Bulat A. Ziganshin

Deep hypothermic circulatory arrest

Effective cerebral protection remains the principle concern during aortic arch surgery. Hypothermic circulatory arrest (HCA) is entrenched as the primary neuroprotection mechanism since the 70s, as it slows injury-inducing pathways by limiting cerebral metabolism. However, increases in HCA duration has been associated with poorer neurological outcomes, necessitating the adjunctive use of antegrade (ACP) and retrograde cerebral perfusion (RCP). ACP has superseded RCP as the preferred perfusion strategy as it most closely mimic physiological perfusion, although there exists uncertainty regarding several technical details, such as unilateral versus bilateral perfusion, flow rate and temperature, perfusion site, undue trauma to head vessels, and risks of embolization. Nevertheless, we believe that the convenience, simplicity and effectiveness of straight DHCA justifies its use in the majority of elective and emergency cases. The following perspective offers a historical and clinical comparison of the DHCA with other techniques of cerebral protection.

Routine Genetic Testing for Thoracic Aortic Aneurysm and Dissection in a Clinical Setting

BACKGROUND Hereditary factors play an important etiologic role in thoracic aortic aneurysm and dissection (TAAD), with a number of genes proven to predispose to this condition. We initiated a clinical program for routine genetic testing of individuals for TAAD by whole exome sequencing (WES). Here we present our initial results. METHODS The WES was performed in 102 patients (mean age 56.8 years; range 13 to 83; 70 males [68.6%]) with TAAD. The following 21-gene panel was tested by WES: ACTA2, ADAMTS10, COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, ELN, FBLN4, FLNA, FBN1, FBN2, MYH11, MYLK, NOTCH1, PRKG1, SLC2A10, SMAD3, TGFB2, TGFBR1, TGFBR2. RESULTS Seventy-four patients (72.5%) had no medically important genetic alterations. Four patients (3.9%) had a deleterious mutation identified in the FBN1, COL5A1, MYLK, and FLNA genes. Twenty-two (21.6%) previously unreported suspicious variants of unknown significance were identified in 1 or more of the following genes: FBN1 (n = 5); MYH11 (n = 4); ACTA2 (n = 2); COL1A1 (n = 2); TGFBR1 (n = 2); COL3A1 (n = 1); COL5A1 (n = 1); COL5A2 (n = 1); FLNA (n = 1); NOTCH1 (n = 1); PRKG1 (n = 1); and TGFBR3 (n = 1). Identified mutations had implications for clinical management. CONCLUSIONS Routine genetic screening of patients with TAAD provides information that enables genetically personalized care and permits identification of novel mutations responsible for aortic pathology. Analysis of large data sets of variants of unknown significance that include associated clinical features will help define the mutational spectrum of known genes underlying this phenotype and potential identify new candidate loci.

Straight deep hypothermic circulatory arrest for cerebral protection during aortic arch surgery: Safe and effective

OBJECTIVE To evaluate our extensive clinical experience using deep hypothermic circulatory arrest (DHCA) as a sole method of cerebral protection during aortic arch surgery, with an emphasis on determining the safe duration of DHCA. METHODS A total of 490 consecutive patients (303 males [61.8%], mean age, 62.7 ± 13.5 years) underwent surgical interventions on the aortic arch with straight DHCA for cerebral protection. Of the procedures, 65 (13.3%) were either urgent or emergency. Aortic aneurysms (n = 417, 85.1%) and dissections (n = 71, 14.5%) were the main indications for surgery. RESULTS The mean DHCA duration was 29.2 ± 7.9 minutes at a mean bladder temperature of 18.7°C. The overall mortality was 2.4% (12 of 490), and elective mortality was 1.4% (6 of 425). The seizure rate was 1.4% (7 of 490). Six patients (1.2%) developed renal failure that required dialysis. The postoperative stroke rate was 1.6% (8 of 490) and was 1.2% (5 of 425) for the elective cases. The overall stroke rate for patients requiring <50 minutes of DHCA was 1.3% (6 of 478), significantly different from the 16.7% (2 of 12) stroke rate for patients requiring >50 minutes of DHCA (P = .014). Multivariate analysis revealed a DHCA time >50 minutes (odds ratio, 5.11 ± 4.01, P = .038) and aortic dissection (odds ratio, 3.59 ± 1.72, P = .008) to be strong predictors of composite adverse outcomes. CONCLUSIONS Straight DHCA is a safe and effective technique of cerebral protection for the absolute majority of interventions involving the aortic arch. At experienced centers, up to 50 minutes of DHCA can be considered safe, without significant postoperative mortality or neurologic sequelae.

