[Contribution of CT-scan fusion imaging for interventional cardiology]. / Apport de la fusion d'images de scanner en salle de cathétérisme.

Fusion imaging is developing fast, allowing improvements in interventional cardiology procedures workup and guidance. Computed-tomography (CT) scan and fluoroscopy fusion guidance used in procedures such as left appendage occlusion or perivalvular leak closure permit prediction and simulation of the appropriatedevice, as well as implantation guidance. In the era of tailored medicine, CT/fluoroscopy fusion imaging guidance is an interesting tool for individualizing and adapting the devices implanted to each patient, as well as improving the outcomes and safety of each procedure.

[IRM et myocardite infectieuse]. / IRM et myocardite infectieuse.

Over the past ten years, cardiac MRI has become an indispensable tool for acute myocarditis diagnosis. Under appropriate conditions, cardiac MRI may allow postponement of initial coronary angiography in many instances. The 2020 ESC guidelines give a class I recommendation to its use in the setting of MINOCA for differential diagnosis between acute myocardial infarction, myocarditis, Tako-Tsubo and other cardiac pathologies, in order to improve therapeutic management and follow-up. This article describes the technical characteristics of MRI in myocarditis (Lake Louise diagnostic criteria and criteria based on myocardial tissue mapping), the main differential diagnoses, the prognostic value and addresses the issue of myocarditis in the setting of COVID-19.

[TAVI in women, very encouraging results]. / TAVI chez les femmes, des résultats très encourageants.

The population of elderly patients comprises a high percentage of women. This population is more vulnerable due to the presence of numerous comorbidities and is, therefore, particularly exposed to the risk of aortic valve degeneration, resulting in aortic valve stenosis whose symptoms are predictors of poor short-term outcomes. In the presence of symptomatic aortic stenosis, the recommended therapeutic option in this vulnerable population is the implementation of transcatheter aortic valve implantation, preferably via the femoral route. The outcomes of this procedure are better in women than in men despite a more frequent occurrence of vascular, bleeding and cerebral complications. Several hypotheses have been reported in the literature regarding the reasons for such differences. Among other reasons, it is likely that in female patients, the myocardium adjusts better to the occurrence of aortic stenosis and that recovery after valve treatment is also more optimal. Another explanation is the higher frequency of coronary artery disease in this older population. This has a considerable impact on the outcome even when coronary lesions are treated prior to valve implantation. There is still room for improvement and progress can be achieved by further reducing the size of the equipment used in order to decrease the diameter of the vascular access, and by continuing to simplify TAVI procedures. Less invasive techniques should result in decreased complication rates. In addition, dedicated studies should allow us to further improve our practice in this growing population of vulnerable patients.

Novel integrated 3D multidetector computed tomography and fluoroscopy fusion for left atrial appendage occlusion procedures.

OBJECTIVES: This report demonstrates the application and feasibility of novel 3D-MDCT real-time fusion technology with fluoroscopy, for left atrial appendage (LAA) occlusion procedures. BACKGROUND: A successful LAA occlusion procedure relies on multiple imaging modalities, including TEE or 3D-MDCT, and fluoroscopy. Effectively integrating these imaging modalities may improve implantation safety and success. To our knowledge this technique has not been previously described for LAA occlusions. METHODS: This observational study compared clinical and procedural parameters for procedures performed with or without fusion integration. All patients had a pre-procedural 3D-MDCT for LAA measurements, along with 3D analyses of LAA morphology and surrounding structures. Using the image fusion software (Valve ASSIST 2, GE Healthcare, UK), landmarks were identified on fluoroscopy, and MDCT LAA anatomy outlines were then projected onto the real-time fluoroscopy image during the procedure, to guide all steps of the intervention. RESULTS: A total of 57 patients underwent LAA occlusion, with 16 performed using fusion software. In comparison to the pre-fusion group, reductions in contrast volume (21.0 ± 11.7 vs. 95.9 ± 80.5 ml, P < 0.001), procedure time (63.0 ± 22.0 vs. 87.3 ± 43.0 min, P = 0.01), and fluoroscopy time (6.2 vs. 8.3 min, P = 0.03) were observed. Incomplete sealing (0 vs. 14.6%, P = 0.16) and device deployment success (100 vs. 92.7%, P = 0.17) were not significantly different. CONCLUSIONS: The addition of this novel fusion technology is safe and feasible. To optimize LAA procedural success, fusion integration may offer a promising addition, or alternative, to current imaging modalities. © 2017 Wiley Periodicals, Inc.

