Effects of Postischemic Regional Left Ventricular Diastolic Wall Motion Abnormalities or Delayed Relaxation Following Coronary Vasospasm on Global Diastolic Function

Evaluation of left ventricular diastolic function by fractional area change using cine cardiovascular magnetic resonance: a feasibility study

BACKGROUND

Evaluation of left ventricular (LV) diastolic function is essential for the management of heart failure. We verified whether LV diastolic function could be evaluated by measuring the fractional area change (FAC) using cine cardiovascular magnetic resonance (CMR).

METHODS

We collected clinical data from 59 patients who underwent echocardiography and cine CMR. Normal, impaired relaxation, pseudonormal, and restrictive LV filling were observed in 15, 28, 11, and 5 patients, respectively. We calculated FAC during the first 30% of diastole (diastolic-index%) in the short-axis view, by tracing the contours on only three MR cine images.

RESULTS

The diastolic index was significantly lower (p < 0.0001) in patients with impaired relaxation (32.4 ± 7.5), pseudonormal filling (25.4 ± 5.6), and restrictive filling (9.5 ± 1.5) compared to those with normal diastolic function (67.7 ± 10.8), and the index decreased significantly with worsening of diastolic dysfunction. The diastolic index correlated positively with early diastolic mitral annular velocity measured by tissue Doppler imaging (r = 0.75, p < 0.0001), respectively.

CONCLUSIONS

Measurement of FAC can be useful for the evaluation of LV diastolic function using cine CMR.

Fluorouracil Induces Myocardial Ischemia With Increases of Plasma Brain Natriuretic Peptide and Lactic Acid but Without Dysfunction of Left Ventricle

Purpose

Fluorouracil (FU) is a cornerstone of colorectal cancer treatment; however, it has clinical and subclinical influence on the heart. This study aimed to clarify the pathophysiology, risk factors, and long-term effects of FU cardiotoxicity.

Patients and Methods

The study prospectively accrued colorectal cancer patients (n = 106) completely resected and adjuvantly treated with FU and oxaliplatin according to the FOLFOX4 regimen (infusional FU, folinic acid, and oxaliplatin). Serial measurements were made of systolic and diastolic features of the left ventricle by radionuclide ventriculography, plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), lactic acid, and ECG before chemotherapy, immediately after a treatment infusion, and at follow-up 2 weeks after cessation of the intended 12 treatment courses and were further evaluated by multivariate regression analysis that included cardiovascular history and its risk factors.

Results

In the entire cohort, NT-proBNP significantly increased from baseline 14.5 ± 3.2 pmol/L (mean ± standard error) to 28.3 ± 5.3 pmol/L during FU therapy (P < .001). Nine patients (8.5%) with cardiotoxicity had significantly higher NT-proBNP of 55.3 ± 40.8 pmol/L compared with 25.4 ± 4.1 pmol/L in those without (P < .001). In multivariate analysis, the FU-induced rise of NT-proBNP was significantly higher in females (P < .001). Plasma lactic acid significantly increased from baseline (1.3 ± 0.1 mmol/L to 1.8 ± 0.1 mmol/L) during FU therapy (P < .001). Left ventricular ejection fraction at baseline of 0.66 ± 0.01 remained unchanged at 0.65 ± 0.01 during FU therapy and 0.66 ± 0.01 at follow-up (P = .4).

Conclusion

FU therapy generally induces myocardial neuroendocrine changes with increasing plasma NT-proBNP and lactic acid but without long-term dysfunction of the left ventricle. The usability of NT-proBNP as a predictive marker for FU cardiotoxicity remains to be clarified.

Relationship between exercise capacity and cardiac diastolic function assessed by time-volume curve from 16-frame gated myocardial perfusion SPECT

OBJECTIVE

Echocardiographic studies have suggested an association between diastolic dysfunction and exercise intolerance. The aim of this study was to examine the relationship between exercise capacity and left ventricular (LV) function during stress myocardial scintigraphy, and to investigate whether or not this relationship is caused by ischemia during exercise.

