Changes in arterial pressure during left heart pullback in patients with aortic stenosis: a sign of severe aortic stenosis

Is There Still a Role for Invasive Assessment of Aortic Gradient?

Advances in technology and imaging have expanded the range of tools for diagnosing aortic stenosis (AS). The accurate assessment of aortic valve area and mean pressure gradient is crucial to determine which patients are appropriate candidates for aortic valve replacement. Nowadays, these values can be obtained noninvasively or invasively, with similar results. Contrariwise, in the past, cardiac catheterization played a major role in the evaluation of AS severity. In this review, we will discuss the historical role of the invasive assessment of AS. Moreover, we will specifically focus on tips and tricks for properly performing cardiac catheterization in patients with AS. We will also elucidate the role of invasive methods in current clinical practice and their additional value to the information provided through non-invasive techniques.

Non-Invasive Assessment of Intravascular Pressure Gradients: A Review of Current and Proposed Novel Methods

Invasive catheterization is associated with a low risk of serious complications. However, although it is the gold standard for measuring pressure gradients, it induces changes to blood flow and requires significant resources. Therefore, non-invasive alternatives are urgently needed. Pressure gradients are routinely estimated non-invasively in clinical settings using ultrasound and calculated with the simplified Bernoulli equation, a method with several limitations. A PubMed literature search on validation of non-invasive techniques was conducted, and studies were included if non-invasively estimated pressure gradients were compared with invasively measured pressure gradients in vivo. Pressure gradients were mainly estimated from velocities obtained with Doppler ultrasound or magnetic resonance imaging. Most studies used the simplified Bernoulli equation, but more recent studies have employed the expanded Bernoulli and Navier⁻Stokes equations. Overall, the studies reported good correlation between non-invasive estimation of pressure gradients and catheterization. Despite having strong correlations, several studies reported the non-invasive techniques to either overestimate or underestimate the invasive measurements, thus questioning the accuracy of the non-invasive methods. In conclusion, more advanced imaging techniques may be needed to overcome the shortcomings of current methods.

Trend and Outcomes of Direct Transcatheter Aortic Valve Replacement from a Single-Center Experience

INTRODUCTION

When transcatheter aortic valve replacement (TAVR) was introduced, pre-implantation balloon aortic valvuloplasty (BAV) was a routine part of the procedure. Smaller device profiles have resulted in selective use of BAV; however, there is a paucity of data about the trend in use of direct TAVR and the safety of this strategy.

METHODS

All patients who underwent TAVR at a Veterans Affairs Medical Center from September 2013 to November 2016 were included in this retrospective analysis. We reviewed angiography films and verified with procedure reports to assess if direct TAVR was performed. Troponin T was assessed within 72 h after the TAVR. Multivariate analysis examined the association between direct TAVR and periprocedural myocardial infarction (MI) or 1-year mortality.

RESULTS

Overall, 207 patients were available for analysis. The mean follow-up was 13.3 months. A balloon-expandable valve was used 93.2% of the time, and 35.3% of patients were treated with conscious sedation. Periprocedural MI or 1-year mortality occurred in 12.5% of the direct TAVR group versus 18.3% of the pre-implantation BAV group (p = 0.30). After controlling for potential confounding variables, direct TAVR was not associated with periprocedural MI or 1-year mortality.

CONCLUSIONS

Direct TAVR appears to be safe and is not associated with periprocedural MI or 1-year mortality. With current generation devices, this strategy can be considered for most patients undergoing TAVR.

Invasive Hemodynamics of Valvular Heart Disease

In the current era, diagnosis and follow-up of valvular heart disease is performed noninvasively using echocardiography. In some cases, the results of echocardiographic evaluation are inconclusive or discrepant with the patient's clinical symptoms. In such cases, a well-planned and executed cardiac catheterization is invaluable to clarify the clinical dilemma and assist in planning further management. This article reviews the indications, technique, and interpretation of cardiac catheterization in the setting of valvular stenosis and regurgitation.

