Management

Management of Cardiogenic Shock

The first one hour or 'golden hour' is important time for treating heart attack victims

"In recent era, highly educated women belonging to higher economic strata develop cardiogenic shock due to high level of stress producing a disease called Tako Tsubo Syndrome" - Dr M Jawahar Farook Chief Intensivist KG Hospital and Post Graduate Medical Institute Coimbatore

Heart attack is the leading cause of human death. Risk factors leading to heart attack are increasing in epidemic proportion, especially in India due to highly stressful western lifestyle. Early management of heart attack is important to prevent cardiac complications and cardiac death. The first one hour or 'golden hour' is important time for treating heart attack victims because as time advances, severity and extent of cardiac muscle damage increases tremendously. Major complication of heart attack which most often results in death is cardiogenic shock.

Fundamentals

Cardiogenic shock is present on admission in one quarter of patients with complicated heart attack. One quarter develops shock within six hours. One quarter will develop within 24 hours. Subsequently, shock occurs due to recurrent heart attack.

Cardiogenic shock is associated usually with severe cardiac disfunction. When heart chambers fail to pump the adequate volume of blood into the systemic circulation, blood flow to the vital organs reduce and produces a multiple organ failure. So, the cardiogenic shock is often called a state of 'power failure'. Due to unstable conditions of these patients, supportive therapy must be initiated simultaneously with diagnostic evaluation.

Most of the patients have severe continuing chest pain, shortness of breath and they appear pale, sweating, restless and apprehensive. They also have altered sensorium, confusion and agitation. Their pulses are typically weak and rapid. Some of them have heart blocks. Their systolic blood pressure is less than 90 mm hg. They usually have rapid respiratory rate and rhythm due to congestion in the lungs. Their urine output will be reduced. Laboratory evaluation shows elevated blood counts, altered kidney function tests and altered liver function parameters. Blood gas evaluation shows reduced oxygen level in the blood. The cardiac biomarkers used to diagnose the heart attack will be grossly elevated.

Critical Equipment: Echo

Electro cardiogram shows extensive changes suggestive of cardiac ischemia. Some of them have irregular cardiac rhythm. Bed side echocardiogram is extremely useful to assess cardiac function and to rule out mechanical complications like heart wall rupture and blood fluid accumulation around the heart.

Some people have significant valve leak. Echo is also useful to rule out other causes of cardiogenic shock like aortic dissection and pulmonary embolism. When right side of the heart is damaged, echo is useful to detect enlargement of right heart chambers. Coronary angiogram is performed on emergency basis to detect size, type and extent of the pulmonary block. 128 Slice Heart CT Scanner will be useful for triple rule out, ie. to detect coronary block, aortic dissection or pulmonary embolism.

All the patients with cardiogenic shock should be admitted into coronary care unit preferably put on to a resuscitation bed with all the emergency gadgets like ventilator, defibrillator, pacemaker, multi-channel monitor, pressure monitors and emergency cart with all the resuscitation medications available at the bed side. Continuous monitoring with echo will be very useful.

Continuous Monitoring

Initially, these patients are resuscitated with intravenous fluids and medications to improve blood pressure using vasopressors drugs. Continuous monitoring of heart rate, rhythm, pressures, urine output and oxygen saturation should be done meticulously. Intra aortic balloon pump called IABP should be inserted without delay to support the failing ventricle. These devices reduce the load of the failing ventricle and improve the coronary perfusion. IABP insertion should be done at the bed side at the earliest possible.

If there is a mechanical complication like fluid accumulation around the heart, these should be promptly drained to relieve the heart from high pressure compressive effect of blood around the heart.

In a situation where there is no intervention facility is available, these patients should be transferred immediately to a centre where there is angioplasty facility. Angioplasty capable hospitals should be identified, connected and communicated continuously. If there is a possibility of delay in transfer, these patients can be managed with intravenous therapy to lyse the coronary thrombus. Tenecteplase is a very useful lytic agent used to treat heart attack victims. It is given as a single bolus injection. This drug can be delivered at home, road side, offices, ambulances and nursing homes with a minimal bleeding risk. Even after delivering these medications, the patients should be transferred into the Cathlab for possible angioplasty.

Primary Balloon Angioplasty

Cardiogenic shock is best managed with a procedure called primary balloon coronary angioplasty. In this procedure, coronary block site is identified which is responsible for present heart attack. A wire is used to pass the blocked site into the distal part of the coronary artery. Through the wire a balloon is passed into the blocked site and the stenosed segment is dilated; sometimes multiple times until we achieve a good distal blood flow across the blocked segments.

Many a time, these arteries are filled with blood clots which mobilises either distally or proximally during the dilatation. So, these blood clots are removed using a special devise called 'extraction catheters'. Many patients require clot lysing medications delivered directly into the blocked segment to prevent further re-occlusions.

Rescue Angioplasty

If a patient has already received a lytic therapy and has persistent shock, these patients are managed with a procedure called rescue angioplasty. Rescue angioplasty is done after delivering thrombolytic medications when patient has persistent chest pain and shock. If a patient is having unsuitable anatomy for angioplasty, these patients are sent immediately for emergency bypass operation. It is done under considerable high risks. Many of these patients require IABP support for 48 hours. Cardiac rupture and valve leaks also require immediate cardiac surgery. They also may require ventilatory support, renal support, liver support and brain support.

In spite of all these modern gadgets of treatment, death rate due to cardiogenic shock is 80 to 90 per cent. These can be prevented by delivering the lytic therapy or angioplasty within 90 minutes of onset of chest pain. These involve a co-ordinated effort from emergency physician, critical care physician, cardiologist and cardiac surgeon and excellent support from paramedical team.

Other Causes

Apart from heart attack, cardiogenic shock can also occur due to severe valvular heart diseases like severe aortic stenosis and severe sub-aortic obstructions. Sudden severe valve leaks like acute severe mitral valve leak also can lead to cardiogenic shock. Cardiac muscle disease like severe form of a dilated cardo myopathies and myocarditis also leads to cardiogenic shock.

People with severely elevated pulmonary arterial pressure can lead on to cardiogenic shock. The blunt injury of chest producing blood accumulation around the heart can produce cardiogenic shock. In these situations also, patients will be supported with IABP. The underlying cardiac disease should be treated appropriately, like valve replacement for valvular heart diseases and specific drug therapy for myocarditis. Some of them may require assist devices to support heart function and when everything fails, they may require heart transplant. In recent era, highly educated women belonging to higher economic strata develop cardiogenic shock due to high level of stress producing a disease called Tako Tsubo Syndrome, which is common among Japanese and US populations. This form of cardiogenic shock reverses completely and the patients may require IABP support only for 48 to 72 hours.

So, the management of cardiogenic shock is a complex and complicated one, done with a great effort by a multi-speciality approach involving efficient and aggressive professionals with highly sophisticated technology. The prevention of cardiogenic shock is more important than treatment. For that, the general population should have awareness on 'golden hour' concepts.

gb@kggroup.com