Non-Surgical Treatment Of Heart Valves

TAVI and MitraClip methods

TAVI and MitraClip methods

Recently, advancements in technology paved the way for developments at an unprecedented pace in the field of cardiology. Among them are balloon dilatation of coronary arteries and stent implantation as well as treatment of rhythm disorders, medication treatments and preventive therapies. However, the most important achievement in the field of cardiology is non-surgical treatment of heart valve diseases. While surgical techniques and heart-lung machine were required for heart valve diseases approximately a decade ago, such diseases can now be treated with interventional techniques through non-surgical vascular access. The non-surgical treatments of heart valves that have gained popularity and have been proven in recent years are TAVI and MitraClip. TAVI is performed for the aortic valve, while MitraClip is reserved for the mitral valve.

1. TAVI (Transcatheter aortic valve implantation - Non-surgical Implantation of Heart Valve)
What is aorta?
Aortic valve is located between the left ventricle of the heart that pumps the blood to the body and is the greatest artery that originates from the heart, namely aorta.

What is aortic stenosis?
Rheumatic valve disease, congenital aortic valve anomaly and aging may distort and narrow the aortic valve.

What are causes of aortic stenosis?
Today, the most common cause of the aortic stenosis is aging. As the life expectancy gradually increases, calcification develops in aortic valve secondary to use and wearing in a large population, which results in stenosis of the aortic valve.

Progression of the aortic stenosis increases the pressure in the left ventricle and thus, the blood supply to the body decreases. It is a progressive process and unfortunately, there is no medical treatment for aortic stenosis. The only solution is to replace the dysfunctional valve with an intact valve.

When aortic valve becomes severely narrow, movement capacity of the patient decreases. The first symptom to manifest is dyspnea while walking uphill and climbing up stairs. Shortness of breath can be felt even while walking in a straight road or doing simple activities at advanced stages of the disease. Chest pain and fainting are likely at further stages. If the aortic stenosis is not treated at this stage, the risk of death becomes substantially high.

Figure 1. Anatomy of the aortic valve

Figure 2. Normal and calcific aortic stenosis

How is aortic stenosis diagnosed?
Diagnosis of aortic stenosis is based on physical examination and echocardiography. A normal aortic valve area is 3-4 cm2. When the aortic valve area decreases below 1 cm2, complaints of the patient aggravate. In this case, the aortic valve should be corrected without delay.

How is aortic stenosis treated?
More than one method is used to treat the aortic stenosis. Those are:

⦁ Surgical treatment of aortic stenosis

Surgical treatment is the conventional method that has been long used to treat the aortic stenosis. When severity of the aortic stenosis reaches a certain level, an intervention is a must. Surgical treatment of the aortic valve is performed as follows: the chest cavity is opened and the patient is connected to a heart-lung machine. During the procedure, the aortic valve is removed and a mechanical or bioprosthetic valve is placed.

⦁ Balloon dilatation of the aortic valve

Balloon dilatation of the aortic valve is a transient solution for patients who are inoperable, too old and have no other option. This procedure usually relieves the complaints for 1 year. It is reserved for the patients who are not eligible for surgical replacement of the aortic valve due to the high risk or who are not eligible for TAVI due to patient-related factors.

⦁ TAVI – placement of a prosthetic aortic valve through a catheter

TAVI enables replacement of aortic valve with non-surgical approach by accessing through femoral artery without opening the chest cavity for the patients who are not eligible for open heart surgery or are in high risk group regarding surgery. This is the most rapidly advancing field of cardiology in recent years. Aging of the population has turned the aortic stenosis into a serious health problem.

This method is reserved for patients who are inoperable due to very high risk of surgery. Biological heart valves that are made of bovine or porcine pericardial tissue are implanted in TAVI. This biological valve is placed into a stent sheath, inserted into a blood vessel in groin region and implanted to replace the native aortic valve.

