A 16-year-old male presents to the cardiologist after passing out during a basketball practice. An echocardiogram confirmed the diagnosis of hypertrophic cardiomyopathy. The cardiologist advises that a pacemaker must be implanted to prevent any further complications and states the player cannot play basketball anymore. Unfortunately, the coach objects to sidelining the player since a big game against their rivals is next week. The coach asks if the pacemaker can be implanted after the game, which of the following steps should the physician take?

Recommend to the legal guardian that the player stop playing and have the procedure performed

Postpone the procedure so the patient can play

Allow the patient to play and schedule a follow up after the game

Perform the procedure immediately so that both the physician and coach's wishes may be fulfilled

Allow the patient to make the decision regarding his health

A 66-year-old female with hypertension and a recent history of acute ST-elevation myocardial infarction (STEMI) 6 days previous, treated with percutaneous transluminal angioplasty (PTA), presents with sudden onset chest pain, shortness of breath, diaphoresis, and syncope. Vitals are temperature 37°C (98.6°F), blood pressure 80/50 mm Hg, pulse 125/min, respirations 12/min, and oxygen saturation 92% on room air. On physical examination, the patient is pale and unresponsive. Cardiac exam reveals tachycardia and a pronounced holosystolic murmur loudest at the apex and radiates to the back. Lungs are clear to auscultation. Chest X-ray shows cardiomegaly with clear lung fields. ECG is significant for ST elevations in the precordial leads (V2-V4) and low-voltage QRS complexes. Emergency transthoracic echocardiography shows a left ventricular wall motion abnormality along with a significant pericardial effusion. The patient is intubated, and aggressive fluid resuscitation is initiated. What is the next best step in management?

Immediate transfer to the operating room

Immediate cardiac catheterization

Intra-aortic balloon counterpulsation

Administer dobutamine 5-10 mcg/kg/min IV

A 71-year-old woman with a past medical history of type 2 diabetes, hypercholesterolemia, and hypertension was admitted to the hospital 8 hours ago with substernal chest pain for management of acute non-ST-elevated myocardial infarction (NSTEMI). The ECG findings noted by ST-depressions and T-wave inversions on anterolateral leads, which is also accompanied by elevated cardiac enzymes. Upon diagnosis, management with inhaled oxygen therapy, beta-blockers and aspirin, and low-molecular-weight heparin therapy were initiated, and she was placed on bed rest with continuous electrocardiographic monitoring. Since admission, she required 2 doses of sublingual nitroglycerin for recurrent angina, and the repeat troponin levels continued to rise. Given her risk factors, plans were made for early coronary angiography. The telemetry nurse calls the on-call physician because of her concern with the patient's mild confusion and increasing need for supplemental oxygen. At bedside evaluation, The vital signs include: heart rate 122/min, blood pressure 89/40 mm Hg, and the pulse oximetry is 91% on 6L of oxygen by nasal cannula. The telemetry and a repeat ECG show sinus tachycardia. She is breathing rapidly, appears confused, and complains of shortness of breath. On physical exam, the skin is cool and clammy and appears pale and dull. She has diffuse bilateral pulmonary crackles, and an S3 gallop is noted on chest auscultation with no new murmurs. She has jugular venous distention to the jaw-line, rapid and faint radial pulses, and 1+ dependent edema. She is immediately transferred to the intensive care unit for respiratory support and precautions for airway security. The bedside sonography shows abnormal hypodynamic anterior wall movement and an ejection fraction of 20%, but no evidence of mitral regurgitation or ventricular shunt. The chest X-ray demonstrates cephalization of pulmonary veins and pulmonary edema. What is the most appropriate next step in the stabilization of this patient?

Initiate dopamine therapy and diuresis

Obtain blood cultures and start preliminary broad-spectrum antibiotics

Start intravenous fluids and epinephrine therapy

Intubate the patient and perform an emergency cardiocentesis

Insert two large-bore intravenous catheters and start rapid fluid resuscitation

A 23-year-old man comes to the emergency department because of palpitations, dizziness, and substernal chest pain for three hours. The day prior, he was at a friend’s wedding, where he consumed seven glasses of wine. The patient appears diaphoretic. His pulse is 220/min and blood pressure is 120/84 mm Hg. Based on the patient's findings on electrocardiography, the physician diagnoses atrial fibrillation with rapid ventricular response and administers verapamil for rate control. Ten minutes later, the patient is unresponsive and loses consciousness. Despite resuscitative efforts, the patient dies. Histopathologic examination of the heart at autopsy shows an accessory atrioventricular conduction pathway. Electrocardiography prior to the onset of this patient's symptoms would most likely have shown which of the following findings?

Slurred upstroke of the QRS complex

Epsilon wave following the QRS complex

Prolongation of the QT interval

Cyclic alteration of the QRS axis

A 54-year-old man with alcoholism comes to the emergency department because of vomiting blood for 6 hours. He has had 3–4 episodes in which he has vomited dark red blood during this period. He has had no epigastric pain or tarry stools. On arrival, his temperature is 37.3°C (99.1°F), pulse is 134/min, and blood pressure is 80/50 mm Hg. He is resuscitated with 0.9% saline and undergoes an emergency upper endoscopy, which shows actively bleeding varices. Band ligation of the varices is done and hemostasis is achieved. He is diagnosed with Child class B cirrhosis. He is concerned about the possibility of recurrence of such an episode. He is asked to abstain from alcohol, to which he readily agrees. In addition to non-selective beta-blocker therapy, which of the following is the most appropriate recommendation to prevent future morbidity and mortality from this condition?

