Fractional Flow Reserve: The Ideal Parameter for Evaluation of Coronary, Myocardial, and Collateral Blood Flow by Pressure Measurements at PTCA

To overcome the fundamental limitations of coronary arteriography to assess the functional significance of coronary artery disease, it is necessary to obtain direct information about coronary blood flow. Recently we validated three pressure flow equations, which enable calculation of maximum coronary, myocardial, and collateral flow by merely measuring aortic, central venous, and distal coronary pressures under the condition of maximum vasodilation and using an ultra thin pressure monitoring guide wire for distal coronary pressure recording. In this paper, the first clinical experiences of this method are described. For that purpose, the concept of fractional flow reserve (FFR) is important. Fractional coronary flow reserve (FFR_cor) is defined as the maximum achievable blood flow in a stenotic artery, divided by normal maximum flow in that same artery, i.e. maximum flow in that artery in the case that it would be completely normal. Fractional myocardial flow reserve (FFR_myo) is defined in a similar way, and recruitable collateral blood flow is expressed as a fraction of normal maximum myocardial flow. Fractional flow reserve, defined in this way, is easy to obtain at percutaneous transluminal coronary angioplasty (PTCA) by the pressure-flow equations, is independent of pressure changes, applicable to three vessel disease, and enables calculation of the separate contribution of coronary and collateral flow to total myocardial perfusion. In 18 patients a very close correlation was demonstrated between FFR_myo, calculated by pressure recordings at PTCA by the first pressure flow equation, and FFR_myo obtained by positron emission tomography, which is considered the gold standard for myocardial perfusion. In 60 other patients, maximum recruitable collateral blood flow at balloon inflation (Q_c/Q^N) was calculated according to the third pressure-flow equation and correlated to the presence or absence of ischemia. It could be demonstrated that Q_C/Q^N exceeds 22% in all 23 patients without ischemia, whereas Q_c/Q^N was less than 22% in 34 out of 37 patients who experienced ischemia during balloon inflation. This margin value of 22% is very close to the theoretically expected value of 20%. based upon a coronary flow reserve of 5 under standard physiologic conditions. It can be concluded that the concept of fractional flow reserve provides a rapid, accurate, and elegant way for quantitative assessment of maximum coronary and myocardial blood flow before and after PTCA. Moreover, this is the first method that enables quantitative calculation of collateral blood flow in clinical practice. (J Interven Cardiol 1993; 6:331–344)     

The Impact of Downstream Coronary Stenosis on Fractional Flow Reserve Assessment of Intermediate Left Main Coronary Artery Disease: Human Validation

ObjectivesThe aim of this study was to determine the impact of downstream coronary stenosis in the left anterior descending coronary artery (LAD) or left circumflex coronary artery (LCx) on the assessment of fractional flow reserve (FFR) across an intermediate left main coronary artery (LMCA) stenosis in humans with the pressure wire positioned in the nondiseased downstream vessel.BackgroundAccurate assessment of intermediate LMCA disease is critical for guiding decisions regarding revascularization. In theory, FFR across an intermediate LMCA stenosis will be affected by downstream disease, even if the pressure wire is positioned in the nondiseased downstream vessel.MethodsAfter percutaneous coronary intervention of the LAD, LCx, or both, an intermediate LMCA stenosis was created with a deflated balloon catheter. FFR was measured in the LAD and LCx coronary arteries before and after creation of downstream stenosis by inflating an angioplasty balloon within the newly placed stent. The true FFR (FFR_true) of the LMCA, measured in the nondiseased downstream vessel in the absence of stenosis in the other vessel, was compared with the apparent FFR (FFR_app) measured in the presence of stenosis.ResultsIn 25 patients, 91 pairs of measurements were made, 71 with LAD stenosis and 20 with LCx stenosis. FFR_true of the LMCA was significantly lower than FFR_app (0.81 ± 0.08 vs. 0.83 ± 0.08, p < 0.001), although the numerical difference was small. This difference correlated with the severity of the downstream disease (r = 0.35, p < 0.001). In all cases in which FFR_app was >0.85, FFR_true was >0.80.ConclusionsIn most cases, downstream disease does not have a clinically significant impact on the assessment of FFR across an intermediate LMCA stenosis with the pressure wire positioned in the nondiseased vessel.     

