John P. Finley

Heart rate variability in infants, children and young adults

Heart rate variability was studied in normal subjects age 1 month-24 years while awake and in active and quiet sleep using 24 h continuous recordings of the ECG. Variability was quantified by spectral analysis for the two frequency bands: low frequency (LF) 0.03-0.15 Hz, high frequency (HF) 0.15-0.6 Hz. Heart rate variability showed an age dependence, being in general an increase in LF, HF and total power from 0-6 years, followed by a decrease to 24 years. The infant group showed some exceptions to this trend. Developmental changes of parasympathetic and sympathetic mediation of heart rate are postulated as important determinants of age dependence of heart rate variability.

Echocardiography by telephone—Evaluation of pediatric heart disease at a distance

A 24-hour telephone transmission service was established for pediatric echocardiography between a general hospital and a childrens hospital 500 km distant. Studies were transmitted in real time for interpretation and diagnosis by a pediatric cardiologist. In the first 9 months of operation, studies were transmitted for 18 children with a median age of 5 months. Image and sound quality was excellent. Complete segmental diagnosis was made in 16 patients, and further study was needed in 2 others. In 8 of the 18 patients a new diagnosis was provided, and in 10 patients diagnosis was confirmed. Congenital heart disease was found in 12 patients, other heart disease in 2 and a normal heart in 4. The population included 2 fetuses whose echocardiograms showed hypoplastic left heart and intracardiac tumor. In 4 patients transport was avoided. This is the first report of echocardiographic transmission by telephone, which was shown to be clearly feasible, cost-effective and diagnostic. It provides emergency access to specialist expertise, and may avoid hazardous and expensive transport of ill children.

Thallium-201 myocardial imaging in anomalous left coronary artery arising from the pulmonary artery: Applications before and after medical and surgical treatment

Thallium-201 myocardial imaging was performed on six patients with an anomalous left coronary artery arising from the pulmonary artery. Initial images in three children (aged 4 months, 12 months and 2 1/2 years, respectively) demonstrated anterolateral perfusion defects in agreement with the electrocardiographic localization of infarction. Repeat imaging in two patients 2 to 3 months later, after clinical improvement with anticongestive therapy, demonstrated a reduction in the perfusion defect. In 3 other patients (aged 16, 16 and 20 years, respectively) thallium-201 scans performed during exercise stress demonstrated normal myocardial perfusion 7 to 15 years after operation (ligation of anomalous left coronary in two, ligation plus bypass graft in one). Thallium-201 imaging appears to be helpful in monitoring changes in myocardial perfusion before and after medical or surgical treatment of an anomalous left coronary artery, and may shed light on the pathophysiology of the defect. A possible practical limitation of thallium-201 imaging in this condition is the difficulty of imaging subendocardial infarction.

Heart rate response to tilting in newborns in quiet and active sleep.

The heart rate response to tilting was investigated in active and quiet sleep in 19 normal newborns (age 1-7 days) and 11 healthy premature infants (age 2-19 days). RR intervals were determined by computer from the ECG for 30-60 s periods immediately before and after each tilt. Term infants had a significant (p less than 0.005) decrease in RR interval for head-up tilting and significant (p less than 0.005) increase in RR with head down tilts. There was no significant difference in the magnitude of RR change between upward and downward tilt or between active and quiet sleep. For premature infants, the response to tilting was similar to that of the term infants, especially with allowance for the faster heart rates of the former. Respiratory rate changes were an important source of variability in the heart rate response to tilting and are likely the source of previous inconsistencies. Our results indicate that healthy newborns have a well-developed heart rate response to tilting, suggesting considerable maturity of neural control of heart rate.

A case series of systemic right ventricular dysfunction post atrial switch for simple D-transposition of the great arteries: the impact of beta-blockade.

BACKGROUND Patients with atrial switch (Mustard or Senning) repair of D-transposition of the great arteries (D-TGA) are at increased risk for atrial arrhythmias, systemic right ventricular (RV) dysfunction and late mortality. OBJECTIVES To evaluate case series from a single-centre experience with beta-blocker use in adult, post atrial switch, simple D-TGA patients. METHODS The Adult Congenital Heart Disease Clinic (Halifax, Nova Scotia) database was used to identify patients with post atrial switch, simple D-TGA. Treatment effect of beta-blockade was evaluated. RESULTS Eight patients were treated with beta-blockers for systemic RV dysfunction (n=2), arrhythmia (n=2) or both (n=4). Median follow-up was three years, at which time seven of eight patients were still on beta-blockade. Of those patients with complete data, two of five had improved systemic ventricular dysfunction, two of four had improved tricuspid regurgitation and four of six had improved functional capacity, as determined by history or exercise testing. Beta-blockade was well tolerated in seven of eight patients without any significant clinical deterioration. CONCLUSIONS Beta-blockade was used infrequently in patients with a prior Mustard procedure. When beta-blockade was prescribed to patients with a prior atrial switch procedure, the drugs were well tolerated and were associated with trends toward improved symptoms, less tricuspid regurgitation and improved functional status in patients with reduced systemic RV function. These data support the need for a randomized trial of beta-blockade in patients with a previous Mustard or Senning operation and RV dysfunction.

An incremental cost analysis of telehealth in Nova Scotia from a societal perspective

We examined the costs of telehealth in Nova Scotia from a societal perspective. The clinical outcomes of telepsychiatry and teledermatology services were assumed to be similar to those for conventional face-to-face consultations. Cost information was obtained from the Nova Scotia Department of Health, the Canadian Institute for Health Information, and questionnaires to patients, physicians and telehealth coordinators. There were 215 questionnaires completed by patients, 135 by specialist physicians and eight by telehealth coordinators. Patient costs for a face-to-face consultation ranged from

Assessing Children’s Heart Sounds at a Distance With Digital Recordings

240 to

Cardiac rhythm, rate and ventricular repolarization properties in infants at risk for sudden infant death syndrome: Comparison with age- and sex-matched control infants☆

1048 (all costs in Canadian dollars), whereas patient costs for telehealth were lower, from

Spectral Analysis of Periodic and Nonnal Breathing in Infants

17 to

Periodic Breathing in Infants: A Model Study

70. However, from a societal perspective, the overall cost of providing face-to-face services was lower than for telehealth: the total costs for face-to-face services ranged from