The Generation of Ideas as a New Model

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- M-mode and 2D – Echo (Both for assessing systolic function).

(c) Place of Study

The study was done at the University of Nigeria Teaching Hospital (UNTH) Enugu, which is a 700-bed hospital providing tertiary health care. The hospital is designated the Centre of Excellence for cardiovascular diseases in Nigeria, and because of this, it draws its patient population from all over Nigeria. However, a great majority of patients come from Enugu State where the hospital is located; and from the neighbouring Anambra, Ebonyi, Benue, Kogi, Abia, Akwa Ibom Cross-River, Rivers, Delta and Bayelsa States.

(d) Type of Study

It is a case-control hospital-based study.

(e) Subjects

i. Ethical approval: Clearance was obtained from the Ethical Committee of the University of Nigeria Teaching Hospital, Enugu. -

ii. Patients: Consent was obtained from the patients after explaining the purpose of the study, the little inconvenience involved and for the fact that they are not expected to pay for the cost of the

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echocardiography and the absence of any significant side effects.

iii. Control group: Healthy volunteers who were staff of the UNTH, Enugu and patients relations as well as those attending mature programmes in nursing and anaesthesia were selected using the same criteria as for the patients in the study. They were sex and age matched with the study subjects.

METHODS:

This study commenced after due approval was given by the Hospital Ethical Committee. Patients were recruited from the Diabetic Cardiology and Medical out-patient clinics as they presented for the first time in the hospital. They were clerked to ascertain the on-set of symptoms and the type of treatment being given (if any). They were also recruited with either fasting blood glucose or 2 hour postprandial blood glucose.

i. Inclusion Criteria:

Consecutive Type 2 diabetic patients with diagnosis, duration of symptoms and age as defined above were recruited. They were on diabetic diet with or without oral hypoglycaemic agents for control of blood glucose. There was no history of Ketosis and patients were not on

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insulin.

ii. Exclusion Criteria:

1. Hypertension – Using the 1999 WHO – ISH Guidelines for the*

Measurement and Management of Hypertension^317,318 2. Microangiopathy

a. Retinopathy-as evidenced by fundoscopy b. Microalbuminuria-using Micral test Kits³¹⁹

c. Autonomic Neuropathy-using modified autonomic neuropathy disability score³²⁰

3. Hypercholesterolaemia-maximum of 6.2 mmol/L (Defined by the chemical pathology department of the UNTH.)

4. Ischaemic heart disease-assessed by the patients history and resting and exercise electrocardiography.

5. Others: Current or past history of smoking, clinical evidence of valvular heart disease, heart failure, atrial fibrillation and multiple ectopic beats, thyroid diseases and other endocrinopathies.

Diabetic Complication Score Scale ³²¹

TABLE 3.1:CARDIAC AUTONOMIC NEUROPATHY (CAN) SCORE DESCRIPTION

0 Normal

1 Early parasympathetic function abnormality of one 3 tests 2 Definite parasympathetic function abnormality of 2 of 3 – 4

tests

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3 Combined parasympathetic and sympathetic damage where in addition

To abnormal parasympathetic test results findings in one or both of the

Sympathetic tests are abnormal

TABLE 3.2: RETINOPATHY SCORE DESCRIPTION

0 Normal

1 Background or nonproliferative retinopathy 2 Proliferative retinopathy

TABLE 3.3: PROTEINURIA

SCORE DESCRIPTION

0 Normal

1 30mg/24hrs

2 >30mg/24hrs

PARASYMPATHETIC FUNCTION TEST

1. Ewing test (30:15 ratio), normal value >1.04 2. Valsava ratio, normal value >1.21

3. Heart rate variation during deep breathing (beats/min), normal value

>15

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SYMPATHETIC FUNCTION TEST

1. Systolic blood pressure fall on standing at 1-2mins, normal value

<10mmHg

Adopted from Ewing et al, ³²¹

iii. Sample Size:

Sample size was calculated from the World Health Organization formular for sample size determination in an infinite population using the prevalence of DM as roughly 2% in Nigeria.

n = Z² (pq) SE² Where:

n = Sample size

Z = Confidence interval = 1.96

P = Prevalence = 2%

q = 100-p

SE = Standard error in the mean = 5

A minimum number of 82 patients together with 81 volunteers used as control were recruited for this study with a fasting blood sugar. The patients together with the controls (marched for age, sex and BMI) were examined using various echocardiographic modalities:

iv. 2-Dimensional, Motion-mode and Pulsed Doppler Modalities:

Parameters measured included:

Systolic Functions o Ejection fraction

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o Fractional Shortening

o Mean Velocity of circumferential fibre shortening o Stroke index

Diastolic Function

o Left atrial emptying index

o Isovolumic relaxation time (IVRT)

o Slope of anterior mitral valve leaflet in early diastole.

o E:A Ratio o Em : Am Ratio

APPARATUS

I Prestige Smart system Blood Glucose meter

II Standard Sphygmomanometer with appropriate cuff size III Three channel ECG Machine the BTL 08 – ECG series.

IV Micral Test kits from Boehringer V Echocardiographic Equipment:

The machine used for this study was SONOS 2000 Hewlett Packard echocardiograph machine. It has facilities for M-mode, two-dimensional, pulsed wave Doppler, continuous wave Doppler and colour flow Doppler.

It also has facilities for simultaneous electrocardiographic display used in timing cardiac events, a video-recorder which can also play back either at normal speed or in slow motion and a video print-out which produces hard copies of the picture on paper.

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VI Echocardiographic Examination:

The echocardiographic examination was done with the patient lying down on an examination couch, in a left lateral decubitus position, about 60 degrees to the horizontal plane.

M-mode examination was done with the transducer in the usual

echocardiographic ‘window’ – between the second and fifth intercostal spaces, and within 3 to 4 cm to the left of the left sternal border. M-mode cursor was placed under two-dimensional echocardiographic guidance. All M-mode measurements were made according to the recommendations of the American Society of Echocardiography³²².

Two dimensional echocardiographic examinations were done with the transducer in the parasternal echocardiographic window – between the second and fifth intercostal spaces, and within 2-4cm to the left of left of sternal border – for the parasternal long axis and short axis views; the transducer was placed at the apex for the apical four-chamber view.

The pulsed wave Doppler (transmitral) examinations were performed with the transducer at or slightly to the left of the apical impulse. The apical 4 chamber view, optimized to visualize the left ventricular cavity and the maximal excursion of the mitral valve leaflets was used. The cursor was positioned through a plane traversing the left ventricle from apex to the mitral valve annulus, with care taken in obtaining the smallest possible angle between the direction of diastolic blood flow and the orientation of the ultrasonic beam. The sample volume was positioned in the inflow area of the left ventricle between the mitral leaflet tips, and its position along the cursor line adjusted until the

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highest early and late peaks of diastolic flow velocity were recorded.

Each measurement of the indices was obtained for 5 cardiac cycles and averaged.