Effects of exerimental right ventricular hypertrophy on myocardial blood flow in conscious dogs.

The effects of right ventricular hypertrophy on the overall and regional distribution of myocardial blood flow in the absence of an elevated coronary arterial driving pressure were evaluated in 18 concscious dogs subjected to a chronic pressure overload of the right ventricle induced by pulmonary artery constriction. The sustained pressure overload for duration of 4--6 wk or 4--5 mo resulted in significant increases in right ventricular mass (45 and 110%, respectively) and right ventricular fiber diameter (22 and 60%, respectively). Moreover, the presence of moderate and severe hypertrophy was associated with marked increases in transmural blood flow per gram to the right ventricle proportional to the observed increases in mass, i.e., of 36 and 109%, respectively, from a normal value of 0.67 +/- 0.04 ml/min per g, whereas left ventricular blood flow remained unaltered from a normal value of 1.00 +/- 0.06 ml/min per g. Despite the large increase in blood flow per gram to moderately and severely hypertrophied right ventricle, no significant changes in the ratio of capillary:muscle fiber number were observe. These data suggest that the development of right ventricular hypertroph is characterized by a sustained compensatory response of the coronary circulation to the augmented work load and mass, and that is not associated with a proliferative response of the vasculature supplying the enlarged ventricle.     

The effects of atrial fibrillation on coronary blood flow and performance of ischaemic myocardium in dogs with coronary artery stenosis

1. Atrial fibrillation may impair coronary blood flow by tachycardia and reflex vasoconstriction. It has not been documented, however, whether in the presence of coronary stenosis atrial fibrillation exceeds the effects of rhythmic atrial tachycardia. 2. The effects of experimentally induced atrial fibrillation compared with atrial tachycardia, therefore, were tested in 22 anaesthetized dogs. Stenosis of the left anterior descending coronary artery was induced to reduce coronary blood flow by about 40%. 3. In the presence of coronary stenosis, atrial fibrillation (ventricular rate: 234 +/- 21 beats/min) reduced coronary blood flow from 58 +/- 7 to 44 +/- 8 ml min-1 100 g-1 (P less than 0.001, mean +/- SEM) and subendocardial segment shortening (ultrasonic crystals) from 12 +/- 2 to 4 +/- 2% (P less than 0.0025), and resulted in a lactate production of 30 +/- 11% (P less than 0.005 vs sinus rhythm). 4. Atrial tachycardia (heart rate: 216 +/- 21 beats/min, NS vs atrial fibrillation) did not significantly change coronary blood flow and reduced segment shortening to 7 +/- 3% (P less than 0.05 vs atrial fibrillation). Significant lactate production did not occur. 5. Since mean arterial pressure fell from 100 +/- 4 mmHg at sinus rhythm to 89 +/- 3 mmHg (P less than 0.01) during atrial fibrillation but not during atrial tachycardia, it was held constant in 13 dogs by a pressurized blood reservoir. Coronary blood flow, however, fell from 43 +/- 6 to 36 +/- 5 ml min-1 100 g-1 (P less than 0.0025). 6. Thus atrial fibrillation may reduce coronary blood flow and induce myocardial ischaemia in the presence of coronary stenosis in excess of atrial tachycardia.     

Distribution of coronary blood flow during acute coronary occlusion in dogs. Effect of nicotinic acid and sodium salicylate

The effects of the antilipolytic agents nicotinic acid (NA) and sodium salicylate (SS) on the distribution of coronary blood flow during acute myocardial ischaemia were studied in open chest dogs. Fifteen min following experimental coronary artery occlusion, blood flow in the ischaemic myocardium was on average 28% of flow in the non-ischaemic myocardium. The reduction in blood flow in the ischaemic mycardium was more pronounced in the endocardial than in epicardial halves of the myocardium. No significant change in blood flow was observed after administration of NA or SS in either the ischemic or nonischemic part of the myocardium. Both drugs reduced the extent of myocardial ischaemic injury as shown by reduced epicardial ST-segment elevations. Arterial concentrations of fatty acids were lowered by NA or SS, whereas the mechanical activity of the heart remained unchanged. It is concluded that the reduction of acute myocardial ischaemic injury effected by NA or SS is not due to changes in myocardial blood flow, but more likely to lower myocardial oxygen demand related to reduced fatty acid utilization.     

