Case Study: Ventricular Tachycardia in a Normal Heart…Now What?

Case Study: Ventricular Tachycardia in a Normal Heart…Now What?
Case Study: Ventricular Tachycardia in a Normal Heart…Now What?
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Author(s): 

Kimberly Clawson, RN, RCES, Tharen J. Leesch, RCES, CVT-AAS, Dr. Nadim Khan, Dr. Huy Khuu
Florida Hospital Zephyrhills, EP Lab
Zephyrhills, Florida

In this next case installment from the Florida Hospital Zephyrhills, the authors describe a diagnosis of idiopathic ventricular tachycardia (VT) in a patient who works as a skydiving instructor.

Case Description
A 60-year-old Caucasian male, who is a skydiving instructor visiting from Germany, is visiting and performing skydiving lessons. He was urgently rushed to the ER at Florida Hospital Zephyrhills (FHZ) after experiencing a terrifying episode during a jump. The patient states that he began to have weakness and fatigue during his last jump; while making his descent from the plane, he became very dizzy and thinks that he may have passed out for a brief period of time. He states that he barely made it to the ground without major injury. Upon arrival to the ER, he was found to be in a wide complex ventricular tachycardia (VT) at a rate of 214 beats per minute (bpm). His systolic blood pressure was found to be 58 mmHg. He was cardioverted and given a bolus of IV amiodarone. The patient was then rushed to the cardiac cath lab.

His medical history included hypertension and what he called extrasystoles, or premature ventricular contractions (PVCs); he had no surgical history and denied being diabetic, even though his blood glucose level was 350mg/dl upon initial testing. The initial Basic Metabolic Panel (BMP) showed: Sodium = 139, Potassium = 3.5, Chloride = 104, CO2 = 16.0, BUN = 19, Creatinine = 1.3, and Magnesium = 2.2. All cardiac markers were within normal limits.

A day later, his blood glucose level had dropped to 177 mg/dl and trended downward to 114 mg/dl during the course of the hospital stay.

Cardiac Cath Findings
Post cardioversion in the ER, the patient returned to sinus rhythm with a severe first-degree atrioventricular (AV) block, which was asymptomatic. The electrocardiogram (ECG) showed: PR = 364ms, QRS = 122ms, QT = 416ms, QTc = 405, and HR = 57 bpm. At this time, the patient felt he had returned to his baseline with no further symptoms. The cardiac cath showed no evidence of coronary artery disease (CAD), and the patient was found to have a preserved, normal left ventricular systolic function.

Possible Diagnosis
At first thought after the normal cardiac cath, the diagnosis was a possible idiopathic VT. According to Lerman et al,1 “Idiopathic VT is a generic term that describes various forms of ventricular arrhythmias that occur in patients without structural heart disease and in the absence of long QT syndrome.” This type of VT is extremely difficult to reproduce in the electrophysiology (EP) lab during a study. Lerman et al[1] also state that a “variety of idiopathic VT is an automatic VT, which originates from either ventricle, can be neither initiated nor terminated with programmed stimulation, is facilitated by catecholamine stimulation, and is responsive to B-blockade.” We believe that idiopathic VT would be the correct diagnosis for our skydiving patient; and, in conjunction, and according to Sei Iwai et al,[2] “‘Idiopathic’ ventricular arrhythmias most often arise from the right ventricular outflow tract (RVOT), although arrhythmias from the left ventricular outflow tract (LVOT) are also observed” and through studies “electrophysiologic and pharmacologic properties, including sensitivity to [catecholamine infusion, verapamil, and] adenosine, are similar for RVOT and LVOT arrhythmias.”[2]

