Giant cell arteritis (GCA)

Vignette says a 55 year old female presented to the neurology clinic with a history of headache in the right temporal region for 7 days; This morning, she experienced sudden episode of blurry vision in her right eye with spontaneous improvement in 15-20 minutes ; She also reports of pain and stiffness in the bilateral shoulders, scalp tenderness while combing hair, jaw claudication with chewing, fatigue, weight loss and mild fever over the past 6 months; Vital signs show blood pressure of 130/80 mm of Hg, pulse rate of 88 bpm, respiratory rate of 18 breaths/min, oxygen saturation of 98% in RA and temperature of 99.9 F; Examination shows tender, thickened right temporal artery with weak pulsation on palpation; Neurological examination is normal; Laboratory studies show ESR of 100 mm/hr, CRP of 75 mg/L; Temporal artery biopsy shows granulomatous inflammation with giant cells and intimal fibrosis; CT angiography shows arterial wall thickening and luminal narrowing of the right carotid artery; Diagnosis?

Diagnosis is Giant cell arteritis (GCA). 

Giant cell arteritis (GCA) is a large vessel vasculitis characterized by the granulomatous inflammation commonly affecting branches of the carotid artery; It is also known as temporal arteritis.

Presents with fever, fatigue, weight loss, unilateral temporal region headache, scalp tenderness, jaw claudication and vision problems; Associated with polymyalgia rheumatica.

The American College of Rheumatology (ACR) criteria for diagnosing temporal arteritis; three of the five criteria must be present to make the diagnosis which includes:-
1. Age greater than or equal to 50 at the onset of symptoms.
2. New onset headache.
3. Temporal artery abnormalities such as tenderness of the superficial artery or decreased pulsation.
4. ESR greater than or equal to 50 mm/hr.
5. Abnormal artery biopsy, including vasculitis (i.e. predominance of mononuclear cell infiltration or granulomatous inflammation, or multinucleated giant cells).

Diagnosis:-
1. CBC shows anemia of chronic disease.
2. Inflammatory markers (i.e. ESR and CRP) are elevated; ESR >100 mm/hr.
3. Creatine kinase is normal.
4. Duplex sonography of the temporal artery shows a "halo sign" (i.e. a circumferential hypoechoic area around the artery).
5. Biopsy shows granulomatous inflammation with giant cells and intimal fibrosis.
6. CTA or MRA shows arterial wall thickening, luminal narrowing and stenosis, contrast enhancement of the vessel wall of the carotid artery.

Management:-
1. Aspirin is given to reduce ischemic complications.
2. Steroids (i.e. IV methylprednisolone is given prior to temporal artery biopsy in order to prevent blindness as giant cell arteritis can lead to irreversible blindness from ophthalmic artery occlusion (AION)); IV methylprednisolone 1g/day is given for 3 days, then switch to oral prednisone 40- 60 mg/day and gradually taper the prednisone.
3. Tocilizumab (monoclonal antibody against IL-6 receptor) is used in patients with relapsing or refractory disease or those needing to reduce corticosteroid use. 
4. Calcium, Vitamin D and Bisphophonates (for osteoporosis prevention).

Graves disease

Vignette says a 38 year old female presents to her primary care physician with a 3 month history of weight loss despite good appetite, palpitations, and difficulty sleeping; She also reports of feeling increasingly anxious and has noticed a tremor in her hands; Vital signs shows heart rate of 110 beats per minute, and blood pressure of 140/80 mmHg; Examination shows exophthalmos (bulging eyes), a diffusely enlarged, non-tender thyroid, and a fine tremor in her hands; Thyroid function tests show low TSH and high free T4 and free T3 levels; Serology shows positive thyroid-stimulating immunoglobulin (TSI); Radioactive iodine uptake shows diffuse uptake; Diagnosis? 

Diagnosis is Graves disease. 

Graves disease is an autoimmune disease that occurs due to autoantibodies against TSH receptors of the thyroid gland, causing overproduction of thyroid hormone. It is the most common cause of hyperthyroidism in the United States.

