Show notes
Cardiogenic shock is a state of cardiac dysfunction leading to hemodynamic instability and end-organ hypoperfusion. At the bedside, clinicians take various data points – from history to physical exam to labs/imaging and invasive hemodynamics – to make an assessment of the etiology, severity and management of cardiogenic shock. Health systems have developed “Shock Teams” to collectively interpret this data to deliver the optimal care for each patient. In this episode, Dr. Mark Dela Cruz (Advanced Heart Failure and Transplant Fellow at University of Chicago), CardioNerds Critical Care Series Co-Chairs Dr. Mark Belkin (Advanced Heart Failure and Transplant Fellow at University of Chicago) and Dr. Karan Desai (General Cardiology Fellow at University of Maryland), and CardioNerds Co-Founder Dr. Daniel Ambinder (Structural Fellow at Johns Hopkins Hospital) join Dr. Anu Lala (Director of the AHFT Fellowship, Associate Professor of Medicine and Cardiology at Mount Sinai Hospital and Deputy Editor of the Journal of Cardiac Failure) on a Shock Team Call! Dr. Lala leads us in a discussion of the systematic bedside evaluation of cardiogenic shock, from understanding a patient’s physiology and their humanity, to manage their illness and make a rapid but thorough evaluation when on the Shock Call. Audio editing and episode introduction by CardioNerds Academy Intern, Hirsh Elhence.
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Pearls and Quotes - Shock Team Call
The classic definition of cardiogenic shock was derived from studies of left ventricular dysfunction in the setting of acute myocardial infarction. With the advent of early primary percutaneous coronary intervention (PCI) and trends in cardiovascular disease risk factors, the prevalence of non-ischemic etiologies of cardiogenic shock (e.g., progression/exacerbation of chronic heart failure) has increased significantly.
The diagnosis of cardiogenic shock should be made by integrating key clinical features such as physical exam findings and objective laboratory and imaging data in an iterative fashion. Focused transthoracic echocardiography and invasive hemodynamics are helpful in further characterizing the type of shock and the etiology of cardiogenic shock.
Early evaluation of right ventricular function is an important aspect of cardiogenic shock evaluation. Significant RV dysfunction portends poor prognosis, can necessitate more aggressive interventions, and defines the types of mechanical circulatory support necessary.
Classification systems for cardiogenic shock help to further characterize a patient’s illness severity. The INTERMACS and SCAI classification systems are particularly designed to allow for early identification of patients who would most benefit from more advanced interventions such as vasoactive medications or mechanical circulatory support.
Shock Team Calls improve mortality for patients in cardiogenic shock. By rapidly bringing together heart failure specialists, interventional cardiologists, cardiothoracic surgeons, and critical care physicians, appropriate interventions and contingencies can be discussed and quickly implemented without adding delays to patient care. Importantly, these calls should attempt to integrate patient goals of care in order to best serve our patients.
Show notes - Shock Team Call
1. What is the classic definition of cardiogenic shock?
The classic definition of cardiogenic shock was initially derived from the Shock Trial published in 1999 (1). In this trial, cardiogenic shock was defined as shock due to left ventricular dysfunction occurring in the setting of acute myocardial infarction in the setting of acute MI as confirmed by specific criteria: Clinical criteria: SBP 90mmHgEnd-organ hypoperfusion as defined by cool extremities, UOP 60bpmHemodynamic criteria: CI ≤ 2.2 L/min/m2 BSAPCWP ≥ 15mmHgWith the advent of primary percutaneous coronary intervention, non-ischemic etiologies have become more prevalent as the etiology of cardiogenic shock such as decompensation of chronic heart failure, valvular heart disease, etc.As discussed on the episode, cardiogenic shock occurs on a spectrum from a “pre-shock” state to “extremis.” To facilitate early recognition of cardiogenic shock, appropriate phenotyping (e.g., LV-predominant, RV-predominant, biventricular, pericardial, valvular, pulmonary vascular, etc), timely interventions, and allocation of advanced therapies (e.g., mechanical circulatory support), a more granular approach to the classification is needed (see below regarding SCAI classification).