Invasive assessment of doubtful aortic stenosis by measuring simultaneous transaortic gradient with a pressure wire

Two-dimensional transthoracic echocardiography (2D-TTE) is the reference technique for evaluating aortic stenosis (AS) but may be unreliable in some cases. We aimed to assess whether the use of a pressure wire to measure simultaneous transaortic gradient and aortic valve area (AVA) could be helpful in patients in whom initial noninvasive evaluations were considered doubtful for AS. Fifty-seven patients (mean age 76 years; 39 men) underwent cardiac catheterization with single arterial access for assessment of AVA with the Gorlin and Gorlin formula. Transaortic pressure was obtained by 2 invasive methods: (1) conventional pullback method (PM) from the left ventricle toward the aorta and (2) simultaneous method (SM) with transaortic pressure simultaneously recorded with a 0.014-inch pressure wire introduced into the left ventricle and with a diagnostic catheter placed in the ascending aorta. Reasons for inaccurate assessment by 2D-TTE were low flow states (88%) and/or atrial fibrillation (79%). Agreement for severe AS defined by AVA <0.6 cm²/m² between SM and 2D-TTE and between SM and PM was fair, with kappa coefficients of 0.38 (95% confidence interval [CI] 0.14-0.75) and 0.36 (95% CI 0.22-0.7) respectively; agreement was poor between 2D-TTE and PM (kappa: 0.23; 95% CI 0.002-0.36). SM led to a reclassification of the severity of AS in 9 patients (15.8%) compared with 2D-TTE and in 11 patients (19.3%) compared with PM. In conclusion, invasive evaluation of doubtful AS by measuring simultaneous transaortic gradient using a pressure wire may provide an attractive method that can lead to a change in therapeutic strategy in a substantial proportion of patients.

Accuracy of computer-based quantification of aortic valve stenosis

In patients with aortic valve stenosis, the quantification of stenosis is usually performed using fluid-filled catheters and a computerized calculation program. The aim of this study was to determine the accuracy of this technique in comparison to the manual planimetry of the area between the curves of a simultaneous registration, using a multitip micromanometer catheter. The study was performed in 19 patients, in whom left and right heart catheterization was warranted. Systolic left ventricular and aortic peak pressures were significantly overestimated using a fluid-filled catheter (206 +/- 35 vs. 199 +/- 37 mm Hg, P = 0.0003, and 148 +/- 18 vs. 143 +/- 21 mm Hg, P = 0.0052). However, peak-to-peak pressure gradients were identical comparing both techniques (58 +/- 31 vs. 56 +/- 32 mm Hg, r = 0.983). The mean pressure gradients and aortic valve areas based on simultaneous measurements of left ventricular and aortic pressures by micromanometer catheters were identical to the values determined by a computer-based program using fluid-filled catheters (54 +/- 21 vs. 52 +/- 21 mm Hg, r = 0.923, P < 0.05, and 0.75 +/- 0.25 vs. 0.77 +/- 0.25 cm2, r = 0.935). Thus, the conventional use of fluid-filled catheters and of a computerized calculation of aortic valve area is valid for quantification of aortic stenosis in patients with sinus rhythm and without significant aortic regurgitation.

Evaluation of the significance of a transvalvular catheter on aortic valve gradient in aortic stenosis: a direct hemodynamic and Doppler echocardiographic study

We studied 18 patients with aortic stenosis undergoing routine cardiac catheterization to determine the effect of a transvalvular catheter on transaortic pressure gradients. By measuring the Doppler gradients before and after the withdrawal of the pigtail catheter, we demonstrated significant increases in the peak instantaneous and mean gradients when the catheter straddled the valve, an effect that was more pronounced with increasing severity of stenosis.

The technique and safety of transseptal left heart catheterization: the Massachusetts General Hospital experience with 1,279 procedures

With the introduction of interventional procedures such as percutaneous mitral valvuloplasty and radiofrequency ablation of left-sided bypass tracts, there has been renewed interest in the technique of transseptal left heart catheterization. We review our experience with 1,279 transseptal catheterizations performed over the last 10 years. The most common indications for transseptal catheterization included direct measurement of left atrial pressure or access to the left ventricle in patients with prosthetic aortic or mitral valves, and in patients undergoing percutaneous mitral valvuloplasty. A total of 17 major complications occurred (1.3%), including cardiac tamponade (15 patients, 1.2%), systemic emboli (1 patient, 0.08%), and death secondary to aortic perforation (0.08%). We conclude that when performed by experienced operators, transseptal left heart catheterization is associated with low morbidity and mortality.

Hemodynamic assessment of aortic stenosis

The decision to operate in patients with aortic stenosis is based on the presence of symptoms and hemodynamically significant valvular obstruction. The strengths and limitations of cardiac catheterization and Doppler echocardiography are compared, and the concept of "critical" aortic stenosis is discussed. The recommendation of aortic valve replacement must take into account the symptom status, the hemodynamic significance of the lesion, and the size and type of valve to be implanted.

