Holter monitor findings in asymptomatic male military aviators without structural heart disease.

PURPOSE: Our study was designed to determine the spectrum of Holter monitor findings in normal male military aviators to establish a reference for aircrew populations with cardiac related diagnoses. METHODS: We identified all individuals with normal cardiac catheterization in the United States Air Force Aeromedical Consultation Service cardiac catheterization database from January 1984 to December 1998. Cases with valvular disease, left or right bundle branch block, and referral diagnoses of ectopy or arrhythmia were then excluded. Results of Holter monitor studies performed on the remaining aviators prior to cardiac catheterization were then collected and tabulated. Frequency of isolated ectopy was classified as a percentage of the total beats on the Holter monitor: rare (< or =0.1%), occasional (>0.1 to 1.0%), frequent (>1.0 to 10%) and very frequent (>10%). RESULTS: From 1575 consecutive cardiac catheterizations reviewed, 303 aviators met the above inclusion criteria. Only 36 of 303 (11.9%) had no ectopy at all. Rare, occasional, frequent and very frequent isolated atrial ectopy occurred in 72.9%, 2.6%, 2.3% and 0.3%, respectively. The same categories of isolated ventricular ectopy occurred in 40.9%, 7.9%, 3.3% and 0.0%. Atrial and ventricular pairs occurred in 14.5% and 4.3%, respectively. Nonsustained supraventricular and ventricular tachycardia (duration 3 to 10 beats) occurred in 4.3% (13/303) and 0.7% (2/303), respectively. There were no sustained supraventricular or ventricular tachycardias. CONCLUSIONS: In this population, absence of ectopy is unusual while rare isolated ectopy is common. These findings may help define the aeromedical/clinical significance of Holter monitors performed on aircrew with underlying cardiac complaints or diagnoses.

The natural history of Wolff-Parkinson-White syndrome in 228 military aviators: a long-term follow-up of 22 years.

BACKGROUND: Wolff-Parkinson-White (WPW) syndrome poses a risk for tachyarrhythmias and sudden cardiac death. Most WPW studies have relatively limited numbers of subjects and brief follow-up periods. METHODS: We reviewed records of 238 consecutive military aviators with WPW syndrome evaluated from 1955 to 1999. Follow-up was by questionnaires, telephone interviews, or death certificates. Events included sudden cardiac death and supraventricular tachycardia (SVT) (by electrocardiographic [ECG] documentation or suggestive symptoms). RESULTS: The mean age was 34.3 years (range 17-56 years). Forty-two (42/238, 17.6%) had SVT (WPW syndrome) and 196 of 238 (82.4%) had the WPW ECG pattern only. The mean follow-up of 21.8 years (range 2-41 years) was obtained on 228 of 238 (96%) for a total of 4906 patient-years. Sudden cardiac death occurred in 1 of 228, an incidence of 0.0002 per patient-year (95% confidence interval 0.0-0.001). SVT occurred in 47 of 228 (20.6%) or 0.01 per patient-year. One hundred eighty-seven (187/228, 82%) initially had the WPW ECG pattern only; 28 of 187 (15.0%) reported SVT during follow-up. Forty-one (41/228, 18%) initially had WPW syndrome; 19 of 41(46.3%) reported additional SVT during follow-up. CONCLUSION: Sudden cardiac death risk was low (0.02%/patient-year) in this WPW population. The SVT incidence was 1% per patient-year. Referral bias and some characteristics of the unique military aviator population may partly account for these low event rates. However, these results may be more applicable to unselected populations than are tertiary referral-based studies.

Nonsustained ventricular tachycardia in 193 U.S. military aviators: long-term follow-up.

BACKGROUND: Despite its importance to the aeromedical community, the occupational implications of asymptomatic, nonsustained ventricular tachycardia (VT) are not well described. We sought to clarify this issue via a review of military aviators evaluated for nonsustained VT by defining event rates for sudden cardiac death, syncope, presyncope and sustained VT, and by determining whether any cofactors predicted a subgroup at increased risk for such outcomes. METHODS: We reviewed the records of 193 military aviators evaluated at the U.S. Air Force Aeromedical Consultation Service for nonsustained VT from September 1960 to December 1992. Follow-up information was available on 192 of the 193 aviators over a mean of 10.6 yr. Cofactor analysis focused on idiopathic VT (no associated underlying cardiac disease) and VT associated with mitral valve prolapse (MVP). RESULTS: There was no documented sustained VT; 9 (4.6%) had events including syncope (1), presyncope (5) and sudden death (3). Of these 9, 4 had idiopathic VT. The 3 deaths were associated with coronary artery disease, MVP and cardiomyopathy. No cofactors predicted events in aviators initially presenting with asymptomatic nonsustained VT. For asymptomatic nonsustained VT, the maximum predicted annual event rate was 0.33% for idiopathic VT and 2.3% for VT with MVP (95% confidence limit). CONCLUSIONS: Nonsustained VT did not predict future documented sustained VT. Cofactors failed to predict a subgroup at increased risk for events. Idiopathic nonsustained VT appeared to be a low risk population for whom expanded waiver criteria are proposed with suggested limits on duration and number of episodes of VT.

