Introduction

Acute type A aortic dissection is a cardiovascular event that is often associated with high morbidity and mortality rates, and it remains a challenge to diagnose and treat. If untreated in a timely manner it is associated with devastating events like aortic rupture, extension of dissection into aortic valve, coronary arteries, supra-aortic trunks, visceral arteries or extremities. (1)

Emergency surgery has been proved to be the most effective treatment. Various surgical strategies have been used depending upon the preferences of surgeons and centers. Handling of the dissected aorta is most demanding and technically difficult. Therefore, a more conservative approach preserving pertinent structures and avoiding extensive suturing and anastomoses seems reasonable, especially in view of bleeding complications. Avoiding the implantation of foreign material could additionally reduce the risk of endocarditis and thromboembolism.(2)

Method

This is retrospective analysis of patients who underwent surgery by a single surgeon, Dr Rabindra B. Timala at Shahid Gangalal National Heart Center, Kathmandu, Nepal. All consecutive patients who had undergone surgery from January 2021 to September 2023 were included in the study.

The study was approved by Ethical Committee of Shahid Gangalal National Heart Center. Informed consent was waived considering the retrospective nature of the study.

Operations were carried out under cardiopulmonary bypass with moderate hypothermia. Cross clamp were applied at the base of the innominate artery. Five patients had aortic cannulation into the transverse arch. Under transesophageal echo guidance, guidewire was inserted into the true lumen, after which track was dilated and aortic cannula inserted. Two patients had innominate artery cannulation, one with graft and another had direct cannulation. Right femoral artery cannulation was done in 3 patients and one had distal ascending aortic cannulation. In one patient initial femoral artery cannulation followed by innominate artery cannulation was done. In one patient, left femoral artery cannulation was done.

Modified Bentall’s procedure was done for markedly dilated aortic root and patients with Marfan’s syndrome. When the aortic root was below 4.5 cm in diameter with morphologically normal aortic valves, roots were spared by repairing the root and valves.

Both proximal and distal aortic ends were sandwiched with felt strip for anastomosis with a Dacron tube graft. Anastomosis was done by intussuscepting tube graft inside the aorta both proximally and distally. Bioglue was used on outside of the anastomosis for hemostasis.

Results

The study included 12 consecutive patients operated by a single surgeon from January 2021 to September 2023, over the period of 33 months. Age ranged from 24 years to 61 years with the average age of 48.87 years. Out of 12 patients, 9 were female and 4 were male.

Chest pain was present in 8 patients and back pain in 4 , followed by shortness of breath in 3, abdominal pain in 2 and throat fullness in one. Patients had symptoms from one day to 30 days prior to hospital admission, with the average of 8.22 days. Five patients (41.67%) had blood in the pericardium, which is an ominous sign of ruptured aorta.

Supra-coronary aorta was replaced in 8 patients with Dacron tube graft. Among those, 3 patients had tear extended into the root, which were repaired with felt buttressing both inside and outside of the aorta. Another patient who had dissection extended into the non- coronary sinus, neomedia was created with a piece of felt, which was covered by pericardium on inside of aorta. Aortic valve commissural suspension was done on 3 patients. Two had leaflet plication of their prolapsed leaflets.

Modified Bentall’s procedure was done in 4 patients. One patient with modified Bentall’s procedure also required mitral valve repair with ring annuloplasty and main pulmonary artery plication due to large pulmonary artery. Another patient who underwent modified Bentall’s procedure also had coronary artery bypass grafting to posterior descending artery and left anterior descending artery.

In 11 patients, distal anastomosis was carried out without releasing aortic cross. Only in one patient, open distal anastomosis was done with antegrade cerebral perfusion.

The average cross-clamp time was 153.08 minutes with range from 99 minutes to 254 minutes. The average cardiopulmonary artery bypass time 217.08 minutes with the range from 171 minutes to 364 minutes.

Seven patients (58.33%) underwent primary sternal closure. 5 had delayed sternal closure. The in- hospital mortality in this series of 12 consecutive patients was zero.

Post-operative Period

Average bleeding during the first 24 hours was 534.16 ml (range 130- 1350 ml). The average post op intubation time was 43.58 hours (range: 5-247hours). None of the patient developed acute kidney injury. Only one patient developed left hemiparesis which resolved after a few days.

Frequency of Surgery

12 cases were operated by a single surgeon over 33 months’ time-period, which would mean one case every 2.75 months or 4.36 cases per year for a surgeon.

Discussion

Acute aortic dissection is a rare, life threatening disease. The disease itself can mimic other common conditions like acute coronary syndrome, abdominal pain, neurological condition like stroke, paraplegia etc., delaying diagnosis. Aggressive surgical correction of the dissecting aneurysm may not only help prevent rupture but also is the only option that will provide a reasonable chance of survival to these individuals with otherwise dismal outcome.(3)

In this study, women predominated in number, 75%. However, most of the larger series reports men outnumber women, In international registry for aortic dissection (IRAD) series men constituted 67.5% of type A aortic dissection (TAAD)(4) .

In this study, average age at presentation was 43.5 years, with the range from 24 years to 61 years. The average age +/- standard deviation (SD) in IRAD registry was 61.5 +/- 14.5 years (4) .

