*3.6.2 Pathophysiology of CP*

*Inflammatory Heart Diseases*

**Figure 1.**

*3.5.4 Medical management of pericardial effusions and tamponade*

isolated effusions. In these instances, surgical drainage is indicated.

without effusion but effusive-constrictive forms can occur.

ent in the absence of pericardial membrane thickening [4, 48].

biopsy is negative for restrictive cardiomyopathy [4, 48].

**3.6 Constrictive pericarditis (CP)**

*3.6.1 Causes of constrictive pericarditis*

In about 60% of cases of pericardial effusion, an underlying disease process is known, and medical management would therefore be targeted at the aetiology [6]. In the absence of significant associated inflammation, NSAIDs, colchicine and steroids are generally ineffective, leaving no conservative management options for

*CVP tracing in cardiac tamponade reflecting higher baseline pressures and attenuation of the y descent.*

Chronic inflammation of the pericardium causes it to thicken and become non-compliant and rigid [4, 6, 7, 9, 10, 12, 25, 31, 43–49]. This thickening may be concentric or regional depending on the cause. The pericardial space becomes obliterated as the visceral and parietal layers change and stiffen. Restriction of cardiac chamber expansion during diastole causes impedance of cardiac filling and diastolic dysfunction at both the atrial and ventricular levels. The usual form is constriction

Causes are similar to those for acute and chronic pericarditis including infectious disease, radiation to the mediastinum, trauma and autoimmune conditions [4, 13, 14, 48, 49]. In the developing world, tuberculosis remains the most common cause with a prevalence of >90% in places where the HIV infection rates are high [49]. Post-cardiac surgery is the most common cause of CP in the peri-operative period. The usual presentation is constrictive pathophysiology with an increase in pericardial membrane thickness. However, constrictive pathophysiology may pres-

Post surgery, blood in the pericardial space causes a post-pericardiotomy-type picture with inflammation and adhesions [4, 13, 14]. These adhesions diminish the pericardial space and cause a constrictive pathophysiological picture in spite of normal pericardial thickness. This is termed *normal thickness constrictive pericarditis*. In a Mayo Clinic study from 2003, 18% of patients with proven constriction who underwent pericardiectomy had a normal pericardial thickness of <2 mm on pre-operative imaging [48]. Disease of the pericardium in the normal thickness group consisted of mild focal areas of inflammation, calcification and fibrosis. The majority of patients were post-cardiac surgery and post chest irradiation or had suffered previous infective or idiopathic disease. Pericardiectomy was equally effective in relieving the disease symptoms in these patients compared with those who had a pericardial thickness > 2 mm. It would therefore seem reasonable to consider pericardiectomy in patients with a normal pericardial thickness if the endocardial

**78**

Under normal circumstances, the pericardium can accommodate changes in cardiac volume [4, 6, 9, 12, 25, 43, 46, 47, 49]. With ongoing inflammation, the pericardial compliance decreases. The now thickened, calcified and rigid pericardium encases the heart and limits cardiac chamber expansion during diastole. Initially, early diastolic filling is not affected, and the atrial contribution to ventricular filling is mostly impeded during mid- to late diastole.

Over time, diastolic filling becomes severely impaired, and the total blood volume within the heart remains relatively constant during diastole, leading to a *fixed stroke volume state*. Any increases in tissue perfusion demands must therefore be met by an increase in heart rate.

One of the most important features of CP is that changes in intrathoracic pressures during the respiratory cycle are *not transmitted to the heart*. This is because the pericardial space has been destroyed by the inflammatory process and intrapericardial pressure no longer mirrors intrathoracic pressures [25]. This means that the normal augmentation of venous return to the right heart during inspiration does not occur. Lack of inspiratory decline in the jugular venous pressure leads rather to an increase in CVP with inspiration which is known as Kussmaul's sign.

Respiratory variation in systolic blood pressures may still be seen clinically as the pulmonary veins lie outside of the pericardium and the left atrium is only partially within the pericardial sac. Changes in intrathoracic pressures will therefore still cause changes in pulmonary vein flow despite the uncoupling of intra-pericardial and intrathoracic pressures [4]. During negative pressure ventilation, inspiration will cause the pressure gradient between the pulmonary veins and the left ventricle to decrease, resulting in a decrease in LV filling and a small decrease in systolic blood pressure. This effect, however, is not enough to cause pulsus paradoxus.

