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H ow To D o I t
Transcoronary Ablation of Septal Hypertrophy (Tash)
I Sathyamurthy
Department of Cardiology, Apollo Hospitals, Chennai
INTRODUCTION
Until the early 1990s, surgical myectomy and dual-chamber
pacing were considered treatments of choice for drug-resistant symptomatic hypertrophic obstructive cardiomyopathy
(HOCM). In 1995, Ulrich Sigwart introduced a new technique—transcoronary ablation of septal hypertrophy
(TASH)—at the Royal Brompton Hospital, London.1 The
same year, Kuhn et al. performed the operation in Germany. 2
In India, cases of successful use of the technique were
reported by Bahl et al.3 and Bhargava et al.4 Percutaneous
transluminal septal myocardial ablation (PTSMA), which is
another name for this technique, involves the injection of
absolute alcohol into the target septal perforator branch of
the left anterior descending (LAD) artery. This results in
chemical necrosis, thereby producing a controlled myocardial infarction in the proximal interventricular septum. This,
in turn, helps to achieve reduction of the basal septal thickness and ventricular septal remodeling , which result in the
expansion of the left ventricular outflow tract (LVOT), and
lessening of systolic anterior motion of the mitral leaflet and
mitral regurgitation (MR).
Indications
1. HOCM patients who have New York Heart Association
(NYHA) Class III/IV symptoms despite optimal
medical treatment with beta blockers (if contraindicated, calcium channel blockers) and disopyramide
2. A resting LVOT gradient of more than 30 mmHg
3. A post-ectopic gradient/post-exercise recovery gradient of more than 100 mmHg
4. Persistence of symptoms/recurrence of symptoms
after surgical myectomy/DDD pacing
5. When surgical myectomy is contraindicated due to
co-morbid conditions.
Contraindications
1. Children/adolescents ⬍ 18 years
2. HOCM without resting or provocable outflow gradient
3. Patients with associated valvular or coronary artery
disease
4. Associated MR of 3-plus or more MR due to mitral
valve abnormalities or myxomatous degeneration of
mitral valve
5. Mid-ventricular obstruction
6. Unsuitable septal anatomy
Preparation and Consent
The patient needs to be fasting for four hours before the
procedure and all medications are stopped 48 hours before
the procedure. Pre-procedure echocardiographic evaluation
is done to confirm the diagnosis and to rule out fixed subaortic obstruction, mid-ventricular obstruction and associated
intrinsic mitral valve disease resulting in MR. Informed
consent is taken after explaining that there is a 1–2% risk of
malignant ventricular arrhythmias and death, and a 10% risk
of heart block, requiring the implantation of a pacemaker.5–7
PROCEDURE
Right and left femoral arterial punctures and cannulations
are carried out under local anesthesia, using 2% xylocaine.
The right femoral vein is cannulated for temporary transvenous pacing. If programmed electrical stimulation to
deliver PVCs is planned, the left femoral vein is also cannulated. Inj. heparin (100 U/kg) is administered intravenously.
A routine coronary angiogram is performed to ascertain the
septal anatomy (Figure 1). The left coronary artery is
cannulated using a 6F/7F left coronary guiding catheter. A
high torque floppy guide wire (0.014 inches) is introduced
into the large first septal branch of the LAD or the target
septal artery (TSA). A 1.5 mm/2 mm (rarely, 2.5 mm) overthe-wire balloon of a length of 12–15 mm is then positioned
in the TSA and kept inflated at 4–6 atm. The guide wire is
then retracted. Contrast is injected to check the position of
the balloon, confirm that it is not protruding into the LAD
artery, and ensure that it is tightly obliterating the septal
branch. A temporary balloon occlusion of the TSA usually
results in at least a 50% fall in the resting gradient and a
Correspondence: Dr I Sathyamurthy, Interventional Cardiologist and Director, Department of Cardiology, Apollo Hospitals,
21 Greams Lane, Chennai – 600006
E-mail: [email protected]
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50 mmHg fall in the post-ectopic gradient. After the inflation of the balloon, 1–2 mL of nonionic contrast is injected
through the central lumen (Figure 2). This helps to
(a) check the position of the balloon in the desired septal
branch;
(b) ensure that there is no leakage of the contrast into the
LAD artery;
(c) check the rapid clearance of contrast, if any, into the
venous system or the ventricular chambers (rapid
washout of contrast is usually due to too many collaterals to the venous system, or due to fistulous communications to the left ventricle or right ventricle cavity); and
(d) check the myocardial contrast opacification (tissue
phase), to determine whether the TSA is perfusing
any distant and unwanted areas of the myocardium or
papillary muscles.