How is TAVI performed?
TAVI (Trans-catheter aortic valve implantation), or non-surgical replacement of the aortic valve, is performed under general anesthesia. The procedure lasts approximately for 1 and half hour. A needle is punctured into an artery that is located in groin and a large sheath is inserted that is left in the artery through the procedure and the new valve can be easily advanced through. Next, a long guide wire is advanced in the lumen of the sheath through the artery until the valve is reached and it is passed through the stenotic aortic valve. A balloon is pushed forward over the guide wire and inflated at the level of the aortic valve and thus, an area is created that is wide enough to pass the valve. After the balloon is removed, the new valve that is sent over the guide wire is implanted. The guide wire and the sheath that has been inserted into the femoral artery are removed at the end of the procedure. Finally, several sutures are placed to the puncture site.

In certain patients, it is necessary to perform the procedure by visualizing the femoral artery. In such cases, a surgical incision, measuring approximately 5 cm, is made in the groin and it is stitched after the procedure is completed. If the femoral artery is occluded or stenotic, it is possible to perform all these procedures by puncturing an artery in the arm or making a small incision (4-5 cm) in the chest. Patients are usually monitored in the intensive care unit overnight after the procedure. Later, the patient can be mobilized and discharged within several days.

Who are candidates of TAVI?
TAVI (Trans-catheter aortic valve implantation), or non-surgical replacement of the aortic valve, is reserved for high-risk patients who cannot undergo an open heart surgery. Moreover, although some patients with aortic stenosis may undergo an open surgery, they can be candidate of TAVI due to their special conditions, if their overall health is good. Good candidates of TAVI include elder people and patients with liver or kidney dysfunction or history of open heart surgery.

What are risks of TAVI?
Risk of death and disability arising out of TAVI is higher in comparison to that of other angiographic diagnosis and treatment techniques used in the field of cardiology. However, it is necessary to keep in mind that TAVI is performed for inoperable patients or patients with strikingly high risk and that there is no other treatment option for the existing disease. The risk of death is about 3 to 5 percent during the procedure and within 30 days after TAVI. The risk of a minor or major stroke is about 3 to 4 percent in the first 30 days after the procedure. Excluding death and stroke, other risks of TAVI are largely treatable conditions.

2. MITRACLIP (Non-surgical Repair of Mitral Valve Regurgitation)
What is non-surgical repair of mitral valve with MitraClip method?
Non-surgical repair of mitral valve with MitraClip method involves combining the two cusps of the mitral valve with a clip on the mid-line through femoral artery without need to open the chest cavity. This technique is reserved for patients with mitral regurgitation who are at very high risk regarding mitral valve surgery.

What is mitral valve?
Mitral valve is located between the left atrium and the left ventricle of the heart. This valve allows the flow of the oxygenated blood from the lungs to the left ventricle and hinders the flow of the blood back to the left atrium.

What is mitral valve regurgitation?
If the mitral valve does not properly close, the blood regurgitates to the left atrium, while the blood may flow back even to pulmonary vessels, if the closing function is severely deteriorated. This condition is called mitral valve insufficiency or regurgitation. Mitral valve regurgitation is the most common heart valve disease all around the world.

What are causes of mitral valve insufficiency? Who are at risk of mitral valve insufficiency?
Mitral valve insufficiency develops in 13 to 50 percent of people who survive a heart attack. Many of these patients have past history of bypass surgery or stent implantation. Moreover, mitral valve prolapse (MVP) and sometimes, rupture of the chords that attach the mitral valve to the heart may also cause severe mitral insufficiency. In addition, congenital diseases and acute rheumatic fever in childhood are among the triggering factors of the mitral insufficiency. Moreover, certain myocardial diseases can lead to severe insufficiency in the mitral valve. Severe dilatation of the left ventricle secondary to heart failure is one of the important underlying mechanisms of the mitral insufficiency.

