Cardioplegia Delivery Methods Flashcards

During retrograde cardioplegia delivery, ventricular distension may indicate:

Answer: Thebesian veins shunting cardioplegia directly into the left ventricle

Thebesian veins (anterior cardiac veins) can shunt retrograde cardioplegia directly into the left ventricle, causing distension if not vented properly.

What is the purpose of the 'substrate-enhanced reperfusion' or 'warm induction' phase sometimes given before cold cardioplegia?

Answer: To deliver oxygenated blood and metabolic substrates to normalize ischemic myocardium before cold arrest

Warm induction (or substrate-enhanced induction) uses warm oxygenated blood cardioplegia to repay any oxygen debt and restore metabolic status before imposing cold ischemic arrest.

Cardioplegia delivery flow rates are typically adjusted based on:

Answer: Delivery pressure while targeting adequate flow to achieve and maintain arrest

Flow rates are titrated to maintain appropriate delivery pressures (50–80 mmHg antegrade, <50 mmHg retrograde) ensuring adequate distribution without barotrauma.

Which characteristic of Bretschneider HTK (Custodiol) solution distinguishes it from other cardioplegia types?

Answer: Very low sodium concentration with histidine buffering for intracellular-type protection

HTK solution uses a low-sodium, histidine-buffered intracellular-type formulation with minimal calcium and a unique tryptophan/ketoglutarate composition for membrane stabilization.

When cardioplegia is delivered in a patient with severe left ventricular hypertrophy (LVH), the perfusionist should anticipate:

Answer: Greater difficulty achieving arrest and need for higher volumes or more frequent redosing

LVH myocardium has increased mass, reduced subendocardial perfusion reserve, and higher metabolic demands, requiring more aggressive cardioplegia strategies to ensure adequate protection.

A perfusionist observes that blood cardioplegia temperature leaving the heat exchanger is 4°C but the myocardial temperature probe reads 22°C after delivery. The MOST likely cause is:

Answer: Excessive warming from mediastinal structures, systemic blood, or inadequate delivery volume

Incomplete myocardial cooling despite cold delivery temperature typically reflects rewarming from adjacent warm structures or insufficient volume to cool the myocardial mass.

Which of the following is considered a contraindication to retrograde cardioplegia via the coronary sinus?

Answer: Persistent left superior vena cava draining into the coronary sinus

A persistent left superior vena cava (LSVC) draining into the coronary sinus creates a high-flow venous shunt that dilutes retrograde cardioplegia and makes effective delivery impossible.