microvascular resistance
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Vessel Plus ◽  
2022 ◽  
Author(s):  
Sarena La ◽  
Rosanna Tavella ◽  
Sivabaskari Pasupathy ◽  
John F. Beltrame

Around half of the patients undergoing an elective coronary angiogram to investigate typical stable angina symptoms are found to have non-obstructive coronary arteries (defined as < 50% stenosis). These patients are younger with a female predilection. While underlying mechanisms responsible for these presentations are heterogeneous, structural and functional abnormalities of the coronary microvasculature are highly prevalent. Thus, coronary microvascular dysfunction (CMD) is increasingly recognised as an important consideration in patients with non-obstructive coronary arteries. This review will focus on primary coronary microvascular disorders and summarise the four common clinical presentation pictures which can be considered as endotypes - Microvascular Ischaemia (formerly “Syndrome X”), Microvascular Angina, Microvascular Spasm, and Coronary Slow Flow. Furthermore, the pathophysiological mechanisms associated with CMD are also heterogenous. CMD may arise from an increased microvascular resistance, impaired microvascular dilation, and/or inducible microvascular spasm, ultimately causing myocardial ischaemia and angina. Alternatively, chest pain may arise from hypersensitivity of myocardial pain receptors rather than myocardial ischaemia. These two major abnormalities should be considered when assessing an individual clinical picture, and ultimately, the question arises whether to target the heart or the pain perception to treat the anginal symptoms.


2021 ◽  
pp. 1-11
Author(s):  
Jeffrey T. Kroetsch ◽  
Darcy Lidington ◽  
Steffen-Sebastian Bolz

2021 ◽  
Vol 16 ◽  
Author(s):  
Andreas Seitz ◽  
Johanna McChord ◽  
Raffi Bekeredjian ◽  
Udo Sechtem ◽  
Peter Ong

Coronary functional abnormalities are frequent causes of angina pectoris, particularly in patients with unobstructed coronary arteries. There is a spectrum of endotypes of functional coronary abnormalities with different mechanisms of pathology including enhanced vasoconstriction (i.e. coronary artery spasm) or impaired vasodilatation, such as impaired coronary flow reserve or increased microvascular resistance. These vasomotor abnormalities can affect various compartments of the coronary circulation such as the epicardial conduit arteries and/or the coronary microcirculation. Unequivocal categorisation and nomenclature of the broad spectrum of disease endotypes is crucial both in clinical practice as well as in clinical trials. This article describes the definitions of coronary functional abnormalities with currently accepted cut-off values, as well as diagnostic methods to identify and distinguish endotypes. The authors also provide a summary of contemporary data on the prevalence of the different endotypes of coronary functional abnormalities and their coexistence.


2021 ◽  
Vol 12 ◽  
Author(s):  
Céline Boudart ◽  
Fuhong Su ◽  
Lorenzo Pitisci ◽  
Arnaud Dhoine ◽  
Olivier Duranteau ◽  
...  

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis.Methods: Fourteen pigs were randomized to sham (n = 7) or fecal peritonitis-induced sepsis (n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation.Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I2 receptor, and prostaglandin F2α receptor.Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved.


2021 ◽  
Vol 23 (Supplement_G) ◽  
Author(s):  
Pasquale Paolisso ◽  
Emanuele Gallinoro ◽  
Alessandro Candreva ◽  
Konstantinos Bermpeis ◽  
Davide Fabbricatore ◽  
...  

Abstract Aims Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups. Methods In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperaemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction. Results The median FFR value was 0.83 (0.79–0.87) without any significant difference between the two groups. Absolute resting and hyperaemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperaemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group [CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, (P &lt; 0.05 for both)]. Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all P &lt; 0.05). Conclusions Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperaemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.


2021 ◽  
Vol 78 (15) ◽  
pp. 1541-1549
Author(s):  
Bernard De Bruyne ◽  
Nico H.J. Pijls ◽  
Emanuele Gallinoro ◽  
Alessandro Candreva ◽  
Stephane Fournier ◽  
...  

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
T Toya ◽  
A Ahmad ◽  
M T Corban ◽  
J D Sara ◽  
I Ozcan ◽  
...  

