UMEM Educational Pearls - By Semhar Tewelde

Pulseless Electrical Activity (PEA)

ACLS algorithm for PEA focuses on memorizing the “ H's & T's" without a systematic approach on how to evaluate & treat the possible etiologies

A modified approach to PEA focuses on “cause-specific” interventions utilizing two simple tools: ECG and Bedside Ultrasound (US)

Simplified PEA Algorithm

♦1st obtain the ECG and assess the QRS-complex length (narrow vs. wide)

♦ A narrow QRS-complex suggests a mechanical problem:  RV inflow or outflow obstruction

Utilize bedside US to assess for RV collapsibility vs. dilation

A collapsed RV suggests tamponade, tension PTX or mechanical hyperinflation

A dilated RV suggests PE

The above listed etiologies all have a preserved/hyperdynamic LV Tx begins w/aggressive IVF’s followed by “cause-specific” therapy: pericardiocentesis, needle decompression, forced expiration/vent management, and thrombolysis respectively

♦ A wide QRS-complex suggests a metabolic (hyperK/acidosis/toxins), ischemic, or LV problem

Utilize bedside US to assess for LV hypokinesis/akinesis

For metabolic/toxic etiologies treat w/calcium chloride and sodium bicarbonate +/- vasopressors

For ischemia and LV failure treat w/cardiac cath. vs. thrombolysis +/- vasopressors/inotropes

♦Trauma and several other etiologies of PEA that are seldom forgotten in any critically ill patient (hypothermia, hypoxia, and hypoglycemia) are not included in this algorithm.

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Early Atherosclerosis Detection

50 middle-aged asymptomatic subjects free of vascular disease underwent carotid ultrasound (CUS) for risk stratification were also invited to undergo coronary computed tomography angiography (CCTA) or coronary artery calcium score (CAC) to identify which of the 3 imaging modalities was best at identification of early atherosclerosis

Atherosclerosis was observed in 28%, 78%, and 90% of subjects using CAC, CCTA, and CUS, respectively

36 patients with a CAC score = 0, 69% and 86% had atherosclerosis on CCTA and CUS, respectively

Concordance between modalities was highly variable

CUS and CCTA detection of plaque were significantly more sensitive than CAC 

Considering the prevalence of subclinical disease on CUS and CCTA, the threshold at which to treat warrants further research

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Myocardial Infarction in Women After Childbirth

World Health Organization reports that obesity is the 5^th leading cause of global death with the highest impact on women <65 years of age

The association of obesity and cardiovascular risk in young women is currently being researched

A recent nationwide cohort looking at obesity and future cardiovascular risk looked at Danish women giving birth (2004-2009) and followed them a median time of 4.5 years

This study grouped women via pre-pregnancy body mass index (BMI)

                                            1. Underweight (BMI <18.5)     

                                            2. Normal weight (BMI <25)

                                3. Overweight (BMI <30)

                                4. Obese (BMI >30)

Data revealed that healthy women of fertile age, pre-pregnancy obesity alone was associated with increased risk of myocardial infarction in the years after childbirth

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Pacing Atrioventricular Block

 - Atrioventricular (AV) block is classically treated with restoration of heart rate via right ventricular pacing, however high rates of right ventricular pacing is associated w/ left  ventricular systolic dysfunction  

- A recent multi-center randomized control trial (RCT) assessed the efficacy of right vs biventricular pacing in heart failure w/ AV block [BLOCK HF Trial]

- Primary outcomes of: morbidity, mortality, and adverse left ventricular remodeling were shown to be significantly lower in biventricular vs right ventricular pacing 

- In patients with a high rate of pacing and/or an  abnormally low left ventricular ejection fraction biventricular pacing may be more advantageous than conventional right ventricular pacing

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Assessment of Intermediate Coronary Lesions

- Coronary angiography alone to assess CAD is fraught with subjectivity

- Fractional flow reserve (FFR) has become the standard to assess/quantify obstructive CAD; it determines the myocardial flow in the presence of stenosis identifying the lesion responsible for ischemia

- FFR assesses focal stenosis, but does not consider diffuse atherosclerotic narrowing or microcirculatory dysfunction as contributors of ischemic heart disease

- An index of microcirculatory resistance (IMR) can be concomitantly measured with FFR during cardiac catheterization to specifically evaluate the microvasculature

- Coronary flow reserve (CFR) was the 1^st proposed method for assessment of intermediate coronary lesion, but proved suboptimal because of its variability especially in patients with microvascular dysfunction (diabetes, prior MI, etc.)

