Intravascular Pressure Measurements Research Articles

Quantifying Inferior Vena Cava Compliance and Distensibility in an In Vivo Ovine Model Using 3D Angiography.

Synthetic vascular grafts overcome some challenges of allografts, autografts, and xenografts but are often more rigid and less compliant than the native vessel into which they are implanted. Compliance matching with the native vessel is emerging as a key property for graft success. The current gold standard for assessing vessel compliance involves the vessel's excision and ex vivo biaxial mechanical testing. We developed an in vivo method to assess venous compliance and distensibility that better reflects natural physiology and takes into consideration the impact of a pressure change caused by flowing blood and by any morphologic changes present. This method is designed as a survival procedure, facilitating longitudinal studies while potentially reducing the need for animal use. Our method involves injecting a 20 mL/kg saline bolus into the venous vasculature, followed by the acquisition of pre and post bolus 3D angiograms to observe alterations induced by the bolus, concurrently with intravascular pressure measurements in target regions. We are then able to measure the circumference and the cross-sectional area of the vessel pre and post bolus. With these data and the intravascular pressure, we are able to calculate the compliance and distensibility with specific equations. This method was used to compare the inferior vena cava's compliance and distensibility in native unoperated sheep to the conduit of sheep implanted with a long-term expanded polytetrafluorethylene (PTFE) graft. The native vessel was found to be more compliant and distensible than the PTFE graft at all measured locations. We conclude that this method safely provides in vivo measurements of vein compliance and distensibility.

A primer for the student joining the adult cardiac surgery service tomorrow: Primer 1 of 7

A primer for the student joining the adult cardiac surgery service tomorrow: Primer 1 of 7

A Classification Proposal for Spinal Vascular Lesions.

A Classification Proposal for Spinal Vascular Lesions.

Abstract No. 232 Correlation between the hepatic venous transplant anastomotic gradient and hepatic congestion on transjugular liver biopsy in post-liver transplant patients

Transjugular liver biopsy and intravascular pressure measurement is utilized to detect the presence of post-liver transplant complications, including congestive hepatopathy (CH). Hepatic venous anastomotic pressure gradients are conventionally utilized as part of clinical decision making in patients with suspected CH in addition to histologic manifestations within the liver biopsy specimen. This study aimed to determine if the free hepatic venous to right atrial pressure gradient correlated with the histologic diagnosis of CH.

Nutcracker syndrome: diagnosis and therapy.

Nutcracker syndrome (NCS) is an extrinsic compression of the left renal vein (LRV) by the superior mesenteric artery (SMA) anteriorly and aorta posteriorly resulting in renal vascular congestion manifesting as hematuria, proteinuria, orthostatic hypotension, pain, or even renal dysfunction. Long-standing venous compression can encourage collateral drainage pathways through gonadal and pelvic veins, which may explain reported symptom and syndrome overlap with pelvic congestion syndrome. Diagnosis can be challenging and variable, frequently involving a combination of ultrasound Doppler, cross-sectional, and invasive imaging. Often, intravascular pressure measurements are required to prove a renocaval pressure gradient to aid in a definitive diagnosis. Conservative management is appropriate, especially in children, who tend to outgrow the disorder. In the interim, medical management with angiotensin converting enzyme inhibitors (ACEIs) is a useful therapy to manage orthostatic hypotension in the pediatric population. In adults, invasive therapies are more frequently pursued. These are aimed at relieving the extrinsic compression on the LRV. The standard of care is renal vein transposition, with renal autotransplantation reserved for recalcitrant cases. Endovascular stenting is a less invasive option. Laparoscopic placement of an exovascular stent is a newer therapy intended to minimize trauma to the LRV. In this review, we will discuss the clinical manifestations, diagnostic criterion, imaging features, and conservative and surgical therapies for this condition.