After all these steps have been taken, the patient is sedated
with intravenous morphine, pethidine or midazolam to alleviate pain. Then 2 mL of ethanol (95–98%) is taken in a 2 mL
syringe. Of this, 1 mL is injected into the TSA initially.
Figure 1. Left coronary angiogram: arrows showing large first
septal perforator.
Figure 2. Contrast injection through the lumen of the balloon
catheter. Thick arrow shows balloon position. Thin arrows show
contrast opacification of branches of first septal perforator/branch.
Transthoracic echo transducer also seen.
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Another 0.2mL of alcohol is injected after two minutes, and
the procedure is repeated at two-minute intervals until the
entire 2 mL of alcohol has been injected. Two minutes after
this, 1 mL of saline is injected to wash out the alcohol. The
balloon is deflated after five minutes and pulled back into the
guiding catheter. A check coronary angiogram is performed
to see whether the TSA is closed (Figure 3). It is not always
necessary for the TSA to be totally occluded for a successful
TASH.8 Ethanol-induced damage to the endothelial cells,
interstitial cells, myocardium, and adrenergic and cholinergic
nerve fibres is more significant than the complete occlusion
of the TSA.8
If any resistance is encountered while injecting alcohol into
the TSA, careful adjustment of the position of the balloon is
necessary to relieve any sharp bend at the ostium of the TSA
or at the tip of the guiding catheter. It is preferable to avoid
forceful injection against resistance in order to avoid rupture.
While adjusting the position of the balloon, it is important to
ensure that it does not slip back into the LAD artery.
Target Septal Artery
The identification of the TSA is the key to the success of the
TASH procedure. Usually it is a large first septal branch.
The TSA should not be too small (supplying the inferior part
of the proximal interventricular septum), or course too close
to the LAD artery. The ideal views for identifying the TSA
are right anterior oblique (RAO) 30o, left lateral 90o, and left
anterior oblique (LAO) cranial or caudal views. Milking
effect of the septal branch is not confirmatory of the TSA. If
the TSA divides into two branches, it is preferable to inject
alcohol into the basal side branch.
In 90% of cases, the TSA arises from the LAD or diagonal
artery. In the remaining 10% of cases, it may arise from the
ramus, proximal circumflex, or posterolateral or posterior
descending branches of the right coronary artery (RCA). The
procedure is abandoned if (a) the septal arteries are thin, small
and multiple (Figure 4); (b) there is difficulty passing the wire
due to abnormal angulation of origin; (c) there is rapid
Figure 3. Totally occluded first septal branch after alcohol ablation
(arrow).
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Transcoronary Ablation of Septal Hypertrophy (Tash)
washout of contrast; or (d) there is no significant fall in gradient after temporary balloon occlusion.
The first septal perforator (FSP) need not be the TSA in
every case. The anatomy of the FSP artery is variable, in terms
of size and distribution. An autopsy study by Singh et al.9 covering 10 patients confirmed that the FSP supplies areas other than
the basal septum. This was also reported by our group.10
Echocardiography During Tash
Intraprocedural myocardial contrast echocardiography
during TASH is very useful in identifying the TSA. 11–13
Some operators prefer to use myocardial contrasts like
Albunex, Levovist or Optiscan for this purpose. Our
group, however, uses the routine nonionic angiographic
contrasts like Omnipaque. Contrast by septal brightening
helps one assess the septal opacification. Contrast should
not brighten the right side of the septum, and rapid clearance of contrast into the ventricular chambers is undesirable. Echocardiography also helps measure the fall in
gradient during TASH, as well as assess the degree of MR.
It is preferable to combine the following techniques for
the optimum result.
1. Functional anatomic approach when the culprit or
TSA is exactly identified.
2. Super-selective approach of injecting contrast into
branches of the first septal artery to opacify the basal
septum.
3. Echo monitoring approach.
Dose of Alcohol
According to Kuhn et al., the maximum amount of alcohol
to be injected should not exceed 2 mL in order to minimize
the complications.7 Veselka et al. randomized 17 patients
into two groups, one of which received a maximum of 2 mL
and the other, 3.4 ⫾ 0.9 mL.14 There was no statistically
significant difference in the clinical electrocardiograms
(ECGs) and echocardiographic variables of the patients in
the two groups, except that there was increased release of
MB isoenzyme of creatine kinase (MBCK) in those who
had received more than 2 mL of alcohol.