‘Bovine’ Aortic Arch – A Marker for Thoracic Aortic Disease

Objectives: Very few studies have addressed the clinical significance of ‘bovine’ aortic arch (BA). We sought to determine whether BA is associated with thoracic aortic disease, including thoracic aortic aneurysm, aortic dissection, aortic rupture, and accelerated aortic growth rate. Methods: We retrospectively reviewed CT and/or MRI scans of 612 patients with thoracic aortic disease and 844 patients without thoracic aortic disease to determine BA prevalence. In patients with thoracic aortic disease, we reviewed hospital records to determine growth rate, prevalence of dissection and rupture, and accuracy of radiology reports in citing BA. Results: 26.3% of the patients with thoracic aortic disease had concomitant BA, compared to 16.4% of the patients without thoracic aortic disease (p < 0.001). There was no association between BA and prevalence of dissection or rupture (p = 0.38 and p = 0.56, respectively). The aortic expansion rate was 0.29 cm/year in the BA group and 0.09 cm/year in the non-BA group (p = 0.004). Radiology reports cited BA in only 16.1% of the affected patients. Conclusions: (1) BA is significantly more common in patients with thoracic aortic disease than in the general population. (2) Aortas expand more rapidly in the setting of BA. (3) Radiology reports often overlook BA. (4) BA should not be considered a ‘normal’ anatomic variant.

Atypical aortic arch branching variants: A novel marker for thoracic aortic disease

OBJECTIVE To examine the potential of aortic arch variants, specifically bovine aortic arch, isolated left vertebral artery, and aberrant right subclavian artery, as markers for thoracic aortic disease (TAD). METHODS We screened imaging data of 556 patients undergoing surgery due to TAD for presence of aortic arch variations. Demographic data were collected during chart review and compared with a historical control group of 4617 patients. RESULTS Out of 556 patients with TAD, 33.5% (186 patients) demonstrated anomalies of the aortic arch, compared with 18.2% in the control group (P < .001). Three hundred seventy (66.5%) had no anomaly of the aortic arch. Bovine aortic arch emerged as the most common anomalous branch pattern with a prevalence of 24.6% (n = 137). Thirty-five patients (6.3%) had an isolated left vertebral artery, and 10 patients (1.8%) had an aberrant right subclavian artery. When compared with the control group, all 3 arch variations showed significant higher prevalence in patients with TAD (P < .001). Patients with aortic aneurysms and anomalous branch patterns had hypertension less frequently (73.5% vs 81.8%; P = .048), but had a higher rate of bicuspid aortic valve (40.8% vs 30.6%; P = .042) when compared with patients with aneurysms but normal aortic arch anatomy. Patients with aortic branch variations were significantly younger (58.6 ± 13.7 years vs 62.4 ± 12.9 years; P = .002) and needed intervention for the aortic arch more frequently than patients with normal arch anatomy (46% vs 34.6%; P = .023). CONCLUSIONS Aortic arch variations are significantly more common in patients with TAD than in the general population. Atypical branching variants may warrant consideration as potential anatomic markers for future development of TAD.

Indications and imaging for aortic surgery: size and other matters.

OBJECTIVES To review the current general concepts and understanding of the natural history of thoracic aortic aneurysm and their clinical implications. METHODS Data on the the normal thoracic aortas were derived from the database of the Multi-Ethnic Study of Atherosclerosis (n = 3573), representative of the general population. Data on diseased thoracic aorta were derived from the database of the Aortic Institute at Yale-New Haven Hospital (n = 3263), representative of patients with thoracic aortic aneurysm and dissection. RESULTS Our studies have shown that the normal aorta in the general population is small (3.2 cm for the ascending aorta). Aortas larger than 5 cm are rare in the real world. The aneurysmal aorta grows at a mean of 0.2 cm/y, and larger aneurysms grow faster than do smaller ones. The dissection size paradox (which shows some aortic dissections occurring at small aneurysm sizes) is explained by the huge number of patients with small aortas in the general population. Genetic testing of patients with thoracic aortic disease helps identify genes responsible for aortic aneurysm and dissection. New imaging techniques such as 4-dimensional magnetic resonance imaging may add engineering data to our decision making. CONCLUSIONS Size continues to be a strong predictor of natural complications and a suitable parameter for intervention. As we enter the era of personalized aneurysm care, it is likely that specific genetic mutations will facilitate the determination of the appropriate size criterion for surgical intervention in individual cases.

Sun’s procedure for complex aortic arch repair: total arch replacement using a tetrafurcate graft with stented elephant trunk implantation

The Suns procedure is a surgical technique proposed by Dr. Li-Zhong Sun in 2002 that integrates total aortic arch replacement using a tetrafurcated graft with implantation of a specially designed frozen elephant trunk (Cronus(®)) in the descending aorta. It is used as a treatment option for extensive aortic dissections or aneurysms involving the ascending aorta, aortic arch and the descending aorta. The technical essentials of Suns procedure include implantation of the special open stented graft into the descending aorta, total arch replacement with a 4-branched vascular graft, right axillary artery cannulation, selective antegrade cerebral perfusion for brain protection, moderate hypothermic circulatory arrest at 25 °C, a special anastomotic sequence for aortic reconstruction (i.e., proximal descending aorta → left carotid artery → ascending aorta → left subclavian artery → innominate artery), and early rewarming and reperfusion after distal anastomosis to minimize cerebral and cardiac ischemia. The core advantage of Suns procedure lies in the use of a unique stented graft, which has superior technical simplicity, flexibility, inherent mechanical durability and an extra centimeter of attached regular vascular graft at both ends. Since its introduction in 2003, the Suns procedure has produced satisfactory early and long-term results in over 8,000 patients in China and more than 200 patients in South American countries. In a series of 1,092 patients, the authors have achieved an in-hospital mortality rate of 6.27% (7.98% in emergent or urgent vs. 3.98% in elective cases). Given the accumulating clinical experience and the consequent, continual evolution of surgical indications, the Suns procedure is becoming increasingly applied/used worldwide as an innovative and imaginative enhancement of surgical options for the dissected (or aneurysmal) ascending aorta, aortic arch and proximal descending aorta, and may become the next standard treatment for type A aortic dissections requiring repair of the aortic arch.

