Comprehensive Cardiovascular Review Notes

Electrocardiography & Arrhythmia Management

Standard ECG calibration: $1\,mV$ and $200\,ms$ ( $1$ big box = $5$ small boxes = $200\,ms$ ).
Wide QRS complex definition: $\ge 3$ small boxes.
QTc reference thresholds: Females = $460\,ms$ ; Males = $450\,ms$ ( $460 - 10\,ms$ ).
A $6$ -second ECG strip contains $150$ small boxes.
ECG Rhythm Identification Rules:
- Absence of P wave + fast HR + narrow QRS + irregular rhythm = Atrial Fibrillation.

Atrial Fibrillation ECG Strip

Absence of P wave + fast HR + wide QRS + regular rhythm = Ventricular Tachycardia.

Ventricular Tachycardia ECG Strip

Narrow QRS + regular rhythm = Supraventricular Tachycardia (Initial treatment: adenosine; Alternative: verapamil).
Multiple discrete P wave morphologies + pulmonary disease context = Multifocal Atrial Tachycardia.
- Atrioventricular (AV) Blocks: Constant or fixed PR interval followed by a dropped QRS complex = $2nd$ -degree AV Block Mobitz Type II.
- Cardiac Resuscitation Management:
Unconsciousness with BP = $0\,mmHg$ and HR = $0\,bpm$ : Immediate CPR before epinephrine administration.
Symptomatic Junctional Bradycardia: Initial drug is Atropine (followed by Transcutaneous Pacing, Dopamine, or Epinephrine).
- Electrophysiology: L-type $Ca^{2+}$ channels open during Phase $0$ ; Funny channels operate during Phase $4$ .
- Reversible causes of cardiac arrest ( $5Ts$ and $5Hs$ ): Thrombosis can be either coronary or pulmonary.

Diseases of the Aorta & Vascular Disorders

Aortic Anatomy & Landmarks:
- Arch of the aorta begins at the right brachiocephalic artery.
- Anatomical levels: T4 (nipple line), T6 (xiphoid process), T8 (IVC aperture), T10 (esophageal hiatus), T12 (aorta hiatus - descending thoracic aorta termination), L4 (aortic bifurcation).
Aortic Aneurysms:
- Saccular aneurysm: Asymmetric outpouching involving all vascular wall layers.
- Abdominal Aortic Aneurysm (AAA): Majority originate from the infrarenal artery.
- AAA rapid growth definition: $1\,cm/year$ .
- $5$ -year rupture risk for AAA $> 7\,cm$ : $> 80\%$ .
- Preferred screening modality: Abdominal ultrasound (UTZ).
Aortic Dissection:
- Condition characterized by an intimal tear.
- Stanford Classification: Type A (originates in ascending aorta), Type B (originates in descending aorta).
- DeBakey Classification: Type 1 (involves whole aorta), Type 2 (involves up to aortic arch), Type 3 (involves up to descending thoracic aorta).
- Type B3 involves up to the descending thoracic aorta.
- Major complication: Pseudoaneurysm.
Blood Pressure Measurement: Target SBP inflation level is increased by $30\,mmHg$ above palpated loss of pulse.

Hypertension Mechanisms & Management

Mechanisms of Hypertension:

Mechanisms of HTN Table

Intravascular volume: Pressure-natriuresis impairment leading to NaCl imbalance and volume expansion.
Autonomic Nervous System (ANS): Increased sympathetic outflow and decreased baroreceptor activity reset to higher pressure.
RAAS: Increased renin and angiotensin II, decreased $AT_1$ activity, increased aldosterone.
Vascular mechanism: Increased NHE activity, impaired endothelium-dependent vasodilation, increased stiffness, decreased lumen, and increased SVR.
- BP Targets & Thresholds: Target BP is generally $< 130/80\,mmHg$ . Ambulatory thresholds follow the CAN mnemonic: Conventional ( $140/90\,mmHg$ ), Average ( $130/80\,mmHg$ ), Nighttime ( $120/70\,mmHg$ ).
- First-Line Anti-hypertensive Therapy: ACE inhibitors (perindopril), ARBs (losartan), Calcium-channel blockers (CCBs), Thiazide diuretics.
Beta-blockers (bisoprolol), loop diuretics (furosemide), and alpha-1 blockers (terazosin) are NOT first-line.
- Beta-Blocker Classification: Drug names starting with letters A through N are $\beta_1$ -selective; O onwards are non-selective. Suffixes -ilol or -alol indicate mixed $\alpha/\beta$ blockers (e.g., carvedilol).

