Aortic Dissection in Northern Pakistan and Afghanistan and Its Surgical Outcome

The aorta can be involved in a variety of pathologies, including congenital, syndromic and acquired disorders. The most common pathologies of the aorta that require some form of intervention are aortic aneurysm, aortic dissection and coarctation.¹

Aortic dissection is a lethal aortic pathology. The typical presentation of ascending aortic dissection is a sudden, intense tearing chest pain and/or back pain. However, it is important to note that clinical manifestation can vary, and classical signs and symptoms may not always be evident.²

The Stanford classification is mostly used to describe the anatomical location of the dissection; type A aortic dissection (TAAD) involves either the ascending aorta alone or both the ascending and descending aorta, and type B dissection does not involve the ascending aorta.³

TAAD is a life-threatening condition that occurs when the intimal layer of the aorta tears, creating a false lumen.⁴ This can lead to complications such as aortic rupture, malperfusion, cardiac tamponade or aortic valve insufficiency.⁵ The incidence of TAAD is estimated to be 5–30 per million people per year, with higher rates in older men and patients with hypertension, connective tissue disorders, such as Marfan’s syndrome or previous cardiac surgery.^3,6–8

The primary approach for managing TAAD is a surgical intervention.⁹ Various surgical techniques are available, including the supracoronary tube graft, the Bentall procedure and the Cabrol procedure, depending on the extent and location of the dissection.¹⁰ The worldwide surgical mortality of TAAD ranges from 5% to 20%, depending upon the urgency of the surgery.³ The initial mortality rate of 17.8% for TAAD procedures, as reported in the UK National Adult Cardiac Surgery Audit, corresponds to the period from 2011 to 2012. This decreased over time from 22% in 2009 to 15% in 2018 and was comparable to that observed in the Nordic Consortium for Acute Type A Aortic Dissection of 16%.^11–13

Medical co-management is a cornerstone of successful surgical intervention of acute aortic dissection, with a focus on regulating blood pressure and heart rate and managing pain. Antihypertensive medications, such as β-blockers and calcium channel blockers, are administered to diminish shear stress on the aortic wall and deter further dissection. Analgesics, including opioids, are employed to alleviate pain and discomfort.¹⁴

The purpose of this study was to review surgical procedures undertaken for different pathologies of the aorta and their outcomes in terms of mortality and morbidity.

Methods

A retrospective database review was conducted at the cardiovascular department of a tertiary care hospital. This study included all patients who underwent aortic surgery for various pathologies of the structure in elective and emergency cases, including open and endovascular repairs from January 2017 to December 2023. A total of 115 patients met the inclusion criteria. Local institutional review board approval was obtained. Data were collected retrospectively from electronic medical records.

The type of surgery performed depended on the pathology and the aortic segment involved, following the current guidelines. The aorta is divided into 11 zones as per Ishimaru’s classification (Figure 1). Study subjects were divided into three categories depending on whether they had isolated aneurysm, isolated dissection or both aneurysm and dissection.

A modified Bentall procedure was performed in patients presenting with exclusive involvement of the aortic root, such as those with isolated aneurysms or dissections with aneurysms.

For individuals with an isolated acute type A dissection of the root extending into the ascending aorta, aortic valve resuspension with root reconstruction and replacement of the ascending aorta with a graft was undertaken. This involved obliterating the false lumen and replacing the ascending aorta or arch with a Dacron graft.

Deep, hypothermic circulatory arrest was used when arch surgery was performed. Retrograde cerebral perfusion through the superior vena cava was commonly applied for cerebral protection.

In complicated cases involving the descending thoracic aorta that were refractory to medical treatment, open or endovascular surgical repair was undertaken based on patient pathology. Several patients were operated on for gastrointestinal bleeding because of aorto-enteric fistulas.

All patients underwent proper work-up and anaesthesia assessment before surgery. The blood transfusion was carried out as per American College of Cardiology/American Heart Association guidelines.

The routine stay in the intensive care unit (ICU) was 48 hours; any case requiring >48 hours was considered to have a prolonged ICU stay. Similarly, any patient requiring >24 hours of mechanical ventilation was considered as having a prolonged ventilation time. For endovascular surgeries, routine ICU care was 24 hours. The term ‘inpatient mortality’ refers to fatalities that occur during the hospital stay following surgery within the index hospital admission.

The perioperative variables were extracted from the electronic database and were collected through a predesigned pro forma. Data were analysed using IBM SPSS 25.0, frequencies and percentages were calculated for qualitative variables, and means and standard deviations were calculated for quantitative variables.

