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Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian – Dutch – English (IDEAL) collaborators

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ABSTRACT

Background: Our understanding of human coronary physiological behaviour is derived from animal models. We sought to describe physiological behaviour across a large collection of invasive pressure and flow velocity measurements, to provide a better understanding of the relationships between these physiological parameters and to evaluate the rationale for resting stenosis assessment.

Methods and results: Five hundred and sixty-seven simultaneous intracoronary pressure and flow velocity assessments from 301 patients were analysed for coronary flow velocity, trans-stenotic pressure gradient (TG), and microvascular resistance (MVR). Measurements were made during baseline and hyperaemic conditions. The whole cardiac cycle and the diastolic wave-free period were assessed. Stenoses were assessed according to fractional flow reserve (FFR) and quantitative coronary angiography DS%. With progressive worsening of stenoses, from unobstructed angiographic normal vessels to those with FFR ≤ 0.50, hyperaemic flow falls significantly from 45 to 19 cm/s, Ptrend < 0.001 in a curvilinear pattern. Resting flow was unaffected by stenosis severity and was consistent across all strata of stenosis (Ptrend > 0.05 for all). Trans-stenotic pressure gradient rose with stenosis severity for both rest and hyperaemic measures (Ptrend < 0.001 for both). Microvascular resistance declines with stenosis severity under resting conditions (Ptrend < 0.001), but was unchanged at hyperaemia (2.3 ± 1.1 mmHg/cm/s; Ptrend = 0.19).

Conclusions: With progressive stenosis severity, TG rises. However, while hyperaemic flow falls significantly, resting coronary flow is maintained by compensatory reduction of MVR, demonstrating coronary auto-regulation. These data support the translation of coronary physiological concepts derived from animals to patients with coronary artery disease and furthermore, suggest that resting pressure indices can be used to detect the haemodynamic significance of coronary artery stenoses.

No MeSH data available.


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Relationships between trans-stenotic pressure gradient and flow velocity for coronaries grouped by stenosis severity (left panel according to anatomical severity by percentage of diameter stenosis, and right panel according to physiological severity by fractional flow reserve). Relationships are described by trans-stenotic pressure gradient = A*flow + B*flow2 and can be fitted by three points: the zero TG—zero flow crossing, the mean trans-stenotic pressure gradient and flow during whole cycle at rest, and during hyperaemia. Trans-stenotic pressure gradient and flow during the wave-free period closely follow these relationships, both at rest and during hyperaemic conditions. Curves are fitted by second-order polynomials.
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EHV626F4: Relationships between trans-stenotic pressure gradient and flow velocity for coronaries grouped by stenosis severity (left panel according to anatomical severity by percentage of diameter stenosis, and right panel according to physiological severity by fractional flow reserve). Relationships are described by trans-stenotic pressure gradient = A*flow + B*flow2 and can be fitted by three points: the zero TG—zero flow crossing, the mean trans-stenotic pressure gradient and flow during whole cycle at rest, and during hyperaemia. Trans-stenotic pressure gradient and flow during the wave-free period closely follow these relationships, both at rest and during hyperaemic conditions. Curves are fitted by second-order polynomials.

Mentions: A given stenosis has a unique curvilinear relationship between the flow velocity and the TG across the stenosis. Pressure–flow velocity relationships over the whole cardiac cycle were calculated both during resting and hyperaemic conditions, and averaged for each stratum of stenosis severity. Mean pressure–flow velocity relationships were stratified according to DS% (Figure 4, left panel) and according to FFR classification (Figure 4, right panel).Figure 4


Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian – Dutch – English (IDEAL) collaborators
Relationships between trans-stenotic pressure gradient and flow velocity for coronaries grouped by stenosis severity (left panel according to anatomical severity by percentage of diameter stenosis, and right panel according to physiological severity by fractional flow reserve). Relationships are described by trans-stenotic pressure gradient = A*flow + B*flow2 and can be fitted by three points: the zero TG—zero flow crossing, the mean trans-stenotic pressure gradient and flow during whole cycle at rest, and during hyperaemia. Trans-stenotic pressure gradient and flow during the wave-free period closely follow these relationships, both at rest and during hyperaemic conditions. Curves are fitted by second-order polynomials.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940452&req=5

EHV626F4: Relationships between trans-stenotic pressure gradient and flow velocity for coronaries grouped by stenosis severity (left panel according to anatomical severity by percentage of diameter stenosis, and right panel according to physiological severity by fractional flow reserve). Relationships are described by trans-stenotic pressure gradient = A*flow + B*flow2 and can be fitted by three points: the zero TG—zero flow crossing, the mean trans-stenotic pressure gradient and flow during whole cycle at rest, and during hyperaemia. Trans-stenotic pressure gradient and flow during the wave-free period closely follow these relationships, both at rest and during hyperaemic conditions. Curves are fitted by second-order polynomials.
Mentions: A given stenosis has a unique curvilinear relationship between the flow velocity and the TG across the stenosis. Pressure–flow velocity relationships over the whole cardiac cycle were calculated both during resting and hyperaemic conditions, and averaged for each stratum of stenosis severity. Mean pressure–flow velocity relationships were stratified according to DS% (Figure 4, left panel) and according to FFR classification (Figure 4, right panel).Figure 4

View Article: PubMed Central - PubMed

ABSTRACT

Background: Our understanding of human coronary physiological behaviour is derived from animal models. We sought to describe physiological behaviour across a large collection of invasive pressure and flow velocity measurements, to provide a better understanding of the relationships between these physiological parameters and to evaluate the rationale for resting stenosis assessment.

Methods and results: Five hundred and sixty-seven simultaneous intracoronary pressure and flow velocity assessments from 301 patients were analysed for coronary flow velocity, trans-stenotic pressure gradient (TG), and microvascular resistance (MVR). Measurements were made during baseline and hyperaemic conditions. The whole cardiac cycle and the diastolic wave-free period were assessed. Stenoses were assessed according to fractional flow reserve (FFR) and quantitative coronary angiography DS%. With progressive worsening of stenoses, from unobstructed angiographic normal vessels to those with FFR ≤ 0.50, hyperaemic flow falls significantly from 45 to 19 cm/s, Ptrend < 0.001 in a curvilinear pattern. Resting flow was unaffected by stenosis severity and was consistent across all strata of stenosis (Ptrend > 0.05 for all). Trans-stenotic pressure gradient rose with stenosis severity for both rest and hyperaemic measures (Ptrend < 0.001 for both). Microvascular resistance declines with stenosis severity under resting conditions (Ptrend < 0.001), but was unchanged at hyperaemia (2.3 ± 1.1 mmHg/cm/s; Ptrend = 0.19).

Conclusions: With progressive stenosis severity, TG rises. However, while hyperaemic flow falls significantly, resting coronary flow is maintained by compensatory reduction of MVR, demonstrating coronary auto-regulation. These data support the translation of coronary physiological concepts derived from animals to patients with coronary artery disease and furthermore, suggest that resting pressure indices can be used to detect the haemodynamic significance of coronary artery stenoses.

No MeSH data available.


Related in: MedlinePlus