Another important pathophysiological feature of CP is the dramatic increase in ventricular interdependence [45]. Pressure changes in one ventricle will be transferred to the other which explains the observed equilibration of diastolic ventricular pressures. This increase in ventricular coupling means that there is little, if any, trans-septal pressure gradient during diastole. Abnormal shifting of the intraventricular septum has been observed in some studies but because the ventricles are operating at much higher baseline diastolic pressures, small changes in pressures caused by septal shift have very little effect on overall ventricular filling.

Chronic constriction of the myocardium can lead to damage of the underlying muscle tissue. Constriction causes the ventricles to operate at the lower end of the Frank-Starling curve which causes a kind of disuse atrophy within the myocardium. Myocardial atrophy may present with continued diastolic dysfunction coupled with significant systolic dysfunction even after successful pericardiectomy is performed and the myocardium is released. Often these patients will require ongoing inotropic support in the peri-operative setting.

#### *3.6.2.1 Clinical signs and diagnosis*

Signs and symptoms are usually non-specific and mimic right ventricular failure making diagnosis difficult [4, 6, 12, 25]. Tachycardia is the predominant sign because of the fixed stroke volume state. Arrhythmias, especially atrial fibrillation, are not uncommon. Fluid overload ranging from peripheral oedema to anasarca is a usual finding. This is due to venous hypertension which is often worsened by protein-losing enteropathy in decompensated disease. Patients may have associated pleural effusions and cachexia, indicating a chronic and insidious disease process.

#### *Inflammatory Heart Diseases*

Decreased cardiac output with shortness of breath and fatiguability are almost always elicited on thorough enquiry. Ascites, hepatomegaly, pleural effusion and peripheral oedema can be misdiagnosed as chronic liver disease.

Classical clinical findings in CP include a pericardial knock and Kussmaul's sign. A pericardial knock is a high-pitched sound occurring in early diastole before the third heart sound. It indicates the cessation of ventricular filling at the end of the early diastole due to the pericardial constriction.

Kussmaul's sign is a paradoxical increase in jugular venous pressure on inspiration. It reflects an increase in right atrial preload from an increase in intra-abdominal pressure during inspiration. This increased venous return from the intra-abdominal veins is independent of intrathoracic pressure changes. The increase in preload cannot be accommodated because of the fixed pericardial constriction, and the back pressure is transmitted to the systemic venous system. This is detected clinically as increased pressure in the jugular vein.

The differential diagnosis for constrictive pericarditis is important to consider as clinical signs can be confusing. Restrictive cardiomyopathy, pulmonary embolus, right ventricular infarction, pleural effusion and chronic obstructive pulmonary disease can all have a similar clinical presentation.

#### *3.6.2.2 Special investigations*

The diagnosis of constrictive pericarditis remains challenging, and the clinical picture of unexplained venous congestion should be clarified with multiple imaging modalities to ensure accurate and efficient diagnosis [4, 6, 12, 25, 31].

Chest X-ray may show a ring of calcification around the heart and cardiomegaly if there is an associated effusion.

ECG may show low voltages, non-specific upward sloping ST-T wave changes, atrial fibrillation and P mitrale, indicating chronic atrial hypertension.

CT scan and MRI are both useful to confirm pericardial thickening and calcification [4, 31]. CT scan can delineate and quantify the degree of calcification based on CT scan score, and MRI has a 93% accuracy for differentiating CP from restrictive cardiomyopathy based on a pericardial thickness of >4 mm.

TOE has a high sensitivity for the detection of features consistent with the diagnosis [12]. An increase in pericardial thickness > 2 mm, abrupt inspiratory posterior motion of the intra-ventricular septum in diastole and a non-pulsatile dilated IVC indicating venous hypertension are all expected echocardiographic features.

Pulsed wave Doppler on echocardiography can be used to assess the mitral trans-valvular inflow velocity pattern. Classically, an increase in the E wave velocity represents rapid early diastolic filling. Significant reductions in the A wave velocity represents decreased flow in mid- to late diastole. This indicates rapid early filling with premature equalisation of left atrial and left ventricular pressures from pericardial constriction.

Reverse pulmonary vein flow changes will be detectable as the poor left atrial compliance and raised left atrial pressures redirect flow back into the pulmonary veins. This results in decreased left atrial filling and decreased left ventricular enddiastolic volume.