Transjugular intrahepatic portosystemic shunt

A 22-year-old medical student presents to a community health center due to an episode of loss of consciousness 3 days ago. She also has a history of multiple episodes of dizziness in the last year. These episodes almost always occur when she is observing surgery in the operating room. She describes her dizziness as a feeling of lightheadedness, warmth, excessive sweating, and palpitations. She feels that she will fall down if she stood longer and usually sits on the floor or leaves the room until the feeling subsides. Three days ago, she collapsed while observing an open cholecystectomy but regained consciousness after a few seconds. Once she regained consciousness, she was pale and sweating excessively. Her medical history is significant for migraines, but she is not on prophylactic therapy. Her younger brother has cerebral palsy, and her uncle had a sudden death at the age of 25. Her blood pressure is 120/80 mm Hg when lying down and 118/80 mm Hg when in a standing position. The rest of the physical examination is within normal limits. What is the next best step in the management of this patient?

Psychiatric evaluation for anxiety

Pacemakers and ICDs for USMLE Step 3: High-Yield Internal Medicine Lessons

Indications & Basics - Why We Need Wires

Core Problem: Failure of the heart's intrinsic conduction system, leading to symptomatic bradycardia or risk of sudden cardiac death (SCD) from tachyarrhythmias. Pacemakers provide a safety net; ICDs provide a shock.
Pacing for Bradycardia:
- Symptomatic sinus node dysfunction ("sick sinus syndrome").
- High-grade AV block: Mobitz II, Third-degree (complete) AV block.
- Symptomatic bradycardia post-MI or drugs.
ICD for Tachycardia:
- Primary Prevention: Cardiomyopathy with LVEF ≤ 35%.
- Secondary Prevention: History of survived SCD due to VT/VF.

⭐ For primary prevention, an ICD is indicated in HF patients with LVEF ≤ 35% on optimal medical therapy for >3 months, at least 40 days post-MI.

Pacemaker and ICD lead placement in heart chambers

Device Types & Pacing Codes - Alphabet Soup of Pacing

NBG Pacemaker and ICD Code

Device Types

Device	Core Function	Key Indication(s)
Pacemaker (PPM)	Bradycardia treatment	Symptomatic bradycardia, high-degree AV block
ICD	Terminates tachyarrhythmias	Primary/secondary prevention of sudden cardiac death
CRT	Resynchronizes ventricles	Heart failure (EF ≤35%), LBBB with wide QRS

- 📌 **P**aced, **S**ensed, **R**esponse: Position I, II, III.

⭐ Magnet Application: Placing a magnet over an ICD disables its antitachycardia functions (shocking/ATP), but does not affect its pacemaker function. In a pacemaker, a magnet induces an asynchronous pacing mode (e.g., VOO/DOO).

ECG Findings - Reading the Pacer Spikes

Pacer Spike: A sharp, vertical line on the ECG indicating pacemaker discharge.
Spike Location & Morphology:
- Atrial Pacing: Spike before the P wave.
- Ventricular Pacing: Spike before a wide QRS complex (often LBBB-like).
- Dual-Chamber (AV Sequential): Spikes appear before both the P wave and QRS complex.
Capture: Each pacer spike is followed by the expected electrical event (P wave or QRS). Failure to capture means the stimulus was insufficient.
Sensing: The pacemaker correctly inhibits firing when it detects an intrinsic beat.

⭐ Placing a magnet over a pacemaker usually forces it into a fixed-rate, asynchronous pacing mode, overriding its sensing function. This helps assess battery status and capture function without interference from the patient's intrinsic rhythm.

Complications & Management - When Good Wires Go Bad

Lead Complications:
- Dislodgement/Fracture: Most common early issue. Leads to failure to sense or capture. Seen on CXR.
- Perforation: Can cause chest pain, hiccups (phrenic nerve stimulation), or pericardial effusion.
Pocket Issues:
- Infection/Erosion: Erythema, pain, drainage. Requires entire system explant & antibiotics.
- Twiddler’s Syndrome: Patient manipulation of generator causes lead dislodgement.
ICD-Specific:
- Inappropriate Shocks: Often due to SVT (like AFib) misidentified as VT. Manage underlying arrhythmia; reprogram device.

⭐ Device Infection Management: Superficial infection may be treated with antibiotics, but any evidence of deeper pocket or device infection necessitates removal of the entire pacemaker/ICD system (generator and leads).

Pacemakers are for symptomatic bradycardia (e.g., 3rd-degree AV block, sick sinus syndrome).

ICDs are for primary prevention (HFrEF with EF <35%) and secondary prevention (post-VT/VF arrest).

A magnet over a pacemaker causes asynchronous pacing (AOO/VOO/DOO).

A magnet over an ICD disables shock therapy but does not affect pacing.

Failure to capture shows pacer spikes not followed by a QRS or P-wave.

Failure to sense occurs when the pacemaker doesn't detect intrinsic cardiac activity.

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