[Left atrial appendage closure and embolic events]. / Fermeture d'auricule et pathologie embolique.

Atrial fibrillation (AF) is frequent and responsible for embolic events. Currently, the gold standard to prevent such embolic events is anticoagulant therapy with vitamin K antagonist (VKA) or direct oral anticoagulant in nonvalvular AF. Recently, left atrial appendage closure was proposed as an alternative to anticoagulant inpatient with high embolic risk and contraindication to anticoagulant therapy. Data from randomized trials were consistent with a non-inferiority of left atrial appendage closure in comparison to VKA in terms of stroke and cardiovascular death. However, despite improvements in procedure results and complications reduction, this invasive strategy has to be performed with optimal security as this strategy is a preventive treatment in high-risk patients. These improvements may allow an extension of indications of left atrial appendage closure to lower profile risk patients as an alternative to anticoagulant. Indeed, anticoagulant is a risky therapy with hemorrhagic events and observance is a real issue in an asymptomatic population. Finally, there is a lack of data in recent literature comparing left atrial appendage closure to direct oral anticoagulant, widely used in daily practice, as well as cost-effectiveness of this procedure in comparison to anticoagulant.

[Transfemoral TAVI procedure in women: Minimally-invasive technique]. / Procédure de TAVI par voie fémorale chez la femme : technique minimaliste.

Demographic data point to a substantial proportion of women in the population of elderly patients with an increasing prevalence of aortic stenosis. Implantation of an aortic bioprosthesis via an endovascular approach known as Transcatheter aortic valve implantation (TAVI) in patients presenting with a symptomatic tight aortic stenosis (severe aortic stenosis) (AS) is an alternative therapeutic option to surgical aortic valve replacement in patients at high surgical risk or ineligible for surgery. The literature has shown that this technique seems to be particularly beneficial in female patients. In the Partner A trial, the 1-year mortality rate was significantly lower in women compared to their male counterparts. Other data revealed that although women have a higher risk of experiencing periprocedural complications (vascular events, bleeding and stroke), their outcome is good and often better than that of men. These results are continuously improving thanks to the enhancement of techniques and devices. In view of the published reports reflecting the increasing experience of the teams, it clearly appears that the simplification of TAVI procedures has resulted in improved outcomes. We report here the case of a patient treated by means of a "minimalist" approach to TAVI allowing a reduction of the risks inherent in the procedure. This simplified strategy relies on an optimal use of CT scan findings prior to TAVI. The procedure is carried out under local anesthesia and the main access site is sutured percutaneously (Proglides). The radial artery is used as a secondary access site. Contrast medium is diluted and stimulation is administered via the intraventricular guidewire. Direct stenting is performed when deemed feasible on the basis of CT scan results. Simplified procedures such as these contribute to the improvement of TAVI outcomes. However, further studies focusing on female patients are warranted in order to corroborate these findings.

[Renal denervation by trans-radial access for resistant hypertension]. / Dénervation rénale par voie radiale pour le traitement d'une hypertension artérielle résistante.

Renal denervation which consists in the ablation of the sympathetic fibers located in the adventitia of renal arteries is a therapeutic strategy allowing improved arterial hypertension control in patients who do not respond to medical treatment. This technique is currently performed using the femoral approach in the majority of cases. The diameter and the length of the ablation catheters limit their use via the radial route. The most frequent peri-procedural complications are vascular problems. We report here two cases of renal denervation via the trans-humeral and trans-radial routes respectively.

[Renal denervation a treatment for resistant hypertension: a French experience]. / La dénervation rénale un traitement pour l'hypertension artérielle résistante : expérience française.

