Balloon Aortic Valvuloplasty

Fig. 13.1

Hemodynamics during rapid right ventricular pacing. Systolic pressure and pulse pressure fall with rapid pacing, and nearly vanish with balloon inflation (From Witzke et al. [26] with permission)

Fig. 13.2

Watermelon seeding of the balloon without rapid pacing. Note the exaggerated “J” on the wire to deflect the balloon from the myocardium (From Witzke et al. [26] with permission). A-C, progressive balloon watermelon seeding.

Fig. 13.3

Hemodynamics during balloon inflation. With loss of aortic pressure but marked elevation in LV generated pressure (From Carroll [61] with permission)

Fig. 13.4

Changes in aortic valve area with and without RV pacing

Another modification that has made BAV technically safer is the introduction of different balloon shapes and materials. The only balloons available in the early years of balloon valvuloplasty were made by Mansfield (Billerica, MA) and had large shafts and bulky balloons that once inflated, could only come out through a very large sheath. More often, these balloons were inserted through a 12F sheath and once BAV was complete, the deflated balloon and sheath were removed “en-block” over a still wire and a new 12F or larger sheath was inserted. This left a large and perhaps ragged arteriotomy and led to the high incidence of vascular injury and transfusion seen in the early valvuloplasty experience. Newer, lower profile balloons made of more foldable, less bulky polymers such as the Z-Med balloon (Braun Interventional Systems, Bethlehem PA), the True balloon (Bard, Tempe Az) and the Tyshak balloon (Numed, NY), have made vascular access easier, and although difficult to demonstrate in studies, have made vascular complications less frequent. The Inoue balloon (Toray Medical, Houston Tx), initially designed for mitral balloon valvuloplasty, has been adapted for BAV [27–29] with good hemodynamic and clinical results, entirely bypassing the issue of large bore arterial access if the antegrade technique is used. To utilize this technique, significant transseptal experience is mandatory, and care needs to be taken to preserve a large loop in the ventricle around the anterior mitral leaflet to prevent damage to this structure and catastrophic mitral insufficiency. Another other novel design balloon is the V8 balloon (InterValve Inc, Plymouth MN). This balloon with a 12F shaft, is hourglass shaped and is sized by the waist in the hourglass which naturally seats itself in the stenotic valve as it is expanded, applying force directly on to the valve and also limiting the “watermelon seeding” motion of the balloon. This has lessened the need for the rapid ventricular pacing described above.

Perhaps the most dramatic change in retrograde BAV technique has been the adaptation of closure devices of various types to the large arteriotomy defects left by the large sheaths involved in BAV. Since they are involved directly in the prevention of vascular complications, they will be described in full in that section.

A list of commonly used valvuloplasty balloons and their manufacturers is listed in Table 13.1 and Fig. 13.5 demonstrates some of the commercially available balloons.

Table 13.1

Common types of valvuloplasty balloons

Balloons	Z-Med/Z-Med II/NuCLUES/NuCLEUS-X/TYSHAK/TYSHAK II	V8	True balloon
Advantages	Quick inflation and deflation time Short flexible distal tip with short balloon taper aids maneuverability through tortuous anatomy Coaxial haft design provides enhanced column strength and pushability Z-Med II provides higher strength and in some instances a larger introducer	Designed to lock into valve, limiting movement Shape maintained reducing likelihood of annular rupture Quick inflation and deflation time	True reliable sizing Fast Rupture resistant
Balloon diameter (mm)	Z-Med: 10–25, Z-Med II: 5–25, Z-Med II TAVR: 20–25, NuCLEUS-X: 18–30	Waist: 17–23 mm/bulbous segment: 22–27.5 mm	20–26 mm
Balloon length (cm)	Z-Med: 2–4, Z-Med II: 2–6, Z-Med II TAVR: 4.5, NuCLEUS: 4–6		4.5 cm
Introducer size (Fr)	Z-Med: 7–12, Z-Med II: 6–14, Z-Med II TAVR: 11–12, NuCLEUS: 10–14	12 Fr	11–13 Fr
Shaft size (Fr)	Z-Med: 6–9, Z-Med II: 5–9, Z-Med II TAVR: 10, NuCLEUS: 9
Usable length (cm)	Z-Med: 100, Z-Med II: 100, Z-Med II TAVR: 110, NuCLEUS: 110		110 cm
Guide wire (inches)	Z-Med: 0.035, Z-Med II: 0.025–0.035, Z-Med II TAVR: 0.035, NuCLEUS: 0.035	0.035 in.
Rated burst (ATM)	Z-Med: 9–3, Z-Med II: 15–4, Z-Med II TAVR: 5–4, NuCLEUS: 4–2
Nominal pressure (ATM)	Z-Med: 4–2, Z-Med II: 6–2, Z-Med II TAVR: 2	Inflation volume: 17 mm/16 cc, 19 mm/20 cc, 21 mm/23 cc, 23 mm/27 cc

Fig. 13.5

Commonly available valvuloplasty balloons: top left (a) Z-Med, bottom left (c) NuCLEUS, top right (b) V8, and bottom right (d) True balloon

