Early Results of Ascending Aorta and Aortic Arch Surgery in Albania

Keywords

Ascending aorta, Aortic arch, Surgery, Albania, Results, Circulatory arrest.

Background

Treatment of aneurysms of the ascending aorta, arch aorta, or both are surgically challenging and has traditionally carried a high hospital mortality rate [1-5]. The development of low porosity or impermeable grafts [6], the introduction of hypothermic circulatory arrest with anterograde or retrograde cerebral perfusion [7], enhanced intraoperative myocardial protection, and improved hematologic treatment have resulted in reduced hospital mortality and morbidity rates. Moreover, advances in diagnostic studies, like, computed tomographic scanning [8,9], magnetic resonance imaging [10,11] and transesophageal echocardiography [12,13], as well as better patient selection have contributed to improved results [14].

Patients and Methods

Patient Population

We conducted a prospective analysis of 74 consecutive patients who underwent surgical procedures for graft replacement of the ascending aorta or transverse aortic arch in the period between January 2011 and January 2014. We used different types of statistical tests to analyze the data: Mann Whitney test, Chi Square test and Logistic Binary Regression test (for odds ratio).

In this patient population there were 58 men (78.4%) and 16 women (21.6%). The mean age was 55.3±9.8 years (range 30 – 74 years). Minimal age was 30 years (1 patient) and maximal age was 74 years (1 patient). Etiology of the aneurysm was medial degeneration in 44 patients (59.5%), bicuspid aortic pathology in 28 patients (37.8%) and aortic dissection in 2 patients (2.7%). Fifteen patients (20.3%) were operated on an emergency basis for aortic dissection. Other data related to this patient cohort are shown in the following table 1.

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We can highlight that the prevalence of smoking was 21.6% and the prevalence of arterial hypertension was, as expected, much higher up to 63.5%. On the other hand 6.8% of the patients suffered from diabetes mellitus and 12.2% from dislipidemia.

Most of the patient was diagnosed with an aneurysm of the thoracic aorta because of the aortic valve pathology related symptoms. In the following table 2 are shown the causes which brought to a diagnosis of ascending aorta aneurysm.

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CAD: Coronary Artery Disease

Operative technique

Median sternotomy where the surgical approach of choice in allpatients, except two of them, in whom was released partial sternotomy “J” to the fourth intercostal space. Arterial calculation was done in the distal ascending aorta, femoral artery or axillary artery, depending on the extent of the pathology and the venous cannulation was achieved via the right atrial appendage with a dual stage cannula. Moderate hypothermia in 30° C was generally used during the extracorporeal circulation. In cases of hypothermia circulatory arrest with retrograde cerebral perfusion the body was cooled down to 18° C, and in cases with anterograde cerebral perfusion to 24-26° C. Anterograde mixed cold blood cardioplegia was used as myocardial protection every 20 minutes.

The choice of the surgical technique was done according to the extent of the aneurysmal disease, involvement of the coronary sinuses in the process and the situation of the aortic valve. In case of a normal aortic valve, we replaced only the ascending aorta with a prosthetic graft. If the coronary sinuses were not dilated, separate replacement of the aortic valve and ascending aorta was done. The basic procedure applied when we had to deal with the aortic root was the modified Bentall procedure. In some cases we replaced also totally or partially the aortic arch due to its involvement in the pathology (dilatation or dissection).

Results

Operative data

The ascending aorta was replaced in 69 patients (93,2%) and plicated in 5 patients (6.8%). Ascending aorta and aortic arch were replaced in 9 patients (12.1%). 17 patients had only ascended aortic procedure, 35 patients had separate aortic valve and ascending aorta replacement (47.3%), and 18 patients (24.3%) received a valved conduit (Modified Bentall procedure). Concomitant bypass grafting was performed in 9 patients.

Mean cross-clamp and cardiopulmonary bypass times were 115.38±41.19 min and 143.26±55.79 min respectively.

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* Number of individuals and percentage in brackets, † P value according to chi square test
CABG: coronary artery bypass grafting

Hospital Morbidity Rate

The main complications observed in the immediate postoperative period are shown in the following table 4.

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* Number of individuals and percentage in brackets, † P value according to chi square test
AF: Atrial Fibrillation, AV: Atrioventricular

We had also a case of acute cardiac tamponade and one case of gastric perforation.

In the following table 5 are shown relationships between some of the complications and selected variables calculated by logistic binary regression test.