Insights from intravascular pressure measurement of renal artery revascularization in patients with fibromuscular dysplasia: The DYSART study

ObjectiveThe indication of percutaneous renal transluminal angioplasty (PTRA) in fibromuscular dysplasia (FMD) is mainly based on renal artery stenosis (RAS) due to atherosclerosis criteria, which are not specific to FMD. Consequently, the selection of patients who could benefit from this treatment and its effectiveness remain uncertain. The aims of this study were to: (1) report the effects of PTRA guided by trans-stenotic pressure measurements on hypertension 7 months after treatment; (2) assess the impact of pressure measurement to guide treatment efficacy in comparison to visual angiographic parameters; and (3) evaluate the reproducibility and accuracy of the stenosis measurement using a 4F catheter in comparison to a pressure guidewire. MethodsThis prospective multi-centric study analyzed 24 patients with hypertension with RAS due to FMD that required PTRA. Clinical, duplex ultrasound, and angiographic indices were collected, and patients were followed up for 7 months (±1 month). Angiographic indices were measured twice both by a pressure guidewire and a 4F catheter. Assessment of procedural and clinical success of angioplasty was performed for all patients. ResultsTwenty-three patients (96%) had procedural success (considered as a post-PTRA translesional systolic gradient ≤10 mmHg or reduced by at least 80%) with a significant decrease in the systolic gradient after angioplasty (26.50 mmHg; [interquartile range, 16.75-38.75] vs 0.00 [interquartile range, 0.00-2.00]; P < .01). Three patients (12%) had complications, including two renal artery dissections and one partial renal infarction. Twenty-one patients (88%) were clinical responders to angioplasty at follow-up. Visual stenosis assessment showed a poor correlation with systolic gradient measurement before and after PTRA (R from −0.05 to 0.41; P = 0.06-0.82). High correlations were found between pressure measurements made by a 4F catheter and guidewire (R from 0.64 to 0.89; P ≤ .003). ConclusionsIn patients selected by clinical indicators and duplex ultrasound, reaching a translesional systolic gradient ≤10 mmHg or reduced by at least 80% after angioplasty, promotes a high success rate for PTRA in hypertension due to FMD RAS.

Endovascular Dural Venous Sinus Stenting for the Treatment of Papilledema in Idiopathic Intracranial Hypertension

Abstract Introduction: Recently a subset of patients with Benign Intracranial hypertension has been identified that have cerebral dural venous stenosis. Recent studies have demonstrated that venous sinus stenting can result in normalization of these pressures and resultant resolution of ophthalmologic findings. Methods: Twenty-six patients were referred to a single institution for optic nerve swelling due to Benign Intracranial hypertension and found to have cerebral dural venous sinus stenosis. These patients subsequently underwent cerebral venous sinus stenting. Ophthalmic manifestations were evaluated pre and post procedure as well as intravascular pressure measurements and pressure gradients before and after the stenting procedure. The pre and postoperative ophthalmologic findings were tabulated as well as the pre and post procedure pressure measurements before and after stenting. Results: The average preprocedural pressure gradient measured 13.8 mmHg and was reduced to 1.3 mmHg after the stenting procedure. 25 of 26 patients had improvement in their papilledema after the stenting procedure. No complications occurred during or after the procedure. Conclusion: Endovascular Dural Venous sinus stenting is a safe and effective treatment modality for the ophthalmic manifestations of Benign Intracranial Hypertension in those patients found to have cerebral venous sinus stenosis.

A FBG-OCT Catheter to Reconstruct Vascular Shape in Intravascular Optical Coherence Tomography

We propose a novel fiber Bragg grating (FBG)-optical coherence tomography (OCT) catheter to reconstruct vascular shape by intravascular OCT imaging of the actual curvature as well as the bending direction of the vascular in real-time. Compared with the traditional OCT catheter, the FBG-OCT catheter uses the FBG encapsulated with half- sectioned stainless-steel tube as a flexural sensitive component. With the 360-degree rotation of the catheter, the encapsulated FBG will produce maximum tension and maximum compression at the bend of the blood vessel, and then get the solution of the curvature and direction of the bending catheter as well as the OCT imaging simultaneously. To test the proposed catheter for real-time measurement, a bending calibration system and a vascular prosthesis model to simulate the actual vascular bending morphology are manufactured through three-dimension (3D) printing. Experimental data shows that the new FBG-OCT catheter can acquire the OCT images and FBG bending parameters real-timely and synchronously. Further, the obtained bending parameters and OCT images are used to restore the morphology of the vascular model, which will provide corrective data for accurate measurements of further vascular plaques, blood flow, and intravascular pressure.