Results

Our study included a total of 115 patients, of whom the majority were male (n=96; 83.4%). Table 1 summarises the preoperative demographics. The mean age was 44.9 ± 18.3 years, and 23 patients (20%) were active smokers. The most common comorbidity was hypertension (n=48; 41.7%), followed by dyslipidaemia (n=19; 16.5%) and diabetes (n=9; 7.8%. The most common presenting complaints were shortness of breath (New York Heart Association III functional class; n=42; 36.5%) and Canadian Cardiovascular Society II functional class chest pain (n=29; 36.7%). Most procedures were elective (n=94; 82%).

Table 2 summarises the intra- and postoperative parameters of aortic surgical patients. Of our patients, 52.1% underwent off-pump procedures whereas 47.8% were on cardiopulmonary bypass (CPB).

In off-pump procedures (abdominal aorta, endovascular, arch or coarctation repair), 10 (16.6%) patients received an intraoperative blood/blood product transfusion; 14 (23.3%) received a postoperative blood/blood product transfusion.

The mean ventilation time was 11.5 ± 25.9 hours with a mean ICU stay of 42.1 ± 30.7 hours. One (1.6%) patient required prolonged ventilation, while three (5%) underwent reopening for bleeding/tamponade. The overall inpatient mortality of off-pump cases was 5%. In on-pump (CPB) procedures (aortic root, ascending, arch or descending aorta), the mean cross-clamp time was 98.9 ± 3 9.4 minutes, while the bypass time was 159.3 ± 48.4 minutes.

Of the CPB cases, 72.7% received an intraoperative blood/blood products transfusion. Similarly, 38 (69.1%) received postoperative blood/blood products transfusion. The mean ventilation time was 23.3 ± 19.5 hours, with a mean ICU stay of 62.5 ± 47.8 hours. Nine (16.4%) patients underwent revision surgery for bleeding/tamponade, and nine (16.4%) required extended hours of ventilation. The overall inpatient mortality of on-pump cases was 18.2%. The overall inpatient mortality of both on- and off-pump cases was 11.3% (13 patients). Of these, eight (61.5%) patients had dissection while five (38.4%) had no dissecting flap (Figure 2).

Our study includes 20 cases of TAAD involving the root or ascending aorta and an additional 30 cases of ascending aortic aneurysm. Surgical interventions were tailored to the specific pathology of each case. Aortic root replacement was performed in 40 patients. The overall mortality rate for TAAD was seven out of 20 patients. All of them were men with a mean age of 43.8 ± 16.3 years.

Apart from the open surgical procedures, there were several endovascular interventions, including thoracic endovascular aortic repair (two patients), abdominal endovascular aneurysm repair (one patient) and endovascular abdominal aortic thrombus retrieval (two patients). The most common off-pump procedure was coarctation of the aorta repair, carried out in 36 patients (31.3%) with no inpatient mortality.

In our study, isolated aortic aneurysm was the most common pathology for which operative intervention was necessary; 48 patients (41.7%) underwent surgery for the above-mentioned pathology, followed by 36 (31.3%) patients suffering from coarctation of the aorta then both aortic aneurysm and dissection with 13 patients (11.3%). Isolated aortic dissection was less common; only 11 patients (9.5%) required surgery for this pathology, indicating that only a few made it to the hospital alive (Table 3).

A summary of the different pathologies for which operative interventions were performed is shown with distribution according to the anatomical location of the aortic intervention and their percentage in Figure 1.

A summary of the geographical distribution of different aortic pathologies is depicted in Figure 3. Our cases are from Pakistan and Afghanistan, as our centre receives patients from both countries. The majority of patients, 18 (25.0%), were from Kabul (Afghanistan), followed by the district Peshawar (20.8%), the capital of Khyber-Pakhtunkhwa province of Pakistan.

Discussion

Our study showed the mean patient age was 44.9 ± 18.3 years and a male sex predominance of 96 (83.4%), which corresponds to Hassan et al.’s finding that aortic disease is 3–5 times more common in men.¹⁵ Most patients with thoracic aneurysms are hypertensive, which is comparable with our results showing that the most common comorbidity was hypertension.¹⁶

Developing countries, such as Pakistan, are lagging behind regarding aortic surgery. Aortic surgery is still considered to be of very high risk with high mortality rates. With advances in diagnostic modalities, more people are being diagnosed with aortic disease despite being asymptomatic. Open surgical repair and new and evolving endovascular techniques are the treatment of choice for numerous aortic pathologies.