Successful Ablation
When the procedure is successful, an echocardiogram
taken after six months shows a progressive decrease in the
gradient. The septal thickness regresses and there is interventricular septal remodeling, with a resultant enlargement
of the LVOT area.8,11,15–18
Biphasic Response
There can be an acute response with a total abolition of the
gradient due to stunned myocardium. This may be followed
by the reappearance of 50% of the pre-procedural gradient
after 48 hours. At six months’ follow-up, the gradient falls
again. This is termed the ‘biphasic response’.19
Risk in Creatinine Phosphokinase (CPK)
A twofold to tenfold rise in CPK can occur depending upon
the amount of alcohol injected. This results in the production
of a necrotic area equivalent to 3–10% of the left ventricular
mass (approximately 20% of septal myocardium).6,18
COMPLICATIONS
The mortality rate is 1–4%, and complete heart block requiring the implantation of a pacemaker has been reported in
10% of the cases. Premature ventricular contractions and
non-sustained ventricular tachycardia are commonly noted.
Right bundle branch block (RBBB) is encountered in
50–70% of cases after TASH. Certain rare complications,
like acquired ventricular septal defect, stroke, massive
myocardial infarction due to alcohol leakage into the LAD
and left main coronary artery dissection related to the
guiding catheter, have also been reported.11,15–18
AFTER PROCEDURE
Figure 4. Left coronary angiogram showing multiple thin septal
perforators not found suitable for TASH.
Indian Heart J 2006; 58: 371–374
1. CPK and MBCPK must be assessed at 1 hour,
6 hours, 12 hours and 24 hours after TASH.
2. ECG monitoring and intravenous administration of
heparin or low-molecular-weight heparin must be
continued for seven days after the procedure.
3. An ECG and echocardiogram must be done soon
after the procedure, after 24 hours, at discharge and
6 months’ follow-up. The echocardiogram is done to
assess the LVOT gradient, severity of MR, intraventricular septal thickness and LVOT area.
4. The temporary pacemaker can be removed after
48–72 hours if there is no evidence of any high-grade
atrioventricular block.
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5. If high-grade atrioventricular block persists beyond
72 hours, the patient needs implantation of a permanent pacemaker (preferably, a DDD pacemaker and
VDD if there are economical constraints).
6. Discharge can be planned on the tenth day.
Redo Tash
If there is no reduction in the LVOT gradient after TASH, or
if there is reappearance of more than 50% of the gradient at
six months’ follow-up, the patient needs to undergo TASH
again. In some cases, one may then need to choose septal
branches of the posterior descending artery, or the posterior
lateral branch, or septals not arising from the LAD or D1.
3.
4.
5.
6.
7.
8.
CONCLUSION
The TASH procedure is a promising non-surgical technique
for the reduction of symptoms and the LVOT gradient in
HOCM. Various workers have reported good clinical success
rates with this technique, varying from 90–100%.15–19 The
reduction in the LVOT gradient matched the clinical improvement, as well as the improvement in exercise capacity.20 The
most frequent complication is the occurrence of RBBB in
almost 50% of patients and high-grade atrioventricular block
requiring permanent pacing in 10%. It has been shown that
the use of intraprocedural myocardial contrast echocardiography and limiting the amount of alcohol to 2 mL can reduce
the need for pacing to the minimum.11–14 The most dreaded
complication is sudden in-hospital death, the incidence of
which was about 3–4% in the above series. However, with
advancement and modification of the technique and the experience gained by the operators, it has fallen to 1–2%.
We reported our experience with 31 patients who underwent TASH and were followed up at two years.21 There was
a reduction in the LVOT gradient in all but one patient (4%).
There were two in-hospital deaths (6.4%). Total abolition of
the gradient was noted in 9.7%, and more than 50% reduction in gradient in 71%. The peak systolic LVOT gradient
decreased from a mean of 79 ⫾33 mmHg to 32 ⫾20 mmHg.
The septal thickness decreased from 24 ⫾14 mm pre-procedure to 18 ⫾3 mm at follow-up.
The TASH procedure requires expertise and experience
which has a learning curve. Hypertrophic obstructive
cardiomyopathy is an uncommon disease and a small
number of patients are eligible for TASH. The procedure
should not be regarded as a routine one and should be
restricted to centers, and more particularly, to interventional
cardiologists, with experience in TASH.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
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