Vascular Physics: Explaining the Nature of Escape Veins and When to Use Endovascular Ligation.

Small branching veins that arise from the venous outflow of surgical arterial-venous fistulas (AVFs) are frequently seen during fistulograms performed to evaluate for poorly functioning AVFs. It is hypothesized that the presence of escape veins can decrease the performance of native AVFs during hemodialysis by diverting flow. Though interventional methods for exclusion of escape veins are effective, the mechanism of disruption these small branching vessels cause on flow through AVFs is unknown. Furthermore, an objective method for identifying escape veins that cause significantly diminished venous flow has not been defined. The following describes the detrimental nature of escape veins using tenants of physics and electrical circuitry. Subsequently, the proceeding study shows the identification of small branching escape veins in patients during fistulography. Intravascular pressure measurements were obtained proximal and distal to the ostium of the offending collaterals in these patients. Escape veins causing a pressure gradient of at least 5 mmHg were treated, and pressure measurements were repeated following intervention. The patients were entered into a database and hemodialysis blood flow rates were monitored to determine if escape vein intervention increased AVF performance.

Utility of Functional Hemodynamics and Echocardiography to Aid Diagnosis and Management of Shock.

The utility of functional hemodynamics and bedside ultrasonography is increasingly recognized as advantageous for both improved diagnosis and management of shock states. In contrast to conventional "static" measures, "dynamic" hemodynamic measures and bedside imaging modalities enhance pathophysiology-based comprehensive understanding of shock states and the response to therapy. The current editions of major textbooks in the primary specialties--in which clinicians routinely encounter patients in shock--including surgery, anesthesia, emergency medicine, and internal medicine continue to incorporate traditional (conventional) descriptions of shock that use well-described (but potentially misleading) intravascular pressures to classify shock states. Reliance on such intravascular pressure measurements is not as helpful as newer "dynamic" functional measures including ultrasonography to both better assess volume responsiveness and biventricular cardiac function. This review thus emphasizes the application of current functional hemodynamics and ultrasonography to the diagnosis and management of shock as a contrast to conventional "static" pressure-based measures.

O-011 Quantitative MRA is Correlated with Intravascular Pressures Before and After Venous Sinus Stenting: Implications for Treatment and Monitoring

IntroductionEndovascular stenting is an effective treatment available for patients with clinically significant cerebral venous sinus stenosis. Traditionally, stenting success has been determined by intravascular pressure measurements; new imaging modalities, however,...

E-004 Vascular Causes of Pediatric Intracranial Hypertension

PurposeAfter space-occupying lesions and mechanical disruptions of CSF drainage have been excluded, intracranial venous hypertension (ICVH) often is the central mechanism leading to intracranial hypertension and its causes can be...

Uso do Sistema Manom&amp;#233;trico Miniaturizado Pressure-Wire em Cardiopatias Estruturais Cong&amp;#234;nitas e Adquiridas

Introdução: Historicamente, o registro de pressões intravasculares contribuiu para o desenvolvimento da cardiologia intervencionista. Embora atualmente novos recursos de imagem sejam preponderantes, a medida acurada de pressões intravasculares ainda é essencial em muitos contextos diagnósticos e de aferição de métodos terapêuticos intervencionistas. Descrevemos a utilização do sistema manométrico miniaturizado (pressure-wire) para obtenção de curvas pressóricas em cardiopatias estruturais congênitas e adquiridas. Métodos: Foram utilizados os sistemas RADI Analyzer® Xpress (St. Jude Medical Inc., St. Paul, Minnesota, Estados Unidos) e PressureWire® Certus durante procedimentos com cateteres diagnósticos 5 F realizados sob anestesia geral e suporte ventilatório em crianças. Traçados manométricos foram obtidos simultaneamente com o pressure-wire e o cateter 5 F em pacientes para os quais era imperativa a decisão terapêutica com base em análise das pressões intravasculares e nos quais não era possível obtê-las acuradamente pelos métodos convencionais. Resultados: O pressure-wire foi utilizado para obtenção de pressões intravasculares pulmonares em pacientes com colaterais sistêmico-pulmonares, com estenoses angiográficas ou não, e com variadas cardiopatias estruturais, na avaliação de estenoses de ramos pulmonares, na localização de estenoses de condutos cirúrgicos (por exemplo: após cirurgia de Rastelli), shunts cirúrgicos (como de Blalock-Taussig) e na avaliação pré-operatória de derivações cavo-pulmonares. O procedimento foi realizado com segurança, tendo sido obtidos traçados manométricos com qualidade adequada. Conclusões: O sistema manométrico miniaturizado está consagrado no cenário da cardiologia intervencionista, enquanto modalidade diagnóstica complementar para avaliação funcional de lesões coronárias. Esse sistema também constitui método diagnóstico complementar em diversas cardiopatias estruturais, congênitas e adquiridas.