Arterial hypertension is the largest single contributor to global mortality, and is poorly controlled in approximately 50% of patients despite lifestyle and pharmacologic interventions. Randomized clinical trials have demonstrated that catheter-based renal sympathetic denervation reduces blood pressure (BP) in patients with resistant hypertension. We sought to evaluate the efficacy of this novel therapy in "Real World" clinical practice. Consecutive patients with treatment-resistant primary hypertension, as defined as home BP>160 mmHg despite treatment with ≥3 antihypertensive drugs, were selected for denervation following renal artery screening. Ambulatory and home BP monitoring was performed in all patients prior to and following percutaneous renal sympathetic denervation. In total, 35 patients were selected for catheter-based renal sympathetic denervation. The mean age was 63.6 ± 11.7 years, 37.1% were women, 37.1% were diabetic, and 11.4% had renal impairment (GFR<45 mL/min). The basal BP (home or ambulatory) was 179.1 ± 20.75/99.66 ± 19.76 mmHg, despite an average of 4.91 ± 0.98 medications per patient. Successful bilateral sympathetic denervation was performed in 33/35 patients (1 renal artery stenosis on angiography [not ablated], 1 patient with renal artery spasm [unilateral denervation]), with an average 5.9 ± 1.6 ablations per renal artery. No procedural complications occurred. At 6 months, blood pressure was 15.5 ± 22.37/87.76 ± 13.97 mmHg (P<0.01). At 2 years follow-up, systolic blood pressure (ABPM or Home BP) was 143.8 ± 15.30 mmHg (P<0.0001) and diastolic 83.42 ± 12.80 mmHg (P=0.0004). There were no adverse events during follow-up, and no deterioration in renal function was observed. Catheter-based renal denervation is safe and efficacious treatment, which results in significant reductions in blood pressure in patients with treatment-resistant hypertension, stable at 2 years follow-up. These results are applicable to real-world patient populations.

[The use of the Five-in-Six System for stent delivery in challenging coronary lesions: a multi-center experience]. / L'utilisation du cathéter Heartrail II « 5-in-6 ¼ dans l'angioplastie coronaire complexe : expérience multicentrique.

BACKGROUND: The mother and child "5-in-6" technique using the Heartrail II catheter is a novel tool allowing stent delivery in challenging lesions, when conventional techniques have failed. METHODS: A total of 147 consecutive patients underwent percutaneous coronary intervention (PCI) using the "5-in-6" Heartrail II catheter was restrospectively identified in the Institut Cardiovasculaire Paris Sud, (Jacques-cartier hospital), Institut hospitalier Claude-Galien (Claude-Galien hospital) and European hospital of Paris between July 2009 and September 2012. RESULTS: Ten interventional cardiologists treated 147 patients with the new device. The patients mean age was 68.5 ± 21.5 years, 78% were men. Radial access was used in 128 cases (87.9%). The treated vessels were the right coronary artery in 82%, left anterior descending in 22%, left circumflex in 18%, marginal branch in 9%, the posterior descending artery in three patients, retroventricular artery in one patient and a saphenous graft in two patients. Most lesions (70%) had American Heart Association/American College of Cardiology (AHA/ACC) type B2 or C, and greater than 50% were located in distal vessel segments. Mean lesion length was 16 ± 4 mm, which is indicative of long lesion. Most (62%) lesions were moderately to heavily calcified and 22 (14%) were chronic total occlusions. Problems with stent delivery were due to poor guide catheter support or excessive calcification. Introduction of the "Heartrail II" catheter allowed successful stent delivery in 139 cases (94%). CONCLUSION: The "5 in 6" Heartrail II catheter is a simple and easy-to-use device that can improve the success of stent delivery in challenging coronary interventions.

[Multicentric experience with the use of Sheathless 6.5 French-size catheter in coronary angioplasty for bifurcation lesions: feasibility and safety]. / Expérience multicentrique de l'utilisation du Sheathless 6.5 French dans l'angioplastie coronaire des lésions de bifurcation : faisabilité et sécurité

BACKGROUND: Transradial intervention of coronary lesion is increasing in frequency and is associated with lower major vascular access site complications. However, the small size of the radial artery is a major limitation of this technique, especially for bifurcation lesions, because 6-French guiding catheters are necessary to optimize the technique. A Sheathless guiding catheter has recently been introduced, optimizing a large lumen with a small size. OBJECTIVES: The aim of this study is to report our preliminary experience performing bifurcated transradial interventions using a 6.5 French Sheathless guide catheter. PATIENTS AND METHODS: From March 2009 to February 2012 in three hospitals, 46 consecutive patients were enrolled in this study who underwent transradial approach (TRA) for percutaneous bifurcation coronary interventions using the 6.5 French Sheathless Eaucath guiding catheter system because of small radial artery caliber. RESULTS: In this study, 46 patients were enrolled with mean age of 72.13 ± 16.41 years. The majority of patients were females with sex-ratio 0.53. Procedural success using the 6.5 French Sheathless guide catheter system was 100 % with no cases requiring conversion to a conventional guide and catheter system. During procedures, adjunctive devices used in this cohort included IVUS (2 patients), 35 bifurcated lesions were treated with a kissing-balloon technique in the group of 46 patients undergoing bifurcation PCIs, one patient required rotational atherectomy, thrombus-aspiration catheters had used in four patients, FFR-guided angiography in four patients. We report one case of chronic total occlusion bifurcated lesion successfully treated using this hydrophilic catheter. There were no radial artery site complications. CONCLUSION: The treatment of coronary bifurcation lesions with 6.5 French Sheathless guiding catheter by transradial approach is feasible and appears safe in this multicenter study.