In our study, the mortality rate in patients undergoing aortic surgery was 11.3%. The two most common entities that carry high mortality without treatment are aortic aneurysm and aortic dissection.¹ Mortality in patients with thoracic aortic aneurysm depends on the location of the disease; the arch and descending aorta have the highest mortality, which can also be seen in our study.¹⁷ The high mortality of thoracic aneurysm open repair can be attributed to the number of causes, as shown by studies, and the surgical volume/learning curve has a high impact on the outcomes as well.¹⁸ Aortic root and ascending aorta surgery has evolved over the years, and the operative mortality decreased over time with improving experience.¹⁹

The abdominal aorta is another common site for aneurysm formation, and this is mostly diagnosed in elderly patients. Both surgical and endovascular techniques can be applied for successful aneurysm repair, as our outcomes demonstrated. Open versus endovascular repair of thoracoabdominal aortic aneurysms has been studied in multiple randomised controlled trials, revealing a decrease in early mortality in the endovascular group, but the long-term outcomes are still to be established.²⁰

Compared to isolated aneurysm formation, aortic dissection is seen less often in hospitals since it is more lethal, and only a few people reach the hospital with TAAD in certain regions with limited transport facilities. For TAAD, surgical outcomes remain suboptimal, with early mortality rates ranging from 9% to 25%.²¹ Isolated dissection is less common; aneurysm leading to dissection is more common, as also can be seen in our study.

Postoperative blood and blood products transfusion is another challenging component of open aortic surgery. We experienced a 65.8% transfusion rate of different blood products in patients with open surgical repair; in complex repairs, patients undergoing endovascular repair did not require significant blood transfusion. It is evident from numerous studies that blood transfusion in aortic surgery increases morbidity and mortality by elevating the risk of extended ventilation time, kidney injury and likelihood of pneumonia.^22,23

Up to 20–25% of people with TAAD have an inherited genetic condition. It is important to diagnose which patients carry the genes for such aortic anomalies so family members at risk for such a heritable thoracic aortic disease can be identified. Eleven genes have been confirmed to result in a highly penetrant risk for heritable thoracic aortic disease: FBN1, LOX, COL3A1, TGFBR1M, TGFBR2, SMAD3, TGFB2, ACTA2, MYH11, MYLK and PRKG.²⁴ While family screening for the presence of the above genes is essential, genetic testing not only poses financial burdens but also may not be available in every region.

Aortic pathologies are relatively common in our area (northern Pakistan and Afghanistan) and can be treated surgically well. The introduction of endovascular techniques has provided an alternative approach to treating these pathologies but open surgical repair remains the gold standard for the majority of patients.²⁵

The common risk factors of mortality in our patients include dissection, emergency presentation, the presence of aortic rupture and an infected aorta. One common reason for opting for open surgery over endovascular procedures is the higher cost of the latter. Hypertension, a prevalent comorbidity among our patients, constitutes a significant risk factor. Furthermore, many patients present late in the disease process to the hospital, complicating their management.

To address these issues, several measures are recommended. First, enhancing primary care services is crucial for prevention and to ensure early detection with screening programmes and early referral to aortic centres. Second, improving hypertension control through widespread public health initiatives and accessible medical treatment can reduce the incidence and severity of related complications. Lastly, improved access to healthcare in terms of both training in aortic diseases treatment and rapid transport of acute patients is essential to optimise patient outcomes.

Study Limitations

Our main limitations result from a varied group of aortic pathologies, a retrospective study design, short-term outcomes and it being a single-centre study.

Conclusion

Aortic pathology frequently manifests in various anatomical locations in both elective and emergency scenarios. Although surgical interventions successfully address various aortic pathologies, these procedures are still bound with certain risks. The presence of dissection and emergency presentation is a major risk factor.

The study reveals trends in patient outcomes and procedural efficacy, guiding improvements in treatment protocols and risk stratification, particularly in low-to-middle-income countries. It serves as a foundation for larger studies, to influence resource allocation and to prompt exploration of alternative techniques suitable for low-resource environments. The study highlights challenges in managing aortic dissection in low-to-middle-income countries, contributes to global knowledge and may foster international collaboration.

Recommendations include strengthening primary care for early detection and timely referral of aortic diseases, developing specialised aortic centres with advanced diagnostic and therapeutic capabilities, establishing rapid transport systems for timely patient transfers and addressing geographical disparities by setting up satellite clinics or telemedicine hubs. Regarding prevention, screening programmes for high-risk populations should be implemented, educational campaigns on aortic disease awareness launched and risk stratification tools used to guide preventive measures. In addition, clinicians should be offered continuous medical education and specialist training in aortic disease management, and multidisciplinary collaboration should be promoted through regular case conferences and workshops.