The 30 day mortality rate in this series of 17.6% is high by western standards but is not dissimilar to that of established OHS programs in West Africa where 30 day mortality from published data ranges from 5-13% [11, 12]. These mortalities need to be viewed in the context of the particular challenges presented by our environment. These challenges will be highlighted as the mortalities are discussed.
Limitations in the diagnostic armamentarium in some cases led to missed diagnosis and in others failure to adequately assess the risk for surgery. Patient 1 had severe pulmonary hypertension as the pulmonary artery was found to be twice the size of the aorta intra operatively (Table 3). Cardiac catheterization was not available at this stage and the echocardiography machine was of limited functionality with poor resolution. This also contributed to the problems in patient 2 who underwent repair of a Ventricular Septal Defect (VSD) but a Patent Ductus Arteriosus (PDA) was missed during preoperative transthoracic echocardiogram (Table 3). Following institution of CPB, aortic cross clamping, cardioplegic arrest of the heart and opening of the right atrium, the Perimembranous VSD could not be visualized due to copious return of aortic blood to the right ventricle. A PDA was suspected but despite reducing CPB flows to reduce aortic return and improve visualization, it could not be located. Following cooling, circulatory arrest was instituted and the PDA was successfully located and ligated. The VSD was then repaired. Though the patient came off CPB he deteriorated postoperatively and died.
Though attempts were made to stick to simple cases in the early years as has been recommended for fledgling programmes [13, 14] this was not always possible as if cases are turned away they often have no other recourse to surgery. This was the case with patients 5 and 9 despite euroscores of 14 and 10 respectively (Table 3). Both patients presented in cardiogenic shock, patient 5 following dissection of the circumflex coronary artery during percutaneous transluminal angioplasty and patient 9 secondary to obstruction of the mitral valve from a giant left Atrial Myxoma.
Inadequate stocks of consumables as well as missed preoperative diagnosis were contributory to the mortality in patient 4 (Table 3). She was scheduled for Mitral Valve replacement but moderate aortic regurgitation which was missed preoperatively meant that antegrade cardioplegia regurgitated into the left ventricle with ensuing distension. Retrograde cardioplegia was also unsuccessful as the retrograde catheter would not stay in the aneurysmal coronary sinus. Cannulae for direct coronary ostial cannulation were not available and the procedure was therefore abandoned. The patient however required progressively increasing inotropic support and eventually died of myocardial failure 24 hours post operatively.
The first Tetralogy of Fallot (TOF) case (patient 7) succumbed to right ventricular failure following placement of a transannular pericardial patch in the right ventricular outflow tract and resection of the pulmonary valve leaflets as the right ventricle appeared to be unable to tolerate the ensuing pulmonary regurgitation. In the second TOF case (patient 8) we were able to spare the valve and avoid pulmonary regurgitation. The patient did very well initially postoperatively, being extubated on minimal inotropic support. At the time the hospital blood bank had limited blood supplies and packed cells required for transfusion was obtained from a private blood bank. This resulted in a severe pyrogenic blood transfusion reaction with severe hypotension which though controlled, resulted in acute renal failure. The patient was subsequently refused renal dialysis as he was hepatitis B positive and the hospital had just two dialysis machines (and there were concerns that Hepatitis B would be spread to other patients). Prior to completing arrangements for alternate dialysis he deteriorated further and died.
Of the 42 OHS cases done by visiting teams, there were 6 mortalities (Table 3). Out of the 9 cases done by the local team there were 3 mortalities (Table 4). Overall mortality was therefore 17.6%. Table 5 summarises the cause of death for each mortality.
A number of lessons have been learnt from the challenges faced that resulted in mortalities. The equipment and consumable base has been strengthened as a cardiac store has been established and links developed with various medical suppliers. All patients are screened preoperatively and without exception are excluded if they are positive for HIV or Hepatitis. More care is being taken to rigidly exclude high risk cases and emergency cases unfortunately can’t be done at this stage of our development. Blood bank facilities have been improved and in addition time is spent recruiting multiple donors to get freshly screened and cross matched blood for surgery. Blood from outside private laboratories is no longer allowed.