[Renal artery denervation for treating refractory hypertension]. / La dénervation rénale un traitement pour l'hypertension artérielle résistante.

Arterial hypertension is a major healthcare issue affecting between 30 and 40% of the adult population in industrialized countries. Despite the availability of numerous pharmaceutical treatments, arterial hypertension often remains uncontrolled. A non-negligible percentage of patients are refractory to multiple-drug therapy, which exposes them to an increased risk of cardiovascular events. Percutaneous, renal denervation using a catheter connected to a low energy radiofrequency generator has proven effective in decreasing arterial pressure in patients resistant to medical therapy, by reducing afferent nerve activity. In order to be eligible for this therapeutic approach, patients must have uncontrolled essential hypertension despite treatment with a combination of three anti-hypertensive drugs including a diuretic agent, and ≥ 45mL/min glomerular filtration rate. The initial registry study demonstrated that catheter-based sympathetic renal denervation was a simple and safe procedure resulting in a significant and durable reduction in arterial pressure. Subsequently, a randomized controlled trial (the Symplicity HTN-2 trial) showed a mean 32/12 mmHg decrease in blood pressure measurements in the group of patients who underwent renal denervation whereas no difference was observed in the control group. The reduction in blood pressure was still present at 24-month follow-up. No procedure-related complications were reported and no instances of renal artery stenosis or aneurysmal dilatation were evidenced during the follow-up period. No cases of renal function impairment or deterioration were recorded. This technique seems to be a promising strategy in patients suffering from this serious condition. In order to demonstrate the actual benefit of this technique, we report the case of two patients who underwent renal denervation in our institution.

[Electromechanical mapping of myocardial ischemia in coronary occlusion in the pig]. / Cartographie électromécanique du myocarde ischémique dans un modèle d'occlusion coronaire progressive chez le porc.

The NOGA-Biosense catheter-based mapping technique has been well studied experimentally in infarction model. However, chronic myocardial ischemia with this new device has not been well explored. Thus, the aim of our study was to assess electromechanical changes in a pig aneroid constricor model. To achieved this aim, ten pigs were studied 21 days after the implantation of an aneroid constrictor around the circumflex artery. Coronary reserve assess by intracoronary Doppler flow wire was reduced in the ischemic lateral area (ILA) compared with the nonischemic zone (NIZ) (1.3 +/- 0.1 in the ILA vs. 2.3 +/- 0.2 in the NSZ; p < 0.01). TM echocardiography was used to evaluate myocardial regional contractility under basal condition and after stress induced by rapid atrial pacing. In stress state, the ischemic zone showed an impaired contractility compared with basal state (wall thickening, 32.7 +/- 7.4% vs. 59.7 +/- 8.6%; p < 0.05) whereas the non ischemic zone did not (53.8 +/- 7.6% vs. 60.8 +/- 10.1%; p = ns). Constrast echography showed a decrease in contrast intensity in subendocardium of the ila compared with the niz (46.2 +/- 16.6 vs. 99.2 +/- 35.6; p = 0.03) in pacing. Ventricular mapping quantified unipolar (UV). bipolar (BV) voltage potentials and endocardial local shortening (LLS) in 9 left ventricular regions. In basal state, electrical potentials were preserved in both zones (UV: 9.1 +/- 1.8 mV in the ischemic vs 11.3 +/- 3.6 mV in the non ischemic zone; p = ns; BV: 4.2 +/- 1.1 mV in the ILA vs. 3.9 +/- 1.5 mV; p = ns). In contrast, LLS was significantly lower in the ischemic compared with non ischemic zone (6.4 +/- 5.4% vs. 17.9 +/- 3.0%, p < 0.001). In conclusion, ventricular mapping with the NOGA-Biosense system can identify the ischemic myocardium. In this pig model, the association of a preserved electrical activity and an impaired mechanical activity characterizes the ischemic myocardium. These findings could be interesting in this model in regard of the new developments of the system in particular in the field of angiogenesis.