Abstract Background Coronary vasomotor response is different between males and females. However, the prognostic impact of this difference in coronary physiologic indices has not been characterized in patients with no obstructive coronary artery disease (NOCAD). Purpose We aimed to investigate the sex-specific differences of coronary vasomotor function in response to adenosine in a large cohort of patients with NOCAD and its impact on long-term clinical outcomes Methods We included 668 NOCAD patients who underwent invasive coronary vasoreactivity testing using intracoronary incremental doses of adenosine (18–72 μg) with available follow-up data. Indices of coronary vasomotor response were compared between males and females, and their prognostic impact on major adverse cardiovascular events (MACE: death, myocardial infarction, revascularization, and stroke) were analyzed based on sex. Results Females (N=461, mean age 54±12 years) had lower baseline microvascular resistance (BMR) and higher baseline average peak velocity (APV) than males (N=207, mean age 53±13 years), while hyperemic microvascular resistance (HMR) and hyperemic APV were similar between males and females. Consequently, coronary flow reserve (CFR: hyperemic/baseline APV) and resistive reserve ratio (RRR: BMR/HMR) were lower in females than males (Figure 1A). Lower CFR and RRR, as well as lower BMR and higher baseline APV were associated with MACE only in males, but not in females. Higher HMR was the only predictor for MACE in females (Figure 1B). Conclusions Sex-specific differences in coronary vasomotor response to adenosine may provide different prognostic values between males and females. FUNDunding Acknowledgement Type of funding sources: None.


Author(s):  
Atefeh Razavi ◽  
Shagun Sachdeva ◽  
Peter Frommelt ◽  
John LaDisa

Abstract Anomalous aortic origin of a coronary artery (AAOCA) is the second most common cause of sudden cardiac death in young athletes. One of the hypothesized mechanisms of ischemia in these patients is the lateral compression of the anomalous artery with an intramural or interarterial course. The presence of a narrowing in the anomalous artery will cause physiologic changes in downstream resistance that should be included for computational assessment of possible clinical ramifications. In the current study, we created different compression levels, i.e., proximal narrowing, in the intramural course of a representative patient model and calculated virtual fractional flow reserve (vFFR). Models also included the effect of the distal hyperemic microvascular resistance (HMR) on vFFR. Our results were in agreement with similar FFR studies indicating that FFR was increased with increasing HMR, and that different compression levels could have similar FFR depending on the HMR. For example, vFFR at HSR:1.0-1.3 and HMR: 2.30 mmHg/cm/s is 0.68 and close to vFFR at HSR:0.6-0.7 and HMR: 1.6 mmHg/cm/s, which is 0.7. The current findings suggest that functional assessment of anomalous coronary arteries through FFR should consider the vascular resistance distal to the narrowing in addition to the impact of a proximal narrowing and provides computational approaches for implementation of these important considerations.


2021 ◽  
Vol 26 (3) ◽  
pp. 553-560
Author(s):  
Eun Ye Lim ◽  
Dong Won Yang ◽  
A Hyun Cho ◽  
Yong S. Shim

Background & Objective: Cerebral microbleeds (CMBs) are considered key markers of small vessel pathology linking mechanisms relating to ischemic and amyloid related vascular damage in Alzheimer disease (AD). We aim to investigate the differences of hemodynamic markers between patients with and without CMBs who presented with cognitive decline using transcranial Doppler (TCD) ultrasonography. Methods: We consecutively enrolled patients who were diagnosed with mild cognitive impairment (MCI) and probable AD dementia from May 2011 to December 2012. Using TCD ultrasonography, cerebrovascular reactivity (CVR) was evaluated with hyperventilation (HV) and breath-holding (BH) tests in addition to mean flow velocity (MFV) and pulsatility index (PI) of the middle cerebral artery. The number and location of CMBs were visually analyzed by two independent neurologists. Results: A total of 134 patients (probable AD, n=81; MCI, n=53) were enrolled in this study. Among them, 28 (20.9%) patients had CMBs; 18 (64.3%) lobar CMBs, 7 (25.0%) non-lobar CMBs. Patients with CMBs showed reduced MFV, higher resistance index value, and lower CVR compared with patients without CMBs after adjusting for age, vascular risk factors, and white matter hyperintensity. Multiple regression models showed that PI was dependent on age and presence of CMBs in frontal and parietal areas. CVR was closely associated with WMH severity and presence of CMBs in temporal. Conclusions: Our study showed that patients with CMBs had higher microvascular resistance and decreased cerebrovascular autoregulation compared to those without.


2021 ◽  
Vol 17 (7) ◽  
pp. 569-575 ◽  
Author(s):  
Takumi Toya ◽  
Michel T. Corban ◽  
Ji Young Park ◽  
Ali Ahmad ◽  
Ilke Ӧzcan ◽  
...  

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