Which indexes of filling behavior should be used to characterize left ventricular diastolic function when changes in heart rate and atrioventricular delay occur?
The routine use of the peak early-to-peak atrial velocity, early velocity integral-to-atrial velocity integral, and early velocity integral-to-the total filling velocity integral ratios are limited because they are influenced by heart rate and atrioventricular delay. Hence, we sought to establish whether these ratios could be normalized to account for the differences in cycle length (RR interval) and diastolic filling period when heart rate and atrioventricular delay were altered in 18 patients with programmable dual-chamber pacemakers. We further explored whether these and other parameters of the mitral velocity profile could be used to characterize the mitral filling pattern during isoproterenol and methoxamine infusions-interventions that are likely to change both heart rate and left ventricular filling. The early velocity integral-to-atrial velocity integral and early velocity integral-to-the total filling velocity integral ratios were more sensitive to minor variations in heart rate and atrioventricular delay than the peak early-to-peak atrial velocity ratio. The early velocity integral-to-atrial velocity integral and early velocity integral-to-total filling velocity integral ratios could not be normalized to account for differences in RR interval or diastolic filling period, whereas the peak early-to-peak atrial velocity ratio became less sensitive to changes in heart rate when it was divided by the RR interval, or diastolic filling period, or square root of diastolic filling period. Because the diastolic filling period is affected by atrioventricular delay independent of changes in the RR interval, these ratios were also corrected for the functional cycle length, defined as the interval from R-wave of the electrocardiogram to the end of the diastolic filling period. When corrected for either the functional cycle length or diastolic filling period or square root of diastolic filling period, only the peak early-to-peak atrial velocity ratio became less sensitive to variations in the atrioventricular delay. The ratio of diastolic filling period expressed as a proportion of RR interval or functional cycle length changed significantly when heart rate and atrioventricular delay were altered and did not improve when diastolic filling period was divided by the square root of RR or square root of functional cycle length. However, when the square root of diastolic filling period was divided by the RR interval or functional cycle length, the effects of heart rate and atrioventricular delay were not apparent. Of all the ratios, the ratio of square root of diastolic filling period expressed as a proportion of RR interval or functional cycle length was the most useful to differentiate the confounding effects of heart rate (+/-atrioventricular delay) from the effects of isoproterenol and methoxamine on left ventricular filling. Hence, this ratio appeared to be a heart rate- and atrioventricular delay-independent index of left ventricular diastolic function.
Meyer
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TE
Department of Cardiovascular Medicine, John Radcliffe Hospital, Worcester, MA, USA.
Casadei
B
B
Aurigemma
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GP
Gaasch
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WH
D000368:Aged; D016275:Atrial Function / Q000187:drug effects / Q000502:physiology; D001283:Atrioventricular Node / Q000187:drug effects / Q000502:physiology*; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology*; D002304:Cardiac Pacing, Artificial; D002316:Cardiotonic Agents / Q000494:pharmacology; D003971:Diastole / Q000187:drug effects / Q000502:physiology*; D015150:Echocardiography, Doppler; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006327:Heart Block / Q000503:physiopathology / Q000628:therapy; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D008875:Middle Aged; D008943:Mitral Valve / Q000187:drug effects / Q000502:physiology; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000503:physiopathology / Q000628:therapy; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*
D002316:Cardiotonic Agents; D014662:Vasoconstrictor Agents; D008729:Methoxamine; D007545:Isoproterenol