Distribution of coronary blood flow during acute coronary occlusion in dogs. Effect of nicotinic acid and sodium salicylate

The effects of the antilipolytic agents nicotinic acid (NA) and sodium salicylate (SS) on the distribution of coronary blood flow during acute myocardial ischaemia were studied in open chest dogs. Fifteen min following experimental coronary artery occlusion, blood flow in the ischaemic myocardium was on average 28% of flow in the non-ischaemic myocardium. The reduction in blood flow in the ischaemic mycardium was more pronounced in the endocardial than in epicardial halves of the myocardium. No significant change in blood flow was observed after administration of NA or SS in either the ischemic or nonischemic part of the myocardium. Both drugs reduced the extent of myocardial ischaemic injury as shown by reduced epicardial ST-segment elevations. Arterial concentrations of fatty acids were lowered by NA or SS, whereas the mechanical activity of the heart remained unchanged. It is concluded that the reduction of acute myocardial ischaemic injury effected by NA or SS is not due to changes in myocardial blood flow, but more likely to lower myocardial oxygen demand related to reduced fatty acid utilization.     

Effect of acute hyperhomocysteinemia on coronary flow reserve in healthy adults

BACKGROUND: B-mode ultrasound studies indicate that hyperhomocysteinemia is associated with preclinical structural and functional arterial abnormalities. This study was designed to evaluate the effect of elevated plasma homocysteine levels on coronary flow reserve (CFR). METHODS: A total of 20 healthy subjects aged 41 +/- 7 years were studied on 2 separate days, a week apart, before and after methionine load (100 mg/kg of body weight) or placebo in a double-blind crossover study. At each visit, homocysteine levels were measured by high performance liquid chromatography and CFR was determined by transthoracic Doppler echocardiography. RESULTS: After methionine load, plasma homocysteine increased from 10.7 +/- 2.8 mumol/L to 30.4 +/- 5.1 mumol/L ( P < .0001) and CFR decreased from 3.0 +/- 0.4 to 2.3 +/- 0.3 ( P < .001). CFR was inversely related to postload homocysteine levels ( r = -0.21, P = .02). After placebo, there was no change in CFR. CONCLUSION: In asymptomatic adults, acute hyperhomocysteinemia is associated with a significant reduction in CFR.     

Doppler estimation of reduced coronary flow reserve in mice with pressure overload cardiac hypertrophy

Aortic banding produces pressure overload cardiac hypertrophy in mice, leading to decompensated heart failure in four to eight weeks, but the effects on coronary blood flow velocity and reserve are unknown. To determine whether coronary flow reserve (CFR) was reduced, we used noninvasive 20-MHz Doppler ultrasound to measure left main coronary flow velocity at baseline (B) and at hyperemia (H) induced by low (1%) and high (2.5%) concentrations of isoflurane gas anesthesia. Ten mice were studied before (Pre) and at 1 d, 7 d, 14 d and 21 d after constricting the aortic arch to 0.4 mm diameter distal to the innominate artery. We also measured cardiac inflow and outflow velocities at the mitral and aortic valves and velocity at the jet distal to the aortic constriction. The pressure drop as estimated by 4V2 at the jet was 51 +/- 5.1 (mean +/- SE) mm Hg at 1 d, increasing progressively to 74 +/- 5.2 mm Hg at 21 d. Aortic and mitral blood velocities were not significantly different after banding (p = NS), but CFR, as estimated by H/B, dropped progressively from 3.2 +/- 0.3 before banding to 2.2 +/- 0.4, 1.7 +/- 0.3, 1.4 +/- 0.2 and 1.1 +/- 0.1 at 1 d, 7 d, 14 d and 21 d, respectively (all p < 0.01 vs. Pre). There was also a significant and progressive increase the systolic/diastolic velocity ratio (0.17 Pre to 0.92 at 21 d, all p < 0.01 vs. Pre) suggesting a redistribution of perfusion from subendocardium to subepicardium. We show for the first time that CFR, as estimated by the hyperemic response to isoflurane and measured by Doppler ultrasound, can be measured serially in mice and conclude that CFR is virtually eliminated in banded mice after 21 d of remodeling and hypertrophy. These results demonstrate that CFR is reduced in mice as in humans with cardiac disease but before the onset of decompensated heart failure.     

