The numbers of patients with congenital heart disease (CHD) surviving to adulthood are increasing due to advances in both surgical and interventional cardiological techniques. In the USA it is estimated that >10 × 106 adult patients have CHD (grown-up congenital heart disease, GUCH), and in the UK the number of adult patients with moderate-severe lesions is predicted to increase by approximately 1600 per annum. The commonest indication for reintervention in GUCH is for treatment of dysrhythmia; however, this only rarely directly demands intensive care admission.
Most GUCH patients requiring ongoing medical and critical care attention are at the more severe end of the disease spectrum, requiring repeated interventions to replace valves or conduits, and to address persistent/ worsening haemodynamic compromise. Critical care of the adult GUCH patient can be extremely challenging, as the pathophysiology of the patient may be complex, and response to usual intensive care interventions unpredictable or even harmful. In such patients, morbidity and mortality have been shown to increase with increasing complexity of disease; therefore expert advice should be sought, particularly at the complex end of the spectrum. Although recommendations are that critically ill GUCH patients be managed in specialist centres, where they present with medical emergencies, there may be insufficient time to transfer for treatment. Thus all cardiothoracic intensivists should have the knowledge and skills to assess and manage these patients whilst seeking expert advice.
This chapter will outline the general principles involved in the care of the critically ill GUCH patient, particularly where they differ from those of the general population. In addition, some of the commonly occurring medical presentations that any intensivist may face will be addressed, together with management of the postoperative GUCH patient.
Patients are generally classified as having simple, moderately complex and complex congenital heart disease according to the Canadian Consensus definitions, with increasing complexity of disease associated with higher ICU interventions, morbidity and mortality. Approaching such patients when critically ill demands application of a number of basic principles. The first principle of GUCH ICU management is to understand the cardiopulmonary anatomy of the individual patient. This involves knowledge of the primary lesion, the type of any corrective/palliative surgery or intervention performed, and the presence of any residual haemodynamic lesions – either dynamic or fixed. Second, an understanding of the normal physiology of the patient is essential. This includes the normal haemoglobin, oxygen saturations, systemic and pulmonary blood pressure and surface electrocardiogram. Third, the ICU clinician must consider how the effects of any supportive and therapeutic interventions might affect the circulation. This is of particular importance in the univentricular heart, in the presence of systemic-pulmonary shunts and in the Fontan circulation. In GUCH patients (particularly where complex) performance of relatively simple investigations and interventions may differ from those in the non-GUCH population. In addition to the basic anatomy and physiology, there are further aspects relevant to ICU care that must be considered in this patient population (Table 51.1).
|Pulmonary/respiratory||Cardiovascular||Renal, GI, endocrine, fluids|
|Difficult intubation: multiple GUCH lesions associated with difficult intubation||Absent or abnormal connections expected, i.e. Fontan or TCPC, or unexpected, i.e. persistent LSVC||May have associated asplenia, GI or renal malformations|
|Associated congenital pulmonary disease: i.e. hypoplastic lung/lung tissue/severe congenital V/Q mismatch||Multiple previous arterial/venous cannulations, difficult vascular access – ultrasound may be essential||Renal impairment is common, particularly in cyanotic patients, and is associated with increased mortality|
|Lung reperfusion injury: ARDS-like picture (unilateral/bilateral) may occur||Air filters on all lines in patients with potential for right-left shunting||Severe right heart failure may necessitate low rates of enteral feeding where cardiac output is borderline|
|Difficulty weaning: associated congenital musculoskeletal deformities||Abnormal liver function is common, and associated with increased postoperative mortality post cardiac surgery|
|Previous cardiac surgery: possible phrenic nerve palsy||Transvenous pacing, may have no access to the heart from the venous circulation (e.g. Fontan circulation)||High incidence of abnormal thyroid function in GUCH patients – associated with increased ICU mortality|
|Difficult tracheostomy: presence of collaterals, abnormal neck/trachea||ECG, atrial re-entry tachycardia may mimic sinus tachycardia, comparison with previous ECGs essential||Tolerance of fluid loading varies depending on the underlying diagnosis, i.e. TV repair versus Fontan/TCPC|
|Pulmonary hypertension: may need treating, care where possibility to shunt bidirectionally||Differential effects of vasoactive drugs on pulmonary and systemic vasculature may have unpredictable effects on CO and saturations||Patients with preoperative erythrocytosis may require higher haemoglobin levels postoperatively than is generally accepted on the ICU|
Abbrevations: TCPC total cavopulmonary connection; LSVC left superior vena cava; GI gastrointestinal; V/Q ventilation/perfusion; ARDS adult respiratory distress syndrome; PA pulmonary artery; ICU intensive care unit; ECG electrocardiogram; TV tricuspid valve.
In all patients, close liaison between specialists in GUCH, heart failure, congenital cardiac surgery and echocardiography is crucial as the management of such patients demands a multidisciplinary approach.
Cyanotic congenital heart disease is not a contraindication to ICU admission as such patients may have a relatively good prognosis, with mortality generally related to the admission diagnosis. The cyanotic patient has adaptive mechanisms to increase oxygen delivery, including a rightward shift in the oxyhaemoglobin dissociation curve, an increase in cardiac output, and an increased haematocrit. The resultant erythrocytosis may result in the hyperviscosity syndrome; however routine venesection is not recommended, and iron deficiency in these patients is common. Haemostatic changes including abnormalities of prothrombin time, partial thromboplastin time, factors V, VII, VIIII, IX and thrombocytopenia have been documented, but will not usually require treatment. When assessing the cyanotic patient, citrate bottles adjusted for the haematocrit must be used.