- Utilization of FFR, IMR, and CFR together support the existence of differentiated patterns of ischemic heart disease & may help to determine future ischemic events 

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Metoprolol Usage Cardioprotective

• Intravenous (IV) metoprolol is sparingly used in STEMI given concern about precipitation of cardiogenic shock (COMMIT/CCS-2 Trial)
• A recent study (n=220) looked at usage of IV metoprolol versus controls in patients with STEMI and a killip class II or less prior to primary PCI
• MRI was preformed 5-7 days after STEMI revealing reduced infarct size and increased left ventricular ejection fraction in the IV metoprolol group
• IV beta-blockade appears cardioprotective in those with a low killip score and should be considered prior to primary PCI in certain subgroups  

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ECG Following Cardiac Transplant

• Suturing of donor atria to the corresponding structures of a recipient’s residual atria produces two sets of P-waves:
  • A small native P-wave (often so small it may not been visualized)
  • Followed by a donor P-wave of normal size associated w/ a QRS complex
• A complete or incomplete right bundle branch develops in >80% transplant recipients
• ~7–25% of recipients also demonstrate a left anterior fascicular block (LAFB)
• The transplanted heart contracts faster than the atrial remnant secondary to autonomic denervation frequently resulting in an increased resting heart rate 

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Attachments

• 1312011353_TransplantECG.jpg (160 Kb)

Utility of Intra-Aortic Balloon Pump (IABP)

• IABP therapy has not been proven to reduce mortality in all-comers with cardiogenic shock complicating acute myocardial infarction (IABP-SHOCK II)
• A recent retrospective review of IABP therapy in patients with mechanical complications (ventricular septal rupture [VSR] or mitral regurgitation [MR]) following acute myocardial infarction has proven efficacious in this subset
• • IABP reduced mortality in patient with shock (61% vs 100%, p = 0.04)
  • IABP reduced preoperative mortality (11% vs 88%, p <0.001)
• Post infarction VSR or MR with signs of cardiogenic shock should be considered for an IABP as a bridge to emergent surgical repair
• Patients with mechanical complications without shock were not shown to benefit from an IABP and should undergo cardiac surgery after medical stabilization

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Secondary Prevention in AMI

Just as aspirin is pivotal in the treatment of acute coronary syndrome, medications such as beta-blocker, statins, and angiotensin-converting enzyme inhibitors have been proven to be essential in secondary prevention of AMI.

Patients after AMI are typically discharged on appropriate secondary prevention medications; however the prescribed doses are often far below the proven efficacy based on clinical trials.

A review of 6,748 patients from 31 hospitals enrolled in 2 U.S. registries (2003 to 2008) illustrated that only 1 in 3 patients were prescribed these medications at goal doses.

Of patients not discharged on goal doses, up-titration during follow-up occurred infrequently ~25%.

Optimal medication dosing and appropriate titration is integral to prevention of further morbidity and mortality.

