto her side
Allergies
NKDA
Medications
  • Prenatal vitamins
Current Findings
  • Supine BP 92/58 with lightheadedness and nausea
  • Pulse 96
  • Symptoms resolve with left-side positioning
  • Reports normal fetal movement
  1. Question 1
    Moderate
    This pattern is best described as:
  2. Question 2
    Moderate
    The cause is compression of the:
  3. Question 3
    Easy
    The best position for her is:
  4. Question 4
    Moderate
    Her faintness is due to a fall in:
  5. Question 5
    Moderate
    For elective dental care in pregnancy, the most comfortable approach is:

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Patient case: An irregularly irregular pulse at the chair
0 of 5 answered, 0 correct
Patient
Male, 70 years old
Chief Complaint
"My pulse always feels irregular," he notes while you take vitals.
Background and/or Patient History
  • Presented for a crown preparation
  • Known atrial fibrillation
  • Takes a blood thinner
  • No chest pain or palpitations today
Allergies
NKDA
Medications
  • Apixaban
  • Metoprolol
Current Findings
  • Irregularly irregular pulse
  • Rate around 80 and controlled
  • BP 128/78
  • No signs of bleeding or distress
  1. Question 1
    Easy
    An irregularly irregular pulse most suggests:
  2. Question 2
    Moderate
    In atrial fibrillation, ventricular filling is reduced because:
  3. Question 3
    Hard
    Loss of the atrial kick matters most in patients who also have:
  4. Question 4
    Moderate
    His apixaban most affects dental care by increasing:
  5. Question 5
    Hard
    For a routine extraction, the usual recommendation regarding his anticoagulant is to:

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Patient case: Fasted too long before sedation and feels weak
0 of 5 answered, 0 correct
Patient
Male, 22 years old
Chief Complaint
"I fasted since last night and feel a bit weak," he says before sedation for third molars.
Background and/or Patient History
  • Scheduled for surgical removal of impacted third molars under sedation
  • NPO since the previous evening, longer than instructed
  • Also skipped fluids
  • Otherwise healthy
Allergies
NKDA
Medications
  • None
Current Findings
  • Resting BP 104/62, pulse 92
  • Dry mucous membranes
  • Lightheaded when sitting up
  • No chest pain or difficulty breathing
  1. Question 1
    Easy
    His borderline low blood pressure and dry mucosa suggest:
  2. Question 2
    Moderate
    Low intravascular volume reduces cardiac output by lowering:
  3. Question 3
    Hard
    Why does this matter before sedation?
  4. Question 4
    Moderate
    The best step before proceeding is to:
  5. Question 5
    Easy
    Which monitoring is most appropriate during his sedation?

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