Use of the Miniature Pressure-Wire Manometric System in Congenital and Acquired Structural Heart Diseases

Historically, intravascular pressure recording has contributed to the development of interventional cardiology. Although new imaging resources have gained much attention, accurate intravascular pressure measurement remains essential for the diagnosis and evaluation of interventional therapy methods. We describe the use of the miniature manometric system (pressure-wire) to obtain pressure curves in congenital and acquired structural heart diseases. The Radi Analyzer® Xpress (St. Jude Medical Inc., St. Paul, MN, USA) and PressureWire® Certus systems were used in procedures with 5 F catheters under general anesthesia and ventilatory support in children. Manometric tracings were obtained simultaneously from pressure-wire and the 5 F catheter in patients whose therapy strategies were dependent on the analysis of intravascular pressures, and in whom it was not possible to obtain them accurately by conventional methods. Pressure-wire was used to obtain pulmonary intravascular pressures in patients with systemic-pulmonary collaterals with or without angiographically detected stenosis, and with different structural heart diseases, in the evaluation of pulmonary branch stenosis, in the localization of surgical conduit stenosis (e.g. after Rastelli surgery), surgical shunts (such as Blalock-Taussig) and in the preoperative evaluation of cavopulmonary shunts. The procedure was performed safely, and manometric tracings were obtained with an adequate quality. The miniature manometric system is well accepted as a complementary diagnostic modality for the functional assessment of coronary lesions in interventional cardiology. It is also a complementary diagnostic method in different structural, congenital and acquired heart diseases. Uso do Sistema Manométrico Miniaturizado Pressure-Wire em Cardiopatias Estruturais Congênitas e Adquiridas Historicamente, o registro de pressões intravasculares contribuiu para o desenvolvimento da cardiologia intervencionista. Embora atualmente novos recursos de imagem sejam preponderantes, a medida acurada de pressões intravasculares ainda é essencial em muitos contextos diagnósticos e de aferição de métodos terapêuticos intervencionistas. Descrevemos a utilização do sistema manométrico miniaturizado ( pressure-wire ) para obtenção de curvas pressóricas em cardiopatias estruturais congênitas e adquiridas. Foram utilizados os sistemas RADI Analyzer® Xpress (St. Jude Medical Inc., St. Paul, Minnesota, Estados Unidos) e PressureWire® Certus durante procedimentos com cateteres diagnósticos 5 F realizados sob anestesia geral e suporte ventilatório em crianças. Traçados manométricos foram obtidos simultaneamente com o pressure-wire e o cateter 5 F em pacientes para os quais era imperativa a decisão terapêutica com base em análise das pressões intravasculares e nos quais não era possível obtê-las acuradamente pelos métodos convencionais. O pressure-wire foi utilizado para obtenção de pressões intravasculares pulmonares em pacientes com colaterais sistêmico-pulmonares, com estenoses angiográficas ou não, e com variadas cardiopatias estruturais, na avaliação de estenoses de ramos pulmonares, na localização de estenoses de condutos cirúrgicos (por exemplo: após cirurgia de Rastelli), shunts cirúrgicos (como o de Blalock-Taussig) e na avaliação pré-operatória de derivações cavo pulmonares. O procedimento foi realizado com segurança, tendo sido obtidos traçados manométricos com qualidade adequada. O sistema manométrico miniaturizado está consagrado no cenário da cardiologia intervencionista, enquanto modalidade diagnóstica complementar para avaliação funcional de lesões coronárias. Esse sistema também constitui método diagnóstico complementar em diversas cardiopatias estruturais, congênitas e adquiridas.

