Is Aortic Z-score an Appropriate Index of Beneficial Drug Effect in Clinical Trials in Aortic Aneurysm Disease?

Aortic Z-score (Z-score) is utilized in clinical trials to monitor the effect of medications on aortic dilation rate in Marfan (MFS) patients. Z-scores are reported in relation to body surface area and therefore are a function of height and weight. However, an information void exists regarding natural, non-pharmacological changes in Z-scores as children age. We had concerns that Z-score decrease attributed to "therapeutic" effects of investigational drugs for Marfan disease connective tissue diseases might simply reflect normal changes ("filling out" of body contour) as children age. This investigation studies natural changes with age in Z-score in normal and untreated MFS children, teasing out normal effects that might erroneously be attributed to drug benefit. (1) We first compared body mass index (BMI) and Z-scores (Boston Children's Hospital calculator) in 361 children with "normal" single echo exams in four age ranges (0 to 1, 5 to 7, 10 to 12, 15 to 18 years). Regression analysis revealed that aging itself decreases ascending Z-score, but not root Z-score, and that increase in BMI with aging underlies the decreased Z-scores. (2) Next, we examined Z-score findings in both "normal" and Marfan children (all pharmacologically untreated) as determined on sequential echo exams over time. Of 27 children without aortic disease with sequential echos, 19 (70%) showed a natural decrease in root Z-score and 24 (89%) showed a natural decrease in ascending Z- score, over time. Of 25 untreated MFS children with sequential echos, 12 (40%) showed a natural decrease in root Z-score and 10 (33%) showed a natural decrease in ascending Z-score. Thus, Z-score is over time affected by natural factors even in the absence of any aneurysmal pathology or medical intervention. Specifically, Z-score decreases spontaneously as a natural phenomenon as children age and with fill out their BMI. Untreated Marfan patients often showed a spontaneous decrease in Z-score. In clinical drug trials in aneurysm disease, decreasing Z-score has been interpreted as a sign of beneficial drug effect. These data put such conclusions into doubt.

Direct axillary cannulation with open Seldinger-guided technique: is it safe?

OBJECTIVES: Axillary artery cannulation is commonly used in thoracic aortic surgery, often utilizing a sidearm graft. Although our institutional preference is femoral cannulation, we use axillary cannulation in select cases with a 'dirty' aorta on computed tomography scan or intraoperative transoesophageal echocardiography. Since 2011, we have routinely used an open Seldinger-guided approach for axillary cannulation. Here, we report our experience with open Seldinger-guided technique, evaluating its safety and efficacy. METHODS: A retrospective analysis of our institutional database from 2011 to 2016 was performed to find cases of peripheral arterial cannulation for thoracic aortic surgery. We identified 404 consecutive patients who underwent peripheral arterial cannulation. Of these, 352 were femoral and 52 were axillary cannulations. All axillary cannulations were performed for ascending and/or arch surgery. The technique involves a surgical exposure of the artery which is then cannulated by guidewire inside a purse string without arterial incision. RESULTS: Indications for surgery included aneurysm in 63.5% (33/52), dissection in 30.7% (16/52) and pseudoaneurysm in the remaining 5.8% (3/52). Hospital survival was 98.1% (51/52). There were no instances of axillary arterial injury or intraoperative malperfusion phenomena. No postoperative limb ischaemia or stroke was evident. No wound infections or late pseudoaneurysms were observed. CONCLUSIONS: The open Seldinger-guided technique for axillary artery cannulation is safe and effective. We strongly recommend this technique, given its speed and simplicity. The vessel is not snared, thereby preserving distal arterial flow and minimizing the risk of acute limb ischaemia. Furthermore, the limited manipulation of the artery lowers the risk of local complications.

Open Seldinger-Guided Femoral Artery Cannulation Technique for Thoracic Aortic Surgery.

BACKGROUND: Debate regarding the optimal cannulation site for aortic surgery continues. We report our recent experience with a simple and rapid open Seldinger-guided technique for femoral cannulation. Aside from speed and simplicity (no need for arterial incision or suture closure), this technique has the added benefit that the distal limb continues to be perfused, as no arterial snare is required. METHODS: We recently began routinely utilizing an open Seldinger-guided technique for femoral artery cannulation. The artery is exposed surgically but cannulated by guidewire inside a pursestring without arterial incision. The pursestring is simply tied when decannulation is performed. We report our experience with the routine application of this technique from August 2011 to April 2015. RESULTS: We reviewed the outcome of 337 consecutive peripheral arterial cannulations performed for thoracic aortic surgery (303 femoral, 34 axillary) using the open Seldinger technique. Within the femoral cannulation group, the hospital survival rate was 97% (295 of 303). The survival rate for elective operations was 98% (277 of 283), and 90% (18 of 20) for emergent/urgent. Seldinger-guided femoral cannulation was performed for replacement of the ascending/aortic arch in 88% (266 of 303), the descending thoracic aorta in 7% (22 of 303), and the thoracoabdominal aorta in 5% (15 of 303). There were no instances of intraoperative malperfusion phenomena, arterial dissection, or vascular injury or rupture. No patients had postoperative acute limb ischemia. Local wound complications were observed in 1% of patients (3 of 303). The stroke rate was 1.6% (5 of 303). The same open Seldinger technique was also used without complication in the axillary cannulation group. CONCLUSIONS: An open Seldinger-guided femoral (or axillary) cannulation technique is quick and easy to perform, with minimal vascular or other complications and extremely low risk of stroke. This technique is recommended for its speed, simplicity, and effectiveness, and for its preservation of distal arterial flow (which is occluded with the traditional arterial incision/arterial snare technique).