The results described above have been achieved against a background of a number of challenges. These challenges are discussed below. Though discussed separately for ease of discussion there is considerable overlap between these challenges.
1. Low volume of cases. Only 51 cases have been performed over the 6 years of active surgery, averaging about 8 cases annually. Most of these cases have been done in batches, so there are periods of activity in between which there is no OHS activity. Apart from the cases in the early years which were funded entirely be LSG for Cardiac Missions, funds now need to be sought for referred patients which is not always successful, and causes long delays. Some cases are assessed as being too challenging to be done locally with the current constraints in the working environment (discussed below) and are referred abroad. Most patients that attend our clinics are self-referred or from our institution. Referrals from Cardiologists outside our institution are almost non-existent. It is unfortunately more profitable for most cardiologists to refer patients to facilities abroad as a stipend is received for such referrals. This medical tourism impacts negatively on local development of OHS programmes and contributes to the low number of cases done. This causes a vicious cycle as with the low volumes it has been difficult to generate the positive results that would build up the confidence of the public and referring cardiologists to encourage more referrals.
2. Unstable working environment. The model for OHS in our institution has involved the surgery being done in CCU. This has raised a number of challenges which are not unusual in a developing country. Funding is irregular which has caused difficulty in maintaining equipment and stock of consumables. Like the rest of the country, electrical power is a major issue as the supply from the national grid is unreliable and the power surges which often occur risk damage to vital equipment. The hospital is powered by 5 generators, 2 of which are connected to the CCU. As these are in constant use they often break down and it is therefore part of the checklist to liaise with the engineering department to be sure power is guaranteed during the period of surgery and immediate recovery. Postoperatively the power issue has been partly addressed by an inverter system which powers two of the beds in the intensive care unit and ensures that critical equipment have backup power for at least 6–8 hrs. In addition, all equipment purchased has the backup of internal batteries.
3. Training and exposure. Some members of the cardiac team have had foreign training and exposure while other members of the team have had more limited exposure to OHS. The low volume of cases as discussed above has severely limited the hands-on exposure available and is also leading to deskilling of the trained staff. As suggested by Ghosh  the minimum number of OHS cases annually to provide training and maintain skills should be 100. Our average of 8 cases annually falls well short of this. Some members of the team have been sent for short periods of exposure in high volume centers in India. Further funding is required to be able to sustain these efforts. In addition regular surgery needs to become the norm otherwise these personnel return but are unable to apply the skills they have acquired and end up losing these skills. Visits by foreign expert teams have been too brief and infrequent to allow for regular skills transfer. Efforts have been made to get foreign teams to visit more frequently but unfortunately financial considerations have so far limited this option.
4. Laboratory support facilities. Successful OHS requires 24 hour laboratory support, an active blood bank and cardiac catheterization support. Access to these various support facilities has been very variable and limited over the years though this is gradually being developed. Support is available during working hours from the hospital laboratories for full blood counts, clotting profiles, electrolytes and liver function tests. Arterial blood gases were initially available in the side laboratory in CCU but as CCU funding dried up the Cardiac Unit had to source for alternatives. Arterial blood gases are now done using a point of care device called the I-stat (Abbott, England) which also covers basic electrolytes. Activated clotting times as well as prothrombin time/International Normalized Ratio are done using a Hemochron Junior.
This has been particularly challenging. In the early cardiac missions transthoracic echocardiography was available using a portable ultrasound machine (sonosite) which lacked adequate resolution and contributed to some cases being wrongly or inadequately diagnosed. This was improved with the purchase of a Vivid I echocardiogram machine (GE Healthcare Systems England) which has enhanced echocardiographic diagnosis as well as made available transoesophageal echocardiography. Chest radiography is available at the hospital radiology department but despite the purchase of a portable X-ray machine great difficulty is experienced in trying to get portable chest radiograms done, largely due to local logistical issues. The majority of OHS cases done therefore do not get portable chest radiograms.
