Session 1

How does hyperthyroidism cause Atrial Fibrillation?

Patients with hyperthyroidism are more likely to have PACs, more sustained supraventricular tachycardias, increased heart rate, and reduced heart rate variability. Atrial fibrillation occurs in 10-15% of patients with hyperthyroidism, especially in patients >/= 60 y.o

Treatment of hyperthyroidism results in conversion to sinus rhythm is up to two-thirds of patients. Beta-blockers may also be used since they work by reducing left ventricular hypertrophy and atrial and ventricular arrhythmias in patients with hyperthyroidism.

Hyperthyroidism is associated with shortening of action potential duration (APD) resulting in atrial fibrillation. Studies have shown that action potential duration was shorter in hyperthyroid than in euthyroid myocytes. ECG may be helpful in identifying hyperthyroid subjects at risk for developing atrial fibrillation. Maximum P wave duration and P wave dispersion were higher in both subclinical and overt hyperthyroidism. Overt hyperthyroidism induces a hyperdynamic cardiovascular state (high cardiac output with low systemic vascular resistance) which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function, and increased prevalence of supraventricular tachyarrhythmias. Some mechanisms that are thought to lead to a fib secondary to hyperthyroidism are:

Increased supraventricular ectopic activity

increase in potassium

increased atrial pressure

ischemia resulting from increased resting heart rate

Shortened refractory periods

Some complications of atrial fibrillation in patients with hyperthyroidism are heart failure and thromboembolism. About 55 to 75 percent of patients with atrial fibrillation secondary to hyperthyroidism and no other underlying cardiac valvular disease will return to sinus rhythm within three to six months after treatment of the thyrotoxic state. For patients with persistent atrial fibrillation there may be the need for additional forms of therapy addressing rate/rhythm control.

Session 2

Order of operation for treatment. What is the order for the treatment?

• Problem list:
• Foot ulcer/ debridement
• Renal failure
• Dm
• Anemia
• Psychiatric: anxiety, depression, PTSD
• Denies suicidal thoughts, interest in doing things
• Homicidal idealizations

 

1. Admit the patient
2. Asses for ischemia, all patients should have ABI and toe pressure measurements
3. Culture the wound sample and get blood cultures. Before an infected wound is cultured, any overlying necrotic debris should be removed by scrubbing the wound with saline-moistened sterile gauze to eliminate surface contamination
4. Stabilize the patient’s metabolic status
   1. Start empiric parental antibiotic therapy (done within the first hour)
   2. Administration of intravenous fluids (IVF), usually crystalloids (balanced crystalloids or normal saline) given at 30 mL/kg (actual body weight), started by one hour and completed within the first three hours following presentation.
   3. Anemia- Pt needs transfusion (HB OF 6.6)
   4. Treat kidney failure
   5. Monitor glucose levels
5. Get surgical consult
6. PSYCH consult

Session 3

Lyme Carditis

Background:

Lyme disease is caused by an infection with Borrelia burgdorferi. Cardiac involvement happened in the early disseminated phase of the disease, which is around a few weeks to a few months from the onset of infection. Atrioventricular (AV) block is the most common clinical feature of Lyme carditis it may be due to a dysfunction of the conduction system and a decrease in contractility due to myopericarditis.

Recent studies show that carditis occurs in 4-10% of adults with intreated Lyme disease. There is limited information on the pathophysiology of Lyme carditis. This is because biopsies of the heart are rarely preformed and Lyme carditis is not usually fatal. Therfore, the information that we do have is based on animal studies that show inflammation in parts of the heart due to the increase of macrophages and lymphocytes. In mice, the heaviest areas of infiltration are at the base of the heart in the connective tissue. In humans with fatal pancarditis, diffuse infiltrated affecting multiple areas of the heart have been seen.

Presentation

Lyme carditis can be the only feature of the disease or it can occur together with other features of early Lyme disease like erythema migrans or early neurologic symptoms. These patients may be asymptomatic or complain of lightheadedness, syncope, shortness of breath, palpitations and/or chest pain, palpitations was mites to be the most common manifestation. Patients with AV block usally have 1^st degree or 2^nd degree and they can sometime be asymptomatic. Myopericarditis may also occur which is often self-limited and mild. The most frequent manifestation of myocardial involvement in Lyme disease is nonspecific ST and T wave changes on the electrocardiogram.

Diagnosis

• Clinical features with positive results of Lyme serologic testing. (This is very important since AV block from Lyme carditis is usually short-lived and can be managed with a temporary pacemaker and a permanent pacemaker is not need)
• History of tick bite
• Coexistence of neurologic dysfunction
• Coexistence of erythema migrans
• Coexistence joint involvement

 

Treatment

• Lyme carditis treatment should begin with empiric antibiotics
• Patients who are symptomatic (syncope, dyspnea, or chest pain) have second or third degree AV block or 1^st degree with PR interval >/= 300 milliseconds should be hospitalized, placed on cardiac monitor and treated with IV antibiotics (Ceftriaxone 2g IV once daily in adults ) then switch to oral therapy for 21-28 days
• Oral therapy for asymptomatic patients with early disseminated disease and first degree AV block with a PR interval <300 milliseconds who are not admitted to the hospital. Oral therapy includes:

Prognosis

Good prognosis among treated patients. AV block caused by Lyme disease persisted for 3 to 42 days. Complete AV block typically resolves within one week, and more minor conduction disturbances within six weeks.

 

Sources:

https://www.osmosis.org/learn/Borrelia_burgdorferi_(Lyme_disease)

https://www.uptodate.com/contents/lyme-carditis?search=lyme%20carditis&source=search_result&selectedTitle=1~15&usage_type=default&display_rank=1

https://www.uptodate.com/contents/treatment-of-lyme-disease?search=lyme%20carditis&topicRef=7915&source=see_link