Conscious Sedation for Transcatheter Aortic Valve Implantation

Comparative Study of Propofol Versus Dexmedetomidine for Conscious Sedation During Transcatheter Aortic Valve Implantation

Aortic valve stenosis is the heart valve disease with the highest prevalence among the elderly, and may lead to heart failure. Until recently, the only definitive treatment was surgical replacement (SAVR). However, the increased risk associated with the surgical procedure excluded patients with multiple co-morbidities. As the population is aging and more and more patients may present with aortic stenosis, the need of a less invasive approach has emerged. Transcatheter Aortic Valve Replacement (TAVR) offered an alternative therapy for these high risk patients. This new method has seen worldwide acceptance, has been proven very beneficial for these patients, and therefore its indications have been expanded to intermediate risk patients, as well. Until recently, general anesthesia was the primary anesthetic technique for TAVR, but conscious sedation or monitored anesthesia care (MAC) is gaining more and more popularity lately. Our knowledge regarding the comparison between general anesthesia and MAC in TAVR procedures is derived mainly from observational studies and few randomized trials. MAC seems to be associated with less inotropic drug usage, shorter procedural times, shorter intensive care unit (ICU) and hospital length of stay. However, according to published data, there were no differences in 30-day mortality and complications between these two techniques. Even less are known about the most suitable anesthetic agent for MAC during TAVR. Many drugs have been used, with propofol and dexmedetomidine being the most popular. However, there are only few comparative studies and their results are not conclusive. This study compares MAC under propofol and MAC under dexmedetomidine for TAVR in order to examine which method of conscious sedation comes with more beneficial postoperative outcomes for the patients.

Aortic valve stenosis is the most common heart valve disease among the elderly, and eventually may lead to heart failure. Its surgical replacement (SAVR) was the only definitive treatment, but this operation is considered to be of increased risk for morbidity and mortality. Also, there is a growing number of elderly with severe co-morbidities, who are considered as high risk patients, that cannot undergo such an operation. Transcatheter Aortic Valve Replacement (TAVR) offered an alternative method of treatment for these patients. Furthermore, its indications were expanded to intermediate risk patients due to its advantages over SAVR. At first, general anesthesia was the most popular anesthetic method for TAVR. However, conscious sedation and Monitored Anesthesia Care (MAC) have emerged as advantageous alternatives, in terms of inotropic drug usage, procedural times, intensive care unit (ICU) and hospital length of stay. However, few data exist about the anesthetic agents that are most suitable for TAVR under MAC, with propofol and dexmedetomidine being the most popular of them. This is a prospective comparative study of propofol versus dexmedetomidine used for MAC in TAVR procedures. The patients will be randomly allocated into two groups and will be sedated by continuous infusion of either propofol or dexmedetomidine during the TAVR procedure. These two groups will be assessed for the overall quality of the sedation method, the clinical outcomes, the adverse events and the duration of hospitalization. At the preoperative evaluation, detailed patients' medical history will be taken, their comorbidities, physique, heart echocardiography measurements, level of frailty, renal function and neurocognitive level will be assessed and recorded and, finally, signed consent will be obtained. During the procedure, the depth of sedation will be monitored with the use of Patient State Index (PSI) and the fluctuation of arterial pressure, heart rate, and oxygen saturation, the administration of vasoactive agents and fluids, apnea episodes and diuresis will be also recorded. By the end of the procedure, the volume and type of contrast agent used, the type of the implanted valve and the duration of both the sedation and the operation will be documented. Throughout their hospitalization, adverse events, renal function and neurocognitive level will be recorded, along with the occurrence of postoperative delirium. After patients' discharge, their duration of hospitalization, both in cardiac intensive care unit and cardiology clinic will be recorded. Follow up of the patients will be completed after thirty days. All-cause mortality will be assessed at this point and there will be a detailed recording of any adverse events and/or re-hospitalization along with long-term assessment of renal and cognitive function.

transcatheter aortic valve replacement, dexmedetomidine, propofol, conscious sedation, monitored anesthesia care

Sedation under continuous infusion of propofol. Small doses of fentanyl will be administered if needed.

Sedation under continuous infusion of dexmedetomidine. Small doses of fentanyl will be administered if needed.

Assessment of renal function by serial measurements of serum creatinine (mg/dL) at four different time points (at baseline, at 24 hours, at 48 hours and at 30 days postoperatively).

Assessment of renal function by serial measurements of BUN (mg/dL) at four different time points (at baseline, at 24 hours, at 48 hours and at 30 days postoperatively).

Assessment of renal function by serial measurements of serum cystatin C (mg/l) at four different time points (at baseline, at 24 hours, at 48 hours and at 30 days postoperatively).

Assessment of renal function by serial calculations of GFR (ml/min) at four different time points (at baseline, at 24 hours, at 48 hours and at 30 days postoperatively) using the Cockcoft-Gault equation.

Assessment of renal function by serial calculations of GFR (ml/min) at four different time points (at baseline, at 24 hours, at 48 hours and at 30 days postoperatively) using the MDMR equation.

Assessment of neurocognitive function of the patient with the use of the mini mental state examination (MMSE) score.

The usage of norepinephrine, epinephrine, phenylephrine, ephedrine, nitroglycerin, atropine, or other relevant agents will be recorded as the cumulative dosage of each administered during the procedure.

The occurrence of myocardial infraction after the procedure will be assessed as a binary outcome variable (yes/no).

The occurrence of acute heart failure after the procedure will be assessed as a binary outcome variable (yes/no).

The occurrence of life threatening arrythmias after the procedure will be assessed as a binary outcome variable (yes/no).

The occurrence of headache after the procedure will be assessed as a binary outcome variable (yes/no)

The occurrence of nausea/vomiting after the procedure will be assessed by a 5-point scale (0 to 4, with 4 indicating the worse outcome).

The occurrence of pruritus after the procedure will be assessed by an 11-point scale (0 to 10, with 10 indicating the worse outcome).

The occurrence of hypoxemia after the procedure will be assessed by continuous monitoring of oxygen level (SpO2).

The duration of sedation is defined as the time (minutes) from the start of the sedative agent administration to patient recovery (alert and able to communicate).

Rapid pacing time is defined as the cumulative time (seconds) of rapid ventricular pacing performed during the procedure.

The satisfaction of the interventional cardiologists performing the procedure will be assessed by the Likert satisfaction scale.

Occurrence of intraoperative awareness of the patient will be assessed using the Michigan Awareness Classification Instrument.

Inclusion Criteria: Patients scheduled for TAVR Exclusion Criteria: Emergency operation Pre-existing neurocognitive dysfunction (Mini Mental State Examination score <23) Inability to cooparate - communicate End Stage Renal Disease Allergy to any of the administrated drugs No consent