Impact of right atrial pressure on fractional flow reserve calculation in the presence of a chronic total occlusion

BackgroundThe aim of this study was to assess the impact of right atrial pressure (Pra) on non-CTO vessels FFR measurements in patients with a chronic total occlusion.MethodsConsecutive patients who underwent PCI for a CTO of the right coronary artery (RCA) were included. Prior to RCA recanalization, FFR and FFR_myo were measured in non-CTO vessels. FFR was calculated using the Pd/Pa equation during maximum hyperaemia and also accounting for right atrial pressure (Pd-Pra/Pa-Pra). Non-CTO vessels were characterised as major or minor donors based on angiographic assessment of provided collaterals.ResultsFFR and FFR_myo were measured in 68 arteries (34 LAD and 34 Cx) in 34 consecutive patients with successful RCA CTO PCI. Patients' mean age was 62 ± 10 years old and 88% were male. Mean left ventricular ejection fraction was 51% ± 20. During maximum hyperaemia, mean Pra, Pa, and Pd were 4.1 ± 3.8 mm Hg, 82.6 ± 12.2 mm Hg, and 63.8 ± 14.3 mm Hg, respectively. In the major donor vessel, FFR_myo showed a difference of 0.007 to FFR (0.760 ± 0.113 vs. 0.767 ± 0.112, p = 0.004). In the minor donor vessel the difference was 0.004 (0.895 ± 0.067 vs. 0.899 ± 0.065, p < 0.001). There was a strong positive correlation between the FFR and FFRmyo in both the major and minor donor vessel groups (r = 0.993, p < 0.001 and r = 0.996, p < 0.001 respectively).ConclusionIn the presence of a CTO, RA pressure adjustment of FFR in the non-CTO vessels leads to trivial numerical changes, which are statistically significant but clinically negligible.     

The functional reserve of collaterals supplying long-term chronic total coronary occlusions in patients without prior myocardial infarction.

AIMS: Chronic total coronary occlusions (CTOs) with angiographically well-developed collaterals may be considered to provide sufficient blood supply to the occluded segment, and the indication for revascularization may be questioned. Therefore, the collateral function and functional reserve in patients with a CTO without a prior Q-wave myocardial infarction (MI) were assessed. METHODS AND RESULTS: Invasive assessment of collateral function was done during successful percutaneous coronary intervention in 107 patients with a CTO and no prior Q-wave MI. Intracoronary Doppler flow velocity and pressure recordings were obtained distal to the occlusion before the first balloon inflation and collateral function indexes calculated. In 62 patients, additional pharmacological stress testing was done by intravenous adenosine (140 microg/kg/min) to assess the collateral flow reserve. Patients with normal and impaired regional dysfunction were compared. Collateral function was similar in patients with and without regional left ventricular (LV) dysfunction. In both groups, 78% collaterals provided a collateral pressure index at baseline > 0.3, sufficient to prevent ischaemia during a balloon occlusion, with a minimum of 0.2 in those with preserved LV function. A Doppler-derived function index showed a wider variation due to the high prevalence of microvascular dysfunction in CTOs. Only 7% of patients had an increase in collateral flow reserve > 2.0 during pharmacological stress, whereas coronary steal occurred in one-third independent of regional LV function. CONCLUSION: A limited increase in collateral flow and the high prevalence of coronary steal during stress underscore the functional limitation of collaterals in CTOs without prior Q-wave MI. Even presumably 'well-collateralized' CTOs may benefit from a revascularization.     

