UBP 4.8 (Short Form): CV – Cardiac Ablation

Question 1

What are your concerns with this patient?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 1

My primary concerns for this patient include the increased risk for the following:

1. cardiac arrhythmias, which could lead to impaired cardiac output and end-organ ischemia;
2. myocardial ischemia, secondary to chronic hypertension (i.e. hemodynamic instability and increased afterload), atrial fibrillation (impaired cardiac output), and/or possible coronary artery disease (i.e. hypercholesterolemia, diabetes mellitus, hypertension, obesity, increased age, tobacco use, history of stroke, and atrial fibrillation) and mitral valve stenosis (suggested by the history of rheumatic fever and the development of atrial fibrillation);
3. acute ischemic stroke, either embolic (atrial fibrillation or thrombotic material) or thrombotic (the patient’s diabetes mellitus, hypertension, and history of stroke suggest the possibility of cerebral vascular disease);
4. hemodynamic instability, secondary to chronic hypertension, atrial fibrillation, and possible mitral valve stenosis;
5. congestive heart failure, secondary to myocardial ischemia or the right ventricular pressure overload associated with mitral valve stenosis (again, the possibility of mitral valve stenosis is suggested by the patient’s history);
6. aspiration, secondary to her GERD and the gastroparesis often associated with diabetes mellitus;
7. the complications associated with smoking, such as pulmonary disease, bronchospasm, hypoxia, cerebral vascular accident, prolonged mechanical ventilation, infection, and impaired wound healing;
8. hypoglycemia or hyperglycemia, secondary to her diabetes mellitus;
9. coagulopathy, secondary to the effects of coumadin; and
10. the complications associated with the procedure, such as cerebral vascular accident, atrial perforation, cardiac tamponade, pericardial effusion, complete AV block, pulmonary vein stenosis, valve trauma, phrenic nerve paralysis, and atrial-esophageal fistula.

Question 2

What do you think may have led to this patient’s A-fib?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 2

While the etiology of atrial fibrillation could be completely idiopathic, it is more often associated with a cardiac condition such as – valvular disease, left ventricular hypertrophy, coronary artery disease, hypertension, cardiomyopathy, sick sinus syndrome, or pericarditis.

Considering this patient’s hypercholesterolemia, diabetes mellitus, hypertension, obesity, increased age, tobacco use, and history of rheumatic fever, it is very likely that her atrial fibrillation is the result of coronary artery disease, hypertension, and/or mitral valve stenosis.

Less frequently, there are non-cardiac factors that contribute to the development of atrial fibrillation, such as – hyperthyroidism, pulmonary embolism, excessive alcohol consumption, or caffeine intake.

Given these potential causes of atrial fibrillation, my preoperative evaluation would include a history and physical focusing on signs and symptoms of coronary artery disease, congestive heart failure, and thyroid dysfunction.

I would also review her EKG, to see her current rhythm and look for signs of ischemia, previous myocardial infarction, and/or left ventricular hypertrophy; order a chest radiograph, to identify any cardiomegaly and/or pulmonary edema; and review the results of any additional cardiac testing that had been performed.

If her risk for myocardial ischemia remained unclear, despite my examination and review of the available information, I would consider further cardiac testing.

Question 3

How will you evaluate this patient pre-operatively?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 3

Given her atrial fibrillation and history of rheumatic fever, I would –

• review any previous workup and current medical treatment;
• order an 12-lead EKG (to evaluate her current rhythm and look for signs of myocardial ischemia and/or right heart strain secondary to pulmonary hypertension),
• chest radiograph (cardiomegaly and/or pulmonary edema),
• hemoglobin/hematocrit,
• echocardiogram (to identify wall motion abnormalities; estimate cardiac output; identify and assess the severity of any structural heart disease that may have resulted from rheumatic heart disease; and to identify any atrial thrombus), and
• electrolyte levels (magnesium and potassium are of particular importance in the presence of atrial fibrillation, especially in this patient taking HCTZ, which may lead to decreased potassium); and
• evaluate her for signs and symptoms of coronary artery disease, congestive heart failure, and thyroid dysfunction.

