Effect of coronary microvascular dysfunction on cardiac mechanical indices in patients with non-obstructive coronary artery disease / 中华超声影像学杂志

Objective:To investigate the effect and relationship of coronary microvascular dysfunction (CMD) on cardiac mechanical indices in patients with non-obstructive coronary artery disease(NOCAD) in the resting state.Methods:This study was a single-center retrospective study. Seventy-nine NOCAD patients who hospitalized in Qilu Hospital of Shandong University from July 2017 to March 2022 were recruited. All patients underwent conventional echocardiography examination and the examination of coronary flow velocity reserved by transthoracic Doppler echocardiography (TTDE-CFVR). Based on the results of TTDE-CFVR, patients were divided into CMD group (CFVR<2.5, 32 cases) and a control group (CFVR≥2.5, 47 cases). Clinical data, routine echocardiographic parameters, regional mechanical indices including regional myocardial work index(RWI) and regional longitudinal strain(RLS), global mechanical indices including left ventricular global longitudinal strain(GLS), global longitudinal strain in the endocardial layer(GLS-endo), global longitudinal strain in the epicardial layer(GLS-epi), left ventricular global work index(GWI), global contractive work(GCW), global waste work(GWW), global work efficiency(GWE) were compared between two groups. Binary logistic regression was used to analyze the risk factors of CMD. ROC curve was used to construct a prediction model for CMD.Results:There was no significant difference in sex ratio, BMI, smoking history, diabetes, hypertension and dyslipidemia between CMD group and control group. Age was significantly higher in the CMD group than in the control group. RWI, GWI, GCW, GWE and the absolute values of RLS, GLS, GLS-endo and GLS-epi were significantly lower in the CMD group than in the control group. Logistic regression analysis showed that the decrease of absolute value of GLS was an independent risk factor for the CMD( OR=1.335, 95% CI=1.041-1.713, P=0.023). ROC curve showed that myocardial strain-related indexes had a good decrease value for the CMD. Conclusions:For patients with NOCAD, the presence of CMD is associated with the decrease of left ventricular regional and global systolic function.

Reserva de Velocidade de Fluxo Coronariano durante o Ecocardiograma sob Estresse com Dobutamina / Coronary Flow Velocity Reserve during Dobutamine Stress Echocardiography

Fundamento: A reserva de velocidade de fluxo coronariano (RVFC) ≥ 2 é adequada para inferir bom prognóstico ou ausência de coronariopatia importante. Objetivo: Identificar parâmetros relevantes na obtenção da RVFC (adequada ou inadequada) na descendente anterior (ADA), durante o ecocardiograma sob estresse com dobutamina (EED). Métodos: Avaliação de 100 pacientes encaminhados para pesquisa de isquemia miocárdica através do EED, orientados para suspender o betabloqueador 72 horas antes do exame. Calculou-se a RVFC pela divisão do pico de velocidade (cm/s) diastólica (PVD) verificado no EED (PVD-EED) pelo de repouso (PVD-REP). No grupo I, a RVFC < 2 e no grupo II a RVFC ≥ 2. Foram utilizados o teste t de Student e o exato de Fisher. Significância estatística quando p < 0,05. Resultados: Em repouso, o tempo (segundos) para obter o Doppler na ADA nos grupos I e II não diferiu (53 ± 31 vs. 45 ± 32; p = 0,23). No EED, registrou-se a ADA em 92 pacientes. O grupo I evidenciou pacientes mais velhos (65,9 ± 9,3 vs. 61,2 ± 10,8 anos; p = 0,04), menor fração de ejeção (61 ± 10 vs. 66 ± 6%; p = 0,005), maior PVD-REP (36,81 ± 08 vs. 25,63 ± 06 cm/s; p < 0,0001) e menor RVFC (1,67 ± 0,24 vs. 2,53 ± 0,57; p < 0,0001), entretanto o PVD-EED não diferiu (61,40 ± 16 vs. 64,23 ± 16 cm/s; p = 0,42). A suspensão do betabloqueador associou-se à chance 4 vezes maior de ocorrer RVFC < 2 (OR = 4; 95% IC [1,171 - 13,63], p = 0,027). Conclusão: O PVD-REP foi o principal parâmetro para determinar uma RVFC adequada. A suspensão do betabloqueador associou-se significativamente com RVFC inadequada. A elevada exequibilidade e o tempo para registro da ADA favorecem a utilização dessa metodologia. .

Background: A coronary flow velocity reserve (CFVR) ≥ 2 is adequate to infer a favorable prognosis or the absence of significant coronary artery disease. Objective: To identify parameters which are relevant to obtain CFVR (adequate or inadequate) in the left anterior descending coronary artery (LAD) during dobutamine stress echocardiography (DSE). Methods: 100 patients referred for detection of myocardial ischemia by DSE were evaluated; they were instructed to discontinue the use of β-blockers 72 hours prior to the test. CFVR was calculated as a ratio of the diastolic peak velocity (cm/s) (DPV) on DSE (DPV-DSE) to baseline DPV at rest (DPV-Rest). In group I, CFVR was < 2 and, in group II, CFVR was ≥ 2. The Fisher's exact test and Student's t test were used for the statistical analyses. P values < 0.05 were considered statistically significant. Results: At rest, the time (in seconds) to obtain Doppler in LAD in groups I and II was not different (53±31 vs. 45±32; p=0.23). During DSE, LAD was recorded in 92 patients. Group I patients were older (65.9±9.3 vs. 61.2±10.8 years; p=0.04), had lower ejection fraction (61±10 vs. 66±6%; p=0.005), higher DPV-Rest (36.81±08 vs. 25.63 ± 06cm/s; p<0.0001) and lower CFVR (1.67 ± 0.24 vs. 2.53 ± 0.57; p<0.0001), but no difference was observed regarding DPVDSE (61.40±16 vs. 64.23±16cm/s; p=0.42). β-blocker discontinuation was associated with a 4-fold higher chance of a CFVR < 2 (OR= 4; 95% CI [1.171-13.63], p=0.027). Conclusion: DPV-Rest was the main parameter to determine an adequate CFVR. β-blocker discontinuation was significantly associated with inadequate CFVR. The high feasibility and the time to record the LAD corroborate the use of this methodology. .