冠状动脉慢性完全闭塞病变侧支压力大小与闭塞远端心肌灌注的临床研究

目的 分析冠状动脉慢性完全闭塞病变（CTO）侧支大小与闭塞远端心肌灌注水平的关系和闭塞远端不同灌注水平对CTO开通术后远端心肌灌注恢复和心功能的影响。 方法 连续入选2018年1月1日至2018年10月1日就诊于西京医院的CTO患者。所有患者术前完善心肌声学造影以评价闭塞远端心肌血流灌注[峰值强度(A)、血流速度(β)、心肌血流量(A×β）]。开通CTO支架植入后使用温度压力导丝测定冠状动脉楔压Pw,并计算侧支压力指数（CPI）。以CPI≥0.25和CPI<0.25分为侧支丰富组和侧支不良组。观察两组患者术前在A、β、A×β方面的差异。采用心肌声学造影半定量分析,根据闭塞远端心肌灌注水平分为灌注缺损组和灌注延迟组。观察两组患者术前、术后1d、术后1个月在A、β、A×β方面的差异以及心功能恢复情况。 结果 ①CPI<0.25和CPI≥0.25两组患者闭塞远端心肌灌注水平在术前,术后1d,术后1个月的差异无统计学意义。②灌注缺损组术前A[（4.9±0.6）dB vs (5.8±0.8) dB]和A×β[（14.1±2.4）dB/s vs (16.2±2.2) dB/s]显著低于灌注延迟组（均P<0.01）;β在两组间的差异无统计学意义。③CTO开通术后1d,1个月,灌注缺损组A[术后1d (6.1±0.8)dB vs (6.9±0.9) dB,P=0.01],[术后1个月（7.7±1.1）dB vs（8.5±1.0）dB,P<0.05]仍显著低于灌注延迟组;灌注延迟组和灌注缺损组远端心肌的 β和A×β差异无统计意义。④灌注缺损组术前左室射血分数(LVEF)显著低于灌注延迟组[（45±7）%vs（49±4）%,P<0.05）];CTO开通术后1个月灌注延迟组射血分数较术前提高,差异有统计学意义[（50±3）% vs（49±4）%,P=0.02]。灌注缺损组CTO开通术后1个月的LVEF与术前相比未见明显变化[（45±7）% vs (45±6)%]。 结论 ①CPI无法预测CTO闭塞远端心肌的灌注水平;②CTO开通后,闭塞远端心肌的灌注恢复不受CPI的影响;③CTO开通后远端心肌灌注水平和心功能的恢复受术前闭塞远端心肌灌注水平的影响。     

Percutaneous Intervention of Circumflex Chronic Total Occlusions Is Associated With Worse Procedural Outcomes: Insights From a Multicentre US Registry

BackgroundWe sought to determine whether outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) vary according to CTO target vessel: left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA).MethodsWe evaluated the clinical and angiographic characteristics and procedural outcomes of 636 patients who underwent CTO PCI at 6 high-volume centres in the United States between January 2012 and March 2014.ResultsThe CTO target vessel was the RCA in 387 cases (61%), LAD in 132 (21%), and LCX in 117 (18%). LCX lesions were more tortuous and RCA lesions had greater occlusion length and Japanese Chronic Total Occlusion (J-CTO) score, but were less likely to have a side branch at the proximal cap and had more developed collateral circulation. The rate of procedural success was lower in LCX CTOs (84.6%), followed by RCA (91.7%), and LAD (94.7%) CTOs (P = 0.016). Major complications tended to occur more frequently in LCX PCI (4.3% vs 1.0% for RCA vs 2.3% for LAD; P = 0.07). LCX and RCA CTO PCI required longer fluoroscopy times (45 [interquartile range (IQR), 30-74] minutes vs 45 [IQR, 21-69] minutes for RCA vs 34 [IQR, 20-60] minutes for LAD; P = 0.018) and LCX CTOs required more contrast administration (280 [IQR, 210-370] mL vs 250 [IQR, 184-350] mL for RCA and 280 [IQR, 200-400] mL for LAD).ConclusionsIn a contemporary, multicentre CTO PCI registry, LCX was the least common target vessel. Compared with LAD and RCA, PCI of LCX CTOs was associated with a lower rate of procedural success, less efficiency, and a nonsignificant trend for higher rates of complications.     

A case of successful angioplasty by the “double retrograde” approach for chronic total occlusion in the left circumflex artery

Currently introduced retrograde approach may increase the success rate of percutaneous coronary interventions on chronic total occlusion (CTO) lesion. This article describes a case of CTO in the left circumflex artery (LCX), which did not allow the regular retrograde approach to deliver a guide wire. At first, a guide wire was attempted to advance from the apical collateral channel, which supplied the distal LCX. However, wiring was extremely difficult because the collateral channel was headed reversely against the direction that the wire was going. Different angle angiogram revealed the existence of another collateral artery, which supplied the distal RCA (posterior descending branch). A guide wire was successfully advanced from the distal RCA, through apical collateral channel, and reached the distal LCX. After the wire was retrieved from the guiding catheter engaged in the left main trunk, antegrade access for balloon and stent delivery was obtained. This method, a sort of “double retrograde” approach, would be worthy to consider when recanalization is failed by other approaches. © 2011 Wiley Periodicals, Inc.     

