Septal Flash-like Motion of the Earlier Activated Ventricular Wall Represents the Pathophysiology of Mechanical Dyssynchrony in Single-Ventricle Anatomy
Hayama Y, Miyazaki A, Ohuchi H, Miike H, Negishi J, Sakaguchi H, Kurosaki K, Shimizu S, Kawada T, Sugimachi M.
J Am Soc Echocardiogr. 2020 Feb 20. pii: S0894-7317(19)31183-6. doi: 10.1016/j.echo.2019.11.016. [Epub ahead of print]
PMID: 32089381
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Take Home Point:
- In patients with single ventricle physiology and a prolonged QRS, early shortening and paradoxical post systolic stretch are associated with poorer clinical state according to greater BNP and reduced peak VO2.
Commentary from Dr. Helen Parry (Leeds UK), section editor of ACHD Journal Watch:
Aim:
To assess whether dyssynchrony of contraction has clinical consequences in univentricular hearts
Methods:
Inclusion criteria:
- Post op Glenn or Fontan
- Prolonged QRS defined as z score >=2 in patients under 18 or >120ms in patients 18 or over
- Regular R-R interval
- Good echo windows
Patients fulfilling these criteria had echocardiography with strain, focusing on the apical view that included the aorta, the free wall of the dominant/ apex forming ventricle and its opposite wall/ septal remnant.
AV valve and aortic valve opening and closure times were assessed using pulsed wave Doppler. Strain studies (GLS) were then performed on the 2 walls as divided above.
Strain ratio (Rs) was used to quantify early shortening followed by post systolic paradoxical stretch – Rs= (100+ GLS at aortic valve closure)/(100+ GLS at aortic valve opening)
BNP was measured in all patients and exercise testing was undertaken where possible to allow comparison between degree of dyssynchrony and clinical status.
6 patients underwent CRT for heart failure symptoms refractory to medical management
Results:
70 patients were enrolled. 25 were female.
Time to peak strain of the earlier activated wall was associated with BNP levels (p<0.001). Strain ratio was associated with both BNP and peak VO2 (p<0.001 for both). There were no statistically significant associations between BNP and peak VO2 and either time to peak strain or strain ratio of the later activated wall.
Patients who underwent CRT had improvement in dyssynchrony quantified by improved strain ratio as above.
Discussion:
The authors conclude that early shortening and paradoxical post systolic stretch are associated with poorer clinical state according to greater BNP and reduced peak VO2.
Strengths of the study:
- Novel
- Clear strategy for assessment of dyssynchrony in single ventricle physiology outlined
- Pathophysiology seems logical
Weaknesses:
- The number of patients undergoing CRT was too small to draw any conclusion
- Single centre study
- GLS on Phillips machine- specific to this machine and cannot be compared with other manufacturers
- Many patients with single ventricle physiology do not have good enough transthoracic windows for strain
