What’s wrong with this heart?
Dr Jennifer Hares, Dr Nitin Arora
1. ST5, West Midlands Deanery, 2. Consultant, Heart of England NHS Trust
Cardiomyopathies are defined as diseases of the myocardium associated with cardiac dysfunction.
In 1995 the World Health Organisation and the International Society and Federation of Cardiology classified cardiomyopathies as dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy (1).
DCM is a progressive disease of the heart muscle characterized by dilatation and impaired contraction of the left ventricle or both ventricles. It has many causes including idiopathic, familial/genetic, viral and/or immune, alcoholic/toxic, or associated with recognized cardiovascular disease. (1)
Although peripartum cardiomyopathy (PPCM) closely resembles Dilated Cardiomyopathy, it is now accepted that PPCM is a distinct entity.
The clinical course of PPCM has features that are unusual in other forms of cardiomyopathy. It has a highly variable and, sometimes, rapid progression to end-stage heart failure and, as in this case presentation, can often occur within a few days. The other specific feature to PPCM is the potential for spontaneous and complete recovery of ventricular function (2).
Significance of Case
Peripartum cardiomyopathy is an idiopathic cardiomyopathy presenting with heart failure secondary to left ventricular (LV) systolic dysfunction towards the end of pregnancy or in the months following delivery, where no other cause of HF is found.
It is a diagnosis of exclusion.
The LV may not be dilated but the ejection fraction (EF) is nearly always reduced below 45% (4).
In this case presentation there may be another cause for the development of cardiomyopathy – a profoundly hypothyroid state.
Reduced T3 production is known to have a negative impact on cardiac function, however Tang et al (3) proposed, using an animal model, that a low thyroid state causes cardiac atrophy with chamber dilatation, impaired myocardial blood flow, loss of arterioles, and severe systolic dysfunction. A dramatic reduction in myocardial arterioles results in impaired myocardial blood flow.
34-year-old lady who was 31 weeks pregnant, gravida 8 para 4.
She had a past medical history of;
Her current obstetric history included;
She was seen in antenatal clinic by a consultant obstetrician and booked to attend labour suite the following day for steroids and a variable rate insulin infusion.
Presented the following day with shortness of breath,
On examination, hypoxic, tachypnoeic and tachycardic
CTPA: Consolidation bilaterally; no PE
Accepted for ICU with working diagnosis of Community Acquired Pneumonia
Management on ITU
CPAP with 10cm H2O
Dexamethasone given, with plan for LSCS if deteriorates
Overnight: Patient tiring. NIV started
BP rising so given stat dose of oral Labetolol
NIV iPAP +14 ePAP +10
BP 140/89 mmHg
Lower Segment Caesarean Section performed
Formal ECHO report
Biologically active T3 influences several important genes encoding for structural and functional proteins of the myocardium. These include contractile proteins within the thick filament of the myocyte and effects on the sarcoplasmic reticulum controlling calcium cycling. These effects on the cardiac myocyte result in thyroid function being intimately associated with cardiac function. Thyroid hormone also has extra nuclear nongenomic actions on ion pumps and enzymes with rapid, direct effects on the cardiac myocyte and on the systemic vasculature. Together, the genomic and nongenomic effects of T3 act together to regulate cardiac function.
Not only does hypothyroidism plays an important role in the progression of IDCM but it can also orchestrate cellular changes within the myocardium which resemble the pathological changes in IDCM