Results of Holter monitoring U.S. Air Force aircrew with ectopy on 12-lead electrocardiograms.

PURPOSE: To evaluate the results of 24-h Holter monitoring performed on healthy U.S. Air Force aircrew with asymptomatic ectopy on resting electrocardiograms (ECG). METHODS: A historical review of the USAF Central ECG Library database was conducted on all Holter studies completed for evaluation of ECG ectopy between 1 Jan 86 and 31 Dec 97. Univariate and multivariate statistical analyses were performed to determine the association between ectopy and the aeromedical dispositions of aircrew evaluated for incidental ECG ectopy. RESULTS: During this period, 147,571 resting ECGs were submitted to the Aeromedical Consultation Service (ACS) for interpretation. The mean age of the subjects was 35 yr (range 19 to 57 yr). There were 480 24-h Holter studies performed for ECG ectopy. Of these, 49% had normal or normal variant findings; another 11% were found acceptable for flying after normal treadmill testing and echocardiography. ACS evaluation was required for the remaining 40% of subjects. Overall, 4% were permanently disqualified, and 17% were lost to follow-up. Excluding subjects lost to follow-up, 95% of aircrew were returned to flying status (with or without a waiver). CONCLUSIONS: When controlled for age, no significant difference of aeromedical outcome was seen when comparing supraventricular and ventricular ectopy. Of the subjects, 51% had abnormal Holter studies, but the vast majority were returned to flying. Results of this study provide information useful in further defining aircrew medical evaluation protocols for evaluation of asymptomatic ECG ectopy with Holter monitoring.

Case report of an aviator with a single episode of altered consciousness due to Hymenoptera hypersensitivity.

This case is presented to: a) emphasize the importance of a careful history, including interviewing witnesses and considering a complete differential diagnosis when evaluating aviators with a history of an episode of altered consciousness; and b) demonstrate an appropriate use of literature review, subspecialty consultations, and U.S. Air Force Aeromedical Guidelines to arrive at an aeromedical disposition for an unusual case. A military aviator experienced an episode of syncope/near syncope, initially felt to be caused by a primary seizure or an arrhythmia. Subsequent thorough evaluation included careful history taking, extensive interviewing of witnesses, subspecialty consultations, review of appropriate literature and deliberation by a board of experienced military aeromedical physicians. Cardiac and neurologic diagnoses were considered but careful history and witness interviews revealed that the aviator had sustained an insect sting just minutes before the episode. Evaluation by allergy specialists, including skin testing, identified him as being hypersensitive to Hymenoptera stings. A diagnosis of hypersensitivity reaction to a Hymenoptera sting was determined to be the cause of the altered consciousness episode. Review of the literature revealed that immunotherapy for Hymenoptera sensitivity reduces the risk of future anaphylaxis to only 1-2% after maintenance dose is achieved. Consideration of the risk of future events and the success of rush immunotherapy resulted in a recommendation for a waiver to return the aviator to unrestricted flying duties. The importance of diligent history taking must never be forgotten. In this aviator it led to the correct diagnosis and definitive therapy. In addition, appropriate consideration of the literature and knowledge of outcome rates allowed a return to unrestricted flying for this aviator. If the original diagnosis of seizure or arrhythmia had been accepted, this aviator would have been disqualified without waiver and a valuable flying asset would have been lost.

Percutaneous transluminal coronary angioplasty (PTCA): long-term outcome and aeromedical implications.

