D. Mooney

Biochemical and functional abnormalities of left and right ventricular function after ultra-endurance exercise

Background: There is evidence that ultra-endurance exercise causes myocardial injury. The extent and duration of these changes remains unresolved. Recent reports have speculated that structural adaptations to exercise, particularly of the right ventricle, may predispose to tachyarrhythmias and sudden cardiac death. Objective: To quantify the extent and duration of post-exercise cardiac injury with particular attention to right ventricular (RV) dysfunction. Methods: 27 athletes (20 male, 7 female) were tested 1 week before, immediately after and 1 week after an ultra-endurance triathlon. Tests included cardiac troponin I (cTnI), B-type natriuretic peptide (BNP) and comprehensive echocardiographic assessment. Results: 26 athletes completed the race and testing procedures. Post-race, cTnI was raised in 15 athletes (58%) and the mean value for the entire cohort increased (0.17 vs 0.49 μg/l, p<0.01). BNP rose in every athlete and the mean increased significantly (12.2 vs 42.5 ng/l, p<0.001). Left ventricular ejection fraction (LVEF) was unchanged (60.4% vs 57.5%, p = 0.09), but integrated systolic strain decreased (16.9% vs 15.1%, p<0.01). New regional wall motion abnormalities developed in seven athletes (27%) and LVEF was reduced in this subgroup (57.8% vs 45.9%, p<0.001). RV function was reduced in the entire cohort with decreases in fractional area change (0.47 vs 0.39, p<0.01) and tricuspid annular plane systolic excursion (21.8 vs 19.1 mm, p<0.01). At follow-up, all variables returned to baseline except in one athlete where RV dysfunction persisted. Conclusion: Myocardial damage occurs during intense ultra-endurance exercise and, in particular, there is a significant reduction in RV function. Almost all abnormalities resolve within 1 week.

Effect of Heart Rate on Tissue Doppler Measures of Diastolic Function

Background: Our aim was to study the independent effect of heart rate (HR) on parameters of diastolic function, particularly mitral annular velocities measured by tissue Doppler imaging (TDI), an effect which is not well understood. Methods: Sixteen patients with dual chamber pacemakers attending for routine pacemaker review underwent detailed echocardiographic assessment during atrial pacing with intact atrioventricular conduction at baseline and accelerated HRs. Mitral inflow and annular tissue Doppler velocities and systolic strain parameters were compared. Results: Parameters of systolic function were unaffected by increased HR. When these parameters were compared at baseline (mean 67 bpm) and accelerated HR (mean 80 bpm), the following was observed: a significant decrease in early mitral inflow (E) wave (70.5 ± 5.5 cm/s vs 63.5 ± 4.9 cm/s, P < 0.02) and early mitral annular (E′) velocities (7.0 ± 0.5 cm/s vs 6.3 ± 0.6 cm/s, P < 0.003) and a significant increase in mitral inflow A wave (70.3 ± 4.5 cm/s vs 77.3 ± 4.4 cm/s, P < 0.05) and late mitral annular (A′) velocities (9.3 ± 0.6 cm/s vs 10.8 ± 0.5, P < 0.00004). Conclusion: Changes in HR have previously unrecognized significant effects on tissue Doppler parameters of diastolic function. Further study is required to determine if tissue Doppler derived annular velocities should be corrected for HR.

Is there still a role for the classical Cox-Maze III?

Background:  The incidence of surgery for atrial fibrillation (AF) is rising, paralleled by an increase in the types of lesion sets and energy sources used. These alternate energy sources have simplified the surgery at the expense of increased cost of consumables. The classical Cox‐Maze III is the gold standard therapy with a proven efficacy in curing AF. Our complete experience with this procedure is presented.

Transit of micro-bubbles through the pulmonary circulation of Thoroughbred horses during exercise

It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with lower pulmonary artery pressures, enhanced right ventricular function and greater exercise capacity. In the exercising Thoroughbred horse, extraordinarily high cardiac outputs exert significant pulmonary vascular stresses. The aim of this study was to determine, using contrast echocardiography, whether Thoroughbred horses performing strenuous exercise developed pulmonary transit of agitated contrast microbubbles (PTAC). At rest, agitated contrast was observed in the right ventricle, but not in the left ventricle. However, post-exercise microbubbles were observed in the left ventricle, confirming the occurrence of PTAC with exercise but not at rest. Further investigation is warranted to investigate whether this phenomenon may be associated with superior physiology and performance measures as has been implicated in other species.