Assessment of Coronary Flow Velocity Reserve by Noninvasive Transthoracic Doppler Echocardiography in Patients with Angiographically Normal Coronary Arteries / 华中科技大学学报（医学）（英德文版）

The measurement of coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) with invasive intracoronary Doppler flow wire technique (ICD) was validated and the pathologicalfactors which influence CFVR in patients with angiographically normal coronary arteries were analyzed. CFVR was determined successfully in left anterior descending artery (LAD) in 37 of 40 patients with angiographically normal coronary arteries (men 22, women 15, age 20-75 years, mean age 54 ± 12 years). Coronary flow velocity was measured in the distal LAD by TTDE with contrast enhancement at baseline and during intravenous adenosine infusion of 140 μg/kg per min within 48 h after ICD technique. Average peak velocity at baseline (APVb), average peak velocity during hyperemia (APVh) and CFVR determined from TTDE were correlated closely with those from ICD measurements (APVb: y=0. 64x+5. 04, r=0. 86, P＜0. 001;APVh: y=0.63x+14.36, r=0.82, P＜0.001; CFVR: y=0.65x+0.92, r=0.88, P＜0. 001).For CFVR measurements, the mean differences between TTDE and ICD methods were 0. 12 ±0.39. CFVR in patients with history of hypertension was significantly lower than that in patients without history of hypertension (P＜0.05). Intravascular ultrasound (IVUS) was performed in 34patients. Plaque formation was found in LAD by IVUS in 17 (50 %) patients. No significant difference in CFVR was found between the patients without plaque formation (3. 11±0. 49) and those with plaque formation (2. 76±0.53, P=0. 056). It is suggested that TTDE with contrast enhancement provides reliable measurement of APV and CFVR in the distal LAD. The early stage of atherosclerosis could be detected by IVUS, which may be normal in angiography. CFVR is impaired in patients with history of hypertension compared with that in patients without history of hypertension.

Assessment of coronary artery stenosis with intracoronary Doppler guide wire and modified continuity equation method ; A comparison with dipyridamole stress Thallium-201 SPECT

BACKGROUND: Previous studies of animal and human experiments have shown excellent correlation between true or angiographic stenosis severity and stenosis severity calculated from intracoronary Doppler flow measurements and continuity equation method. However, there remains practical problems to be solved on its clinical application. To minimize these problems, the concept of modified continuity equation method, calculating the percent area stenosis by comparing the maximal in-stenosis flow velocity to the distal reference flow velocity, was introduced and compared with dipyridamole stress thallium-201 SPECT. METHODS: In this prospective study, 102 patients (mean age 57+/-10 years, 69 men, 33 women) with coronary artery stenoses ranging from 23-89% in percent diameter stenosis, who received coronary angiography, dipyridamole stress thallium-201 SPECT, and successful intracoronary flow velocity measurements were included. Modified continuity equation method and distal coronary flow velocity reserve were compared to the result of dipyridamole stress thallium-201 SPECT and quantitative coronary angiography. RESULTS: Measurements of adequate intralesional and stenosis distal flow velocities were successful in 102 out of 106 stenoses (96%). Minimal luminal area and percent area stenosis calculated from modified continuity equation method showed significant correlations with those of quantitative coronary angiography. Modified continuity equation method significantly underestimated the severity of stenosis than quantitative coronary angiography did. The test accuracy in relation to the result of dipyridamole stress thallium-201 SPECT were 91% in modified continuity equation method, 80% in quantitative coronary angiography and 63% in distal coronary flow velocity reserve. CONCLUSION: Application of intracoronary Doppler guide wire and modified continuity equation method appears to provide useful on-site implications for the anatomic and functional assessment of coronary artery stenosis. The modified continuity equation method would be one of the promising concepts for clinical decision making during coronary interventions.

Coronary Flow Velocity Pattern in Patients with Myocardial Bridging of Coronary Artery

Myocardial bridging is a systolic compression(milking effect) of mainly the left anterior descending coronary artery with coronary angiography. This phoenomenon is known to occur when a segment of an artery travels through the myocardium. The function significance of this finding remains controversial. We identified angiographic systolic compression of the coronary artery in two patients and documented the coronary flow velocity patterns and coronary flow velocity reserve with intracoronary injection of adenosine. The intracoronary flow velocity patterns distal to the myocardial bridging segment of the left anterior descending artery show the attenuated systolic component and abnormal diastolic flow velocity pattern with the exaggerated early acceleration, a diastolic spike and dome shape of coronary flow. The coronary flow velocity reserve was reduced.