血流储备分数测定用于冠脉介入术中的循证护理

目的探讨血流储备分数(FFR)测定用于冠脉介入术中的循证护理配合方法及效果。方法选取2015年5月至2017年5月于武汉市第一医院行冠脉介入(PCI)手术治疗的患者106例,按随机数表法将其分为观察组和对照组,各53例。对照组患者采用循证护理配合冠状动脉造影(CAG)后进行PCI治疗,观察组患者实施循证护理模式配合FFR后行PCI治疗。比较两组患者手术相关情况及手术并发症发生情况,并做统计学分析。结果观察组患者人均支架数量、人均住院费用、人均材料费用及人均对比剂用量均显著低于对照组,观察组患者术后并发症发生率显著低于对照组,差异均有统计学意义(均P<0.05)。结论循证护理配合FFR可更直观准确评估拟行冠脉介入术患者心供血状况,增强手术效果,减少术后并发症。     

冠脉血流显像技术对急性主动脉瓣反流时冠脉血流储备的实验研究

目的 探讨急性主动脉瓣反对冠脉血流储备（CFR）的影响,方法 应用彩色多普勒冠脉血流显像技术（CDCFI）检测7条开胸杂种犬作为对照组及由猪尾管赞成的轻,中,重度急性主动脉瓣反流各组,静脉注射潘生丁前后心外膜冠脉血流的变化,CFR以用药后与用药前冠脉血流的速度时间积分比和峰值血流速度比来计算,结果 最大血流变化出现在注药开始后4－6min,平均5min,用药后与用药前速度时间分比与峰值血流速度比均随主动脉瓣反流程度的增加而逐渐减少,各组之间的CFR（速度时间积分比和峰值血流速度比）差异均有显著性意义（P＜0．01）;相关分析显示,两种方法计算的CFR与主动脉瓣反流程度的增加均呈高度负相关,相关系数分别为－0．978。各组CFR之间差异均有显著性意义（P＜0．01）,两种方法计算的CFR差异无显著性意义（P＜0．05）,结论 随着主动脉瓣反流程度的加重,CFR逐渐降低。     

Regional blood flow during cardiopulmonary resuscitation with abdominal counterpulsation in dogs

The addition of abdominal counterpulsation to standard cardiopulmonary resuscitation (AC-CPR) during ventricular fibrillation has been shown to improve cardiac output, oxygen uptake, and central arterial blood pressure in dogs. The present study was performed to determine the effect of AC-CPR on regional blood flow. Regional blood flow was measured with radioactively labeled microspheres during sinus rhythm and during alternate periods of AC-CPR and standard CPR (STD-CPR) in nine dogs anesthetized with pentobarbital. Blood pressures and oxygen uptake were measured continuously. As in previous studies, diastolic arterial pressure was higher (30.8%) during AC-CPR than during STD-CPR, as were cardiac output (24.5%) and oxygen uptake (37.5%). Whole brain and myocardial blood flow increased 12.0% and 22.7%, respectively, during AC-CPR. Blood flow to abdominal organs was not changed appreciably in response to abdominal compression, and postmortem examination revealed no gross trauma to the abdominal viscera. The AC-CPR technique is simple and is easily added to present basic life support procedures. In light of the improvements observed in myocardial and cerebral blood flow, AC-CPR could significantly improve the outcome of CPR attempts.     

Effect of renal denervation on coronary flow reserve in patients with resistant hypertension

Renal denervation (RDN) is a potential modality in the treatment of patients with resistant hypertension (RH) and has shown beneficial effect on a variety of cardiovascular surrogate markers. Coronary flow reserve, as assessed by transthoracic Doppler echocardiography (TDE‐CFR) is impaired in patients with hypertension and is an independent predictor of cardiac morbidity. However, data on the effect of RDN on TDE‐CFR are scarce. The main objective of this study was to assess the effect of RDN on TDE‐CFR. Twenty‐six consecutive patients with RH (9 female and 17 male; mean age 62 ± 8 years; mean number of antihypertensive drugs 4·2 ± 1·6) underwent bilateral RDN. CFR was assessed at baseline and 6 months after intervention. Mean flow velocity was measured in the left anterior descending artery by transthoracic Doppler echocardiography at baseline and during adenosine infusion (TDE‐CFR). Systolic office blood pressure was reduced at follow‐up (174 ± 24 versus 162 ± 27 mmHG; P = 0·01). Mean systolic ambulatory blood pressure decreased from 151 ± 21 to 147 ± 18 (P = 0·17). TDE‐CFR remained unchanged 6 months after intervention (2·7 ± 0·6 versus 2·7 ± 0·7; P = 0·67). In conclusion, renal denervation was not associated with any changes in regard to coronary flow reserve at 6‐month follow‐up.     