[Angioplasty of a right coronary artery arising from a single coronary artery during acute myocardial infarction]. / Angioplastie d'une artère coronaire droite issue d'un tronc commun unique à la phase évolutive d'un infarctus du myocarde.

The authors report the case of a patient admitted for acute inferior myocardial infarction with right ventricular extension secondary to occlusion of the right coronary artery arising from a single coronary artery treated by angioplasty and stenting by a right radial approach after treatment with Abxicimab.

Impact of microvascular integrity and local viability on left ventricular remodelling after reperfused acute myocardial infarction.

OBJECTIVE: To assess left ventricular remodelling in patients with reperfused acute myocardial infarction and to study its relation to microvascular damage. PATIENTS: 25 patients successfully treated by primary percutaneous coronary angioplasty for acute myocardial infarction. SETTING: University hospital METHODS: Indexed end diastolic (EDVi) and end systolic (ESVi) volumes were assessed on admission and repeated at days 1 and 8. Coronary flow reserve (CFR) was assessed in the infarct related artery on day 1. Myocardial blood volume was assessed on admission and at day 8 by myocardial contrast echocardiography. In patients who manifested persistent myocardial dysfunction at hospital discharge (n = 21), local inotropic reserve was assessed by dobutamine echocardiography at day 7. RESULTS: On admission, patients with and without local viability had similar EDVi and ESVi (EDVi 67 (9) and 73 (14) ml/m(2), respectively; ESVi 34 (8) and 40 (11) ml/m(2), respectively; NS). EDVi increased to 97 (22) ml/m(2) in patients without local viability (p < 0.01 v admission) but remained unchanged at 70 (11) ml/m(2) in patients with viable myocardium (NS v admission). For pooled patient data, the percentage change in EDVi correlated with CFR (r = 0.76, p < 0.0001) and myocardial blood volume in the infarct territory (r = 0.80, p < 0.0001). CONCLUSION: Left ventricular dilatation may preferably occur in patients without local viability and is correlated with early CFR and extent of myocardial blood volume in the infarct territory.

Impact of coronary plaque morphology as assessed by IVUS computer-aided analysis on mechanisms of balloon angioplasty and stenting.

This study was performed in order to quantitate structural coronary plaque modifications after balloon angioplasty and stenting and to evaluate the impact of plaque morphology on the mechanisms of lumen enlargement during angioplasty. Plaque morphology was studied by computer-aided analysis of 60 cross-sectional intravascular ultrasound (IVUS) images of the target lesion in 20 patients undergoing percutaneous coronary angioplasty. Based on a computer-aided video densitometry classification of plaque morphology, three groups of plaques were defined based on the slope value of a fifth polynomial regression of the plaque gray-level distribution. In groups A and B, balloon angioplasty provided significant increases in lumen area (P < 0.0001) and vessel area (P < 0.05) without a reduction in plaque area; neither parameter increased in group C. In group A, stenting was associated with an additional lumen enlargement (P < 0.0001) due to plaque reduction (P < 0.05). In groups B and C, stenting further increased lumen area (P < 0.0001) by improving vessel area (P < 0.001) but without plaque reduction. Balloon angioplasty and stenting provided a significant decrease in plaque area in group A as compared to groups B (P < 0.05) and C (P < 0.01). Finally, vessel area improvement was greater in group B than in groups A (P < 0.01) and C (P < 0.05). The mechanisms underlying lumen enlargement after coronary angioplasty are highly dependent on plaque morphology as defined by an IVUS computer-aided analysis and may differ between balloon angioplasty and stenting.

Physiologically guided angioplasty in support to a provisional stenting strategy: immediate and six-month outcome.

The results of an observational multicenter angioplasty study suggested that stenting decisions may be facilitated by physiologic data. The purpose of this study was to evaluate the early and long-term clinical and angiographic outcome of prospective physiologically guided provisional stenting. Coronary angioplasty using a Doppler-tipped angioplasty guidewire was performed in 68 patients. The provisional stent strategy dictated that balloon angioplasty was to be continued until a coronary flow reserve was >/= 2.2 with a residual diameter stenosis by quantitative coronary angiography < 35%. Repeat coronary angiography was obtained at 6 months. Based on the study criteria, 32/68 patients (47%) received a stent. Compared to the stent group, the angioplasty alone group had higher postprocedural stenosis (23% +/- 13% vs. 13% +/- 10%; P < 0. 05) and lower coronary vasodilatory reserve (2.3 +/- 0.4 vs. 2.6 +/- 0.7; P < 0.05). At follow-up (6.0 +/- 1.5 months), the angiographic restenosis rate was 39% in the angioplasty group and 35% in the stent groups (P = NS). Adverse cardiac events (unstable angina, target lesion revascularization, myocardial infarction, death) occurred in 19% and 18% (P = NS) of the angioplasty and stent patients, respectively. A prospective application of a physiologically guided provisional stent strategy for coronary angioplasty indicated that stent implantation may be required in approximately 50% of patients, an approach that produces similar clinical and angiographic long-term outcomes for stenting and guided angioplasty. These data support a role of coronary physiology as an adjunct in conducting an angioplasty procedure without obligatory stenting.