BACKGROUND: Currently U.S. Air Force aviators are permanently disqualified from all military flying duties after PTCA. HYPOTHESIS: We wondered if a low risk group of post-PTCA patients was identifiable from the literature, such that trained aviators who met the criteria for such a group could be safely returned to military flying duties. METHOD: We reviewed the PTCA literature from 1978-93 for long-term outcome (cardiac events) and patient characteristics that might affect outcome. Cardiac events were cardiac death, myocardial infarction (MI), and need for bypass surgery or repeat PTCA due to restenosis or progression of coronary artery disease (CAD). RESULTS: All patients were at risk for restenosis, the rate being highest in the first year post-PTCA (17-34%), and 10-40% of asymptomatic patients had restenosis. Noninvasive tests during the first 12 mo missed 25-54% of significant restenoses found by angiography. Beginning 1 yr after successful PTCA, cardiac event rates (excluding angina pectoris) were 2.4-4.1% yr, as opposed to < 1%/ yr (including angina) in our asymptomatic, untreated, mild-moderate CAD aviator population. The late annual event rate did not decline in over 5 yr of follow-up. Significant CAD progression in other sites or vessels occurred in 39-45% of asymptomatic patients by 5-8 yr; 13-43% of successful PTCA survivors were experiencing angina 3-6 yr post-PTCA. None of the following patient characteristics lowered the event rates: absence of symptoms before or after PTCA, PTCA in single-vessel disease, age < 40 at time of PTCA, post-PTCA lesion < or = 30%, and lack of prior MI. CONCLUSION: No low risk subgroup of patients or safe waiting period post-PTCA could be identified by literature review. We cannot recommend return to any type of military flying duties at any time after PTCA because of the significant and steady rate of serious cardiac events.

Medication-induced performance decrements: cardiovascular medications.

Clinicians may not give complete consideration to the occupational and recreational impact that prescribed medications can have on patients. Because cardiovascular disease is a major health problem that affects a large segment of the adult population in the United States, a significant portion of the adult work force may be expected to be under treatment with cardiovascular medications. Many may experience decrements in job performance as a result of such therapy. This article discusses the incidence and impact of occupationally relevant side effects of several categories of cardiovascular drugs, including beta blockers, calcium channel blockers, antiarrhythmics, vasodilators, nitrates, lipid-lowering agents, and diuretics.

Ventricular ectopy in totally symptom-free subjects with defined coronary artery anatomy.

Ambulatory ECG recordings were obtained from 313 consecutive, totally symptom-free male subjects on whom cardiac catheterization was subsequently performed for occupational reasons. These recordings were examined for ventricular ectopy and the results were studied in relation to the findings on selective coronary angiography. Ventricular ectopy was a common finding, with 58% of those subjects with normal coronary artery anatomy having at least one ventricular premature beat during the period of monitoring (mean 16 1/2 hours), 22% having greater than one such complex per hour, and 10% having greater than 10 per hour. Complex ventricular ectopy was present in 21% of the normal subjects. No association between the extent or complexity of ventricular ectopy and the presence or grade of anatomic coronary artery disease was demonstrated, nor was ventricular ectopy overrepresented in those with both significant coronary artery disease on angiography and evidence of ischemia on provocative testing.

Radioiodine therapy of hyperthyroidism precludes thallium-201 myocardial scintigraphy.

The authors attempted to perform Tl-201 myocardial perfusion scintigraphy in a 42-year-old man 23 and 35 days after he received 9.8 mCi of oral I-131 for documented Graves' disease. Interference from primary and scattered photons from residual thyroid I-131 made Tl-201 myocardial scintigraphy technically impossible. A series of phantom and patient studies using I-131 and Tl-201 were performed, yielding guidelines for planning Tl-201 myocardial scintigraphy following radioiodine therapy.

Comparison of sustained-release quinidines given twice daily to patients with ventricular ectopy.

To compare the steady-state kinetic profiles and ectopy-suppression rates of two sustained-release forms of quinidine with those of a conventional quinidine preparation, 18 patients with ventricular ectopy were studied in randomized crossover fashion. The drugs were conventional quinidine sulfate 300 mg q6h, sustained-release quinidine sulfate 600 mg q12h, and sustained-release quinidine gluconate 648 mg q12h. Following baseline electrocardiographic ambulatory monitoring, each drug was given for three days, with repeat ambulatory monitoring and serial plasma drug level determinations performed on the third day. There were no washout periods between treatments. Plasma quinidine levels were assayed by both enzyme multiplied immunoassay technique (EMIT) and quinidine-specific high-performance liquid chromatography (HPLC) methods. Using actual steady-state HPLC values, there were no differences in the area under the plasma concentration-time curve (AUC) among the three treatments; the dose-corrected AUC was greater for quinidine gluconate than for the other two preparations. Using EMIT values, mean plasma quinidine levels from the conventional quinidine sulfate regimen were greater during the last five hours of the 12-hour study interval. A consistently strong inverse relationship between EMIT plasma quinidine levels and hourly ectopy rates was present in only one of eight (13%) responders. Diurnal variation of quinidine kinetics was observed after two days of each treatment; trough values at midnight were slightly lower than trough values at noon. Among patients demonstrating at least 70% suppression of premature ventricular contractions (PVCs), there were no differences in ectopy rates or ectopy-suppression rates among treatments. Dosing sustained-release quinidine sulfate 600 mg or quinidine gluconate 648 mg q12h was clinically acceptable in the small number of responders studied.