Simultaneous left ventricular and ascending aortic pressure measurements via single artery access for assessment of aortic stenosis

In order to determine the reliability of a single arterial access technique for hemodynamic assessment of aortic stenosis, data obtained from this method was compared with that from dual arterial access in 13 patients. A 59 cm long, 8 Fr. Mullins Transseptal Sheath (MTS) was placed in the ascending aorta (AA) and a 5 Fr. pigtail catheter advanced through the MTS (using a hemostatic "Y" adapter) into the left ventricle for simultaneous pressure recordings. Another 5 Fr. pigtail catheter (PTC) was advanced in the AA from the contralateral femoral artery. Peak pressures, AA pressure-tracing characteristics, mean gradients, and the aortic valve area using tracings from the MTS and the PTC were compared. Peak pressures 120 +/- 8 vs. 119 +/- 8 mmHg (r = .998), "T" time .16 +/- .01 vs. .15 +/- .01 sec. (r = .913), "U" time .36 +/- .02 vs. .36 +/- .02 sec. (r = .983), mean gradients 38.4 +/- 6.1 vs. 39.6 +/- 6.9 mmHg (r = .990) and the AV area .78 +/- .08 vs. 79 +/- .08 cm2 (r = .994) were similar. Therefore, this single arterial technique provides data comparable to the traditional dual access system for hemodynamic assessment of aortic stenosis.

Doppler echocardiographic determination of aortic valve area using the continuity equation

The noninvasive measurement of aortic valve area by use of the continuity equation has been proposed as an accurate method for determining the severity of aortic stenosis. In 32 patients (mean age 64 +/- 14 years) with proven aortic stenosis and without significant regurgitation, aortic valve areas derived by the Gorlin equation from cardiac catheterisation data were compared with valve areas calculated from the continuity equation using Doppler echocardiography. There was a close correlation between Doppler and catheter derived aortic valve areas (r = 0.87, SEE = 0.17 cm2). The interobserver error for aortic valve area measurement in 20 patients was 9.0 +/- 6.8%. The specificity of this method for critical aortic stenosis (aortic valve area less than 0.75 cm2) was 73% and the sensitivity 88%. We conclude that in an adult, predominantly elderly population with calcific aortic stenosis, this Doppler echocardiographic method is reproducible and can be used accurately to derive aortic valve area.

Advances in the hemodynamic assessment of stenotic cardiac valves

In 1951 Gorlin and Gorlin (Am Heart J 1951;41:1-29) published their formula for calculating the area of a stenotic cardiac valve from hemodynamic data. The important concept implicit in this formula is that the hemodynamic evaluation of a stenotic valve requires that the pressure gradient across that valve be examined in light of the cardiac output passing through the orifice. The concept asserts that if an accurately obtained pressure gradient can be related to an accurate cardiac output by an accurate formula, valve area can be determined. However, recent studies have demonstrated flaws in current practices for obtaining transvalvular gradients and cardiac outputs. Further, new data are available regarding the validation and possible changes in the Gorlin formula, validation and changes that the Gorlins noted might be necessary to make. These new data concerning the three basic requirements of an accurate valve area determination are the subject of this review.

Left atrial and ventricular transseptal catheterization review: losing skills?

Transseptal catheterization has been routinely done at this institution for the past 19 years to evaluate the left heart. Reviewing the last 250 consecutive transseptal heart catheterizations between 1978 and 1986, the left atrium and ventricle were entered in all but six patients. One death occurred with four other major complications. There were 177 males and 73 females ranging from 18 to 84 years of age. Of these 250 studies, 31 were in association with direct left ventricular apical puncture; 42 were in patients with subaortic stenosis; 101 were in aortic stenosis; 26 were in patients with combined aortic and mitral disease; and four were in patients with triple prosthetic valve replacements. No attempts were made to cross the prosthetic mitral valves. A decline in the number of transseptal studies at this institution has been noted over the past 8 years and the technique is not longer taught routinely to Fellows. The reduction is due to increased emphasis on coronary artery anatomy, fewer rheumatic and prosthetic valvular admissions, and improved reevaluation by non-invasive echocardiography and doppler studies. This has resulted in a loss in proficiency among invasive cardiologists. In conclusion, the transseptal technique is potentially hazardous, but continued usage will maintain proficiency and a low major and minor complication rate.