Cardiac catheterisation may reveal a classical square root sign pattern on the right ventricular trace. This is because right ventricular pressures drop rapidly in early diastole which causes a "dip" in the trace as a small amount of blood enters the right ventricle. The limit of RV distensibility is quickly reached because of constriction by the rigid pericardium. Rapid equalisation of right atrial, right ventricular and pulmonary wedge pressures occurs, and blood flow across the tricuspid valve ceases abruptly causing a "plateau" in the pressure tracing (**Figure 2**).

**81**

**Figure 2.**

*case of CP [46].*

*Anaesthesia for Patients with Pericardial Disease DOI: http://dx.doi.org/10.5772/intechopen.82540*

Kussmaul and Vaitkus were the first to delineate criteria for correctly diagnosing CP in patients on whom cardiac catheterisations were performed. They identified three criteria that could be used in the diagnosis: a left and right ventricular end-diastolic pressure difference of <5 mmHg, a ratio of right ventricular end-diastolic pressures to right ventricular systolic pressures of >1.3 and a right ventricular systolic pressure of <50 mmHg. If all three criteria are present and patients have clinical features in keeping with the condition, CP will be correctly diagnosed in >90% of patients [49].

*Right ventricular pressure tracings: pulmonary capillary wedge pressure, pulmonary artery pressure, right ventricular pressure and right atrial pressure with diastolic equalisation of pressures and sharp "y-dip" in the* 

Medical management is focused on the underlying cause of the pathology and may include diuretics, digoxin and beta-blockers to decrease venous congestion and tachyarrhythmias pre-operatively [9, 12, 46, 47, 49]. In the cases of TB pericarditis, anti-tuberculous chemotherapeutic treatment is required for a minimum of 2 months before surgery but can be continued for up to 12 months pre-operatively.

*3.6.4 Differentiating constrictive pericarditis (CP) from restrictive cardiomyopathy (RC)*

fibroelastosis found in scleroderma, radiotherapy or idiopathic disease.

thickness will be normal. Pericardial calcifications will be absent in RC.

Many of the features of CP can also be found in RC making the diagnosis difficult [4, 6, 9, 12]. Restrictive cardiomyopathy is an intrinsic myocardial disease resulting in impaired relaxation and reduced compliance of cardiac chambers with severe diastolic dysfunction and atrial hypertension. Causes include infiltrative disorders such as amyloidosis, haemosiderosis and sarcoidosis or endomyocardial

The most important differentiating features in CP are the uncoupling of intrathoracic and intracardiac pressures and the increased ventricular interdependence. In RC, normal respiratory variation will be found on the CVP tracing. Conduction

Differentiating features can also be elicited on TTE investigation [12]. E wave velocities reflecting early diastolic filling are reduced in RC because the intrinsic myocardial disease affects ventricular filling throughout the whole of diastole. Transmitral inflow velocity variation and respiratory variation in pulmonary vein flows are rarely found in RC. Atrial enlargement is marked reflecting severe atrial hypertension. Left ventricular hypertrophy is a common finding, and pericardial

*3.6.3 Medical management for constrictive pericarditis*

defects are also more common in patients with RC.

*Anaesthesia for Patients with Pericardial Disease DOI: http://dx.doi.org/10.5772/intechopen.82540*

**Figure 2.**

*Inflammatory Heart Diseases*

Decreased cardiac output with shortness of breath and fatiguability are almost always elicited on thorough enquiry. Ascites, hepatomegaly, pleural effusion and

Classical clinical findings in CP include a pericardial knock and Kussmaul's sign. A pericardial knock is a high-pitched sound occurring in early diastole before the third heart sound. It indicates the cessation of ventricular filling at the end of the

The differential diagnosis for constrictive pericarditis is important to consider as clinical signs can be confusing. Restrictive cardiomyopathy, pulmonary embolus, right ventricular infarction, pleural effusion and chronic obstructive pulmonary

The diagnosis of constrictive pericarditis remains challenging, and the clinical picture of unexplained venous congestion should be clarified with multiple imaging

Chest X-ray may show a ring of calcification around the heart and cardiomegaly

CT scan and MRI are both useful to confirm pericardial thickening and calcification [4, 31]. CT scan can delineate and quantify the degree of calcification based on CT scan score, and MRI has a 93% accuracy for differentiating CP from restrictive

TOE has a high sensitivity for the detection of features consistent with the diagnosis [12]. An increase in pericardial thickness > 2 mm, abrupt inspiratory posterior motion of the intra-ventricular septum in diastole and a non-pulsatile dilated IVC indicating venous hypertension are all expected echocardiographic features. Pulsed wave Doppler on echocardiography can be used to assess the mitral trans-valvular inflow velocity pattern. Classically, an increase in the E wave velocity represents rapid early diastolic filling. Significant reductions in the A wave velocity represents decreased flow in mid- to late diastole. This indicates rapid early filling with premature equalisation of left atrial and left ventricular pressures from

