The difficulty in diagnosing and treating pulmonary hypertension in a resource constrained setting – the Trinidad & Tobago experience

Pulmonary hypertension (PH) is a condition that is being currently diagnosed much more frequently in comparison to the past. This pathophysiological condition is defined as a mean pulmonary arterial pressure (PAP) greater than 20 mmHg measured ideally by right heart catheterization (RHC). In the past, the threshold for PAP used to be 25 mmHg; however, since increased mortality has been found even in patients who have mild PH (PAP >19 mm Hg), the guidelines have been updated internationally. Such patients require detailed workup inclusive of mandatory RHC. Echocardiography, specifically transthoracic echocardiography (TTE), can give a provisional diagnosis. In our experience, there have been challenges in obtaining these procedures in the local pulmonary medicine setting. This has resulted in the diagnosis of PH being performed with a computed tomography pulmonary angiogram (CTPA), a trend which is inappropriate and not in keeping with evidence-based medicine.

echocardiogram. Hence, both referrals were returned to the referring physicians with requests for more clinical information, including RVSP.
In Case 1, a transthoracic echocardiogram was done which revealed normal structure and function of the tricuspid and pulmonary valves, mild tricuspid regurgitation (TR), an RVSP of 15 mmHg (normal) and mild concentric left ventricular hypertrophy (LVH) with a preserved ejection fraction (EF) of 60-65%.
With respect to Case 2, the referring physicians did not follow-up the patient with the pulmonologists. Pulmonary hypertension is most commonly caused by left heart disease and this patient had mitral valve disease. The patient also had a mitral valve replacement and was treated for the underlying condition. It would have been interesting to know both the initial RSVP and that after the mitral valve replacement and whether a right heart catherization RHC had been done prior to surgery.
However, the information on this patient remained inadequate.

Diagnosis of Pulmonary Hypertension
The transthoracic echocardiogram (TTE) is an important non-invasive screening tool to diagnose PH. This modality uses many different parameters derived from well-established data (normal as well as abnormal) to predict the likelihood of Pulmonary hypertension. 1 In the local setting, a provisional diagnosis of PH is made when the right ventricular systolic pressure (RVSP) is more than 40 mmHg on echocardiogram. However, Strange et al. have opined that this threshold underestimates the prognostic impact since an RVSP of 30 mmHg has been associated with an increased risk of mortality. 2 Hence, right heart catheterization (RHC) may be mandatory for establishing the diagnosis of PH, particularly when therapeutic strategies are being considered. 3 In the past, a definitive diagnosis of pulmonary hypertension PH was made when the mean PAP was greater than 25 mmHg at rest on RHC. Later, it was found that the mortality risk increased even with a PAP between 20 mmHg and 25 mmHg. Therefore, the diagnosis of PH is now defined as a PAP of 20 mmHg and more, which is 2 standard deviations above the normal mean value of 14.0 ± 3.3 mmHg. 4 WU, Wood Units.
The algorithm for diagnosing PH is summarized in Figure   1. In terms of specific treatment, monotherapy is not advised, even in mild PH, except for a few well-defined clinical scenarios. In the event that a patient improves clinically, stepping down of therapy is not routine.

Treatment of PH
Combination therapy using drugs with different mechanisms of action has been proven to be more effective than single drugs, at least in the initial stages.
For difficult cases, transition between therapies should only be done with careful monitoring in an expert centre. 6 The treatment algorithm in ideal conditions is summarized in Figure 2.
As more patients use these new treatment combinations, we will be able to gather more data on long-term effects on disease progression, survival and health related quality of life. 6 In our setting, it is easier to obtain a CTPA rather than an echocardiogram or a right heart catheterisation RHC.
Even though an echocardiogram is available in the public

CONCLUSION
There are many issues in diagnosing and managing With respect to management, current guidelines suggest It is vital that the treatment approach to pulmonary hypertension includes a multidisciplinary team targeting both the medical and social aspects of this chronic, debilitating disease.

Ethical Approval:
This was a commentary on the state of the management of pulmonary hypertension in Trinidad and Tobago.
There was no direct patient contact and the information was obtained from the referral letters.

Informed Consent:
Not applicable

Funding statement:
No funding was needed as no research was carried out.
Reference articles for literature review were widely accessible.

Authors' contributions:
Dr Chin Soo wrote the skeleton draft. Both authors did research to elaborate and expand on the original version.
Formatting according to CMJ guidelines was done by both authors.