[Physiology of coronary circulation and angioplasty: utopia or clinical reality?]. / La physiologie de la circulation coronaire et l'angioplastie: utopie ou réalité clinique?

Small pressure transducer and Doppler quartz placed at the tip of angioplasty guide wire give the opportunity to measure coronary flow physiology parameters, the physiopathologic impact of an epicardic coronary stenosis and the efficacy of its treatment. This gives the opportunity to over ride the coronary imaging limitations. Doppler and pressure investigate a different and complementary aspect of the pressure-flow relation and may be used together in some special cases. Myocardial fractional flow reserve (FFRmyo) and relative coronary reserve concepts allow to evaluate patients with heterogeneous coronary reserve. Clinical application field is very broad and can be applied to each step of coronary angioplasty from the evaluation of intermediate lesions and the indication of angioplasty to the guidance of the procedure to the evaluation of the result, through the stenting indication and the stent placement optimization. Numerous studies has emphasized the role of physiologic coronary assessment in the cathlab. The time and economic gain of such an attitude has to be confirmed by future trials but it is clear now that it is not possible to continue to take decision on the sol visual aspect of a lesion.

Coronary microcirculation and cardiovascular pathology.

The recent arrival of new techniques for exploring the coronary microcirculation has facilitated assessment of both the incidence and consequences of disorders of this network in a large number of cardiovascular diseases. The microcirculation is affected in numerous cardiomyopathies in the presence of different cardiovascular risk factors and also following cardiac transplantation. Dysfunction of the microcirculation may correspond to a reduction in the surface of the maximum section of coronary arterioles, which involves multiple mechanisms, although this phenomenon does not appear to play a role in ischaemic heart disease. Reduced coronary flow is most frequently related to vascular rarefaction of multifactorial origin, including greater or lesser degrees of intimal proliferation, perivascular fibrosis, hypertrophy of the media and extrinsic compression.

Coronary microcirculation and cardiovascular pathology.

The recent arrival of new techniques for exploring the coronary microcirculation has facilitated assessment of both the incidence and consequences of disorders of this network in a large number of cardiovascular diseases. The microcirculation is affected in numerous cardiomyopathies in the presence of different cardiovascular risk factors and also following cardiac transplantation. Dysfunction of the microcirculation may correspond to a reduction in the surface of the maximum section of coronary arterioles, which involves multiple mechanisms, although this phenomenon does not appear to play a role in ischaemic heart disease. Reduced coronary flow is most frequently related to vascular rarefaction of multifactorial origin, including greater or lesser degrees of intimal proliferation, perivascular fibrosis, hypertrophy of the media and extrinsic compression.

[Coronary microcirculation. Physiologic and pathologic aspects]. / Microcirculation coronaire. Aspects physiologique et pathologique.

The coronary circulation has a protective regulation system which, in extreme haemodynamic conditions, compensates increased myocardial oxygen demand. The coronary reserve, based on this concept defines the capacity of the system to increase flow temporally, and, thereby, myocardial oxygen supply. The introduction of new methods of investigating the coronary microcirculation has enabled the study of this phenomenon in several cardiovascular pathologies. Two types of investigation are used currently for studying the coronary microcirculation: 1) invasive methods, especially the recently developed intracoronary Doppler and pressure guide, 2) non-invasive methods, and, in particular, contrast echocardiography, position emission tomography and magnetic nuclear resonance. These investigations allow measurement of the coronary reserve or the assessment of the myocardial consequences of abnormalities of the microcirculation. Some workers use these methods to investigate pathological coronary microcirculation in different cardiomyopathies, in the presence of different cardiovascular risk factors (hypertension, diabetes, smoking, hypercholesterolaemia) and after cardiac transplantation.