Cardiovascular Journal of Africa: Vol 26 No 4 (July/August 2015)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 4, July/August 2015

AFRICA

175

Previous studies have been carried out, using both sestamibi

and tetrofosmin MPI, with various agents used to reduce infra-

cardiac activity, including the oral administration of various

fluids or solid meals, and the use of pharmacological agents.

8-16

The proposed mechanism of action is to fill the stomach,

increasing the distance between the left ventricle and interfering

infra-cardiac activity, or to increase liver clearance of radiotracer

via gallbladder contraction.

In our study, the rationale for using lemon juice was that

physiologically, acid-rich food or drink has the potential to

facilitate hepatobiliary clearance of the bile by increasing the

secretion of secretin, as was demonstrated by Peace

et al

Milk

was administered in the other group, as it was demonstrated by

Hofman

et al.

that milk resulted in a significant decrease in the

intensity of infra-cardiac activity.

The mechanism of action is

thought to be that administration of a fatty meal delays gastric

emptying, resulting in increased volume in the stomach, and

also that milk stimulates gallbladder contraction, resulting in

movement of tracer from the liver to the duodenum.

The reason

for using milk and lemon juice in our study was the ease of

availability, as well as the simplicity with regard to performing

the study.

Our study, to our knowledge with the largest number of

patients, compared whether the administration of full-fat milk

or diluted lemon juice would improve the activity in the

infra-cardiac region, and these interventions were compared

to a group with no intervention. Our findings are overall in

accordance with earlier studies in showing a decrease in infra-

cardiac activity.

7,8,11-13,15-17

The administration of milk or lemon

juice showed a decrease in the presence of infra-cardiac activity,

both for studies done at stress and at rest. Also it was noted that

the image quality in the groups that had received an intervention

(milk or lemon juice) was better in a greater percentage of

patients, with images showing absent or infra-cardiac activity

less than bowel activity (50% in G0, 55% in G1 vs 34% in G2).

It is known that infra-cardiac activity is more common

in rest myocardial perfusion images,

as was shown in our

study, therefore our current protocol for rest MPI includes

administration of 250 ml full-fat milk immediately after injection

of the radiotracer. It is noted that when comparing patient

satisfaction with regard to the interventions given, there was a

general preference to the taste of milk compared to lemon juice.

Michael

et al.

compared milk versus water in reducing infra-

cardiac activity in

99m

Tc sestamibi MPI. He randomised 198

patients into two groups. One group had 150 ml chilled water and

the other group had 150 ml milk five minutes after completion

of the stress, and again five minutes before image acquisition.

Patients also received 150 ml chilled water or milk five minutes

after the rest injection, and again five minutes prior to image

acquisition (total 600 ml of fluids for stress and rest images).

There was a significant decrease in the intensity of infra-cardiac

activity with milk compared to water. However the reduction in

the intensity of infra-cardiac activity in the milk or water group

did not translate into a statistically significant benefit in the

image quality (

0.563 at stress and

0.502 at rest).

Study limitations

By excluding almost a third of the recruited patients (274)

from the original number (904), the powers in each group were

not the same. There are numerous studies that have looked at

interventions carried out together with the time of imaging

Table 5. Total counts in the myocardium and infra-cardiac area in the anterior and lateral views

Region [median of total counts of ROI (range)] Lemon juice group (G0) Milk group (G1)

Control group (G2)

Overall

-value

Stress, inferior myocardium anterior

634.5 (185–2648)

733 (160–3260)

553 (144–1566)

0.0001

Stress, infra-cardiac anterior

391 (79–1728)

429 (101–2551)

364 (73–1308)

0.0106

Stress, inferior myocardium lateral

584 (103–2100)

673 (175–3913)

534 (172–1693)

0.019

Stress, infra-cardiac lateral

419 (63–2119)

452 (90–2347)

393 (88–1805)

0.1129

Rest, inferior myocardium anterior

633.5 (186–8181)

694 (36–2308)

586 (159–7171)

0.0089

Rest, infra-cardiac anterior

464 (83–2101)

512 (89–2329)

443 (145–1288)

0.088

Rest, inferior myocardium lateral

617.5 (109–2986)

691 (32–2628)

612 (212–1897)

0.007

Rest, infra-cardiac lateral

488.5 (978–2672)

552 (15–3037)

547 (126–1646)

0.020

0.05 between the lemon juice group (G0) and the milk group (G1).

0.05 between the milk group (G1) and the control group (G2).

100%

50%

Control group

(G2)

Milk group

(G1)

Lemon juice

group (G0)

absent infra-cardiac activity

myocardial > bowel activity

myocardial = bowel activity

myocardial < bowel activity

Fig. 4.

Visual grading of myocardial activity for the three

groups at stress.