Aortic stenosis in adults. Non-invasive estimation of pressure differences by continuous wave Doppler echocardiography

The peak and mean aortic transvalvar pressure differences measured invasively and non-invasively by continuous wave Doppler echocardiography were compared in 87 consecutive patients with aortic stenosis. The mean values were calculated from the maximal velocities of the aortic jet recorded with a spectral display of the Doppler frequency shifts and by applying a modified Bernoulli equation. Technically satisfactory velocity curves for estimating the mean pressure differences could not be obtained in three patients and invasive measurements were not obtained in two. In all patients the peak transvalvar pressure difference was calculated since the aortic jet was identified non-invasively. The peak and mean pressure differences measured invasively and non-invasively correlated well--with only minor underestimation of the pressure differences measured with the Doppler technique--regardless of age, sex, and the presence or absence of aortic valvar regurgitation, or other valvar lesions. With a systematic search for the highest velocities in the aortic jet and with on line spectral analysis of the Doppler frequencies the peak and the mean aortic pressure differences can be determined non-invasively with a high degree of precision in almost all patients.

Evaluation of aortic stenosis by spectral analysis of the murmur

A relation between the peak transaortic pressure gradient and the frequency content of the murmur (r = 0.79) was demonstrated in a prospective "test" set of 50 patients with the clinical diagnosis of aortic stenosis. After heart sounds were recorded and digitized, three segments of the systolic murmur were isolated and analyzed by fast Fourier transform technique. An average frequency spectrum was quantitated by a previously described empiric spectral estimator. Clinical data and spectral ratio were correlated with the transaortic pressure gradient and aortic valve area was calculated from cardiac catheterization data. The best prediction of the transaortic pressure gradient was obtained when a 170 ms murmur segment was analyzed and when the predictive algorithm also included the aortic dimension (r = 0.87). The aortic valve area was poorly predicted (r = -0.48) unless estimates of blood flow and valvular calcification were included in the algorithm (r = 0.84). Further refinement of this technique may provide a non-invasive and clinically useful method for the estimation of aortic valve stenosis.

Simultaneous measurement of aortic and left ventricular pressures in aortic stenosis using a double lumen pigtail catheter

This technical note describes a double lumen pigtail catheter that can facilitate measurement of the aortic valve gradient in patients with aortic stenosis. The catheter is passed retrograde into the left ventricle with the aid of a flexible guide wire. In two patients the measured gradient was not significantly different from that obtained using two systemic arterial catheters.

Recent experience with transeptal catheterization

We report our recent experience of 207 consecutive transeptal catheterizations performed in the following groups of patients: aortic valve disease in 152, mitral valve disease in 20, combined aortic and mitral valve disease in 11, hypertrophic obstructive cardiomyopathy in 11, assessment of prosthetic cardiac valves in nine, and four miscellaneous. Transeptal catheterization failed in 20 patients. There was no attempt to advance the transeptal catheter from the left atrium into the left ventricle in 18 patients, and failure to advance the transeptal catheter from the left atrium into the left ventricle occurred in 13 patients. Transeptal catheterization was achieved in a mean time of 9.7 +/- 4.6 SD min. There were no deaths, two major and four minor complications. We conclude that transeptal catheterization remains a useful technique that in experienced hands is both rapid and safe.

A safe, rapid method of transfemoral retrograde left ventricular catheterization in valvular aortic stenosis

We report our experience with the use of a standard left Amplatz coronary catheter and a guidewire to cross the aortic valve in 34 patients being evaluated for valvular aortic stenosis. A number of 2 Amplatz left coronary catheter inserted via the femoral artery was positioned above the noncoronary aortic valve cusp with the tip aligned toward the aortic valve. This catheter allowed a soft-tipped, Teflon-coated guidewire to be guided through the aortic valve orifice. The catheter was then advanced over the guidewire into the left ventricle. This technique was successful within six minutes in 32 of 34 patients (94%). The stenotic aortic valve was crossed in less than two minutes in 15 patients (42%) and in less than four minutes in 31 (91%). The aortic valve was not crossed in two patients. Twenty-one patients (62%) had an aortic valve area of less than 0.75 cm2. There were no complications. We conclude that this technique provides a method for safe, rapid transaortic left ventricular catheterization in patients with aortic stenosis of all degrees of severity.

New preshaped catheter for investigation of aortic stenosis by femoral approach: a study of 100 cases

The authors describe their technique of catheterization of the left ventricle in aortic stenosis by a femoral approach based on a newly designed double-curved catheter. The method has been used succcessfully in 87 of 100 consecutive cases. The advantages and drawbacks of the method are discussed.