A novel in vivo assessment of fluid dynamics on aortic valve leaflet using epi-aortic echocardiogram.

BACKGROUND: Mechanical stress caused by blood flow, such as wall shear stress (WSS) and its related parameters, is key moderator of endothelial degeneration. However, an in vivo method to measure WSS on heart valves has not been developed. METHODS: We developed a novel approach, based on vector flow mapping using intraoperative epi-aortic echocardiogram, to measure WSS and oscillatory shear index (OSI) on the aortic valve. We prospectively enrolled 15 patients with normal valves, who underwent coronary artery bypass graft. RESULTS: Systolic WSS on the ventricularis (2.40 ± 0.44 Pa [1.45-3.00 Pa]) was higher than systolic WSS on the fibrosa (0.33 ± 0.08 Pa [0.14-0.47 Pa], P < .001) and diastolic WSS on the ventricularis (0.18 ± 0.07 Pa [0.04-0.28 Pa], P < .001). Oscillatory shear index on the fibrosa was higher than on the ventricularis (0.29 ± 0.04 [0.24-0.36] vs 0.05 ± 0.03 [0.01-0.12], P < .001). A pilot study involving two patients with severe aortic regurgitation showed significantly different values in fluid dynamics. CONCLUSION: Vector flow mapping method using intraoperative epi-aortic echocardiogram is an effective way of measuring WSS and OSI on normal aortic leaflet in vivo, allowing for better understanding of the pathophysiology of aortic valve diseases.

The anatomy of the aortic root.

The aortic root is the anatomical bridge between the left ventricle and the ascending aorta. It is made up of the aortic valve leaflets, which are supported by the aortic sinuses (of Valsalva), and the interleaflet triangles interposed between the basal attachments of the leaflets. As such, it possesses significant length, and because of the semilunar attachment of the leaflets, there is no discrete proximal border to the root. It is limited distally, nonetheless, by the supravalvar ridge, or sinutubular junction. Descriptions of the aortic root over the years have been bedeviled by accounts of a valve anulus. There are at least two rings within the root, but neither serves to support the valve leaflets, each leaflets being attached in semilunar fashion from the sinutubular junction to a basal ventricular attachment Two leaflets are supported by muscle, and the third has an exclusively fibrous attachment. The root acts as a bridging structure not only anatomically, separating the myocardial and arterial components of the left ventricular pathway, but also functionally, since its proximal and distal components can withstand considerable changes in ventricular and arterial pressures. In this review, we describe the anatomy of this crucial cardiac component, emphasizing the current problems which have arisen due to indiscriminate descriptions of a nonexistent anulus.

Incidental Perforation of Aortic Valve Leaflet Found on Presentation of Cardiogenic Shock.

Aortic regurgitation (AR) is grouped into acute or chronic AR. Acute AR, unlike chronic AR, can manifest with significant hemodynamic compromise. Acute AR is typically due to endocarditis or aortic dissection, and less commonly due to blunt trauma or iatrogenic causes. We present a patient with cardiogenic shock due to severe acute AR from anterior leaflet perforation without an identifiable rheumatologic or infectious etiology.

Influence of aneurysmal aortic root geometry on mechanical stress to the aortic valve leaflet.

AIMS: While mechanical stress caused by blood flow, e.g. wall shear stress (WSS), and related parameters, e.g. oscillatory shear index (OSI), are increasingly being recognized as key moderators of various cardiovascular diseases, studies on valves have been limited because of a lack of appropriate imaging modalities. We investigated the influence of aortic root geometry on WSS and OSI on the aortic valve (AV) leaflet. METHODS AND RESULTS: We applied our novel approach of intraoperative epi-aortic echocardiogram to measure the haemodynamic parameters of WSS and OSI on the AV leaflet. Thirty-six patients were included, which included those who underwent valve-sparing aortic root replacement (VSARR) with no significant aortic regurgitation (n = 17) and coronary artery bypass graft (CABG) with normal AV (n = 19). At baseline, those who underwent VSARR had a higher systolic WSS (0.52 ± 0.12 vs. 0.32 ± 0.08 Pa, respectively, P < 0.001) and a higher OSI (0.37 ± 0.06 vs. 0.29 ± 0.04, respectively, P < 0.001) on the aortic side of the AV leaflet than those who underwent CABG. Multivariate regression analysis revealed that the size of the sinus of Valsalva had a significant association with WSS and OSI. Following VSARR, WSS and OSI values decreased significantly compared with the baseline values (WSS: 0.29 ± 0.12 Pa, P < 0.001; OSI: 0.26 ± 0.09, P < 0.001), and became comparable to the values in those who underwent CABG (WSS, P = 0.42; OSI, P = 0.15). CONCLUSIONS: Mechanical stress on the AV gets altered in correlation with the size of the aortic root. An aneurysmal aortic root may expose the leaflet to abnormal fluid dynamics. The VSARR procedure appeared to reduce these abnormalities.

Aortic Valve Leaflet Disruption: A Severe Complication of Impella 5.5.

A 73-year-old male with a history of severe coronary artery disease and prior coronary artery bypass grafting (CABG) presented with chest pain and elevated troponins. His workup revealed an ejection fraction of 15%, severe native coronary disease, as well as stenosis of his bypass grafts. He underwent a high-risk redo CABG with an Impella 5.5® (Abiomed, Danvers, MA) placement. The device was removed on postoperative day eight, at which time he went into cardiogenic shock from aortic valve leaflet injury. Given that he had no calcium deposits around the aortic valve annulus and severe aortic insufficiency, a multidisciplinary heart team decided he would be best served by a surgical aortic valve replacement. He was taken back to the operating room for a surgical aortic valve and intra-aortic balloon pump. His postoperative course was complicated by pneumonia, sepsis, and renal failure requiring continuous renal replacement therapy. He was discharged to a rehabilitation facility after 42 days. The following case encompasses the high morbidity risk of acute aortic valve insufficiency after Impella placement, never before documented in an Impella 5.5.

Materials and manufacturing perspectives in engineering heart valves: a review.

Valvular heart diseases (VHD) are a major health burden, affecting millions of people worldwide. The treatments for such diseases rely on medicine, valve repair, and artificial heart valves including mechanical and bioprosthetic valves. Yet, there are countless reports on possible alternatives noting long-term stability and biocompatibility issues and highlighting the need for fabrication of more durable and effective replacements. This review discusses the current and potential materials that can be used for developing such valves along with existing and developing fabrication methods. With this perspective, we quantitatively compare mechanical properties of various materials that are currently used or proposed for heart valves along with their fabrication processes to identify challenges we face in creating new materials and manufacturing techniques to better mimick â€‹the performance of native heart valves.

A case of aortic valve leaflet tear and perforations after neocuspidization.

Although aortic valve (AV) replacement is a curative procedure for severe aortic stenosis, prosthetic heart valves have many disadvantages and cause serious complications. A new promising surgical procedure-aortic valve neocuspidization (AVNeo)-has recently been developed; it is an original method of AV reconstruction with autologous pericardium. It has been reported to yield excellent medium-term results with respect to durability and complications. Herein, we encountered a first case of AV leaflet tear and perforations 27 months after AVNeo using autologous pericardium. AV leaflet tear or perforation is well recognized as a long-term serious complication of pericardial xenografts. Interestingly, however, AVNeo caused early structural valve deterioration in the current case. In the present case, an eccentric aortic regurgitation jet observed on colour flow imaging led us to reach the correct diagnosis. Finally, the patient showed complete recovery with redo AV replacement. This case highlights the importance of understanding the potential pitfalls of this new surgical technique and that of colour Doppler echocardiography in reaching a definite diagnosis.