Pulmonary Embolism & Deep Vein Thrombosis

Clinical Symptoms: Lower calf cramp ("Charley horse") is the most common symptom of DVT; unexplained breathlessness is the most common symptom of PE.
Homan Sign: Discomfort behind the knee on forced foot dorsiflexion; lacks sensitivity and specificity for DVT.
PE Pathophysiology: Most common gas exchange abnormalities are arterial hypoxemia and increased alveolar-arterial $O_2$ tension gradient. Also causes increased pulmonary vascular resistance and alveolar hyperventilation.
Diagnostic Findings:
- ECG: $S_1Q_3T_3$ pattern ( $S$ wave in lead I, $Q$ wave in lead III, inverted $T$ wave in lead III) alongside sinus tachycardia.
- Chest X-ray: Hampton sign (triangular wedge-shaped opacity).
- Biomarkers & Imaging: D-dimer upper limit = $500\,ng/mL$ . Venous ultrasonography is the principal imaging modality for DVT.
PE Risk Classification: Low-risk PE presents with normotension without RV dysfunction ( $65\text{--}75\%$ of cases). Submassive PE features normotension with RV dysfunction ( $20\text{--}25\%$ of cases).

Ischemic Heart Disease & Acute Coronary Syndromes

Clinical Examination:
- Levine sign: Patient places a clenched fist over the sternum and leans forward during chest pain.
- Atherosclerosis signs: Xanthelasmas and xanthomas.
- Hypertensive changes: Fundoscopic examination showing increased light reflex and arteriovenous (AV) nicking.
- Palpation/Auscultation: LV dyskinesia on palpation; apical systolic murmur of mitral regurgitation on auscultation.
Myocardial Oxygen Determinants:
- Oxygen Demand: Heart rate, myocardial contractility, myocardial wall tension (preload, afterload, ventricular size).
- Oxygen Supply: Blood oxygen-carrying capacity (inspired $O_2$ , hemoglobin, pulmonary function) and coronary blood flow (vessel diameter, patency, vascular resistance, perfusion pressure, diastolic filling time).
Functional Classification: NYHA Class I represents patients who are asymptomatic during ordinary activity (able to walk $> 4$ blocks or climb $> 3$ flights of stairs).
Acute Management & STEMI Criteria:
- Initial anti-ischemic drugs: Sublingual isosorbide dinitrate and beta-blockers.
- Coronary Anatomy: Inferior wall MI involves the Right Coronary Artery (RCA).
- Revascularization Target Times: Door-to-needle time (thrombolysis) $\le 30\,mins$ ; Door-to-balloon time (PCI) $\le 90\,mins$ . Exact lesion dimensions are required prior to revascularization.

STEMI ECG Criteria

STEMI ECG Criteria: New ST-elevation at J-point in $\ge 2$ contiguous leads: $\ge 0.1\,mV$ ( $1\,mm$ ) in all leads except $V_2\text{--}V_3$ . In leads $V_2\text{--}V_3$ : $\ge 0.2\,mV$ in men $\ge 40$ years, $\ge 0.25\,mV$ in men $< 40$ years, and $\ge 0.15\,mV$ in women.