Computational fluid dynamics simulation to evaluate aortic coarctation gradient with contrast-enhanced CT

Coarctation of aorta (CoA) is a narrowing of the aorta leading to a pressure gradient (ΔP) across the coarctation, increased afterload and reduced peripheral perfusion pressures. Indication to invasive treatment is based on values of maximal (systolic) trans-coarctation ΔP. A computational fluid dynamic (CFD) approach is herein presented for the non-invasive haemodynamic assessment of ΔP across CoA. Patient-specific CFD simulations were created from contrast-enhanced computed tomography (CT) and appropriate flow boundary conditions. Computed ΔP was validated with invasive intravascular trans-CoA pressure measurements. Haemodynamic indices, including pressure loss coefficient (PLc), time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI), were also quantified. CFD-estimated ΔP values were comparable to the invasive ones. Moreover, the aorta proximal to CoA was exposed to altered TAWSS and OSI suggesting hypertension. PLc was found as a further geometric marker of CoA severity. Finally, CFD-estimated ΔP confirmed a significant reduction after percutaneous balloon dilatation and stenting of the CoA in one patient (e.g. from ΔP∼52 mmHg to ΔP∼3 mmHg). The validation of the ΔP computations with catheterisation measurements suggests that CFD simulation, based on CT-derived anatomical data, is a useful tool to readily quantify CoA severity.

Comparison of Non-invasive and Invasive Arterial Blood Pressure Measurement for Assessment of Dynamic Cerebral Autoregulation

There is a growing interest in measuring cerebral autoregulation in patients with acute brain injury. Non-invasive finger photo-plethysmography (Finapres) is the method of choice to relate arterial blood pressure to changes in cerebral blood flow. Among acutely ill patients, however, peripheral vasoconstriction often limits the use of Finapres requiring direct intravascular blood pressure measurement. We evaluated how these two different forms of blood pressure monitoring affect the parameters of dynamic cerebral autoregulation (DCA). We performed 37 simultaneous recordings of BP and cerebral blood flow velocity in 15 patients with acute brain injury. DCA was estimated in the frequency domain using transfer function analysis to calculate phase shift, gain, and coherence. In addition the mean velocity index (Mx) was calculated for assessment of DCA in the time domain. The mean patient age was 58.1±15.9years, 80% (n=12) were women. We found good inter-method agreement between Finapres and direct intravascular measurement using Bland-Altman and correlation analyses. Finapres gives higher values for the efficiency of dynamic CA compared with values derived from radial artery catheter, as indicated by biases in the phase (26.3±11.6° vs. 21.7±10.5°, p=0.001) and Mx (0.571±0.137 vs. 0.649±0.128, p<0.001). Gain in the low frequency range did not significantly differ between the two arterial blood pressure methods. The average coherence between CBFV and ABP was higher when BP was measured with arterial catheter for frequencies above 0.05Hz (0.8 vs. 0.73, p<0.001). Overall, both methods yield similar results and can be used for the assessment of DCA. However, there was a small but significant difference for both mean Mx and phase shift, which would need to be adjusted for during monitoring of patients when using both methods. When available, invasive arterial blood pressure monitoring may improve accuracy and thus should be the preferred method for DCA assessment in the ICU.

Estimation of aortic pulse pressure using fourier velocity encoded M‐mode MR

To use a simplified hemodynamic model and Fourier-encoded velocity data to measure pulse pressure (PP) in the descending aorta. A one-dimensional, cylindrically localized pulse sequence with Fourier velocity encoding (FVE) was used to obtain time-dependent velocity distributions along the descending aorta. Numerical evaluation of a simplified hemodynamic model, based on a cross-sectionally averaged form of the mass conservation equation, allowed estimation of the average pressure waveform and PP along 6-cm-long segments located within the descending aorta. Magnetic resonance (MR)-derived pressures were compared against applanation tonometry (AT) performed in healthy subjects (n = 18) and intravascular pressure measurements (IVPM) obtained in patients (n = 4) undergoing diagnostic cardiac angiography and then found to be either normal or with clinically insignificant coronary artery disease. The root mean square (RMS) error between MR- and AP-derived pressure waveforms was 11.7 ± 5.8%. With respect to IVPM, the RMS error ranged from 4.2% to 14.7%. In terms of pulse pressures, there was good agreement with both AT (bias = 0.99 mmHg; 95% limits of agreement (LOA) = [-5.0 to 7.0 mmHg]; range = 12.0 mmHg) and IVPM (bias = -1.82 mmHg; 95% LOA = [-7.2 to 3.5 mmHg]; range = 10.7 mmHg). FVE M-mode and numerical evaluation of a simplified flow model can be used to estimate central pulse pressures noninvasively and accurately with respect to well-established gold standards.