Renal dysfunction is common and occurs due to the combination of hyperviscosity with arteriolar vasoconstriction, resulting in renal hypoperfusion and progressive glomerulosclerosis, manifesting as proteinuria, hyperuricaemia or varying degrees of renal failure. Where a cyanotic patient is admitted with abnormal neurology, headache or is postictal, a high index of suspicion should exist for intracerebral thrombosis, haemorrhage or abscess. Where intravenous contrast is used, the patient must be well hydrated, and the minimal amount of contrast used as possible, as there is the potential to develop marked hyperkalaemia following administration.
The morphological right ventricle (RV) may be subpulmonary, subaortic or be the only effective ventricle in the univentricular heart. Causes of right ventricular dysfunction include previous cardiac surgery, pulmonary hypertension, Ebstein’s anomaly, a significant shunt, systemic RV and volume overload. The subpulmonary failing RV may be supported using standard inotropic agents whilst avoiding pulmonary vasoconstrictors. Cardiac output may be maintained or improved by minimising RV afterload: minimising ventilator pressures, drainage of pleural collections, bronchodilation, the use of pulmonary vasodilators and early extubation.
Where the morphological RV is systemic (congenitally corrected transposition of the great arteries (ccTGA) and transposition of the great arteries (TGA) with Mustard/Senning) and failing, treatment is challenging. Reversible causes (including arrhythmia and volume overload) should be aggressively sought and treated. Although systemic RV fibrosis is common, the coronary arteries are usually angiographically unobstructed. Standard management of the failing systemic ventricle should be used, including pharmacological and mechanical support, but these may not be effective. In some centres the use of multisite RV pacing has been used with good effect.
This presents many challenges, from prevention of air embolism, to the unpredictability of the effects of vasoactive agents and the adverse effects of positive pressure ventilation. It is important to know the current and most previously documented function of the single ventricle (morphologically right or left), as recent rapid deterioration is often due to development of an arrhythmia. Expert echocardiography is indicated. When considering the use of inotropic and vasoactive agents, the nature of the pulmonary connections must be considered. Where the pulmonary vasculature is protected by PA banding, the relative effects of pulmonary versus systemic constriction or dilatation may be different when compared with where there is an absent pulmonary connection with systemic-pulmonary collaterals/shunts. In the patient with absent pulmonary connection and systemic-pulmonary collaterals/shunts a small increase in PVR may result in a significant reduction in pulmonary blood flow and desaturation. In contrast, an increase in SVR and/or a fall in PVR may result in an increase in systemic-pulmonary shunting with fall in cardiac output. Attention should also be paid to oxygen administration, as this may also alter the balance between pulmonary and systemic circulation.
Mortality in GUCH patients requiring ICU admission for medical indications (excluding arrhythmia) is high (36%) and accurately predicted by the APACHE II score. Where the indication for admission is non-cardiological, the principles of management of the admission diagnosis are the same as for the non-GUCH population.
The commonest indication for hospital admission in the GUCH population is arrhythmia, and on occasion this will require ICU admission, or input from the critical care team. The management of arrhythmia in the ACHD ICU population is complex; however some general principles should be considered. First, the diagnosis of an arrhythmia may be challenging; atrial tachycardia may mimic sinus tachycardia to the non-expert. Here, comparison with previous 12-lead ECGs is useful, and where a pacemaker is implanted, interrogation may be critical in making the diagnosis. Second, as there is a high incidence of thyroid dysfunction and amiodarone prescription in the GUCH population, thyroid function tests should be performed upon diagnosis of a tachycardia or bradycardia. Third, although patients with a univentricular circulation in atrial tachycardia may tolerate a tachyarrhythmia well initially, decompensation may be rapid, and cardioversion should be considered at the earliest opportunity. Such patients should be managed by the most senior clinician, as cardioversion to a malignant arrhythmia is not uncommon, and as there may be no venous access to the heart. Transcutaneous pacing must always be available.
The causes of heart failure in the GUCH population include one or more of: impaired ventricular function (left or right), volume overload, arrhythmia, valve lesions or an excessive shunt. Once an arrhythmia has been excluded, echocardiography is required to make or confirm the diagnosis. Where indicated, urgent surgical or catheter intervention may be required. Pre-optimisation of cardiac output prior to surgery has not been shown to improve patient survival, but if possible pulmonary oedema and sepsis should be treated prior to any run on bypass. Once surgically or catheter-directed correctable causes have been excluded, management is directed to treating ventricular dysfunction.
Haemoptysis in this population – particularly those with pulmonary hypertension – should always be considered a serious event, and early transfer to high level care with advanced airway skills immediately available is important. Minor haemoptysis may herald a major bleed, and patients with major haemoptysis usually die due to their unprotected airway rather than blood loss. Haemoptysis in the GUCH population has been attributed to bronchitis, bleeding diathesis, pulmonary arterial rupture, pulmonary embolism, tracheoarterial fistula (in prolonged intubation or tracheostomy) and rupture of aortopulmonary collaterals. In patients with Eisenmenger physiology, haemoptysis accounts for 11–15% of deaths. Investigation will depend upon the skills available locally, but would normally include plain chest radiography, CT angiography and angiography, with a view to embolisation, where it may be life saving.