Frozen elephant trunk with total arch replacement for type A aortic dissections: Does acuity affect operative mortality?

OBJECTIVE We seek to compare the early outcomes of frozen elephant trunk with total aortic arch replacement using a 4-branched graft (the Sun procedure) in patients with acute and chronic type A aortic dissection (TAAD), identify the risk factors for operative mortality, and determine whether the acuity of TAAD significantly affects operative mortality. METHODS We performed univariate and multivariate analyses of the clinical data from 803 patients with TAAD who underwent the Sun procedure. RESULTS The operative mortality was 6.5% (52 of 803). The overall incidence of stroke and spinal cord injury was 2.0% (16 of 803) and 2.4% (19 of 803), respectively. Patients with acute TAAD had a greater incidence of operative death (8.1% vs 4.3%; P = .031), stroke (2.2% vs 0.6%; P = .046), and respiratory morbidities (20.8% vs 8.6%; P < .001). However, acuity was not identified as a risk factor for operative mortality (odds ratio [OR], 1.67; P = .152). The risk factors were previous cerebrovascular disease (OR, 7.01; P = .001); malperfusion of the brain (OR, 7.10; P = .002), kidneys (OR, 12.67; P = .005), spinal cord (OR, 22.79; P = .008), and viscera (OR 22.98; P = .002); concomitant extra-anatomic bypass (OR, 9.50; P < .001); and cardiopulmonary bypass time >180 minutes (OR, 1.01; P < .001). CONCLUSIONS In this group of patients with type A dissection, acuity was not a risk factor for operative mortality after the Sun procedure. Patients with previous cerebrovascular disease; malperfusion of the brain, kidneys, spinal cord, and/or viscera; concomitant extra-anatomic bypass; and a longer cardiopulmonary bypass time (>180 minutes) were at greater risk of operative mortality.

Pulmonary Artery Aneurysms: Four Case Reports and Literature Review

Aneurysms of the pulmonary artery are proven to be a very rare entity. Association with structural cardiac anomalies, structural vascular anomalies, pulmonary hypertension, vasculitis, and infection has been noted. Surgical intervention of symptomatic aneurysms is recommended. A more detailed study of the natural history of these aneurysms is needed. Here, we report four cases of pulmonary artery aneurysms as well as a brief review of the literature existing on this subject. The first case is of a 41-year-old woman with the aneurysm located 1 cm distal to the pulmonary valve extending to the bifurcation of the main pulmonary artery. The second case is of a 76-year-old woman with a large aneurysm of the main pulmonary artery and the left pulmonary artery. The third case is of a 61-year-old woman with an aneurysm of the common pulmonary artery and right pulmonary artery. The fourth case is of a 28-year-old woman with a 5-cm symptomatic aneurysm extending from the valve up to the pulmonary bifurcation. Surgical excision and reconstruction was ordered for cases 1, 2, and 4.

Sun’s procedure for chronic type A aortic dissection: total arch replacement using a tetrafurcate graft with stented elephant trunk implantation

The Sun’s procedure is a surgical technique that integrates total arch replacement using a tetrafurcated graft with implantation of a special stented graft in the descending aorta, as a treatment option for extensive dissections or aneurysms involving the ascending aorta, aortic arch and descending aorta (1-3). To illustrate our technique for performing the Sun’s procedure (1,2), we present a video of this approach in a 38-year-old man with chronic type A aortic dissection (Video 1). Video 1 Suns procedure for chronic type A aortic dissection: total arch replacement using a tetrafurcate graft with stented elephant trunk implantation Clinical vignette The patient had a history of hypertension for twenty years and experienced an episode of chest and flank pain after exertion one year ago. Transthoracic echocardiogram detected dilated ascending aorta, aortic arch and descending aorta, as well as intimal flaps in the ascending aorta, and a dilated aortic root with severe regurgitation. Computed tomographic angiogram confirmed a chronic type A dissection, with the intimal tear in the ascending aorta, extending distally to the right iliac artery, and the arch vessels involved. Of note, the innominate artery was both aneurysmal and dissected for the entire length extending to the level of bifurcation. There was also a coronary anomaly, in which the left and right coronary arteries arose from the left coronary sinus. Considering the complex pathology of arch vessel involvement, innominate artery aneurysm, aortic root dilation with severe regurgitation and coronary artery anomaly, we decided to perform the Sun’s procedure, in combination with composite root replacement with a mechanical valved conduit.