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Ebstein's Anomaly

• Congenital defect of the tricuspid valve (TV) and the right ventricle (RV)
• TV septal and posterior leaflets are apically displaced resulting in "atrialization" of a portion of the right ventricle (ultimately a large right atrium and small right ventricle)
• ~40-50% of individuals with Ebstein anomaly have evidence of Wolf-Parkinson-White, secondary to the atrialized right ventricle
• ECG abnormalities include:
  • Right atrial enlargement or tall and broad P waves (Himalayan P waves) 
  • Prolonged PR interval
  • Right bundle branch block 
  • Low amplitude QRS complexes in the right precordial leads
  • T wave inversions V1-V4 and/or Q waves V1-V4

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Acute Aortic Syndromes

Classically, aortic dissection is considered the primary culprit in patients with chest pain that radiates to the back (aortic pain) or chest pain combined with ischemia (cerebral, cardiac, peripheral), syncope, or cardiac arrest. However, it should not be your only concern: the rate of aortic rupture is much higher in penetrating atheromatous ulcer (42%) and intramural hematoma (35%) than in aortic dissection (types A 7.5% and type B 4.1%).

Chest pain with concomitant ischemic symptoms and acute decompensation should prompt consideration of several etiologies under the umbrella of aortic syndromes and not limited to dissection :

1. Penetrating atheromatous ulcer - rupture of an atheromatous plaque through the internal elastic lamina, with subsequent localized medial disruption and potential dissection, pseudoaneurysm formation, or free rupture
2. Intramural hematoma - rupture of the vasa vasorum or hemorrhage within an atherosclerotic plaque followed by aortic wall infarct
3. Aortic dissection- an intimal tear with resultant propagation within the middle third of the medial layer of the aorta
4. Aneurysm leak or rupture - progressive vessel dilation and increased wall tension
5. Traumatic transection - rapid deceleration forces or direct trauma, commonly shearing distal to left subclavian artery at aortic isthmus where the aorta is fixed by ligamentum arteriosum

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Is RBBB More Indicative of Large Anteroseptal MI?

• Conventionally a new onset left bundle branch (LBBB) with acute myocardial infarction (MI) is associated with a massive MI
• Proximal left anterior descending artery (LAD) septal perforators perfuse the right bundle branch and the anterior fascicle of the left bundle branch ~90% of cases
• The right coronary artery (RCA) perfuses the posterior fascicle of the left bundle branch ~90% of cases
• Given the anatomy, a LAD occlusion should cause RBBB and/or LAFB; both a proximal LAD and RCA occlusion would be required for MI to cause LBBB
• A recent cohort study analyzed 233 patients to evaluate if RBBB or LBBB was associated with a large anteroseptal scar:
  • RBBB was associated with larger scar size (24% vs. 6.5%; p<0.0001)
  • RBBB was more indicative of ischemic heart disease (79% vs. 29%; p<0.0001)
• Based on this preliminary data RBBB may have a stronger association with ischemia and anteroseptal scarring than LBBB (*limitations - small cohort of cardiomyopathy patients with an EF<35%, further study is required)

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• In 1936 early repolarization (ER) was 1st described as ST-segment elevation in the absence of coronary artery disease, typically viewed as a benign ECG finding (BER) not association with increased cardiovascular mortality
• Classically the prevalence of BER tends to be associated with young athletes, male sex, and black race
• Recent data from Haissaguerre et al. and Tikkanen et al. suggest that certain subtypes of ER may be associated with a predisposition for malignant arrhythmias and sudden cardiac death (SCD)
• Although ER has various definitions contingent on the author, it consists of two components:
  • 1.) Prominent J wave
  • 2.) ST-segment elevation
• This article (9/13 JACC) focuses on the analysis and importance of the ST-segment contour and its possible relation to “malignant” repolarization
• Several studies (subgroup analysis) have found that a rapidly ascending ST-segment blending with the T-wave (Figures: A & C) confers BER, whereas a flat, horizontal, or even descending ST-segment (Figures: B & D) prior to the T-wave has potential to be malignant

*Please see the attachment below for Figures A-D

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Attachments

• 1309081121_gr1.jpg (74 Kb)