Comparison between angiography and fractional flow reserve versus single-photon emission computed tomographic myocardial perfusion imaging for determining lesion significance in patients with multivessel coronary disease

We hypothesized that myocardial perfusion imaging (MPI) would fail to identify all vascular zones with the potential for myocardial ischemia in patients with multivessel coronary disease (MVD). MPI is based on the concept of relative flow reserve. The ability of these techniques to determine the significance of a particular stenosis in the setting of MVD is questionable. Fractional flow reserve (FFR) can determine the significance of individual stenoses. Thirty-six patients with disease involving 88 arteries underwent angiography, FFR, and MPI. FFR was performed using a pressure wire with hyperemia from intracoronary adenosine. Myocardial perfusion images were analyzed quantitatively and segments assigned to a specific coronary artery. The relation between FFR and perfusion was determined for each vascular zone. Of the 88 vessels, the artery was occluded (n=20) or had an abnormal FFR相似文献   

First reported revascularization of complex occlusion of the right coronary artery using the IVUS-guided reverse CART technique via a gastroepiploic artery graft

When patients who have previously undergone coronary artery bypass graft surgery develop ischemia symptoms that cannot be controlled by optimal medical therapy, repeat revascularization is indicated. The revascularization strategy should be based on individual clinical and anatomical characteristics. We report here a challenging patient who presented with recurrent stable angina due to worsening of a proximal right coronary artery (RCA) stenosis to chronic total occlusion (CTO) after anastomosis of the right gastroepiploic artery (GEA) to the posterior descending artery. A soft guidewire was advanced through the right GEA collateral channel to the distal end of the CTO, but the dedicated CTO guidewires could not be advanced across the severely calcified CTO using the retrograde wire crossing or kissing wire techniques. The RCA was eventually revascularized by implantation of drug-eluting stents using the intravascular ultrasound-guided reverse controlled antegrade and retrograde subintimal tracking technique.     

Finecross微导管在逆行导丝技术治疗冠状动脉慢性完全闭塞病变中的应用

目的观察Finecross微导管在逆行导丝技术治疗慢性完全闭塞病变（CTO）中应用的效果。方法 35例CTO患者,其中20例右冠闭塞,15例前降支闭塞,闭塞病变的靶血管远端均有良好的侧支循环血管逆行供血,35例均采用Finecross微导管支撑导丝进行逆行冠状动脉介入治疗。结果 Finecross微导管直接通过侧支循环为25例,经小外径球囊低压力扩张侧支循环血管后Finecross微导管通过侧支循环为8例,手术最终成功30例,3例逆行导丝未通过闭塞病变,无并发症发生;2例Finecross微导管因侧支循环血管迂曲故未通过,其中1例导丝通过后微导管无法通过,且发生心包填塞,经及时治疗后未发生心血管事件,余34例未发生心血管事件。结论冠脉慢性完全闭塞病变血管成形术中合理应用Finecross可获得较好的安全性和有效性。     

Simultaneous Assessment of Coronary Flow Reserve and Fractional Flow Reserve with a Novel Pressure-Based Method

Coronary flow reserve (CFR) and fractional flow reserve (FFR_myo) are two guidewire‐based methods currently used to assess the functional severity of coronary artery lesions. Acquiring both measurements simultaneously may provide complementary information, but would require the passage of two different guidewires and complex instrumentation for their calculation. This study assessed the procedural safety and performance of a novel personal computer‐based algorithm, the SmartFlow Intravascular Processor (SFIP), which utilizes a single conventional pressure wire for obtaining simultaneous CFR and FFR_myo measurements for the assessment of coronary artery lesion severity. In 20 consecutive patients with 21 lesions, pressure‐derived CFR, FFR_myo and SFIP‐FFR_myo measurements were obtained during adenosine‐induced hyperemia. Intravascular ultrasound and quantitative coronary angiography lesion analysis was done off‐line at the Washington Core Laboratory. Mean FFR_myo was 0.83 ± 0.11, SFIP‐FFR_myo was 0.86 ± 0.06, and CFR was 1.74 ± 0.46. Pairwise correlation analysis showed excellent correlation between the FFR_myo and the FFR_myo‐SFIP (r²= 0.83, P < 0.0001) and a fair degree of relationship between the CFR and minimal lumen diameter (r²= 0.43, P = 0.07). We could not find a correlation between CFR and FFR_myo (r²= 0.22, P = 0.37), between CFR and FFR‐SFIP (r²= 0.05, P = 0.86), or between the hemodynamic measurements and any of the IVUS‐derived measurements. In conclusion, the SFIP is u novel algorithm for obtaining simultaneous CFR and FFR_myo that may provide valuable information for the assessment of lesion severity and clinical decision making.     