Cerebral Aneurysms Treated with Flow-Diverting Stents: Computational Models with Intravascular Blood Flow Measurements

Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measurements into computational models of aneurysms before and after treatment with flow-diverting stents to determine stent effects on aneurysm hemodynamics. Blood flow velocity and pressure were measured in peri-aneurysmal locations by use of an intravascular dual-sensor pressure and Doppler velocity guidewire before and after flow-diverting stent treatment of 4 unruptured cerebral aneurysms. These measurements defined inflow and outflow boundary conditions for computational models. Intra-aneurysmal flow rates, wall shear stress, and wall shear stress gradient were calculated. Measurements of inflow velocity and outflow pressure were successful in all 4 patients. Computational models incorporating these measurements demonstrated significant reductions in intra-aneurysmal wall shear stress and wall shear stress gradient and a trend in reduced intra-aneurysmal blood flow. Integration of intravascular dual-sensor guidewire measurements of blood flow velocity and blood pressure provided patient-specific computational models of cerebral aneurysms. Aneurysm treatment with flow-diverting stents reduces blood flow and hemodynamic shear stress in the aneurysm dome.

Arterial Injury Complicating Subclavian Central Venous Catheter Insertion

n i a a g n c INADEQUATE PLACEMENT of a subclavian venous catheter in the subclavian artery is a well-known complication.1,2 Three cases of accidental arterial puncture occurred with the implantation of subclavian venous catheters, 2 of which involved the subclavian artery leading to percutaneous treatment; and the other involved the aortic arch, resulting in surgical management, are described.

Vascular pedicle width in acute lung injury: correlation with intravascular pressures and ability to discriminate fluid status

IntroductionConservative fluid management in patients with acute lung injury (ALI) increases time alive and free from mechanical ventilation. Vascular pedicle width (VPW) is a non-invasive measurement of intravascular volume status. The VPW was studied in ALI patients to determine the correlation between VPW and intravascular pressure measurements and whether VPW could predict fluid status.MethodsThis retrospective cohort study involved 152 patients with ALI enrolled in the Fluid and Catheter Treatment Trial (FACTT) from five NHLBI ARDS (Acute Respiratory Distress Syndrome) Network sites. VPW and central venous pressure (CVP) or pulmonary artery occlusion pressure (PAOP) from the first four study days were correlated. The relationships between VPW, positive end-expiratory pressure (PEEP), cumulative fluid balance, and PAOP were also evaluated. Receiver operator characteristic (ROC) curves were used to determine the ability of VPW to detect PAOP <8 mmHg and PAOP ≥18 mm Hg.ResultsA total of 71 and 152 patients provided 118 and 276 paired VPW/PAOP and VPW/CVP measurements, respectively. VPW correlated with PAOP (r = 0.41; P < 0.001) and less well with CVP (r = 0.21; P = 0.001). In linear regression, VPW correlated with PAOP 1.5-fold better than cumulative fluid balance and 2.5-fold better than PEEP. VPW discriminated achievement of PAOP <8 mm Hg (AUC = 0.73; P = 0.04) with VPW ≤67 mm demonstrating 71% sensitivity (95% CI 30 to 95%) and 68% specificity (95% CI 59 to 75%). For discriminating a hydrostatic component of the edema (that is, PAOP ≥18 mm Hg), VPW ≥72 mm demonstrated 61.4% sensitivity (95% CI 47 to 74%) and 61% specificity (49 to 71%) (area under the curve (AUC) 0.69; P = 0.001).ConclusionsVPW correlates with PAOP better than CVP in patients with ALI. Due to its only moderate sensitivity and specificity, the ability of VPW to discriminate fluid status in patients with acute lung injury is limited and should only be considered when intravascular pressures are unavailable.