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† P value for every variable according to a model adjusted for sex and age AF: atrial fibrillation
LV: left ventricle, Hct: hematocritis, CPB: cardiopulmonary bypass, CA: circulatory arrest

Hospital Mortality Rate

The hospital mortality rate was 3.38% (2 out of 59 patients) in the elective surgery group, 26.67% in the emergency group (4 out of 15) and the overall hospital mortality was 8,1% (6 out of 74 patients). In the following table 6 are shown the causes of inhospital deaths.

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In the following table 7 are shown the risk factors for early hospital mortality, according to the statistical analysis with the binary logistic regression test.

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We can note that the main predictive factors for early mortality are long cross-clamp and bypass times, low hematocritis during extracorporeal circulation, circulatory arrest application and its prolonged time.

Follow up

Follow up data were collected from 63 patients (92.6%). The follow up ranged from 59 days to 3.17 years with a mean of 16.35±11.77 months. All the patients were examined by echocardiography and some of them by computed tomography. At the completion of the follow up all the hospital survivors (100%) were alive and without any important complications. Two patients had minimal prosthetic leaks and one patient dilatation of the aortic root, without a surgical indication in all of the cases.

Discussion

Early Mortality

Contemporary and modern surgical treatment of the ascending aorta and aortic arch aneurysms has significantly improved early and long term results. But, these results vary according to different authors [1-5]. However, some of the series excludes cohorts of high risk patients [15].

Mortality in elective surgery ranges from 2 to 5% and in emergency surgery goes sometimes beyond 20 % [16]. IRAD consortium which includes a group of studies, reports a dramatic increase up to 20% in the early mortality of acute aortic dissection patients [17]. But these results can be highly improved in the excellent surgical centers [7,8,18].

According to these data we can say that we have very good results in elective surgery and acceptable results in emergency surgery for acute aortic dissection. However, the comparison is very difficult because of the heterogeneity of the patient groups. Some of the series does not report emergency cases and redo cases, meanwhile there is a great variation in the arch replacement between the groups.

The main reported cause of hospital mortality is cardiac failure,followed by bleeding and respiratory failure [19-23].

Emergency surgery is the clearest predictive factor for early mortality [24-26]. Other reported predictive factors of hospital mortality include advanced age [22,24,25], long cardiopulmonary bypass time [21,22], previous cardiac operation [23,24] and the need for simultaneous coronary bypass surgery.

We attribute these results to the growing experience of the surgical team, an aggressive treatment in the preoperative and postoperative period and the application of improved surgical techniques. Careful preoperative evaluation of pulmonary function and appropriate medical treatment before surgical intervention has allowed us to treat potential respiratory problems more effectively. The usage of transesophageal echocardiography avoids contrast material in patients with marginal renal function and in cases of acute dissection, it allows for more rapid surgical intervention. In addition, the use of transesophageal echocardiography interpretive aids in selecting the aortic cannulation site, documenting the success of aortic valve repair, assessing the adequacy of daring techniques, and evaluating ventricular function when cardiopulmonary bypass is discontinued.

We prefer the Bentall button technique because it is more anatomically correct and prevents suture line tension. The Bentall button technique for reimplanting the coronary Ostia as opposed to the classic Bentall or Cabrol technique avoids reported complications of false aneurysm formation [27] and graft thrombosis [5,15].

Stroke

Stroke is one of the most important complications of aortic aneurysm surgery associated high morbidity and mortality. We had 3 patients (4.1%) with stroke in the early postoperative period, and it is a good value compared with other groups of patients in the literature.

Nowadays, cerebral protection is considered a key factor in the prevention of stroke after this type of surgery. Although there is a wide consensus that anterograde cerebral perfusion is superior to retrograde perfusion and deep hypothermia, some studies demonstrate that for short periods of time up to 30 minutes, the method of cerebral protection is not important [28,29]. Despite this, our team is oriented in applying as much as possible the selective cerebral perfusion in cases of circulatory arrest. Unfortunately, the number of patients (7 pts with anterograde cerebral perfusion, 3 points with retrograde cerebral perfusion) which underwent circulatory arrest was too small to allow statistical analysis in our series.

Conclusions

Surgery of the ascending aorta and aortic arch can be performed with low morbidity and mortality rates at our clinic in Albania. Surgical techniques include all the spectrums of the routine procedures applied nowadays widely. Avoidance of the modifiable risk factors can also contribute to better early results. Experience is necessary to improve the results in emergency surgery for acute aortic dissection. We have to follow up this population of patients to evaluate long term survival and morbidity.