Effect of Revascularization of Chronic Total Occlusion on Tandem Stenoses in a “Donor” Artery

The presence, severity, and extent of ischemia predict the outcome of coronary artery disease. Indeed the extent of myocardial ischemia and viability determines the value of revascularization in coronary stenosis after acute myocardial infarction. In multivessel coronary artery disease, noninvasive methods for the evaluation of ischemia are often inadequate to guide percutaneous coronary intervention. It is a common misperception that revascularization might not benefit a myocardial segment in the chronic total occlusion distribution when that segment is supplied by well-developed collateral vessels, because severe ischemia is unlikely to be present under these circumstances.An 82-year-old man presented with acute coronary syndrome, tandem stenoses in a “donor” artery, and a chronic total occlusion of the right coronary artery. We present a rationale for using fractional flow reserve to determine the existence of ischemia and to aid in deciding the best approach to the treatment of that ischemia.     

A pitfall of fractional flow reserve associated with the presence of collateral circulation

An 82-year-old man had a severe stenosis in the proximal left anterior descending artery (LAD) and an intermediate stenosis in the distal right coronary artery (RCA). The territory of mid to distal LAD was perfused via an angiographically well-developed collateral circulation from the distal RCA. Fractional flow reserve (FFR) in the distal RCA was 0.84. After successful coronary intervention for the proximal LAD, repeat FFR in the distal RCA was 0.96. In this case, the severity of the stenosis in the donor artery was overestimated by using FFR due to the presence of well-developed collateral circulation.     

Retrograde balloon hemostasis

Despite improvements in current devices and techniques for complex chronic total occlusion (CTO) percutaneous coronary intervention (PCI), procedural complications, including coronary perforation, still occur and could be life-threatening. A patient with a history of multivessel coronary artery disease and a CTO of the right coronary artery (RCA) underwent successful retrograde crossing of an RCA CTO. After wiring the CTO body and lesion dilatation, a drug-eluting stent was implanted in the distal RCA toward the posterior descending artery. A large Ellis type III perforation occurred at the distal edge of the stent. Septal crossing with a balloon and tamponade of the perforation site through the retrograde collaterals followed, as the RCA was not suitable to accommodate easily both the covered stent and the balloon simultaneously. This case report presents a novel approach the “septal retrograde ping-pong” technique, which demonstrates successful treatment of coronary perforations by utilizing a retrograde approach through a septal collateral. This technique proves to be effective in situations where the conventional antegrade balloon or covered stent delivery methods are not feasible or unsuccessful. This innovative approach offers a promising alternative for managing challenging cases of coronary perforations, providing new insights and potential solutions for interventional cardiologists.     

Determinants of target vessel failure in chronic total coronary occlusions after stent implantation. The influence of collateral function and coronary hemodynamics

OBJECTIVES: The goal of this study was to assess the influence of collateral function, coronary hemodynamics, and the angiographic result on the risk of target vessel failure (TVF) after recanalization of a chronic total coronary occlusion (CTO). BACKGROUND: Collaterals may have an adverse effect on TVF. METHODS: In 111 consecutive patients, a CTO (duration >2 weeks) was successfully recanalized with stent implantation. Collateral function was assessed by intracoronary Doppler flow velocity and pressure recordings distal to the occlusion. Baseline collateral function was determined before the first balloon inflation, and recruitable collateral function after stenting during a balloon reocclusion. Finally, the coronary flow velocity reserve (CFVR) and the fractional flow reserve (FFR) were measured. RESULTS: Angiographic follow-up after 5 +/- 4 months in 106 patients showed a reocclusion in 17% and a restenosis in 36%. The major determinants of TVF were the stent length (p < 0.01) and number of implanted stents (p < 0.01). No difference was observed in baseline or recruitable collateral function between patients with and without TVF; 52% of patients had a CFVR >or= 2.0, and only 18% a CFVR >or=2.5 after percutaneous transluminal coronary angioplasty, but neither cutoff-value predicted TVF. A low FFR discriminated patients with reocclusion (0.81 +/- 07 vs. 0.86 +/- 08, p < 0.05) but not with restenosis (0.87 +/- 0.06). CONCLUSIONS: This study showed that there is no relation between a well-developed collateral supply and the risk of TVF in recanalized CTOs. This was rather determined by the stented segment length. There was also no adverse effect of the frequently observed impaired CFVR on TVF, whereas a low FFR was associated with a higher risk of reocclusion.     

