Adrenalectomy — a surgical intervention that consists of excising an adrenal gland — is recommended for patients whose CT scan and AVS results indicate that excess aldosterone is originating in one of the two adrenal glands.
In most cases, the surgery is performed laparoscopically. This minimally invasive procedure requires fewer incisions, causes less pain, and offers faster recovery than traditional open surgery.
Most patients leave the hospital in one to two days, and resume normal activities within weeks.
An alternative minimally invasive posterior approach — retroperitoneal adrenalectomy — is also used, and is estimated to further improve operation time, pain score, blood loss, and complication rates.
While a successful adrenalectomy is expected to resolve primary aldosteronism, the extent to which the disease is “cured” varies widely by age, gender, race, duration of hypertension, and presence of comorbidities such as left ventricular hypertrophy and renal impairment. Instead of cure, the term “remission” is increasingly found in the literature to describe the outcomes of adrenalectomy.
The wide variations in reported outcomes have been attributed to a lack of standard indicators. In 2017, the first international effort was undertaken to determine which clinical and biochemical criteria should be taken into account to assess outcomes:
- Biochemical Outcome. The vast majority of patients who undergo adrenalectomy after successful AVS experience complete biochemical normalization: hypokalemia is corrected, and ARR values are restored to the normal range. In all other cases, partial and failed biochemical normalization are usually attributed to misdiagnosed bilateral disease, thereby highlighting the importance of adrenal venous sampling performed by skilled interventional radiologists in Centers of Excellence with high case volume and high success rate.
- Clinical Outcome. Hypertension is normalized in 30 to 60% of patients who undergo adrenalectomy after successful AVS. Blood pressure is markedly improved in all other cases. Partial and failed clinical normalization are associated with incomplete biochemical normalization, and with factors such as age, duration of hypertension, and renal function. Large-scale longitudinal studies are still needed to fully determine the rate of persistence and reoccurrence of the disease, impact on comorbidities such as diabetes, dyslipidemia or osteoporosis, and whether quality of life is sustainably restored.
To exclude the persistence or reoccurrence of primary aldosteronism, follow-up is recommended on:
- Blood pressure and plasma potassium at 3 months,
- Blood pressure, plasma potassium, aldosterone concentration and renin activity at 6 to 12 months, and on an annual basis indefinitely thereafter.
Overall, the benefits of adrenalectomy outweigh its risks. Benefits are experienced by most patients, and are believed to be greater for young and female patients. The diagnosis of primary aldosteronism according to US Endocrine Society guidelines is thus indispensable since, even in the absence of clinical success, postoperative biochemical benefits are derived, including in older patients and regardless of gender.
Selecting the Right Surgeon
Like any surgical intervention, the chance of having a safe and successful surgery depends, in large part, on the experience of the surgeon.
Studies consistently show that surgical expertise is associated with complication rates in a statistically significant way.
According to the American Association of Endocrine Surgeons, which offers an online directory of qualified physicians, endocrine surgeons should perform more than 20 adrenal operations a year to be considered experts. Patients should not undergo adrenalectomy unless they have confidence that their surgeon handles sufficient cases.
Partial vs Total Adrenalectomy
With partial adrenalectomy, a margin of surrounding tissues is removed along with the adenoma instead of the entire gland.
The procedure has been advocated to preserve adrenal function in the presence of aldosterone-producing adenoma.
To-date, few studies have been conducted to compare partial and total adrenalectomy. Some invoke a risk of persistence or reoccurrence of primary aldosteronism, others emphasize a very low risk of adrenal insufficiency.
In the absence of conclusive results, whether partial surgery is preferable remains controversial.
As a result, total adrenalectomy continues to be the preferred surgical option to ensure that all lesions are effectively removed, including micronodular tissues adjacent to adenomas which could also cause aldosterone hypersecretion.
More effective and less invasive solutions are needed if the true prevalence of primary aldosteronism is to be addressed in a sustainable way.
Ablation is commonly used to treat solid neoplasms, either with heat (radiofrequency and microwave ablation) or freezing (cryoablation with liquid nitrogen or argon gas).
The procedure is under consideration for the treatment of functional adenomas. A clinical trial was completed in France in 2019, and another trial involving PET CT imaging and ultrasound-guided radiofrequency ablation (cauterization with electric current) is currently underway in the UK.
Risks Associated with Adrenalectomies
Postoperative morbidity of laparoscopic adrenalectomy (i.e. for all causes and types of disease) is estimated at 8%, and its mortality between 0 and 0.8%.
Few studies report the risks associated with the use of the procedure to treat primary aldosteronism. The disease accounts for only a small portion of adrenalectomies which, in this context, have a lower rate of complications (less than 5%).
This is in part due to the small size of the lesions, limited use of insufflation pressure, and the fact that patients are encouraged to ambulate as soon as possible.
Complication rates vary with patient-specific factors (e.g. sex, age, high body mass index, comorbidities), the side of operation or the position of the patient on the operating table. It is however important to note that these differences are usually not statistically significant. The only factor consistently found to be statistically significant is the surgeon’s case volume.
Hyperkalemia is one of the more frequent complications for patients with primary aldosteronism. It is usually temporary, but requires immediate treatment. If it occurs, patients are given medication to restore their electrolyte balance.
Because adrenal glands are surrounded by important anatomic structure, bleeding and injury to other organs may occur. Since the abdomen is asymmetrical, different types of risks affect left and right adrenalectomies:
- The right adrenal vein is short and directly enters the inferior vena cava. Bleeding thus occurs more frequently on the right;
- The left adrenal gland is close to the spleen, colon and pancreas. Damage to these organs is thus more frequent on the left.
Conversion to open laparotomy may be required in the presence of more serious events such as bleeding or inadequate visualization of the adrenal gland, and requires longer hospitalization.
Complication rates are markedly higher when primary aldosteronism and Cushing’s syndrome coexist. Added to excess aldosterone, hypercortisolism has immune-suppressing effects which make patients more vulnerable to infections. Metabolic complications and respiratory insufficiency are also higher in the presence of Connshing syndrome. Poor wound healing, deep venous thrombosis, and pulmonary embolism are also found more frequently due to the inhibition of collagen synthesis and increased blood coagulability. The prevalence of Connshing syndrome is unknown, but as more adrenalectomies are performed to treat primary aldosteronism, more cases are being reported postoperatively. Under strict adherence to diagnosis guidelines, these cases should be identified well before surgery. Not only to enable patients to make informed decisions about their surgical intervention, but because they must be made aware of its consequences, i.e., potential temporary adrenal insufficiency and need for perioperative and postoperative glucocorticoid supplementation.
Because they have a low occurrence, and are usually resolved without sequelae, adverse events are not believed to outweigh the benefits of an adrenalectomy which is the recommended treatment of aldosterone-producing adenomas diagnosed by successful adrenal venous sampling.
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