The heart functions as a muscular pump, circulating blood throughout the body with precise efficiency. Cardiomyopathy is a general term referring to diseases of the heart muscle itself, often resulting in weakened pumping ability. Constrictive Cardiomyopathy (CCM) is a specific type of heart disease where the issue lies not with the muscle but with the sac surrounding the heart, known as the pericardium. This condition involves the pericardium becoming rigid and inelastic, which severely impedes the heart’s natural filling cycle. This restriction prevents the heart from expanding and filling with blood, leading to a backup of fluid in the body’s circulation.
Defining Constrictive Cardiomyopathy
Constrictive Cardiomyopathy is primarily a disorder of the pericardium, the thin, two-layered sac that encases the heart. Chronic inflammation causes the pericardium to undergo fibrosis, thickening, and sometimes calcification, transforming it into a stiff, non-compliant shell. This rigid, scarred tissue traps the heart and prevents the ventricles from expanding fully during diastole, the relaxation phase when the chambers fill with blood.
The constraint limits ventricular filling once the heart reaches the boundary of the inelastic sac. This impaired diastolic filling causes pressure to build up equally in all four heart chambers, preventing the normal return of blood from the body. This high pressure limits the total volume of blood the heart can pump, leading to reduced cardiac output.
Underlying Conditions and Etiology
The constricting process usually follows an initial inflammatory insult to the pericardium, though the cause varies widely. In developed nations, the most common causes are often classified as idiopathic (unknown origin) or follow a viral infection. Up to 60% of cases in these regions may be attributed to these non-specific causes.
Cases are also linked to prior medical interventions or diseases, often developing months or years later. Prior cardiac surgery is a known risk factor, as post-pericardiotomy inflammation can evolve into chronic constriction. Mediastinal radiation therapy, used to treat chest cancers, is another documented cause.
Globally, the leading cause remains tuberculosis (TB), especially in developing nations. Tuberculous pericarditis frequently progresses to constriction, even with appropriate anti-tuberculosis therapy. Less common causes include connective tissue disorders like lupus and rheumatoid arthritis, uremia from kidney failure, and fungal or bacterial infections.
Recognizing the Signs of Heart Restriction
The heart’s inability to properly fill leads directly to a backup of fluid in the systemic circulation, causing symptoms that often mimic heart failure. Common signs include severe peripheral edema, presenting as swelling in the legs and feet. Patients also experience fatigue and dyspnea (shortness of breath) due to low cardiac output resulting from restricted filling.
Fluid accumulation can also lead to ascites and increased abdominal girth. This fluid backup causes pressure in the liver, resulting in tenderness. A specific physical finding is the Kussmaul sign, a paradoxical rise or lack of fall in jugular venous pressure (JVP) during inspiration.
Normally, inhalation lowers JVP by drawing blood into the heart. In CCM, the rigid pericardium prevents this normal filling, causing the neck veins to remain distended or swell further upon inspiration. Another finding is a “pericardial knock,” an extra heart sound occurring early in diastole when rapid ventricular filling abruptly stops against the rigid pericardium.
Diagnostic Procedures and Differentiation
Diagnosing constrictive cardiomyopathy requires high suspicion because its symptoms overlap with conditions like restrictive cardiomyopathy (RCM). Differentiation is important because CCM is potentially curable with surgery, while RCM, a disease of the heart muscle, is not. Physicians use a multi-modality imaging approach to confirm the diagnosis.
Echocardiography (ECHO) is typically the initial diagnostic tool, providing dynamic images of heart function. Findings suggesting CCM include exaggerated respiratory variation in blood flow across the valves (transmitral inflow velocity) and the “septal bounce,” where the interventricular septum shifts abruptly during early diastole.
Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) visualize the pericardium, which often appears thickened or calcified in CCM. However, thickening is not always present, nor does a thickened pericardium always cause constriction. Cardiac catheterization provides definitive hemodynamic confirmation, showing the equalization of diastolic pressures across all four chambers and the characteristic “dip-and-plateau” waveform (square root sign). Respiratory variation in ventricular pressures measured during catheterization helps distinguish CCM from RCM.
Management and Therapeutic Approaches
The definitive treatment for symptomatic constrictive cardiomyopathy is surgical removal of the rigid pericardium, known as pericardiectomy. The goal is to completely free the heart from its constricting shell, allowing the ventricles to expand and fill normally. This is a major cardiac operation, usually performed through a median sternotomy.
The surgeon removes a large portion or the entire parietal pericardium, aiming for complete stripping to prevent the return of constriction. Although the procedure carries risks like bleeding and infection, it offers the best chance for a cure and immediate symptomatic relief. Patients undergoing complete pericardiectomy, especially those with idiopathic or post-infectious causes, generally experience the best long-term outcomes.
Medical management is used only to alleviate symptoms, not as a cure. Diuretics are commonly prescribed to manage systemic fluid overload, reducing edema and ascites. If a specific infectious cause, such as tuberculosis, is identified, anti-infective drug therapy is initiated. However, surgery is often still required to remove the fibrotic pericardial scar tissue, even after successful treatment of the underlying infection.
The prognosis following pericardiectomy depends heavily on the underlying cause and the patient’s health before the operation. Patients with constriction resulting from radiation therapy or those presenting with advanced symptoms tend to have a less favorable long-term outlook. Conversely, those with idiopathic causes often have higher survival rates, with studies indicating a five-year survival rate exceeding 80% following successful surgery.