冠状动脉血流储备在冠状动脉微血管病变中的应用进展

冠状动脉微血管病变（CMVD）普遍存在于无梗阻性冠状动脉疾病的胸痛患者中,并与不良心血管预后相关。测定冠状动脉血流储备（CFR）是评价CMVD的有效方法之一。临床上可通过多种有创或无创性检查方法定量测定CFR,对早期诊断CMVD、预后评估及制定临床治疗方案等均有重要价值。本文就CFR在CMVD中的应用进展进行综述。     

Effect of vasoactive agents on intestinal oxygen consumption and blood flow in dogs.

A comparison study of several vasoconstrictor and vasodilator agents was conducted measuring changes in intestinal blood flow and oxygen consumption during 10-min periods of intra-arterial infusion. Blood flow was measured in a branch of the superior mesenteric artery of anesthetized dogs with an electromagnetic blood flow meter, and the arteriovenous oxygen content difference across the gut segment was determined photometrically. Vasopressin (4 x 10(-3) and 7x 10(-4) U/kg-min) diminished blood flow 60 and 28% and reduced oxygen consumption 54 and 22%, respectively (all P less than 0.001). In a dose which did not lower blood flow, vasopressin still caused a decline in oxygen consumption (P less than 0.01). Epinephrine (5 x 10(-2) mug/kg-min) decreased blood flow 19% (P less than 0.001) but did not reduce oxygen consumption. After beta-adrenergic blockade, however, the same dose of epinephrine decreased blood flow 41% and oxygen consumption 33% (both P less than 0.001). Responses to angiotension II, calcium chloride, and prostaglandin F2alpha resembled effects of vasopressin rather than those of epinephrine, namely decreased blood flow and decreased oxygen consumption. The vasodilator agents, prostaglandin E1, is isoproterenol, and histamine, increased (P less than 0.001) both blood flow (130, 80, and 98%, respectively) and oxygen consumption (98, 64, and 70%, respectively). Vasopressin, angiotensin II, calcium chloride, and prostaglandin F2alpha appear to contract arteriolar and precapillary sphincteric smooth muscle indiscriminately to evoke both intestinal ischemia and hypoxia. Epinephrine is the exceptional constrictor in this case, producing diminished blood flow without a reduction in oxygen uptake.     

Transthoracic echocardiographic visualization of coronary artery blood flow and assessment of coronary flow reserve in the right coronary artery: a first report of 3 patients.

Assessment of coronary flow reserve (CFR) has proven to be an important diagnostic tool providing useful clinical and physiologic information about coronary artery function. In several studies, the transthoracic echocardiographic assessment of CFR, defined as a ratio of hyperemic to basal coronary flow velocity, was validated in the left anterior descending artery. But so far, the visualization of coronary flow and the measurement of CFR were limited to the mid and distal portion of the left anterior descending artery. Introduction of a modified 2-chamber view enables the recording of coronary blood flow and the assessment of CFR in the posterior descending branch of the right coronary artery in selected patients. This report of 3 cases describes for the first time a method to visualize and measure coronary blood flow in the distal right coronary artery by precordial Doppler echocardiography.     

冠脉血流显像技术无创性评价轻度高血压患者冠脉血流储备

目的　了解轻度高血压是否存在冠脉循环的功能性损害。方法　应用经胸超声心动图冠脉血流显像技术测量 2 3例无症状轻度高血压患者在静脉输注潘生丁溶液结合等长握力负荷状态下前降支冠脉血流的速度变化 ,并与 2 1例正常健康者对照。结果　轻度高血压组最大冠脉血流与基础冠脉血流速度比值较对照组降低 (峰值速度比为 3 .0 2± 0 .64vs 3 .77± 0 .5 8,P <0 .0 5 ) ,最小冠脉血管阻力指数较对照组增大 ( 0 .3 4± 0 .0 6vs 0 .2 6± 0 .0 8,P <0 .0 5 ) ,舒张功能出现轻度异常。两组左室腔径、左室重量和左室收缩功能无明显改变。结论　无症状的轻度高血压患者可出现冠脉储备降低和舒张功能异常。冠脉血流显像技术为评估冠脉循环功能提供了无创、简便、实用的冠脉血流储备检测手段。     

Coronary blood flow reserve response to left anterior descending coronary artery stenting and its value in predicting coronary restenosis.