None of the patients had any significant health checkup in the past. No previous medical records were available. No previous risk factors could be known among patients from our study.

Most of the patients presented with chest pain and backpain, seven and four respectively. Most of the patients presented quite late after their symptoms onset. They ranged from one day to 30 days with the average of 8.22 days. Most of the patients came from rural areas, outside of Kathmandu valley. ‘Diagnostic delay’ and road travel were the main cause of delayed presentation.

Surgical Procedure

In the current study, supra-coronary aorta was replaced in 8 (66.67%) patients. Modified Bentall’s procedure in 4 patients (33.33%). 3 patients had tear extended into aortic root, which were repaired with felt buttressing both inside and outside of aorta. In one patient, neo-media creation was done in non- coronary sinus with felt. Aortic valve repair with commissural suspension was done among 3 patients, while aortic leaflet plication was done among 2 patients.

In IRAD series, supra-coronary ascending aorta replacement was performed in 59% of patients. More extreme aortic resections involving aortic root replacement were performed in 34% of patients (valve sparing 6%, composite root replacement 16%, proximal hemiarch replacement in 27%, total arch replacement in 12%. An open procedure with hypothermic circulatory arrest (HCA ) in 92%, with cerebral perfusion in 51%. (5)

Various authors have advocated for aortic valve preservation .Following conservative valve surgery the reoperation rate on the aortic valve was only insignificantly increased. [2,6,7,8,9,].

Mortality

TAAD is one of the most lethal diseases that requires instant complicated surgery. The surgical mortality and morbidity remained considerable despite numerous diagnostic and therapeutic improvements over the last decades.

In this series in hospital mortality was zero. As per International Registry for Aortic Dissection (IRAD) registry, with the data on more than 7300 patients, the hospital mortality for TAAD was 25% in 1999, which declined to 18.4% in 2013 among patients who had undergone surgical repair (4).

Study by Niederhauser et al (2) showed that among surgically treated TAAD, early mortality among 199 patients was 23.6% (47/199 patients). In the valve/root-replacement group early mortality was 20.6% (15/73 patients) compared with 25.4% (32/126 patients) in the valve/root-reconstruction group (P =0.43767). Preoperative myocardial ischemia or ST-T elevation on electrocardiogram before the operation was identified as an independent factor for increased operative mortality in TAAD patients [10,11,12].

IRAD study published in 2016 showed shock occurred in 15% of TAAD and was associated with higher in-hospital mortality rates (30.2% versus 23.9%, P=0.007)(13).

Postoperative acute kidney injury (AKI) is a common serious complication in patients who received surgical repair of TAAD with a reported incidence more than 40% [14]. Study by Fann et al consistently showed that renal dysfunction per se was an independent predictor of 30-day death after surgery [15].)

Postoperative bleeding is a leading cause of perioperative morbidity and mortality [16,17,18], as it could lead to hemodynamic instability or organ dysfunction in patients who received TAAD surgeries. Meanwhile, increased bleeding after surgery requires more blood transfusions. In recent years, many studies showed that postoperative blood transfusion was not only related to increasing perioperative complications, but also negatively affected the patient’s short-term survival [19,20]. So it is obvious that an effective hemostasis strategy during operation for type I AD patients is critical in reducing 30- day mortality

In this study, 5 (41.67%) patients presented with blood in the pericardium. They already had ruptured aorta, which was sealed at the time of surgery. Though hemodynamic measurements were not done, they may also be having cardiac tamponade in various degrees. The mortality for tamponade in this setting remained significantly high (44% versus 20%, P< 0.001) (21).

This series consisted mostly women, 9 out of 12 (75%) patients. TAAD in women is associated with higher surgical mortality of 32% versus 22% in men (P=0.013) (4).

This series consisted mostly of relatively young patients, with an average age of 43.5 years, ranging from 24 to 61 years. According to the IRAD report, the surgical mortality was 21% in patients < 70 years of age and 31% in those > 70 years of age (P=0.003)(4).

Survival

Aortic root management in type A acute aortic dissection is controversial. IRAD study published in 2014 showed similar 3 year survival and freedom from aortic root reintervention between root replacement and root conservation group (22). Niederhäuser et al (2) showed survival was 61% after 8 years without difference between the two groups (P = NS) of root replacement vs root conservation. Similar finding was made by Fann and Jex (6,7). Lytle et al. [23] documented significantly inferior late survival following composite graft insertion compared with the replacement of the ascending aorta alone or in combination with separate aortic valve replacement.

Limitations

This is case series of consecutive patients operated by a single surgeon, so the sample size is small. It’s retrospective study, so all the possible risk factors for mortality couldn’t be assessed.

Conclusion

The proximal aorta is the primary target of the emergency intervention in order to prevent death from complete rupture of the dissected aorta and from heart failure due to acute and massive valve regurgitation.

Technical difficulties of a more aggressive replacement procedure have to be weighed against potential failures of conservative techniques (2). Preservation of the aortic root is safe in absence of Marfan or annulo-aortic ectasis, but a certain incidence of reoperations on the aortic valve and the aortic root has to be accepted (2).

TAAD is rare and lethal disease requiring big surgery often at odd hours; hospital mortality can be kept low, with appropriate surgical techniques, that the surgeon is comfortable with.

Reference

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