2. What are some of the clinical features of cardiogenic shock?
Physical Exam Findings - A careful head-to-toe assessment should be conducted during the initial patient encounter. Important markers include (but are not limited to):Signs of hypervolemiaPatient positioning as a sign of orthopneaElevated JVPTachypneaPresence of pulmonary ralesLower extremity edemaHepatomegalyAscitesSigns of poor organ perfusionCool extremitiesPoor hourly urine output.Confusion or Altered Mental StatusSigns of poor cardiac outputPulse quality – is it fast, slow, thready?Pulsus alternans – alternation between strong and weak beats in sinus rhythm without change in cadence or cycle length (a marker of low output and ejection from the LV) (2).Narrow pulse pressureClues to help determine the etiology of the shockPoint of maximal impulse displacementRight ventricular heaveAuscultation of murmurs may indicate a valvular and/or congenital anomaliesAn accentuated P2 may indicate pulmonary hypertensionGallops may indicate filling pressures and/or underlying cardiomyopathyA pericardial knock may indicate constrictive pericarditisAn irregular pulse may indicate an arrhythmia causing or contributing to shockLaboratory studiesLaboratory markers of end organ hypoperfusion include markers of renal function such as creatinine and of hepatic injury (AST, ALT) and function (INR).Lactate has also been shown to display prognostic significance though clear correlations between objective thresholds to clinical outcomes have yet to be fully established.More important than individual values themselves are their temporal trends and the integration of multiple data points across numerous variables. Early Imaging studies EKG should be obtained and reviewed early after presentation to evaluate for acute coronary syndrome and need for urgent coronary angiography.Chest x-ray findings of pulmonary edema or effusions, assessment of heart size, and presence of cardiovascular hardware (sternal wires, implantable electrical devices, valvular interventions, etc). Focused transthoracic echocardiography, if available in the acute setting, can be helpful.Focused TTE should assess left and right ventricular morphology and function, the presence of a left ventricular thrombus, stenotic or regurgitant valvular lesions, or dynamic outflow tract obstructions.Echo surrogates of filling pressures may be supportive though may be limited by technique and image quality. Evaluation of RV function and illness severitySignificant RV dysfunction is a marker of illness severity and leads to worse clinical outcomes.RV dysfunction limits total cardiac output, worsens systemic venous congestion, and worsens end organ dysfunction.RV assessment is critical when evaluating for the need for mechanical circulatory support, and severe RV dysfunction may increase the likelihood that MCS will be necessary.Severe RV dysfunction may necessitate the use of specific MCS devices (e.g., RV assist devices). It may also impact decision-making regarding what types of temporary or, even more importantly, durable MCS devices the patient may qualify for. Enjoy the upcoming RV-Predominant Shock Episode with Dr. Ryan Tedford for a more in-depth discussion!Invasive hemodynamic assessment Invasive hemodynamic evaluation with a pulmonary arterial catheter (PAC) is particularly useful for confirming and profiling cardiogenic shock as well as tailoring initial and subsequent management.An accurate assessment of filling pressures, cardiac output (by Thermodilution or Indirect Fick), right ventricular function, systemic vascular resistance, and specific calculated indices (e.g., CPO, PAPi, RA/PCWP) provide a more nuanced evaluation of a patient’s shock.Specifically, a PAC can assist in early identification of an under-recognized form of cardiogenic shock, under the classic Stevenson paradigm, a “wet and warm” picture. These patients have a systemic inflammatory response in addition to or as a result of their cardiac pathology, with a reduced cardiac index, low to normal SVR, and elevated pulmonary capillary pressures.Enjoy the upcoming Invasive Hemodynamics episode with Dr. Nosheen Reza and the following infographic from CardioNerds Academy Fellow, Dr. Ahmed Ghoneem, for more details!
3. How is cardiogenic shock classified and how are these classifications useful in the management of cardiogenic shock?
Differentiating cardiogenic shock from other types of shock and the severity of shock can often be challenging. Constructs such as Dr. Lynne Warner Stevenson’s physical exam-based shock classifications are helpful in broadly phenotyping cardiogenic shock at the bedside (3). However, these classification systems may have their limitations. Determining the underlying etiology relies heavily on integrating various pieces of clinical information ranging from the physical exam as well as laboratory and imaging information. In clinical practice,