BACKGROUND: Heterogeneous results of coronary flow velocity reserve (CFVR) to percutaneous procedures have been reported and the impact of transesophageal echocardiographic evaluation of CFVR in predicting restenosis has not been completely established. Methods and results: We studied 20 control volunteers and 51 patients with left anterior descending coronary artery stenosis to determine the CFVR response to left anterior descending coronary artery stenting, the clinical markers of persistent CFVR impairment, and its value in predicting restenosis. Prestent CFVR was lower in the stenosis group than in control volunteers (1.89 +/- 0.66 vs 3.82 +/- 1.15; P <.001). Although there was a significant increase of CFVR after stenting (2.58 +/- 0.76; P <.001 vs prestent), it remained depressed in 53% of patients and was independently related to multivessel disease (odds ratio, 0.14; 95% confidence interval 0.03-0.55; P =.005), age (odds ratio, 1.07; 95% confidence interval 0.99-1.15; P =.056), and prestent CFVR (odds ratio, 3.78; 95% confidence interval 0.99-14.42; P =.051). CFVR measured both before and early after stenting did not differ between patients with and without restenosis. CONCLUSIONS: CFVR impairment occurs in a large proportion of patients despite successful stenting and appears to be consequent of the extent of atherosclerotic coronary disease. Periprocedural CFVR conferred no predictive value for subsequent intrastent restenosis.     

Treadmill exercise promotes cyclic alterations in coronary blood flow in dogs with coronary artery stenoses and endothelial injury.

We have previously shown in anesthetized, open-chest dogs with coronary stenosis and endothelial injury that serotonin and/or thromboxane A2 (TXA2) receptor activation play a major role in the mediation of platelet-dependent, intermittent coronary occlusion. Using a similar model in awake, closed-chest dogs, we tested the following hypotheses: (a) treadmill exercise promotes the development of cyclic flow variations in dogs with coronary stenoses and endothelial injury; (b) ventricular pacing does not induce cyclic flow variations in the same dogs; and (c) TXA2 and/or serotonin are important mediators of exercise-induced cyclic flow variations in this model. The surgical preparation consisted of the application of a hard, flow-limiting constrictor and a Doppler ultrasonic flow probe around the left coronary artery of 11 dogs. Treadmill exercise resulted in the prompt development of cyclic flow variations in all 11 dogs. Ventricular pacing at rates as high as 170 beats/min induced cyclic flow variations in only one of five dogs. Exercise-induced cyclic flow variations were abolished by TXA2 and/or serotonin receptor antagonists in all but one dog. Thus, (a) treadmill exercise promotes the development of cyclic flow variations in dogs with coronary stenoses and endothelial injury; (b) ventricular pacing does not induce cyclic flow variations in most dogs in the same model; and (c) TXA2 and/or serotonin are important mediators of cyclic flow variations in this model.     

血流储备分数的研究进展

上世纪90年代以来,随着对介入性心脏病学研究的逐渐深入,人们发现冠状动脉造影(Coronary angiography,CAG)作为冠心病诊断和治疗的重要手段,尽管被称为评估冠状动脉狭窄的“金标准”,但由于斑块的复杂性、CAG缺乏生理学信息,对是否需要行进一步血运重建治疗(经皮冠脉介入治疗(Percutaneous coronary intervention,PCI)或冠状动脉旁路移植术(Coronary artery bypass grafting,CABG))以及评价治疗后的功能状况,CAG存在明显的不足.     

冠状动脉血流储备分数研究进展

冠状动脉血流储备分数(FFR)已被国际大规模临床随机对照试验证实为一项良好的评价冠状动脉狭窄程度的功能性指标,可为冠状动脉解剖学狭窄、尤其是中度狭窄患者是否应接受经皮冠状动脉介入治疗提供准确依据。但目前测定FFR仍属有创检查,高昂的诊断费用和尚有争议的判定标准在一定程度上限制了其临床应用。本文就FFR的研究现状及进展做一综述。     

曲美他嗪对X综合征冠状动脉血流储备异常患者的疗效研究

目的 :研究曲美他嗪与传统药物相结合对伴冠状动脉血流储备减低心脏X综合征患者的疗效及耐受性。方法 :3 0例心脏X综合征且冠状动脉血流储备减低者接受曲美他嗪 2 0mg ,每天 3次 ,联合 β受体阻滞剂、钙通道阻滞剂或长效的硝酸酯类治疗 ,随访 12周后的临床情况并复查平板运动试验。结果 :用药后胸痛发作次数显著减少 ,由用药前 (2 1± 2 9)次 /d减少为用药后的 (1 2± 1 7)次 /d(P <0 0 5 ) ,平板运动试验阳性患者减少 ,用药前后分别为 3 0例和 15例 (P <0 0 1) ,平板运动试验到达终点时间明显延长 ,由治疗前 (7 7± 0 4)min延长为 (9 0±0 5 )min (P <0 0 1)。结论 :曲美他嗪与其它药物联合应用能增加心脏X综合征患者的运动耐受量且安全有效