• 1^st generation drug-eluting stents (DES) have been shown to reduce restenosis and target vessel revascularizations (TVR) compared with bare-metal stents (BMS) in patients with STEMI
• 1^st generation DES have also been associated with increased rates of very late stent thrombosis (ST), raising concerns over the safety of these devices in patients with STEMI, who compared to patients with stable coronary artery disease, have greater rates of ST due to heightened platelet activation and the presence of thrombus
• The most important finding in this study is the significantly reduced risk of 1-year cardiac death, MI, and ST with CoCr-EES (cobalt-chromium everolimus eluting stent) compared to BMS
• The observed reduction in MI, ST, and composite cardiac death rates with CoCr-EES compared to BMS is consistent with experimental data suggesting that stents covered by fluorinated polymers are less thrombogenic than even BMS

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• Classically MVP is considered a benign diagnosis associated w/palpitations, atypical chest pain, dyspnea, and carries a low risk of complications 
• A recent study investigated MVP and its association w/ventricular arrhythmias in a cohort of unexplained out-of-hospital cardiac arrest (OHCA)
• A small subset of patients w/MVP experienced life threatening arrhythmias coined "malignant" MVP
• Malignant MVP was most often associated w/female sex, bileaflet valve, and frequent complex ventricular ectopic activity

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Tight glycemic control (HbA1C<7%) has previously been recommended in CAD based on data from the United Kingdom Prospective Diabetes Study (UKPDS)

A recent study (JACC) evaluated the relationship between glycemic control, cardiovascular disease (CVD) risk, and all-cause mortality 

Patients with a mean HbA1C 7-7.4% were compared to those with mean HbA1C <6%; tight glycemic control had a 68% increased risk of CVD hospitalization

Lenient HbA1C>8.5% also had significantly higher risk

CVD risk and all-cause mortality is greater with both aggressive and lax glycemic control and the optimal reference range may lie between 7-7.4%

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• A recent meta–analysis of 12 studies (6,538 patients with 1,824 ROSC) assessed the quality of cardiopulmonary resuscitation (CPR) using either manual vs. mechanical (load-distributing or piston-driven) compressions in out-of-hospital cardiac arrest
• Compared w/manual CPR, load-distributing band CPR had significantly greater odds of ROSC (odds ratio, 1.62 and p<0.001)
• The treatment effect for piston-driven CPR was similar to manual CPR
• The difference in percentages of ROSC rates from CPR was 8.3% for load-distributing band CPR and 5.2% for piston-driven CPR
• Compared with manual CPR, combining both mechanical CPR devices produced a significant treatment effect in favor of higher odds of ROSC with mechanical CPR devices (odds ratio, 1.53 and p<0.001)

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Radiation therapy is frequently utilized in the management of numerous thoracic malignancies

Cardiovascular disease is now the leading cause of nonmalignancy death in radiation-treated cancer survivors

The spectrum of radiation-induced cardiac disease is broad

The relative risk of CAD, CHF, pericardial/valvular disease, and conduction abnormalities is particularly increased

Early identification of potential cardiac complications w/cardiac MR and echocardiography provides an opportunity for regular assessment and potentially improved long term mortality

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1. Typically the normal ECG shows progression of T-wave size across the precordial leads & the T-wave in V1 is inverted or flat
2. A large upright T-wave in V1 can be considered normal when there is high voltage/LVH or LBBB
3. A new upright T-wave in V1 can be indicative of significant atherosclerotic disease
4. If the T-wave in V1 is larger than the T-wave in V6 have a high suspicion for myocardial disease
5. A new tall upright T-wave in V1 has ~84% specificity for ischemic heart disease (Barthwal)

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• Statin therapy significantly reduces the risk for thrombotic events
• A recent study sought to determine the impact of short-term intensive statin therapy on intracoronary plaque lipid content
• 87 patients with multivessel CAD undergoing percutaneous coronary intervention and at least 1 other severely obstructive were randomized to intensive (rosuvastatin
  40 mg daily) or standard-of-care lipid-lowering therapy
• Upon follow-up, median reduction (95% confidence interval) was significantly greater in the intensive versus standard group ( p=0.01)
• Short-term intensive statin therapy in small trials reduces lipid content in obstructive lesions and further large studies with longer follow-up are warranted

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