Ahmed Amro

Multimaterial Cardiovascular Printing

Abstract Tissues are hierarchical structures comprising many different materials that allow them to sustain, and adapt to, demanding mechanical and chemical stresses. The location, amount, and presence of materials can vary depending on a particular disease state. Understanding the different materials that comprise these tissues gives insight into the diagnosis and prognosis of an individual, since ultimately such material properties dictate the function of these tissues. 3D printing has the advantage of fabricating complex structures using a layered approach. For cardiovascular applications, this technology can be used for a variety of purposes, such as 3D models to visualize anatomy, surgical planning for device deployment, and direct fabrication of tissue. The ability to 3D print multiple materials allows the printed part to better recapitulate the tissue being mimicked, whether for visualization or functional purposes. In this chapter, we will review the different tissue types that comprise the cardiovascular system and the current state of literature that utilizes multimaterial 3D printing for either clinical or research applications related to the cardiovascular system.

Urgent Coronary Artery Bypass Grafting Due to Multi- Vessel Coronary Aneurysm

Coronary artery aneurysm (CAA) is defined as a dilation of more than 1.5 times normal in a segment of the coronary artery. The incidence of CAA is highest in the right coronary artery (RCA); left main coronary artery or three-vessel involvement is extremely rare. Wide ranges of factors have been implicated in the cause of CAA; atherosclerosis is the most common at 50%. Congenital CAA occurs in 20-30% of cases followed by connective tissue disease at 10%. Blood stagnation and exposure of the underlying collagen make aneurysms prone to thrombosis, dissection, and vasospasm. Depending on the size, symptoms, and etiology of the aneurysms, a surgical, percutaneous, or medical approach may be used. In this paper, we present a patient who presented to the emergency department (ED) with chest pain due to acute coronary syndrome (ACS) that was found to be due to multi-vessel CAAs. The left main as well as RCA, left anterior descending (LAD) artery and left circumflex artery (LCA) were involved and urgent coronary artery bypass grafting (CABG) was required.

Ammonia vs. Lactic Acid in Predicting Positivity of Microbial Culture in Sepsis: The ALPS Pilot Study

Objective: The use of serum ammonia as a novel marker for sepsis compared to lactic acid levels in intensive care unit (ICU) patients. Design and Interventions: Single arm, prospective clinical trial to collect arterial blood samples from patients with sepsis. Serial ammonia and lactic acid levels were sent every six hours for a total of three days. Measurements and results: Compare mean levels of ammonia and lactic acid in terms of diagnosing sepsis and patient outcome, including length of stay and mortality. A total of 30 patients were enrolled in the pilot study. On admission, mean ammonia level was 35.7 μmol/L and lactic acid was 3.06 mmole/L. Ammonia levels checked at the end of day 2 (ammonia 2-4) and the beginning of day 3 (ammonia 3-1) were higher in patients who had a microbial culture-proven sepsis (p-values 0.029 and 0.002, respectively) compared to those without culture-positive sepsis. Ammonia levels did predict a longer hospital stay; ammonia level of more than 40 μmol/L had a mean hospital stay of 17.6 days vs. patients with normal levels who had a mean hospital stay of 9.62 days (p-value 0.0082). Conclusion: Elevated ammonia level can be a novel biomarker for sepsis, comparable to conventional markers. Ammonia levels have a prognostic utility as elevated levels were associated with longer hospital stay.

Endovascular Therapy of TASC-D Lesion in Critical Limb Ischemia

Critical limb ischemia (CLI) is a terminal stage of peripheral artery disease (PAD); it is defined by the presence of resting pain and/or tissue loss for at least two weeks that may require urgent revascularization to promote healing and prevent limb loss. For patients with infrarenal aortoiliac occlusive disease, the revascularization options are surgery like aortofemoral bypass and axillofemoral bypass or percutaneous intervention. Aortoiliac and aortofemoral bypass procedures are associated with 74% to 95% 5-year patency rates, respectively, which are comparable but not superior to percutaneous therapies. These operations may imply a significant morbidity and mortality on CLI patients who usually have multiple comorbid conditions and are considered high risk patients.

Retrograde Tibiopedal Access as a Bail-Out Procedure for Endovascular Intervention Complications

Introduction. Retrograde pedal access has been well described in the literature as a secondary approach for limb salvage in critical limb ischemia (CLI) patients. In this manuscript we are presenting a case where retrograde tibiopedal access has been used as a bail-out procedure for the management of superficial femoral artery (SFA) intervention complications. Procedure/Technique. After development of a perforation while trying to cross the totally occluded mid SFA using the conventional CFA access, we were able to cross the mid SFA lesion after accessing the posterior tibial artery in a retrograde fashion and delivered a self-expanding stent which created a flap that sealed the perforation without the need for covered stent. Conclusion. Retrograde tibiopedal access is a safe and effective approach for delivery of stents from the distal approach and so can be used as a bail-out technique for SFA perforation.