METHODS

The studied patients underwent technetium-99m sestamibi quantitative gated SPECT, including treadmill exercise. Myocardial stress images were acquired 30 min after the first tracer injection (370 MBq) during maximal exercise. Three hours later, the second tracer (740 MBq) was injected, and resting images were acquired 30 min after this injection. The presence of ischemia was determined by tracer accumulation. From the same data source, LV diastolic parameters [first third filling fraction (1/3FF), first third filling rate (1/3FR), peak filling rate (PFR) and time to PFR (TPF)], and systolic parameters [ejection fraction (EF), peak ejection rate (PER), time to PER (TPE) and first third ejection fraction (1/3EF)] were analyzed.

RESULTS

Subjects with exercise inability (<6 METs) were excluded. In 45 patients, diastolic parameters 1/3FF, 1/3FR, PFR and TPF correlated significantly with exercise duration (r = 0.32*, 0.37*, 0.37* and -0.40(#), respectively; *p < 0.05, (#) p < 0.01), but systolic parameters EF, PER, TPE and 1/3EF did not. At rest, 1/3FF, PFR and PER were significantly increased, suggesting functional deterioration during exercise. Even after 3 h, 1/3FR, PFR and TPF still correlated significantly with exercise duration (r = 0.29*, 0.36* and -0.30*, respectively; *p < 0.05). Such findings were observed even when the 10 patients who exhibited ischemia during exercise were excluded (1/3FR: r = 0.34*; PFR: r = 0.37*; TPF: r = -0.36*; *p < 0.05, n = 35).

CONCLUSIONS

Our findings suggested that LV diastolic dysfunction, not systolic dysfunction, is associated with limited exercise capacity independent of the occurrence of ischemia.

Assessment of left ventricular diastolic function using color kinesis: differentiation between normal and pseudonormalized patterns

PURPOSE

Doppler examination of transmitral flow has been widely used to noninvasively assess left ventricular (LV) diastolic function. However, it has been demonstrated that transmitral flow velocity is dependent on LV relaxation and left atrial pressure. Increases in left atrial pressure compensate for the effects of impaired LV relaxation, frequently resulting in a "pseudonormalization" of the transmitral flow pattern. The purpose of this study was to assess whether analysis of diastolic color kinesis (CK) can be applied to differentiation between normal and pseudonormalized (PN) patterns of LV inflow.

METHODS

We studied 60 subjects with a ratio of early to late transmitral peak velocities (E/A) greater than 1.0 according to conventional Doppler echocardiography. All subjects simultaneously underwent measurement of the early diastolic mitral annular velocity (e'), which was measured by tissue Doppler imaging, and LV ejection fraction (EF), which was calculated by the modified Simpson method. Study subjects were classified into the following three groups according to the value of e' and EF: (1) the normal group (e' > 10 cm/s, EF > 60%), including 20 subjects (mean age 35 ± 10 years); (2) the PN1 group (e' < 7 cm/s, EF > 50%), consisting of 20 patients [mean age 63 ± 11 years, 15 patients with hypertensive heart disease (HHD), 5 patients with aortic valve stenosis]; and (3) the PN2 group (e' < 7 cm/s, EF < 50%), consisting of 20 patients (mean age 61 ± 17 years, 18 patients with dilated cardiomyopathy, 2 patients with HHD). Diastolic CK images were obtained for each subject from the LV midpapillary short-axis view. Analysis of CK diastolic images was performed using ICK software. The CK-diastolic index (CK-DI) was defined as the calculated LV segmental filling fraction during the first 30% of diastole, expressed as a percentage. The mean CK-DI was determined from the average CK-DI of six LV segments.