Reverse pulmonary vein flow changes will be detectable as the poor left atrial compliance and raised left atrial pressures redirect flow back into the pulmonary veins. This results in decreased left atrial filling and decreased left ventricular end-

Cardiac catheterisation may reveal a classical square root sign pattern on the right ventricular trace. This is because right ventricular pressures drop rapidly in early diastole which causes a "dip" in the trace as a small amount of blood enters the right ventricle. The limit of RV distensibility is quickly reached because of constriction by the rigid pericardium. Rapid equalisation of right atrial, right ventricular and pulmonary wedge pressures occurs, and blood flow across the tricuspid valve

ceases abruptly causing a "plateau" in the pressure tracing (**Figure 2**).

ECG may show low voltages, non-specific upward sloping ST-T wave changes,

Kussmaul's sign is a paradoxical increase in jugular venous pressure on inspiration. It reflects an increase in right atrial preload from an increase in intra-abdominal pressure during inspiration. This increased venous return from the intra-abdominal veins is independent of intrathoracic pressure changes. The increase in preload cannot be accommodated because of the fixed pericardial constriction, and the back pressure is transmitted to the systemic venous system.

peripheral oedema can be misdiagnosed as chronic liver disease.

This is detected clinically as increased pressure in the jugular vein.

modalities to ensure accurate and efficient diagnosis [4, 6, 12, 25, 31].

atrial fibrillation and P mitrale, indicating chronic atrial hypertension.

cardiomyopathy based on a pericardial thickness of >4 mm.

early diastole due to the pericardial constriction.

disease can all have a similar clinical presentation.

*3.6.2.2 Special investigations*

if there is an associated effusion.

pericardial constriction.

diastolic volume.

**80**

*Right ventricular pressure tracings: pulmonary capillary wedge pressure, pulmonary artery pressure, right ventricular pressure and right atrial pressure with diastolic equalisation of pressures and sharp "y-dip" in the case of CP [46].*

Kussmaul and Vaitkus were the first to delineate criteria for correctly diagnosing CP in patients on whom cardiac catheterisations were performed. They identified three criteria that could be used in the diagnosis: a left and right ventricular end-diastolic pressure difference of <5 mmHg, a ratio of right ventricular end-diastolic pressures to right ventricular systolic pressures of >1.3 and a right ventricular systolic pressure of <50 mmHg. If all three criteria are present and patients have clinical features in keeping with the condition, CP will be correctly diagnosed in >90% of patients [49].

#### *3.6.3 Medical management for constrictive pericarditis*

Medical management is focused on the underlying cause of the pathology and may include diuretics, digoxin and beta-blockers to decrease venous congestion and tachyarrhythmias pre-operatively [9, 12, 46, 47, 49]. In the cases of TB pericarditis, anti-tuberculous chemotherapeutic treatment is required for a minimum of 2 months before surgery but can be continued for up to 12 months pre-operatively.

#### *3.6.4 Differentiating constrictive pericarditis (CP) from restrictive cardiomyopathy (RC)*

Many of the features of CP can also be found in RC making the diagnosis difficult [4, 6, 9, 12]. Restrictive cardiomyopathy is an intrinsic myocardial disease resulting in impaired relaxation and reduced compliance of cardiac chambers with severe diastolic dysfunction and atrial hypertension. Causes include infiltrative disorders such as amyloidosis, haemosiderosis and sarcoidosis or endomyocardial fibroelastosis found in scleroderma, radiotherapy or idiopathic disease.

The most important differentiating features in CP are the uncoupling of intrathoracic and intracardiac pressures and the increased ventricular interdependence. In RC, normal respiratory variation will be found on the CVP tracing. Conduction defects are also more common in patients with RC.

Differentiating features can also be elicited on TTE investigation [12]. E wave velocities reflecting early diastolic filling are reduced in RC because the intrinsic myocardial disease affects ventricular filling throughout the whole of diastole. Transmitral inflow velocity variation and respiratory variation in pulmonary vein flows are rarely found in RC. Atrial enlargement is marked reflecting severe atrial hypertension. Left ventricular hypertrophy is a common finding, and pericardial thickness will be normal. Pericardial calcifications will be absent in RC.
