Dilated cardiomyopathy and myocarditis in Kenya: an endomyocardial biopsy study

We have studied, by light and electron microscopy, left ventricular endomyocardial biopsy specimens from 18 African patients (14 men) with idiopathic dilated cardiomyopathy in Nairobi. Nine patients (50%) had evidence of healing myocarditis, that is the presence of a mild inflammatory cell infiltration within the myocardium. Interstitial fibrosis was prominent in five patients (28%) and in all 18 specimens there were hypertrophied muscle fibres. Therefore, half of the patients with idiopathic dilated cardiomyopathy had histological signs of a previous myocarditis. There was no serological evidence of a previous or recent coxsackie infection or any other common viral infections. It seems probable that the myocarditis was due to an inappropriate immunological reaction to myocardial muscle.

Epidural spinal electrical stimulation for severe angina: a study of its effects on symptoms, exercise tolerance and degree of ischaemia

The effectiveness of epidural spinal electrical stimulation has been studied in 14 patients with severe intractable angina unresponsive to standard therapies including bypass grafting. After implantation of the neurostimulator units the patients were assessed by a symptom questionnaire, treadmill exercise testing and right atrial pacing. There was a significant improvement of symptoms and GTN consumption fell markedly. With the neurostimulator on, exercise duration increased from a mean (CI) of 414 (153) to 478 (149) s, and total ST segment depression was less both at maximum exercise (7.1 (4.5) vs 5.6 (4.2) mm) and at 90% of the maximum control heart rate (3.5 (3.7) vs 2.6 (4.3) mm), with similar rate-pressure product at maximum exercise. With right atrial pacing the maximum heart rate reached before onset of angina was increased (143 (14) to 150 (7) b.min-1) and total ST segment depression was less at all heart rates. Benefit has persisted in some patients for over 2 years without any apparent adverse sequelae. Epidural spinal electrical stimulation is, therefore, an alternative therapy for some patients with intractable angina which has not responded to standard therapies.

Iontophoretic delivery of nonpeptide drugs: formulation optimization for maximum skin permeability

Although the technique of transdermal iontophoretic drug delivery has been known for many years, its use has been limited clinically to those applications for which a brief drug delivery period is adequate (e.g., delivery of pilocarpine in the diagnosis of cystic fibrosis). For most therapeutic applications, however, it is necessary to have an extended, if not continuous, drug delivery regimen. The use of iontophoresis has been limited in these applications by side effects, primarily skin trauma, associated both with the current density and the total amount of current passed. A mechanism for these side effects will be proposed and techniques to mitigate them will be presented. Many of these techniques involve ways in which the drug formulation can be designed to maximize the fraction of current carried by the drug species. These methods include the following: control of the pH in the bulk solution and in the boundary layer without using conventional buffers; taking advantage of polarization effects; and enhancing the permselectivity of skin. In this way, the therapeutic dose or optimal infusion rate of drug can be achieved with the minimum current and, therefore, the minimum number of side effects.

Respiratory-dependent pacing: a dual response from a single sensor

Five patients with respiratory dependent rate responsive pacemakers (Biorate RDP3, Biotec) were studied using ambulatory telemetry to evaluate the sensitivity of this pacing system to nonrespiratory signals. In each case the pacemaker was implanted in the left infraclavicular position with an impedance sensing electrode inserted into the subcutaneous tissues of the anterior chest wall. The pacing rate was 73 +/- 2 beats per minute at rest and rose by 42 +/- 5 beats per minute when the patients were walking with both arms swinging (mean +/- SEM). Three of the five patients had sensing electrodes that extended across the midline. In this subgroup, pacing rate rose by 26 +/- 4 beats per minute when walking with arms held immobile and by 36 +/- 2 beats per minute during sustained voluntary hyperventilation. These same activities did not elicit any appreciable changes in pacing rate in the remaining two patients whose sensing electrodes were confined to the left hemithorax. Recordings taken from all five patients while they were standing upright and regularly swinging one upper limb showed an increase in pacing rate of 15 + 6 beats per minute with movement of the right arm and 46 + 8 with movement of the left. These observations establish that the Biorate RDP3 pacemaker is capable of responding both to changes in respiratory rate and to movement of the upper limbs. The sensitivity to limb movement is greatest when the chest wall impedance sensor does not extend across the midline and is most evident when the arm ipsilateral to the pacemaker is swung.(ABSTRACT TRUNCATED AT 250 WORDS)

Adverse effect of chronic alcohol ingestion on cardiac performance in spontaneously hypertensive rats

We have compared the cardiac performance of four groups of rats: normotensive control rats (NCR) and spontaneously hypertensive rats (SHR) not drinking alcohol, and NCR and SHR drinking 20% alcohol (NCR-A and SHR-A, respectively), over a period of 6-9 months.