Treatment
Treatment for this patient was given careful consideration due to the high-risk occupation of the patient; with the title of Dive Master and over 10,000 logged skydives to date, we decided on a proper and tailor-made treatment. Even though the standard for identifying the arrhythmia is an EP study to induce the VT, the treatment options for this patient were discussed at length and narrowed. After careful consideration of the patient’s lifestyle and the short duration of his stay here in the United States, it was decided by the patient to defer the EP study at this time when given the options available. He was informed that: 1) he presented with hemodynamically unstable, monomorphic VT, which is a life-threatening arrhythmia; 2) we may not be able to reproduce the “idiopathic” VT during a study in the EP lab; and 3) he would require aggressive treatment because of his participation in dangerous sports activities, but that the physician would prefer an ICD for VT protection. The patient weighed his options, and he decided to undergo a dual chamber ICD implant; he ultimately desired protection from VT while skydiving, and realized that this was the safest and most effective option. It was also explained to the patient that the ICD would record any episode of tachycardia, which could then be used in Germany for possible EP follow-up testing and ablative therapies at a later date. The patient was also informed to consider anti-arrhythmic medications and to continue on beta blockers and Irbesartan for his hypertension; he opted to forgo taking anti-arrhythmic medication at this time.

Summary
Choosing the most effective treatments for this patient proved to be difficult. We know that an EP study with VT mapping and ablation is recommended as customary treatment; however, due to this patient’s very unusual circumstances, including his career, limited time in the United States, and the obvious need to undergo safe and aggressive medical treatment, the patient felt very satisfied and comfortable with the decision to implant an ICD at this time. He felt comfortable that the ICD would afford him the most complete protection during jumps, as well as record any further arrhythmias to aid him in future treatments.

EP is like a puzzle that needs to be pieced together to shape the safest and most effective approach to help patients; it is not a “one size fits all” type of diagnostic tool or treatment. In our skydiving master, quality of life was more important, and we figured that with the ICD in place, we could at least prevent a possible catastrophe. With devices like ICDs, and “given the importance of initiation and termination with regard to VT mechanism[s], research involving intracardiac electrograms recorded on ICDs, especially with regard to timing and morphology of initiating VPDs, may provide fruitful avenues for understanding clinically relevant VTs.”[3]

In addition, we discussed realistic post-op guidelines with the patient, particularly about his extreme sporting activities. Dr. Khan educated him on the risks of skydiving with an ICD, including the chances of: 1) shock during descent; 2) damage to the device or leads due to the harness position; 3) syncope while in descent; or 4) failure of the ICD to terminate an arrhythmia while in descent. According to a survey conducted by Lampert et al,[4] “Some advised against competitive sports or sports with particular risk of injury, including those involving heights […] many physicians individualized recommendations based on underlying cardiac disease.” The consequences of participation in extreme sports show that “while ICD shocks during sports were not uncommon, adverse outcomes of the arrhythmias and/or shocks received during sports were rare […] 1% of physicians reported known injury to patient, 5% reported injury to the ICD system, and <1% of reported failure of shocks to terminate the arrhythmia [...and] exercise increases the risk of sudden cardiac death […] however, if the ICD effectively terminates arrhythmias during sports, without adverse sequelae, athletic participation is a quality-of-life issue.”[4]

In this case, quality of life was more important to our master skydiver.

References: 

1. Lerman BB, Dong B, Stein KM, et al. Right ventricular outflow tract tachycardia due to a somatic cell mutation in G protein subunitalphai2. J Clin Invest 1998;101: 2862–2868. 2. Iwai S, Cantillon DJ, Kim RJ, et al. Right and left ventricular outflow tract tachycardias: evidence for a common electrophysiologic mechanism. J Cardiovasc Electrophysiol 2006;17(10):1052-1058. 3. Riley MP, Marchlinski FE. ECG clues for diagnosing ventricular tachycardia mechanism. J Cardiovasc Electrophysiol 2008;19(2):224-229. 4. Lampert R, Cannom D, Olshansky B. Safety of sports participation in patients with implantable cardioverter defibrillators: A survey of heart rhythm society members. J Cardiovasc Electrophysiol 2006;17(1):11-15.


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