RESULTS

The mean CK-DI was 70.9% ± 6.5% in the normal group, 46.3% ± 10.4% in the PN1 group, and 36.3% ± 5.1% in the PN2 group. The mean CK-DI was significantly reduced in the PN1 and PN2 groups compared with the normal group (P < 0.0001). Although there was no difference in e' (PN1 group: 4.6 ± 1.8 cm/s, PN2 group: 4.4 ± 1.7 cm/s) between the two pseudonormalized patient groups, the mean CK-DI was significantly reduced in the PN2 group compared with the PN1 group (P < 0.005). The reduction in mean CK-DI was seen not only in pseudonormalized patients with LV systolic dysfunction but also in those with preserved LV systolic function.

CONCLUSION

The analysis of diastolic CK with ICK software is a useful method for detecting delayed early diastolic relaxation. We concluded that diastolic CK images may be applied to differentiating between normal and pseudonormalized patterns of LV inflow.

Clinical significance of diastolic function as an indicator of myocardial ischemia assessed by 16-frame gated myocardial perfusion SPECT

OBJECTIVE

Studies have suggested that ischemia-induced diastolic dysfunction persists longer than systolic dysfunction. We examined whether global left ventricular (LV) diastolic function during stress testing assessed by 16-frame gated myocardial perfusion single-photon emission computed tomography (SPECT) is useful as an indicator of myocardial ischemia.

METHODS

Thirty-nine patients underwent 16-frame technetium-99m (Tc-99m) quantitative gated SPECT (QGS), including treadmill exercise testing for suspected ischemic heart disease. Diastolic parameters of the first-third filling fraction (1/3FF), and the peak filling rate (PFR) were calculated by a time-volume curve from the QGS data.

RESULTS

The patients were divided into four groups, namely, IS, NL, DN, and DD, on the basis of tracer accumulation and the LV ejection fraction (LVEF) at rest. In the IS group (reversible tracer uptake reduction suggesting ischemia; n=11), LVEF, 1/3FF, and PFR after stress were significantly lower than those at rest, whereas in the NL group (normal perfusion; n=10) and DN group (fixed tracer uptake reduction with normal systolic function; EF>or=60% at rest; n=10), LVEF, 1/3FF, and PFR after stress did not differ from those at rest. However, in the DD group (fixed tracer uptake reduction with cardiac dysfunction; EF<60%, average 47.1%; n=8), LVEF, 1/3FF, and PFR were significantly altered after stress.

CONCLUSIONS

Altered global LV diastolic function during stress assessed by 16-frame gated myocardial perfusion SPECT is useful for the detection of myocardial ischemia. However, similar findings are observed in patients with cardiac dysfunction but without detectable ischemia. Our findings do suggest that tests should be performed with caution to determine whether ischemia exists on the basis of altered global LV function after stress in patients with cardiac dysfunction.

Cross-Bridge-Dependent Change of the Ca2+ Sensitivity During Relaxation in Aequorin-Injected Tetanized Ferret Papillary Muscles

BACKGROUND The aim of the present study was to indicate the cross-bridge-dependent change in the Ca2+ affinity of troponin-C (TnC) during relaxation in an intact preparation, because the intracellular mechanism of relaxation is not fully understood, although several methods of evaluating global diastolic function have been reported.

METHODS AND RESULTS

The aequorin method was used with intact ferret papillary muscles and a tetanic contraction was induced by a repetitive electrical stimulation in the presence of ryanodine. The extra-Ca2+, the transient increase in the intracellular Ca2+ concentration in response to a rapid reduction in muscle length, which reflects the change in the Ca2+ affinity of TnC because of cross-bridge detachment, was measured, and the cross-bridge-dependent change in the Ca2+ affinity of TnC was estimated by observing the change in the slope of the extra-Ca2+ -tension relation. The extra-Ca2+ -tension relation measured during relaxation became steeper than that during contraction in all cases. The extra-Ca2+ -tension relation became steeper in the presence of 20 mmol/L caffeine during contraction in all cases.

CONCLUSION

During relaxation, the downstream-dependent change in the Ca2+ affinity of TnC was enhanced, compared with that during contraction, because of a decrease in the number of attached cross-bridges.