What are symptoms of mitral insufficiency?
The symptoms that are commonly noticed by patients with mitral insufficiency are shortness of breath, poor exercise capacity, rhythm disorder and pretibial edema. Sometimes, past medical history of stroke may also be a sign. If mechanical repair is not performed for patients with severe mitral valve insufficiency, half of the patients usually die within five years.

How is mitral valve insufficiency treated?
Mitral valve insufficiency is graded as mild, moderate and critical in echocardiography. Medication treatment helps mild to moderate mitral valve insufficiency. Moderate insufficiencies may, sometimes, progress into a serious condition. Replacement or repair of the valve with open heart surgery is the treatment option for critical mitral valve regurgitation. However, open heart surgery poses high risk of death or complication in half of the patients with mitral regurgitation. These high-risk patients either have other serious comorbidities or have lost the contractility of the heart substantially. Sometimes, advanced age is a contraindication for the open surgery. Medication treatment is mostly ineffective for these inoperable patients. Recently, MitraClip method has provided these patients with a source of hope.

Who are candidates of MitraClip?
MitraClip is a treatment option especially for patients who have comorbidities, which may increase the risks of open heart surgery, have severely impaired contractility of heart muscle and are too old. However, MitraClip is not an option for all patients with mitral valve regurgitation (mitral valve regurgitation secondary to rheumatism, structure of the valve not eligible for MitraClip). After diagnosis of severe mitral valve regurgitation is established, the patient is jointly evaluated by cardiologists and cardiovascular surgeons, before the best treatment option is decided. Trans-esophageal echocardiography is used to clarify whether the structure of valve is appropriate for the procedure or not. If the structure of valve allows MitraClip procedure and the patient is at high risk for open heart surgery, the procedure is performed.

How is MitraClip performed?
If the valve structure of the patient is appropriate for MitraClip, or clipping, the patient is transferred to the angiography laboratory together with anesthesiology department. After anesthesia is administered, the procedure is started with trans-esophageal, or endoscopic, echocardiography. Chest cavity is not opened; femoral vein is punctured and catheter is advanced to the right atrium. A small hole is created on the septum located between right and left atria and thus, the left ventricle is accessed. Next, MitraClip device is passed from the right atrium to the left ventricle and the leaflets of the mitral valve are end-to-end clipped at the location of regurgitation. This procedure is similar to stitching in open heart surgery. Next, necessary controls are done and the mitral insufficiency is re-evaluated. If the regurgitation cannot be reduced to target or acceptable level, leaflets are clipped twice or three times or even four times to reduce the insufficiency. If controls demonstrate that the insufficiency is reduced to the target level, MitraClip system is removed from the vein and bleeding is stopped by placing several stitches. If no abnormality is detected in final controls, the patient stays at the hospital for 1 to 2 days for monitoring and next, the patient is discharged.

What are possible changes in lives of patients after MitraClip?
After the regurgitation of the mitral valve is minimized with this method, it is expected that shortness of breath regresses and patients can perform everyday activities more easily.

This procedure also minimizes the requirement of recurrent hospitalizations for patients, who were necessarily hospitalized at frequent intervals in the past. Moreover, it is known that the procedure prolongs the survival in some patients.

Results of 5 to 6-year follow-up reported by European and the U.S. healthcare facilities and of our 2-year follow-up demonstrate that MitraClip method is very efficient and successful in management of the mitral valve insufficiency.

What are risks of MitraClip?
Complications that may develop in and after MitraClip procedure are as follows:

⦁ Urgent surgery is rare and the prevalence is around 0.1 percent.

⦁ Death or myocardial infarction is rare and the prevalence is below 1 percent.

⦁ Cerebral embolism or stroke is rare and the prevalence is below 1 percent.

⦁ Bleeding is the most common complication and the prevalence is 7.4 percent.

⦁ Pericardial tamponade or accumulation of fluid in pericardium occurs by 1.9 percent.

⦁ Perforation of atrial septum.

⦁ Loose attachment of the clip.

⦁ Inability to correct mitral insufficiency efficiently.