Correspondence between left ventricular 17 myocardial segments and coronary arteries.

AIMS: The last guidelines recommend a standardized 17-segment model for tomographic imaging of the left ventricle. The aim of this study is to analyse the correspondence of the 17 left ventricular segments with each coronary artery by myocardial perfusion SPECT studies. METHODS AND RESULTS: Fifty patients selected for percutaneous revascularization of one coronary artery [24 left anterior descending (LAD), 15 right coronary artery (RCA), and 11 left circumflex (LCX)] were included. The (99m)Tc-labelled compound was injected immediately after the inflation of the balloon during percutaneous coronary angioplasty. At least 90 s of complete occlusion time was required. Maximal contour of regions of hypoperfusion corresponding to each coronary artery occlusion were delineated over the polar map of 17 segments. Nine segments corresponded to only one coronary artery: eight to LAD (basal anterior, basal anteroseptal, mid-anterior, mid-anteroseptal, apical anterior, apical septal, apical lateral, and apex) and one to LCX (basal anterolateral). Basal inferoseptal, mid-inferoseptal, and apical inferior segments could correspond to LAD or RCA. Basal inferior, basal inferolateral, mid-inferior, and mid-inferolateral segments could correspond to RCA or LCX, whereas the mid-anterolateral segment could correspond to LAD or LCX. CONCLUSION: The most specific segments (anterior, anteroseptal, and all apical segments except the infero-apical) correspond to LAD but no segment can be exclusively attributed to the RCA. Inferoseptal segments can be attributed to LAD or RCA, inferior and inferolateral segments to RCA or LCX, and mid-anterolateral segment to LAD or LCX.     

血流储备分数结合心脏磁共振评估冠状动脉慢性完全闭塞病变血运重建适应证初探

目的通过血流储备分数(FFR)和心脏磁共振(CMR)成像评估冠状动脉慢性完全闭塞(CTO)病变的血运重建适应证。方法选取2018年7月至12月四川省人民医院冠状动脉造影显示至少一支血管存在CTO病变的患者32例,通过CMR测量心肌延迟强化透壁程度和区域性室壁运动积分指数(RWMSI),比较主要供体血管和CTO病变血管在经皮冠状动脉介入治疗(PCI)前后FFR值的变化,并观察3个月随访期间左心室射血分数(LVEF)的变化情况。结果最终19例患者完成所有检查和随访。CTO-PCI后主要供体血管FFR值[(0.88±0.09)比(0.81±0.12),P=0.031]和CTO病变血管FFR值[(0.85±0.10)比(0.41±0.08),P=0.015]均较CTO-PCI前显著增加,差异均有统计学意义;3个月随访时LVEF较CTO-PCI前有所改善,差异有统计学意义[(51.32±11.72)%比(43.82±10.56)%,P=0.038]。但心肌延迟强化透壁程度>75%和RWMSI>2.0的患者CTO-PCI后FFR<0.8,LVEF无改善。结论即使有良好的侧支循环,CTO病变端心肌仍处于缺血状态。CTO-PCI后CTO病变血管和主要供体血管的FFR值均显著升高,并能带来左心功能的改善。     

Blood flow velocity in donor coronary artery depends on the degree and pattern of collateral vessel development: a study using thrombolysis in myocardial infarction frame count method.

To understand the influence of collateral vessels on the coronary flow, TIMI frame count (TFC) method was applied as a measure of mean coronary blood flow velocity in artery giving collateral blood supply to the other artery in angiograms of 76 patients with single occluded coronary artery: RCA giving collaterals to occluded LAD or LAD giving collaterals to occluded RCA. As a control group, TFC was applied in angiograms of 30 patients with mild or no coronary artery disease. TFC was lower (faster blood flow) in LAD giving collaterals to occluded RCA (43 patients) than in LAD in control group (21.8 +/- 10.5 vs. 33.9 +/- 20.8 frames; P < 0.01). Higher degree of collateral vessels (Rentrop classification) and mixed- and distal-type collaterals (through the interventricular septum and heart apex) was associated with lower TFC. There was no difference in TFC in the RCA giving collaterals to an occluded LAD (33 patients) compared to the TFC in RCA in control group (16.6 +/- 9.0 vs. 18.5 +/- 6.0; P = NS), even in angiograms with higher degree of collateral vessel development. TFC was lower (faster blood flow) only in subgroups with mixed (proximal and distal types together in the same patient) and distal (through the interventricular septum and the apex of the heart) collateral types. A delayed contrast appearance in occluded LAD compared to occluded RCA has been found (35.1 +/- 16.1 vs. 20.2 +/- 7.3 frames; P < 0.001) with earlier contrast appearance in occluded LAD when proximal collateral vessels (through the conal and acute marginal branches of RCA) were presented. The coronary flow in donor arteries depends not only on the degree but also on the pattern of collateral vessels. The simple TFC method may facilitate the study of collateral filling pattern and offer insight into the influence of collaterals on the ventricular function.     