Noninvasive delivery of a novel inotropic catecholamine: iontophoretic versus intravenous infusion in dogs

Using a newly developed iontophoretic delivery device, a novel inotropic catecholamine, pharmacologically similar to dobutamine, has been successfully administered to dogs by noninvasive transdermal infusion for periods of up to 1.5 h. The technique was compared with intravenous infusion and shown to be capable of achieving the same degree of cardiac contractility and steady-state plasma concentrations of the inotrope. There was also a good linear relationship between the applied current and the resulting steady-state plasma concentrations of the inotrope. Approximately 2 mA of applied current during transdermal iontophoresis produced a response equivalent to an intravenous infusion of 1 micrograms/kg/min of the drug.

Peripartum heart disease: an endomyocardial biopsy study

Endomyocardial biopsies were performed in 11 African women in Nairobi who presented with the clinical features of peripartum cardiomyopathy. The samples were studied by light and electron microscopy. In five patients there was evidence of a "healing myocarditis", that is the presence of a mild inflammatory cell infiltration within the myocardium with foci of necrosis and variable amounts of hypertrophy and fibrosis. Of the nine patients who were followed up, three out of four with myocarditis had persistent heart failure and four out of five without myocarditis improved. Peripheral blood T lymphocyte cell subsets were measured in nine patients by means of monoclonal antibodies. A high helper:suppressor T cell ratio was found in three patients. Almost half of this group of patients with peripartum cardiomyopathy had myocarditis in their biopsy specimens. The myocarditis may have been due to an inappropriate immunological reaction in some patients.

T-lymphocyte subsets in idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) is a common clinical problem in Africa. To determine if there is a defect of immune regulation in patients with IDC, the percentage of total T-cells (OKT3 positive), helper/inducer cells (OKT4 positive) and suppressor/cytotoxic cells (OKT8 positive) were measured using monoclonal antibodies in 20 patients with IDC and in 20 age-matched normal control subjects. The percentage of helper/inducer cells was significantly higher in the IDC patients (45 +/- 2% mean +/- standard error) than in the normal subjects (33 +/- 2%) and 8 of the 20 IDC patients had a helper/suppressor cell ratio (OKT4/OKT8) higher than the normal range. Of the 8 patients with this abnormality, 7 were studied within 3 months of the onset of their illness. Results suggest that an excessive immune reaction is part of the pathogenesis of IDC in Africans.

Baroreceptor function in the hypertensive black African

Hypertension in the black African differs in some respects from white Europeans: complications due to accelerated atherosclerosis are rare and treatment with beta-blockers alone is ineffective. It is not known if baroreceptor function is depressed in African hypertensives to the same extent as it is in whites. Therefore, we have assessed baroreceptor reflex sensitivity (BRS) by the phenylephrine method in 19 African hypertensive patients living in the Gambia, West Africa. The results were compared to predicted BRS values for white patients of the same age and blood pressure calculated from a regression equation derived from 61 hypertensive patients studied in Oxford. It was found that baroreceptor reflex sensitivity was reduced in the African hypertensives and the log mean BRS was similar to the predicted value for Europeans of the same age and level of blood pressure (0.473 +/- 0.24 msec/mmHg and 0.489 +/- 0.21 msec/mmHg respectively). The resting mean arterial pressure in the African patients varied from 117 to 194 mmHg. The results indicated that African hypertensives have a depression of baroreflex sensitivity which is similar to European hypertensive patients.

Effect of chronic alcohol ingestion on the heart and blood pressure of spontaneously hypertensive rats