Considering her history of CVA, GERD, and tobacco use, I would perform a careful neurologic examination to determine the severity and scope of her residual weakness, assess the treatment and severity of her GERD, and examine her for signs of COPD (i.e. chest radiograph), respectively.

Moreover, since she is taking Coumadin, I would evaluate her for signs of coagulopathy and check a PTT, PT, and INR.

Finally, I would assess the severity, stability, current therapy, and any end-organ effects of her diabetes and hypertension (i.e. blood sugar; BUN/creatinine to assess her renal function).

Question 4

Why is she taking diltiazem?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 4

Diltiazem is used to control the heart rate in chronic A-fib by decreasing the rate of the SA node and by slowing conduction through the AV node.

Diltiazem, like other calcium blockers, should be used with caution in patients with reduced ventricular function (heart failure) due to its negative inotropic effects.

However, diltiazem produces significantly less myocardial depression than verapamil, and is the preferred drug in patients with systolic heart failure.

Medical treatment for atrial fibrillation depends on the type, severity of symptoms, the underlying cause, and comorbid conditions.

In general, the goal of treatment is threefold:

1. slow down the heart rate,
2. restore and maintain normal heart rhythm, and
3. prevent stroke by anticoagulation.

Question 5

Would you recommend that she continue her diltiazem preoperatively?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 5

The decision to continue her diltiazem preoperatively would depend on her underlying ventricular rate when not on a calcium channel blocker, her risk for myocardial ischemia, and the degree to which diltiazem may interfere with electrophysiologic EP mapping.

Typically, anti-arrhythmic medications are discontinued to facilitate the induction of arrhythmias when mapping the conduction pathways and source of excitability.

However, since calcium channel blockers control the ventricular rate by slowing conduction through the AV node, they have minimal effects on electrophysiologic mapping and should be continued preoperatively.

Moreover, should she have mitral valve stenosis, an increase in ventricular rate, as may occur with the discontinuation of diltiazem, could lead to significantly decreased cardiac output and end-organ ischemia.

Question 6

What are the indications for catheter ablation?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 6

Indications for catheter ablation include:

1. symptomatic supraventricular tachycardia (SVT) due to atrioventricular nodal reentrant tachycardia (AVNRT), Wolff-Parkinson-White syndrome, unifocal atrial tachycardia, or atrial flutter;
2. atrial fibrillation with lifestyle-impairing symptoms and either inefficacy or intolerance of at least one antiarrhythmic agent;
3. symptomatic ventricular tachycardia;
4. patient preference; and
5. noncompliance with drug regimens.

Question 7

What do you think is the cause of her syncopal episode?

Does she need further evaluation?

(A 58-year-old female with chronic atrial fibrillation (A-fib) is scheduled for elective electrophysiologic mapping and catheter ablation. She developed A-fib 4 years ago, has been refractory to standard medical therapy, and reports an episode of palpitations and syncope three weeks ago. Her past medical history is significant for hypertension, tobacco use, Type II diabetes mellitus, gastroesophageal reflux disease (GERD), osteoarthritis, and rheumatic fever. Her history is also significant for a cerebral vascular accident (CVA) that occurred approximately one year ago, with subsequent residual right-sided weakness. Her current medications include diltiazem, coumadin, HCTZ, metformin, naproxen, Prilosec, Lipitor, and a multvitamin. Vital Signs: Weight = 82 kg; BP = 152/89 mmHg; HR = 92; RR = 18; Temp = 36.8 C.)

Answer 7

Given this patient’s chronic atrial fibrillation, history of stroke, and possible mitral valve stenosis (i.e. history of rheumatic fever and atrial fibrillation of unknown etiology),

her recent syncopal episode is most likely secondary to – cardiac arrhythmia and/or transient ischemic attack (TIA).

However, since she is diabetic and has several risk factors for coronary artery disease, I would also consider the possibility of – hypoglycemia or myocardial ischemia.

Finally, I would give consideration to other potential causes of syncope, such as – seizure, aortic stenosis, hypertrophic cardiomyopathy, vasovagal response, or vertigo.

Additional work-up would be based on the suspected etiology of her syncope, and may include –

• an electrocardiogram,
• an exercise stress test,
• an echocardiogram,
• carotid sinus massage, or
• a tilt table test.