Blood bank facilities
The haematology department has been very supportive but has a number of constraints. Blood products can be obtained (fresh frozen plasma, platelets, cryoprecipitate) but require a lot of advance notice for preparation. Preparation of the products is not always possible onsite (erratic electrical power supply, equipment failure) and is sometimes ordered and prepared at the blood bank of a regional general hospital about 20 kilometers away. Blood donors are not readily available as there are local concerns among the populace about having their blood screened for HIV. Relations and friends of intending patients are therefore encouraged to donate. Routine preparation for each OHS case that will require CPB is 4 units of packed cells, 4 units of Platelets, 4 units of Fresh Frozen Plasma and 1 unit of Cryoprecipitate. A blood fridge is available in CCU for storage of the blood products. As further blood products can rarely be obtained if needed urgently for postoperative bleeding strenuous efforts are made to minimize the risk of bleeding. Antifibrinolytics are used routinely (initially Trasylol now Tranexemic Acid). Case selection is limited to those where relatively short pump runs can be achieved. Care is taken to limit the priming volume and ultrafiltration is used where necessary. The screening of blood in private blood banks can be lax with resultant complications as seen in the patient who underwent successful repair of TOF but died from complications of blood transfusion (patient 8). Blood is therefore no longer obtained from private blood banks.
Cardiac catheterization has only become available since 2009. It is currently provided by a large private hospital in Lagos and costs approximately 2000 US Dollars. This is considerably higher than what obtains in countries like India where it can cost as low as 200 US Dollars. Till more centres open and the cost is lower it will limit the availability of this vital diagnostic tool. The lack of cardiac catheterization also limited patient selection to largely those less than 40 years of age who were unlikely to have ischaemic heart disease. This accounts for the mean age in this series of 29 ± 15.6 years.
5. Financial support. In a separate study we have determined the cost of various OHS procedures in our programme. Surgery for ASD closure costs $6,230, Coronary artery bypass grafting $8,430 and Mitral valve replacement $11,200 (personal data). The per capita income in Nigeria is however only 2 USD daily! This therefore makes it very difficult for patients to afford OHS. This has been the Achilles’ heel of our programme since its inception and has severely limited the number of operations that can be done. Urgent assistance in seeking funding for patients is therefore required and the options available include the government, non-governmental organizations, foundations and establishment of national health insurance schemes [11, 13, 14].
6. Moving away from the “Cardiac Mission” Model. The experience at our Institution highlights the huge difficulty in a developing country of making the transition from the model of intermittent cardiac missions to what obtains in the western world and a few cardiac centres in Africa of regular sustainable surgery. The cardiac mission model is not a sustainable one as a lot of effort and expenditure is allocated towards surgery on a few patients [13–15]. These missions are led by foreign experts who can only afford short periods away from their regular jobs. Incurred expenditure may go towards paying for travel of the foreign team, visas, air freight of needed equipment and consumables, local accommodation and transportation. In some cases these experts request exorbitant professional fees for their services. The visiting team has limited time for the exercise which limits the number of cases that can be done. Efforts are made to avoid high risk cases which would consume scarce resources, operating time and tie down intensive care beds . In addition there is the higher risk of mortality if high risk cases are taken on with attendant negative publicity and loss of morale of the cardiac team. Financial support for cardiac missions is very variable as it depends on both political expediency and the priorities of the Government of the day.
Our institution has had some limited success in moving away from the model of cardiac missions but completing the transition from a model of cardiac missions to one of an indigenous programme with regular funding for OHS activity has been very challenging and has resulted in the OHS program in our institution remaining in its infancy as alluded to by Nwiloh et al. . It has often been easier to get funding for cardiac missions than for surgery by the local team. The added burden of the challenges discussed above has severely limited the number of cases that could be done, especially the challenge of an increasingly unstable working environment. Of the 51 OHS cases only 9 have been performed by the local team. All the challenges earlier mentioned need to be addressed to achieve the goal of an independent indigenous programme.