The effect on the heart of a combination of high blood pressure and chronic alcohol ingestion was studied in spontaneously hypertensive rats (SHR) fed ethanol in their drinking water in concentrations of 0%, 5% and 20% for sixteen weeks. Normotensive Wistar rats were used as controls (NCR). In addition some SHR were given alcohol for a shorter period of eight weeks at the end of which time there were no significant differences in mean arterial blood pressure between the groups. After sixteen weeks of ethanol the mean arterial pressure had fallen in those SHR receiving 20% ethanol to 136 +/- 24 mmHg compared to control (180 +/- 27 mmHg; P less than 0.001). This was associated with a lower left ventricular (LV)dp/dt (control 4800 +/- 872 mmHg sec-1; 20% ethanol group = 3450 +/- 1588 mmHg sec-1; P less than 0.025) and a reduced LV weight (corrected for body weight) due to an apparent lack of development of LV hypertrophy between eight and sixteen weeks. Similarly LV volume (corrected for LV weight), did not change from eight weeks to sixteen weeks in those SHR receiving 20% ethanol in contrast to the 0% ethanol SHR group in whom LV volume fell as LV hypertrophy developed. 5% Ethanol had no significant effect on mean arterial pressure, LV peak dp/dt, LV weight or LV volume. In the NCR ethanol had little effect on mean arterial pressure but those receiving 20% ethanol had significantly smaller LV volumes without any increase in LV weight probably reflecting blood volume depletion. Ethanol did not produce any blood pressure elevation in the NCR. No rats (SHR or NCR) developed overt heart failure or a typical cardiomyopathy. However, this study has shown that a high intake of ethanol reduces the blood pressure of a hypertensive rat most likely by its direct toxic action on the myocardium. Thus with chronic alcohol ingestion hypertension can be masked but may still contribute significantly to the development of myocardial disease.

Echocardiographic assessment and systolic time interval measurements in the evaluation of severe hypertension in Nigerian Africans

Echocardiograms, systolic time interval measurements and electrocardiograms were obtained before treatment of 15 Nigerian patients with severe hypertension (WHO stage 2) but without overt heart failure. These were compared with the measurements in 12 normotensive controls. In the hypertensive subjects, left ventricular (LV) posterior wall thickness septal thickness, relative wall thickness and LV wall mass were greater than normal (p less than 0.01 respectively). However, the LV cavity size was within the normal range. The increase in LV wall mass correlated positively with the increase in mean blood pressure (r = 0.96, P less than 0.001). The ejection fraction (EF) and mean velocity of circumferential fibre shortening (mVcF) were decreased (P less than 0.01, P less than 0.05) respectively, while the calculated systemic vascular resistance (SVR) was elevated (p less than 0.01). THe pre-ejection period (PEP) was prolonged, but left ventricular ejective time (LVET) was shortened and therefore PEP/LVET was increased. Electrocardiographic criteria did not detect left ventricular hypertrophy in four out of the 15 hypertensive patients, all of whom had left ventricular hypertrophy by echocardiography. These findings are similar to the abnormalities described for non-African hypertensive patients; and show that hypertension causes LV dysfunction before the onset of overt heart failure.

Echocardiographic features of congestive cardiomyopathy in Nigerians

In this study, we compared the echocardiographic features of thirteen patients with chronic congestive cardiomyopathy (COCM) with those of twelve normal subjects. Characteristically, the patients with COCM had larger than normal left ventricular internal dimensions and estimated volumes in enddiastole and endsystole. Qualitatively the septum had a diminished motion, or was flat, similarly the motion of left ventricular posterior wall was less than normal. The diastolic closure rate of the anterior mitral valve (AMV) was less discriminating between normal and COCM patients. However, the distance between the C - point on the AMV and the left side of the septum was significantly greater than normal in COCM. The excursion of AMV was less than normal. Both leaflets of the mitral valves were recorded easily. Although these features are known, they have not been previously reported for Nigerian patients. Echocardiography is useful in the diagnosis of congestive cardiomyopathy, particularly when there are no facilities for Cardiac catheterization.

Postpartum cardiac failure--heart failure due to volume overload?

Ventricular function has been studied in 43 patients with the peripartum cardiac failure (PPCF) syndrome which occurs around Zaria. All patients had an echocardiogram on admission and 10 patients had right heart catheterization. Despite the gross edema, left ventricular function assessed by echocardiography and systolic time intervals was relatively good and the estimated cardiac output were high. At catheterization, although the pressures were high, the cardiac outputs were greater than normal in four out of six patients. No patient had a low cardiac output. These findings are not compatible with a severe heart muscle disorder, or cardiomyopathy. We suggest that the primary event in PPCF of Zaria is fluid retention which leads to a form of high output cardiac failure. The postpartum practices in this area (taking high sodium diets and lying on heated beds) almost certainly cause the fluid to accumulate initially, but the heart may be unable to meet the demands either because of preexisting heart muscle disease or, more likely, because of a rise of the peripheral resistance due to the volume expansion, overburdens such dilated hearts and leads to myocardial damage. Since there are similarities between this condition and PPCF in temperate climates, it is possible that there is a common mechanism which the traditional practices of this area have unveiled.