Heart Failure, Cardiomyopathies & Peripheral Vascular Disease

Heart Failure Pathophysiology & Management:
- High-Output Heart Failure (HOHF): Results from persistent tachycardia or hypermetabolic conditions (e.g., thyrotoxicosis, chronic lung disease, aging); hypertension does not cause HOHF.
- Ventricular Remodeling: Post-injury changes in LV mass, volume, and shape; includes both concentric and eccentric hypertrophy.
- Endogenous Counter-regulatory Hormones: ANP and $PGE_2$ oppose RAAS and SNS activation.
- Electrolyte Abnormalities in MI: Common changes include hypomagnesemia, hyponatremia, hypercalcemia, and hypophosphatemia.
- GDMT Four First-Line Classes: ARNIs/ARBs, MRAs (spironolactone), SGLT2 inhibitors (dapagliflozin), and proven mortality-benefit beta-blockers (bisoprolol, carvedilol, metoprolol succinate). Metoprolol tartrate does NOT carry proven mortality benefit in HF.
Peripheral Vascular Disease & Cardiomyopathies:
- Severe Raynaud Phenomenon: First-line medical therapy is a dihydropyridine CCB (nifedipine). Beta-blockers and non-DHP CCBs (diltiazem) are avoided.
- Peripheral Artery Disease (PAD): Calf claudication indicates femoral-popliteal involvement. Skin moisturization is a key supportive measure.
- Restrictive Cardiomyopathy: Most common cause is infiltrative disease (specifically amyloidosis, which most commonly presents as heart failure).
- Dilated Cardiomyopathy: Characterized by EF $< 50\%$ ; endomyocardial biopsy provides definitive diagnosis.
- Peripartum Cardiomyopathy: Occurs in the $3rd$ trimester up to $2$ weeks post-delivery; diagnosis is invalid if HF presents early in pregnancy.
- Hypertrophic Cardiomyopathy (HOCM): Risk of sudden cardiac death is driven by LV systolic dysfunction; physical examination shows pulsus bisferiens.

Congenital, Valvular & Pericardial Diseases

Physical Examination Findings: Right Ventricular Heave is assessed by placing the heel of the hand on the left parasternal border.
Congenital Heart Disease (CHD) Associations:
- Down Syndrome: Atrioventricular (AV) canal defect / primum ASD.
- DiGeorge Syndrome: Conotruncal anomalies.
- Williams Syndrome: Supravalvular aortic stenosis.
- Noonan Syndrome: Dysplastic pulmonary valve.
Atrial Septal Defects & Shunts:
- Secundum ASD: Associated with Patent Foramen Ovale (PFO) and fixed split S_2$.\n * Primum ASD: Associated with cleft mitral valve and AV abnormalities.\n * Sinus Venosus ASD: Associated with PAPVR and Scimitar sign.\n * Patent Ductus Arteriosus (PDA): Continuous murmur best heard below the left clavicle causing LA and LV enlargement. Most common shunt is VSD.\n* Pericardial Disease:\n * Cardiac Tamponade: Characterized by Pulsus Paradoxus. Hemodynamically compromised patients require urgent pericardiocentesis.\n * Acute Pericarditis: Diagnostic criteria include chest pain, pericardial friction rub, and diffuse concave ST-elevation with PR depression (in contrast to convex ST-elevation in MI). Elevated CRP is supportive but not a primary diagnostic criterion. Colchicine reduces recurrence rates. Viral infection is the most common cause in developed countries.\n* Valvular Heart Disease:\n * Pulmonic Stenosis (PS): Produces right-sided findings exclusively (RVH, RAE, RAD, RBBB). Murmur does not decrease during squatting.\n * Mitral Stenosis (MS): Displays "hockey stick" and "fish mouth" appearance on echocardiogram; antiplatelets (aspirin/clopidogrel) are not part of treatment.\n * Aortic Stenosis (AS): 70 $-year-old with crescendo-decrescendo systolic murmur at right$ 2nd ICS is most commonly due to calcific degenerative etiology, leading to LV and ascending aorta enlargement.\n * Tricuspid Regurgitation (TR): Systolic murmur with Carvallo sign (intensifies on inspiration).\n * Pulmonic Regurgitation (PR): Diastolic Graham-Steell murmur heard at the left lower sternal border (intensifies on inspiration).\n * Tricuspid Stenosis (TS): Defined as severe if valve area is \le 1\,cm^2 $or pressure half-time is$ \ge 190\,ms$$.