Clinical features:-

1. Diffuse, enlarged thyroid glands; thyroid bruit is heard on auscultation.

2. Features of hyperthyroidism (i.e. anxiety, tremor, tachycardia, AFib, systolic HTN, weight loss

despite good appetite, hyperdefecation, heat intolerance, increased sweating, onycholysis, moist skin and fine hair).

3. Graves ophthalmopathy; It is characterized by upper eyelid retraction, lid lag, periorbital swelling, conjunctivitis, and bulging eyes (exophthalmos or proptosis).

4. Pretibial myxedema.

Diagnosis:-

1. Thyroid function test (TFT) shows low TSH and high fT3/fT4.

2. Anti thyroid receptor antibodies is positive (i.e. Thyroid stimulating immunoglobulins is positive).

3. Radioactive iodine uptake (RAIU) shows diffuse uptake.

4. Thyroid ultrasonography shows diffuse enlarged thyroid gland.

5. Histology shows follicular hyperplasia, intracellular colloid droplets, cell scalloping, a reduction in follicular colloid, and a patchy lymphocytic infiltration.

6. MRI of orbit for evaluating ophthalmopathy.

Management:-

1. Beta blockers are used (e.g. propranolol) for symptoms due to sympathetic overactivity.

2. Anti thyroid drugs are used  (e.g. methimazole, propylthiouracil) to block thyroid hormone synthesis and release; The recommended starting dose is 0.5–1.0 mg/kg/day for methimazole and 5–10 mg/kg/day for propylthiouracil. 

3. Radioactive iodine (RAI) ablation therapy.

4. Total or subtotal thyroidectomy.

Supraventricular tachycardia (SVT)

Vignette says a 28 year old female presents to the emergency department with a sudden onset of palpitations that started 30 minutes ago while she was studying for an exam; She describes the sensation as her "heart racing" and feels lightheaded but denies chest pain, shortness of breath, or syncope; She states that she had similar episodes in the past that resolved spontaneously; She has no significant past medical history and takes no medications; She drinks 2–3 cups of coffee daily; Vital signs show pulse rate of 180 beats/min, blood pressure of 110/70 mm of Hg, respiratory rate of 16 breaths/min, oxygen saturation of 96% in RA and temperature of 98.2 F; The patient appears anxious but is alert and oriented; ECG shows a narrow QRS complex tachycardia at 180 bpm with absent visible P waves in lead II; Diagnosis?

Diagnosis is Supraventricular tachycardia (SVT). Supraventricular tachycardia (SVT) is a tachyarrhythmia originating at or above the atrioventricular node and is defined by a narrow complex (QRS < 120 milliseconds) at a rate > 100 beats per minute (bpm).

Types:-

1. AV nodal reentry tachycardia (AVNRT)

2. Atrioventricular reentry tachycardia (AVRT)

3. Atrial tachycardia (AT)

Presents with symptoms such as palpitations, chest discomfort, dyspnea, dizziness, light-headedness, presyncope, syncope, or anxiety.

Diagnosis:-

1. ECG

2. Cardiac monitoring

3. EP studies

Treatment of SVT:- 

1. If the patient is hemodynamically unstable, consider synchronized cardioversion. 

2. If the patient is hemodynamically stable:- 

• Apply vagal maneuvers (e.g. carotid massage, ice water immersion, modified valsalva maneuver i.e. the modified Valsalva maneuver (mVm) has been shown to have a higher success rate in converting hemodynamically stable SVT to normal sinus rhythm (NSR) when compared to sVm (REVERT trial)).
• Pharmacological therapy includes adenosine, beta blockers (metoprolol), calcium channel blockers (verapamil, diltiazem).

3. Radiofrequency ablation. When to refer to ablation?

• Recurrent episodes despite medications.
• Medication intolerance
• High-risk occupations (pilots, commercial drivers)
• WPW syndrome

ECG of AVNRT shows sinus tachycardia, normal QRS complex (<120ms) complex and P wave inversion in leads II, III and aVF.

Figure:- ECG showing AVNRT