Successful fenestration using a chronic total occlusion-dedicated guidewire in a patient with catheter-induced dissection of the right coronary artery

Guiding catheter-induced coronary artery dissection is a rare, but hazardous complication of percutaneous coronary intervention (PCI) and is associated with the potential risk of impairment of coronary blood flow. Therefore, occurrence of this complication mandates a prompt revascularization procedure. A 68-year-old female patient with acute myocardial infarction caused by total occlusion of the proximal right coronary artery (RCA) underwent PCI. After revascularization by thrombus aspiration, catheter-induced dissection of the ostium of the right coronary artery (RCA) occurred when the guiding catheter and guidewire were accidentally removed. An attempt to engage the guiding catheter and guidewire into the true lumen failed because of total occlusion of the right coronary ostium. A chronic total occlusion (CTO)-dedicated guidewire was then used to create a fenestration of the intimal flap, and after it penetrated into the distal true lumen, a low-profile balloon catheter was dilated, and coronary flow from the false to the true lumen was established. After balloon dilatation, stents were deployed at both the dissection site and in the distal lesion. The final angiogram revealed restoration of coronary blood flow. We propose that application of a CTO-dedicated guidewire to create a fenestration of the intimal flap in the region of the coronary dissection is a feasible and effective alternative to conventional procedures.     

Vascular and cardiac contractile reserve in the dog heart with chronic multiple coronary occlusions.

Nineteen mongrel dogs survived chronic occlusion of the left circumflex and of the right coronary artery without infarction due to the timely development of a collateral circulation. Only 38 per cent of the conductance of the arteries before occlusion was restored by collateral vessels. In these animals and in 15 control dogs with normal coronary arteries myocardial contractility, contractility reserve, and myocardial blood flow were studied. The same was done in dogs with chronic coronary artery occlusion after aortocoronary bypass. Myocardial blood flow was determined woth the tracer microsphere technique. Contractility reserve was tested and defined as isovolumetric left ventricular pressure and dp/dt max with norepinephrine infusion and cross-clamping of the aorta. Contractile reserve was not significantly different between normal dogs and dogs with chronic coronary artery occlusion before and after aortocoronary bypass. Myocardial blood flow during control conditions was homogenously distributed in all three groups studied. The ratio of blood flow to the endocardium and the epicardium was not significantly different from inity. Coronary reserve was determined at peak reactive hyperemia following a 20 second period of coronary artery occlusion, with ongoing norepinephrine infusion. Under these conditions subendocardial fow in normal dogs rose by a factor of 7.9 while subepicardial flow increased 7.4 times. In dogs with chronic occlusion of two coronary arteries the increase of myocardial flow was nonnomogenous; subendocardial flow to areas supplied by a normal coronary artery rose by a factor of 7.0 while subepicardial flow increased 5.7 times control. Subendocardial collateral flow rose by a factor of 2.4 and subepicardial collateral flow increased 3.5 times control. In normal dogs norepinephrine alone did not result in maximal coronary flow but only 57 per cent thereof. Dogs with chronic coronary occlusion, however, required the entire coronary reserve in areas that were supplied by a normal coronary artery, whereas areas supplied by collaterals became ischemic. Opening of an aortocoronary bypass restored normal flow to previously ischemic areas, and reduced the flow to areas supplied by a normal artery. With the bypass open no differences existed between normal dogs and those with two occluded coronary arteries. We conclude that the norepinephrine-stimulated contractile reserve of hearts with chronic coronary occlusion was comparable to that of normal hearts; however, norepinephrine forced these hearts to spend the entire flow reserve of the remaining normal artery while producing ischemia in collateral-dependent areas. The same dose of norepinephrine did not require the entire flow reserve of normal dogs.