Immediate Hemodynamic Results

The immediate hemodynamic results of BAV have been well described in many single center series as well as the Mansfield BAV Registry. These are summarized in Table 13.2. In these large experiences, the immediate hemodynamic effects of BAV are fairly uniform, with roughly a halving of the transaortic gradient and an increase in calculated aortic valve area of 0.3–0.4 cm². The age of the patient seems not to affect the acute hemodynamic outcome [33]. Other hemodynamic effects include a very modest change in cardiac output as well as an increase in central aortic systolic pressure. Immediate changes in right and left heart filling pressures are usually modest in nature. Although larger balloons and multiple balloon techniques have been utilized to improve the acute hemodynamic results, these may come at the cost of increased risk of aortic root disruption or leaflet avulsion. In a large series from the UK [32] there was a weakly positive correlation between both the balloon size and balloon/annulus ration with percent change in aortic valve area, although neither had any effect on mortality or long-term outcome. In a small consecutive series [29], it was suggested that the antegrade Inoue technique resulted in a slightly better hemodynamic result than the standard retrograde technique. The final balloon diameter was larger in the antegrade group than the retrograde group. This series of 13 patients is more hypothesis generating than definitive, and at this point there is no particular technique that has been shown to consistently deliver better acute hemodynamic results.

Table 13.2

Immediate hemodynamic effects of BAV: large series

Reference	N	AVA-pre cm²	AVA-post cm²	Mean gradient pre	Mean gradient post
Safian [6]	170	0.6	0.9	71	36
Letac [7]	218	0.5	0.9	72	29
McKay [8]	492	0.5	0.8	60	30
Lewin [9]	125	0.6	1.0	70	30
Ben-Dor [30]	262	0.6	1.0	–	–
Kapadia [31]	99	0.6	1.0	46	21
Khawaja [32]	423	0.6	0.8	62	28

Acute Complications

To evaluate the potential for catastrophic complications of BAV, Safian et al. [17] performed 33 postmortem BAV procedures, and 6 intraoperative procedures. As described earlier, the mechanism of aortic valve lumen enlargement was elucidated. Fracture of calcific nodules was visually seen in 16 valves, separation of fused commissures were seen in 5 valves (three of the cases were rheumatic), and grossly inapparent microfractures in 12 valves. Leaflet avulsion occurred in one valve that had been dilated with an oversized balloon. The dilated valves were carefully washed for debris and no calcific debris could be recovered. Moreover, no valve ring disruption or mid leaflet tears occurred. With data from this center and others suggesting that major catastrophes should be unlikely, many centers embarked on BAV programs in the mid 1980s.

The most serious complications of BAV that have been reported are death, athero/thromboembolic complications, complications causing disruption of the aortic root or aortic leaflets causing massive aortic regurgitation, myocardial infarction and peripheral vascular injury due to the large size sheaths used. Ventricular perforation has also been reported. Conduction may also be expected, given the proximity of the aortic annulus to the conduction system. In one series [34], the incidence of new conduction defects was 8.5 %, with only 1.5 % of patients required permanent pacing. The risk of new conduction defects was related to the ratio of balloon size to left ventricular outflow tract (1.2 in patients with new conduction defects, 1.15 in patient with no new defect).

Acute complications from major series are shown in Table 13.3 [35]. Mortality rates of 3–10 % as noted are likely due to the high risk nature of these patients, with advanced age and multiple comorbities. The risk of BAV may be reduced by adoption of some of the modifications to the technique as outlined above. In a more contemporary series of 334 patients [34], the mortality was 1.5 %.

Table 13.3

Acute complications of BAV

Reference	N	Death (%)	CVA (%)	Cardiac perforation (%)	AMI (%)	Acute aortic insufficiency (%)	Vascular injury (%)
Cribier [33]	334	4.5	1.4	0.6	0.3	0	13.1
Safian et al. [17]	225	3.1	0.4	1.2	0.5	0.8	7.5
Block and Palacios [36]	162	7.0	2.0	0	0	0	7.0
Lewin [9]	125	10.4	3.2	0	1.6	1.6	9.6
Total	846	5.4	1.5	0.6	0.5	0.5	10.6

From Safian et al. [35] with permission

As noted, the most common complication of BAV when done in the retrograde fashion is vascular injury. Transfusion rates in excess of 15 % were reported in most early series of BAV, when manual compression or planned surgical removal of the sheaths were the only options for hemostasis. Suture mediated (Proglide 6F, Abbott Vascular Devices, Redwood City CA) and collagen based techniques (Angioseal 8F, St. Jude Medical, St. Paul, MN) have both been adapted to large sheath sizes, and have been utilized for vascular closure after BAV. They been demonstrated to decrease the incidence of vascular complication and transfusion [37, 38]. Although direct comparisons are difficult due to the non-randomized nature of these studies, it appears that in patients with suitable anatomy (lack of severe atherosclerotic obstruction, well placed arteriotomy site), these devices do decrease complications as well as improve the patient experience.

Long-Term Followup

The modest improvements in hemodynamics [39] and symptoms afforded by BAV are relatively short-lived, limiting the widespread application of the procedure. Very high rates of recurrent symptoms, repeat procedures or death (Table 13.4) have relegated the procedure to an almost exclusively palliative or “boutique” role, although with increasing application of transarterial valve replacement (TAVR), there is more interest in the use of BAV as a “bridging procedure” as a prelude to TAVR. In a more contemporary BAV series from the United Kingdom [32] involving 423 patients, the 1 year mortality was 36.3 %, with 18.3 % of patients undergoing TAVR following BAV and 7.0 % of patients undergoing SAVR.

Table 13.4

Long term followup following BAV